HK1094046B - Image forming device and developer cartridge for use therein - Google Patents

Description

Image forming apparatus and developer cartridge used therein

Technical Field

The present invention relates to an image forming apparatus such as a laser printer, and a developer cartridge detachably mountable in the image forming apparatus.

Background

In a conventional laser printer, a developer cartridge containing toner is detachably mounted therein. This type of laser printer is provided with a new product detection device for detecting whether or not a developer cartridge installed in the laser printer is a new product and determining the life of the developer cartridge from the moment the new product is detected.

For example, japanese unexamined patent application publication No. 2000-. When a new developer cartridge is mounted in the housing of the electrophotographic image forming apparatus, the convex portion formed on the sector gear is inserted into the new product side sensor, turning on the new product side sensor. After the developer cartridge has been mounted in the housing of the image forming apparatus, the idler gear is driven to rotate. When the idler gear starts to rotate, the sector gear also rotates, moving the convex portion from the new product side sensor to the old product side sensor. The boss is inserted into the old product side sensor, and the old product side sensor is turned on. At the same time, the idler gear reaches the concave portion of the sector gear, and the sector gear stops rotating.

However, in the new product detecting device described in japanese unexamined patent application publication No. 2000-221781, since the convex portion is inserted into either a new product sensor for detecting a new product or an old product sensor for detecting an old product, both the new product sensor and the old product sensor are necessary. Therefore, this structure increases the cost and complexity of the developing device.

Further, in consideration of price and frequency of use, some users are required to freely select an optimum developer cartridge from a plurality of developer cartridges in different price ranges corresponding to the toner containing amounts.

To meet these demands, it is necessary to provide developer cartridges that accommodate different amounts of toner. However, the toners contained in these developer cartridges have different agitation characteristics and different degradation rates depending on the amount of the toners.

In this case, it is not sufficient to merely detect whether the developer cartridge is a new product, because the life of the developer cartridge from the time of detection may differ depending on the amount of toner contained therein. The life of the developer cartridge cannot be accurately determined. Therefore, a developer cartridge that contains a small amount of toner may actually reach its useful life before such a determination is made, resulting in a reduction in image quality.

Disclosure of Invention

In view of the foregoing, it is an object of the present invention to provide an image forming apparatus that can determine information on a developer cartridge while suppressing an increase in production cost and avoiding an increase in complexity of the structure. It is another object of the present invention to provide a developer cartridge mounted in the image forming apparatus.

In order to attain the above and other objects, the present invention provides an image forming apparatus including a main casing, a developer cartridge, a motor, a driving member, a moving member, an information detecting portion, and a controller. The developer cartridge contains developer and is detachable from the main casing. The motor generates a driving force. The driving member is disposed in the developer cartridge and is capable of being driven by the motor from a start position to an end position by a predetermined amount when the developer cartridge is mounted in the main casing. The moving member is disposed in the developer cartridge and associated with the driving member so as to move together with the driving member. The information detecting member detects the moving member when the moving member moves together with the driving member and outputs a detection result. The controller obtains information on the developer cartridge, which indicates not only whether the developer cartridge is a new product but also a maximum number of recording media on which an image can be formed using the developer accommodated in the developer cartridge when the developer cartridge is a new product, based on a detection result output from the information detecting portion.

Another embodiment of the present invention provides an image forming apparatus including a main casing, a developer cartridge, a motor, a driving member, a moving member, an information detecting portion, and a controller. The developer cartridge contains developer and is detachable from the main casing. The motor generates a driving force. The driving member is disposed in the developer cartridge and is capable of being driven by the motor from a start position to an end position by a predetermined amount when the developer cartridge is mounted to the main casing. The moving member is provided in the developer cartridge and associated with the driving member so as to move together with the driving member, and the information detecting member detects the moving member and outputs a detection result when the moving member moves together with the driving member. The controller obtains information on the developer cartridge based on a detection result output from the information detecting portion. The first number of the moving members is set when the amount of the developer accommodated in the developer cartridge is the first number. When the amount of the developer accommodated in the developer cartridge is a second amount smaller than the first amount, a second amount larger than the first amount of the moving member is provided. The controller determines that the developer is contained in the developer cartridge in a first amount when the detected number of the moving members detected by the information detecting portion corresponds to a first number, and determines that the developer is contained in the developer cartridge in a second amount when the detected number of the moving members corresponds to a second number.

Another embodiment of the present invention provides a developer cartridge detachably mountable to an image forming apparatus including an information detecting portion and a controller and accommodating a developer. The developer cartridge includes a driving member and a plurality of contact protrusions. When the developer cartridge is mounted in the image forming apparatus, the driving member can be driven from the initial position to the end position. A plurality of contact protrusions provided in association with the driving member so as to move together with the driving member, the plurality of contact protrusions passing through positions where the plurality of contact protrusions contact the information detecting portion when the driving member is driven from an initial position to an end position when the developer cartridge is mounted in the image forming apparatus, the plurality of contact protrusions being detected by the information detecting portion and outputting a detection result when the plurality of contact protrusions move together with the driving member; obtaining, by the controller, information about the developer cartridge based on a detection result output from the information detecting portion.

Another embodiment of the present invention provides a developer cartridge detachably mountable to an image forming apparatus including an information detecting portion and a controller. The developer cartridge includes a missing-tooth gear and a moving member. When the developer cartridge is mounted on the image forming apparatus, the toothless gear can be driven from the initial position to the end position. The toothless gear is formed with a toothed portion that receives driving force from the motor, and a toothless portion that does not receive driving force from the motor. The plurality of contact protrusions are movable together with the toothless gear. When the toothless gear is driven by the motor, the plurality of contact projections are disposed at positions detected by the information detecting portion, and information on the developer cartridge is obtained by the controller based on a detection result output from the information detecting portion.

Another embodiment of the present invention provides a developer cartridge including a housing, a developing roller gear, a coupling gear, and a plurality of protrusions. The developing roller has a developing roller shaft rotatably supported in the housing. The developing roller gear is fixed to the developing roller shaft. The developing roller shaft gear rotates together with the developing roller shaft. The coupling gear is rotatably disposed in the housing. The coupling gear rotates around the shaft in accordance with the rotation of the developing roller driving gear. Each of the plurality of projections projects in a direction parallel to the shaft from a portion of the surface of the coupling gear, which is different from the portion where the shaft is located.

Another embodiment of the present invention provides a developer cartridge including a housing, a developing roller gear, a supply roller gear, an agitator gear, a transmission mechanism, and a coupling gear. The housing has opposite side walls, and the housing contains developer. The developing roller has a developing roller shaft rotatably supported between the opposing walls. The developing roller gear is fixed with the developing roller shaft. The developing roller gear rotates together with the developing roller. The supply roller supplies the developer to the developing roller. The feed roller has a feed roller shaft rotatably supported between the opposing walls. The supply roller gear is fixed to the supply roller shaft. The supply roller gear rotates together with the supply roller shaft. The agitator agitates the developer in the housing. The agitator has an agitator shaft rotatably supported between the opposing walls. The agitator gear is fixed to the agitator shaft and rotates with the agitator shaft. The transmission mechanism includes an input gear, and transmits a driving force from the input gear to each of the developing roller gear, the supply roller gear, and the agitator gear. The coupling gear is rotatably disposed on one of the opposite side walls. The coupling gear has a circumferential portion formed with a toothed portion. The projection extends from the coupling gear. The rotation of the agitator gear is transmitted to the coupling gear.

Drawings

The particular features and advantages of the invention, as well as other objects, will become apparent from the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a side sectional view of a laser printer according to a preferred embodiment of the present invention;

fig. 2 is a side view of the developer cartridge in the laser printer of fig. 1 when the gear cover is mounted thereon;

fig. 3 is a side view of the developer cartridge with the gear cover removed;

fig. 4A is an explanatory diagram illustrating a mechanism of detecting a new developer cartridge having two contact projections, in which the developer cartridge is about to be mounted in the main casing;

fig. 4B is an explanatory diagram illustrating a mechanism of detecting a new developer cartridge having two contact projections, in which the developer cartridge is mounted in the main casing such that the front contact projection is in contact with the actuator;

fig. 4C is an explanatory diagram illustrating a mechanism of detecting a new developer cartridge having two contact projections, the front contact projection passing through the actuator;

fig. 4D is an explanatory diagram illustrating a mechanism of detecting a new developer cartridge having two contact projections, in which the rear contact projection is about to come into contact with the actuator;

fig. 4E is an explanatory diagram illustrating a mechanism of detecting a new developer cartridge having two contact projections, in which the rear contact projection is in contact with the actuator;

fig. 4F is an explanatory diagram illustrating a mechanism of detecting a new developer cartridge having two contact projections, the latter contact projection being after passing through the actuator;

fig. 5A is an explanatory diagram illustrating a mechanism of detecting a new developer cartridge having one contact projection (having a narrow width), in which the developer cartridge is about to be mounted in the main casing;

fig. 5B is an explanatory diagram illustrating a mechanism of detecting a new developer cartridge having one contact projection (having a narrow width) mounted in the main casing such that the front contact projection is in contact with the actuator;

fig. 5C is an explanatory diagram illustrating a mechanism for detecting a new developer cartridge having one contact projection (having a narrow width) after passing through the actuator;

fig. 5D is an explanatory diagram illustrating a mechanism of detecting a new developer cartridge having one contact projection (having a narrow width), in which the sensor gear is just about to pause;

fig. 6A is an explanatory diagram illustrating a mechanism of detecting a new developer cartridge having one contact projection (having a wide width) which is in contact with the actuator;

fig. 6B is an explanatory diagram illustrating a mechanism of detecting a new developer cartridge having one contact projection (having a wide width) which passes through the actuator;

fig. 6C is an explanatory diagram illustrating a mechanism for detecting a new developer cartridge having one contact projection (having a wide width) in a state after the contact projection passes through the actuator;

FIG. 7 is a block diagram showing a control system controlling a new product determination process;

FIG. 8 is an explanatory diagram showing a table stored in the ROM in FIG. 7;

FIG. 9 is a timing diagram of a new product determination process;

FIG. 10 is a flowchart showing steps in a new product determination process;

FIG. 11 is a flow chart showing steps in a variation of the new product determination process;

FIG. 12 is a flowchart showing steps in a motor speed determination process;

FIG. 13 is a time chart of the new product determination process when the motor is driven to rotate at half speed; and

fig. 14 is a flowchart of steps in the new product determination process when the motor is driven to rotate at half speed.

Detailed Description

An image forming apparatus according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings, in which like parts and components are identified by like reference numerals in order to avoid repetitive description.

1. Integral structure of laser printer

Fig. 1 is a side sectional view of a laser printer 1 serving as an image forming apparatus of the present invention. As shown in fig. 1, the laser printer 1 includes a main casing 2, and, inside the main casing 2, a feeding unit 4 for feeding a sheet 3, an image forming unit 5 for forming an image on the sheet 3 fed by the feeding unit 4, and the like.

(1) Main shell

An access opening 6 through which a process cartridge 20 described later is inserted and removed and a front cover 7 capable of opening and closing the access opening 6 are formed on one side wall of the main casing 2. The front cover 7 is rotatably supported by a cover shaft (not shown) inserted into a bottom end of the front cover 7. Thus, when the front cover 7 is rotated to close about the cover axis, the front cover 7 covers the access opening 6, as shown in fig. 1. When the cover is rotated open (rotated downward) about the cover axis, the access opening 6 is exposed so that the process cartridge 20 can be mounted in the main casing 2 or removed from the main casing 2 through the access opening 6.

In the following description, the side of the laser printer 1 on which the front cover 7 is mounted and the corresponding side of the process cartridge 20 when the process cartridge 20 is mounted in the main casing 2 will be referred to as "front side", and the other side will be referred to as "rear side".

(2) Feed-in unit

The feeding unit 4 includes a sheet tray 8 that can be inserted into or removed from a lower portion of the main casing 2 in the front-rear direction, a separation roller 9 and a separation pad 10 that are disposed above a front end of the sheet tray 8, and a feeding roller 11 that is disposed on a rear side of the separation roller 9 (an upstream side of the separation pad 10 with respect to the conveying direction of the sheet 3). The feeding unit 4 further includes a paper dust roller 12 disposed above and in front of the separation roller 9 (downstream side of the paper conveying direction separation roller 9), and a pinch roller 13 disposed opposite to the paper dust roller 12.

The sheet conveying path turns to the rear side of the laser printer 1 at the feed end, forming a substantially U shape near the paper dust roller 12. A pair of registration rollers 14 is disposed below the process cartridge 20 located farther downstream of the U-shaped portion of the sheet conveying path with respect to the sheet conveying direction.

A paper pressing plate 15 for supporting the stacked sheets 3 is provided inside the paper tray 8. The paper pressing plate 15 is pivotally supported at its rear end so that the front end can be rotated downward to a resting state where the paper pressing plate 15 rests on the bottom plate 16 of the paper tray 8 and can be rotated upward to a feeding state where the paper pressing plate 15 is tilted upward from the rear end to the front end.

A lever 17 for lifting up the front end of the paper pressing plate 15 is provided at the front of the paper tray 8. The rear end of the lever 17 is pivotally supported on the lever shaft 18 at a position below the front end of the paper pressing plate 15 so that the front end of the lever 17 can be rotated between a horizontal position where the lever 17 lies along the bottom plate 16 of the paper tray 8 and an inclined position where the front end of the lever 17 lifts up the paper pressing plate 15. When the rotational driving force is input to the lever shaft 18, the lever 17 rotates about the lever shaft 18 and the front end of the lever 17 lifts the front end of the platen 15, switching the platen 15 to the feeding position.

When the platen 15 is at the feeding position, the paper 3 stacked on the platen 15 is pressed against the feed roller 11. The rotating feed roller 11 starts feeding the sheet 3 to the separation position between the separation roller 9 and the separation pad 10.

When the paper tray 8 is removed from the main casing 2, the front end of the paper pressing plate 15 falls downward due to its own weight, moving the paper pressing plate 15 to the rest position. When the paper pressing plate 15 is in the resting position, the paper 3 can be stacked onto the paper pressing plate 15.

When the feed roller 11 conveys the sheet 3 toward the separation position and the sheet is sandwiched between the separation roller 9 and the separation pad 10, the rotating separation roller 9 separates and supplies one sheet 3 at a time. Each sheet 3 fed by the separation roller 9 passes between the paper dust roller 12 and the pinch roller 13. After the paper dust on the paper 3 is removed by the paper dust roller 12, the paper is conveyed along a U-shaped paper conveying path at the feed end so that the paper is reversed in the main casing 2 and conveyed toward the registration roller 14.

After the sheet 3 is aligned, the alignment roller 14 conveys the sheet 3 to a transfer position between a photosensitive drum 28 and a transfer roller 31, which will be described later, and an image formed on the photosensitive drum 28 at the transfer position is transferred onto the sheet 3.

(3) Image forming unit

The image forming unit 5 includes a scanner unit 19, a process cartridge 20, and a fixing unit 21

(a) Scanning unit

The scanning unit 19 is disposed on the top of the main casing 2 and includes a laser light source (not shown), a polygon mirror 22 capable of being driven to rotate, an f θ lens 23, a mirror 24, a lens 25, and a mirror 26. The laser light source emits a laser beam based on image data. As shown by the broken line in fig. 1, the laser beam is deflected by the polygon mirror 22, passes through the f θ lens 23, is reflected by the mirror 24, passes through the lens 25, and is reflected downward by the mirror 26 to be irradiated onto the surface of the photosensitive drum 28 in the process cartridge 20.

(b) Processing box

The process cartridge 20 is detachably mounted below the scanner unit 19 in the main casing 2. The process cartridge 20 includes a process frame 27, and a photosensitive drum 28, a scorotron charger 29, a developer cartridge 30, a transfer roller 31, and a cleaning brush 32 in the process frame 27.

The photosensitive drum 28 includes a main roller body 33 which is cylindrical and has a positively charged photosensitive layer whose outer surface is formed of polycarbonate or the like, and a metal roller shaft 34 which extends in the longitudinal direction of the main roller body 33 along the central axis of the main roller body 33. The metal roller shaft 34 is supported by the processing rack 27, and the main roller body 33 is rotatably supported with respect to the metal roller shaft 34. With this structure, the photosensitive drum 28 is placed in the process rack 27 and can rotate around the metal roller shaft 34. Further, the photosensitive drum 28 is driven to rotate by a driving force from a motor 59 (see fig. 2).

The charger 29 is supported on the process frame 27 diagonally above and behind the photosensitive drum 28. The charger 29 is disposed opposite to the photosensitive drum 28 but away from the photosensitive drum 28 by a predetermined distance ia so as not to contact the photosensitive drum 28. The charger 29 includes a discharge line 35 disposed opposite to the photosensitive drum 28 but spaced apart from the photosensitive drum 28 by a predetermined distance, and is provided between the discharge line 35 and the photosensitive drum 28 to control the amount of corona discharged from the discharge line 35 onto the photosensitive drum 28. The charger 29 having such a structure can charge the surface of the photosensitive drum 28 uniformly and positively by applying a bias voltage to the grid 36 while applying a high voltage to the discharge wire 35 for generating corona discharge from the discharge wire 35.

The developer cartridge 30 includes a casing 62, and a supply roller 37, a developing roller 38, and a thickness regulating blade 39 inside the casing 62.

The developer cartridge 30 is detachably mounted on the process frame 27. Therefore, when the process cartridge 20 is mounted in the main casing 2, the developer cartridge 30 can be mounted in the main casing 2 by first opening the front cover 7 and then inserting the developer cartridge 30 through the access opening 6 and mounting the developer cartridge 30 on the process cartridge 20.

The housing 62 is box-shaped with a rear opening. The partition plate 40 is provided in the middle of the housing 62 in the front-rear direction to partition the inside of the housing 62. The front area of the casing 62 partitioned by the partition plate 40 serves as the toner containing chamber 41 that contains toner, while the rear area of the casing 62 partitioned by the partition plate 40 serves as the developing chamber 42 provided with the supply roller 37, the developing roller 38, and the thickness regulating blade 39. An opening 46 is formed below the partition plate 40 to allow toner to pass in the front-rear direction.

The toner containing chamber 41 is filled with a positively charged nonmagnetic single-component toner. The toner used in the present preferred embodiment is a polymerized toner obtained by copolymerizing a monomer using a well-known polymerization method such as suspension polymerization. For example, the polymerized monomer may be a styrene monomer such as styrene or an acrylic monomer such as acrylic acid, alkyl (C1-C4) acrylate or alkyl (C1-C4) methacrylate. In order to have fluidity for obtaining high-quality image formation, the polymerized toner is formed into substantially spherical particles.

This type of toner is compounded with a colorant, such as carbon black, or wax, and an additive, such as silica, to improve flowability, the toner particles having an average diameter of about 6 to 10 μm.

The agitator rotation shaft 43 is disposed at the center of the toner accommodating chamber 41. The agitator rotating shaft 43 is rotatably supported in the side wall 44 of the housing 62. The side walls 44 are laterally (a direction perpendicular to the front-rear direction and the vertical direction) opposed to each other but separated from each other by a predetermined distance. The agitator 45 is disposed on the agitator rotating shaft 43. The motor 59 (see fig. 2) generates a driving force that is input to the agitator rotating shaft 43 to drive the agitator 45 to rotate. When the agitation is driven to rotate, the agitator 45 agitates the toner in the toner containing chamber 41 so that some of the toner is discharged toward the supply roller 37 through the opening 46 formed below the partition plate 40.

Toner detection windows 47 for detecting the amount of toner remaining in the toner accommodating chamber 41 are provided on both side walls 44 of the housing 62 at positions corresponding to the toner accommodating chamber 41. The toner detection windows 47 are opposed to each other laterally through the toner accommodating chamber 41. A toner sensor (not shown) having a light-emitting element and a light-receiving element is disposed in the main casing 2. A light emitting element (not shown) is disposed outside one of the toner detection windows 47 on the main casing 2, and a light receiving element (not shown) is disposed outside the other of the toner detection windows 47 on the main casing 2. Light emitted from the light emitting element enters the toner accommodating chamber 41 through one of the toner detection windows 47. The light receiving element detects light as detection light when the light passes through the toner accommodating chamber 41 and goes out of the other toner detection window 47. The toner sensor determines the amount of remaining toner based on the frequency of detecting the detection light. When the toner sensor determines that the amount of toner remaining in the toner-accommodating chamber 41 has decreased to a low level, the laser printer 1 displays a toner-out alarm on a control panel or the like (not shown).

The supply roller 37 is disposed rearward of the opening 46 and includes a metal supply roller shaft 48 covered by a sponge roller 49 formed of a conductive foam material. The metal supply roller shaft 48 is rotatably supported in both side walls 44 of the housing 62 at respective positions of the developing chamber 42. The feed roller 37 is driven to rotate by a driving force input from a motor 59 to the metal feed roller shaft 48.

The developing roller 38 is disposed behind the supply roller 37 and abuts against the supply roller 37 with pressure so that the two are pressed together. The developing roller 38 includes a metal developing roller shaft 50 and a rubber roller 51 formed of a conductive rubber material covering the metal developing roller shaft 50. The metallic developing roller shaft 50 is rotatably supported by the two side walls of the housing 62 in a position corresponding to the developing chamber 42. More specifically, the rubber roller 51 is formed of conductive urethane rubber or silicone rubber containing fine carbon particles, the surface of which is coated with fluorine-containing urethane rubber or silicone rubber. The developing roller 38 is driven to rotate by a driving force input from a motor 59 to the metal developing roller shaft 50. A developing bias is also applied to the developing roller 38 in the developing operation.

The thickness-adjusting blade 39 includes a main blade member composed of a metal leaf spring and a pressure portion 52 provided at a distal end of the blade member. The pressure part 52 has a semicircular cross section and is formed of an insulating silicon rubber. The thickness regulating blade 39 is supported above the developing roller 38 in the casing 62. With this structure, the elastic force of the main blade member causes the pressing portion 52 to press against the surface of the developing roller 38.

The toner discharged from the opening 46 is supplied onto the developing roller 38 by the rotationally feeding roller 37. At this time, the toner is triboelectrically positively charged between the supply roller 37 and the developing roller 38. When the developing roller 38 rotates, the toner supplied onto the surface of the developing roller 38 passes between the rubber roller 51 of the developing roller 38 and the pressure portion 52 of the thickness-regulating blade 39, thereby keeping the thickness of the toner on the surface of the developing roller 38 uniform.

The transfer roller 31 is rotatably supported on the process frame 27, and is opposed to the photosensitive drum 28 from the bottom of the photosensitive drum 28 in the vertical direction and is in contact with the photosensitive drum 28. The transfer roller 31 is constituted by a metal roller shaft covered with a roller formed of a guide rubber material. In the transfer operation, a transfer bias is applied to the transfer roller 31. The transfer roller 31 is rotated by a driving force input from the motor 59.

The cleaning brush 32 is mounted on the processing rack 27. The cleaning brush 32 is opposed to the photosensitive drum 28 on the rear side of the photosensitive drum 28 and contacts the photosensitive drum 28.

When the photosensitive drum 28 rotates, the charger 29 charges the surface of the photosensitive drum 28 uniformly and positively. Then, the laser beam emitted from the scanner unit 19 scans the surface of the photosensitive drum 28 at high speed, forming an electrostatic latent image corresponding to the image formed on the sheet 3.

Next, the positively charged toner carried on the surface of the developing roller 38 comes into contact with the photosensitive drum 28 as the developing roller 38 rotates and is supplied to the area on the surface of the positively charged photosensitive drum 28 exposed to the laser light, thus having a lower potential. In this way, the latent image on the photosensitive drum 28 is converted into a visible image according to the reversal development process, so that the toner image is carried on the surface of the photosensitive drum 28.

When the resist roller 14 conveys the sheet 3 through the transfer position between the photosensitive drum 28 and the transfer roller 31, the toner image carried on the surface of the photosensitive drum 28 is transferred onto the sheet 3 by the transfer bias applied to the transfer roller 31. After the toner image is transferred, the sheet 3 is conveyed to the fixing unit 21.

The toner remaining on the photosensitive drum 28 after the transfer operation is recovered by the developing roller 38, and paper dust from the paper 3 deposited on the photosensitive drum 28 is recovered by the cleaning brush 32.

(c) Fixing unit

The fixing unit 21 is disposed at the rear side of the process cartridge 20 and includes a fixing frame 53; and a heating roller 54 and a pressure roller 55 provided in the holder 53.

The heating roller 54 includes a metal tube, the surface of which is coated with a fluorine resin, and a halogen lamp that heats it is disposed inside the metal tube. The heat roller 54 is driven to rotate by a driving force input from a motor 59.

The pressure roller 55 is disposed under the heat roller 54 opposite to the heat roller 54 and in contact with the heat roller 54. The pressure roller 55 is constituted by a metal roller covered with a roller formed of a rubber material. The pressure roller 55 is driven by the rotation of the heat roller 54.

In the fixing unit 21, the toner image transferred onto the sheet 3 at the transfer position is thermally fixed to the sheet 3 when the sheet 3 passes between the heating roller 54 and the pressure roller 55. After the toner image is fixed to the sheet 3, the heat roller 54 and the pressure roller 55 continue to convey the sheet 3 along the discharge-end sheet conveying path to the discharge tray 56 formed on the upper surface of the main casing 2.

The discharge end sheet conveyance path from the fixing unit 21 to the discharge tray 56 for reversing the conveyance direction of the sheet 3 to the direction toward the front of the laser printer 1 is substantially U-shaped. The conveying roller 57 is disposed at the midpoint of the discharge end sheet conveying path, and the discharge roller 58 is disposed at the downstream end of this path. Therefore, after the sheet 3 passes through the fixing unit 21, the sheet 3 is conveyed along the discharge-end sheet conveying path, where the conveying roller 57 receives and conveys the sheet 3 to the discharge roller 58, and then the discharge roller 58 receives and discharges the sheet 3 onto the discharge tray 56.

A paper discharge sensor 60 is disposed between the conveying roller 57 and the discharge roller 58 along the discharge-end paper conveying path. The sheet discharge sensor 60 rotates one sheet at a time, and the sheet 3 conveyed through the sheet discharge sensor 60 along the discharge-end sheet conveying path. The CPU90 (see fig. 2) provided in the main casing 2 counts the number of times the paper ejection sensor 60 rotates and stores the number as the number of printed sheets in a storage unit such as the NVRAM106 described later.

In the laser printer 1 having this structure, the CPU90 determines whether the developer cartridge 30 mounted in the main casing 2 is a new product and determines the maximum number of sheets to be printed with this developer cartridge 30 when the developer cartridge 30 is new. The CPU90 compares the actual number of sheets printed with the maximum sheet amount printed with the developer cartridge 30 when the new developer cartridge 30 is installed in the main casing 2, and displays a toner out alarm on a control panel or the like (not shown) when the actual number of sheets printed approaches the maximum sheet amount printed.

2. Structure for detecting new developer box

(a) Structure of developer box

Fig. 2 is a side view of the developer cartridge when the gear cover is mounted on the developer cartridge. Fig. 3 is a side view of the developer cartridge when the gear cover has been removed. Fig. 4A to 4F are explanatory diagrams illustrating a mechanism of detecting a new developer cartridge having two contact projections. Fig. 5A to 5D are explanatory views illustrating a mechanism of detecting a new developer cartridge having one contact projection.

As shown in fig. 3, the developer cartridge 30 includes a gear mechanism 63 for rotating the agitator rotating shaft 43 of the agitator 45, the metal supply roller shaft 48 of the supply roller 37, and the metal developing roller shaft 50 of the developing roller 38; and a gear cover 64 covering the gear mechanism 63, as shown in fig. 2.

As shown in fig. 3, the gear mechanism 63 is provided on one of the side walls 44 of the housing 62 constituting the developer cartridge 30. The gear mechanism 63 includes an input gear 65, a supply roller drive gear 66, a developing roller drive gear 67, an intermediate gear 68, an agitator drive gear 69, and a sensor gear 70.

The input gear 65 is disposed between the developing roller shaft 50 and the agitator rotating shaft 43 and is rotatably supported by an input gear supporting shaft 71 projecting laterally outward from one of the side walls 44. The coupling receiving portion 72 is disposed on the axial center of the input gear 65, and the input gear 65 is used to input the driving force from the motor 59 provided on the main casing 2 when the developer cartridge 30 is mounted in the main casing 2.

The supply roller drive gear 66 is disposed below the input gear 65 at one end of the metal supply roller shaft 48 so as to mesh with the input gear 65. The feed roller drive gear 66 is not rotatable relative to the metal feed roller shaft 48.

The developing roller drive gear 67 is disposed diagonally below the rear of the input gear 65, at one end of the metallic developing roller shaft 50, so as to mesh with the input gear 65. The developing roller drive gear 67 is not rotatable relative to the metallic developing roller shaft 50. That is, the developing roller drive gear 67 is fixed to the metal developing roller shaft 50 so as to rotate therewith.

The intermediate gear 68 is rotatably supported on an intermediate gear support shaft 73 in front of the input gear 65. An intermediate gear support shaft 73 projects laterally outwardly from one of the side walls 44. The intermediate gear 68 is a two-stage gear integrally formed by external teeth 74 meshing with the input gear 65 and internal teeth 75 meshing with the agitator drive gear 69.

The agitator gear 69 is rotatably supported on the agitator rotating shaft 43 at a front lower portion of the intermediate gear 68. The agitator drive gear 69 is not rotatable relative to the agitator rotation shaft 43. The agitator drive gear 69 is a two-stage gear integrally formed of internal teeth 76 that mesh with the internal teeth 75 of the intermediate gear 68 and external teeth 77 that mesh with the sensor gear 70.

The sensor gear 70 is rotatably supported on a sensor gear support shaft 78 forwardly and upwardly of the agitator drive gear 69, the sensor gear support shaft 78 projecting laterally outwardly from one of the side walls 44.

The sensor gear 70 is a tooth-missing gear integrally provided by a main sensor gear portion 79, a toothed portion 80, a tooth-missing portion 81, and a contact projection 82.

The main sensor gear portion 79 has a disk shape. The insertion of the sensor gear support shaft 78 through the center of the main sensor gear portion 79 enables the main sensor gear portion 79 to rotate relative to the sensor gear support shaft 78. A substantially fan-shaped opening portion 83 is formed in a part of the main sensor gear portion 79, expanding radially outward from the vicinity of the center of the sensor gear support shaft 78.

Toothed portion 80 is provided at a part of the circumferential surface of main sensor gear portion 79. Specifically, toothed portion 80 is formed as an arc-shaped portion corresponding to approximately half of the circumferential surface of main sensor gear portion 79 from one circumferential end of main sensor gear portion 79 to the other circumferential end. The external teeth 77 of the agitator drive gear 69 mesh with the toothed portion 80, and the drive force from the motor 59 is transmitted.

The toothless portion 81 occupies the remaining portion of the circumferential surface of the main sensor gear portion 79 which is not occupied by the toothed portion 80. When the toothless portion 81 is opposed to the agitator drive gear 69, the external teeth 77 of the agitator drive gear 69 are not meshed with the toothless portion 81, and therefore, the transmission of the drive force from the motor 59 is interrupted.

The contact protrusion 82 is formed on the outer surface of the main sensor gear portion 79 and extends radially outward from the main sensor gear portion 79 portion toward the circumferential surface of the main sensor gear portion 79, and the sensor gear support shaft 78 is inserted through the main sensor gear 79. Each contact projection 82 has a bottom portion on the sensor gear support shaft 78 side, and a top portion on the circumferential side wider than the bottom portion. A generally L-shaped projection 84 is formed on the top of each contact projection 82 and projects in the rotational direction of the sensor gear 70. The top of the contact protrusion 82 including the protrusion 84 is smoothly curved.

The number of the contact projections 82 corresponds to information on the developer cartridge 30, specifically, information on the maximum number of sheets 3 of which the amount of toner accommodated in the toner accommodating chamber 41 can form an image when the developer cartridge 30 is new (hereinafter referred to as "maximum sheets to be printed").

More specifically, when two contact projections 82 are provided, as shown in fig. 3 and 4, this number corresponds to information representing that the maximum sheet tensor is 6000. When only one contact projection 82 is provided, this number corresponds to information representing that the maximum sheet tensor is 3000 as shown in fig. 5.

Further, the contact projection 82 is positioned with respect to the toothed portion 80 of the sensor gear 70 so as to pass through a detection position of an actuator 91 described later in the rotational range of the sensor gear 70, that is, when the toothed portion 80 meshes with the external teeth 77 of the agitator drive gear 69. More specifically, the contact protrusion 82 positioned ahead of the upstream side of the other contact protrusions 82 in the rotational direction of the sensor gear 70 (which rotates counterclockwise) is positioned such that the top of the contact protrusion 82 is opposed to the midpoint (center) of the toothed portion 80 formed on the circumference of the main sensor gear portion 79. The contact projection 82 provided on the rear side of the downstream side with respect to the rotational direction of the sensor gear 70 is positioned such that the top of the contact projection 82 is opposed to the circumference of the sensor gear 70 just outside the downstream side end of the toothed portion 80 with respect to the rotational direction of the sensor gear 70.

The sensor gear 70 further includes a coil spring 85 for urging the upstream end of the toothed portion 80 in the rotational direction of the sensor gear 70 to mesh with the external teeth 77 on the agitator drive gear 69 when the insertion portion of the main sensor gear portion 79 is rotatably mounted to the sensor gear support shaft 78.

A coil spring 85 surrounds the sensor gear support shaft 78, and has one end fixed to one of the side walls 44 and the other end engaged with the opening 83 of the main sensor gear portion 79. With this structure, the coil spring 85 stably urges the sensor gear 70 to rotate in a direction that causes the upstream end of the toothed portion 80 to move toward and mesh with the external teeth 77 of the agitator drive gear 69. Therefore, from the time when the developer cartridge 30 is new, the upstream end of the toothed portion 80 meshes with the external teeth 77 of the agitator drive gear 69. The urging force of the coil spring 85 is set larger than that of an extension spring 97 described later.

As shown in fig. 2, a gear cover 64 is mounted on one of the side walls 44 of the developer cartridge 30 to cover the gear mechanism 63. An opening 86 is formed in the rear side of the gear cover 64 to expose the joint receiving portion 72. Also, a sensor gear cover 87 is formed on the front side of the gear cover 64 to cover the sensor gear 70.

The sensor gear cover 87 is enlarged laterally outward to accommodate the sensor gear 70. A substantially fan-shaped sensing window 88 is formed at the rear of the sensor gear cover 87, exposing the contact protrusion 82 when the top of the contact protrusion 82 moves in the circumferential direction along with the rotation of the sensor gear 70.

(b) Structure of main casing

An information detection mechanism 89 and a CPU90 (serving as a controller) are provided on the main casing 2 for detecting and determining or decoding information on the developer cartridge 30 mounted in the main casing 2. The more specific information detecting mechanism 89 and the CPU90 detect and determine data indicating whether the developer cartridge 30 is a new product and information indicating the maximum number of printed sheets when the developer cartridge 30 is a new product, as described above.

As shown in fig. 2, the information detection mechanism 89 is provided on the inner wall of the main casing 2 and is located near the rear side of the developer cartridge 30 when the developer cartridge 30 is mounted in the main casing 2. As shown in fig. 4, the information detection mechanism 89 includes an actuator 91 and an optical sensor 92.

The actuator 91 is pivotally supported on a pivot shaft 93 projecting laterally inwardly from the inner surface of the main housing 2. The actuator 91 is integrally provided with a cylindrical insertion portion 94 through which the rotation shaft 93 is inserted, a contact pawl portion 95 extending forward from the cylindrical insertion portion 94, and a light blocking portion 96 extending rearward from the cylindrical insertion portion 94.

As shown in fig. 4A, the contact pawl portion 95 is slightly inclined downward when the light blocking portion 96 extends substantially horizontally. The light blocking portion 96 is formed with a thickness in the vertical direction capable of blocking the detection light emitted from the optical sensor 92.

The spring engaging portion 98 is formed at a midpoint of the length of the light blocking portion 96. One end of the extension spring 97 is engaged with the spring engaging portion 98. The extension spring 97 extends downward from the spring engaging portion 98, and the other end thereof is fixed to an inner surface (not shown) of the main casing 2.

A protruding stopper 99 is formed on the circumferential surface of the cylindrical insertion portion 94, protruding radially outward from the top thereof. A stopper contact portion 100 is provided on the main casing 2 near the rear side of the protruding stopper 99 for contact therewith.

As shown in fig. 4A, the light blocking portion 96 of the actuator 91 is stably pushed down by the tension spring 97. The urging force is suppressed by the protruding stopper 99 contacting the stopper contact portion 100. In this normal state, the actuator 91 is held such that the light blocking portion 96 extends substantially in the horizontal direction while the contact pawl portion 95 is slightly inclined to the front side. In this normal state, the contact pawl portion 95 of the actuator 91 is placed at the detection position for detecting the passage of the contact projection 82.

As will be described later, the contact pawl portion 95 is pressed downward when the contact protrusion 82 comes into contact with the contact pawl portion 95 at the detection position. Therefore, the light blocking portion 96 rotates upward and the contact pawl portion 95 rotates downward about the cylindrical insertion portion 94 against the urging force of the tension spring 97 (see fig. 4B). As a result, the protruding stopper 99 is separated from the stopper contact portion 100. Then, when the contact of the contact protrusion 82 with the contact pawl portion 95 is disconnected, the urging force of the tension spring 97 causes the light blocking portion 96 to rotate downward and the contact pawl portion 95 to rotate upward about the cylindrical insertion portion 94 until the protruding stopper 99 comes into contact with the stopper contact portion 100 (see fig. 4C).

Although not shown in fig. 4A to 4F, the optical sensor 92 is disposed in a holding member that is substantially U-shaped in plan view and open at one end such that the light-generating element and the light-receiving element of the optical sensor 92 are opposed to each other with a gap in between. The optical sensor 92 is placed such that the light blocking portion 96 of the actuator 91 is interposed between the holding members. More specifically, when the actuator 91 is in its normal state (see fig. 4A), the optical sensor 92 is disposed such that the light blocking portion 96 blocks the detection light emitted from the light emitting element toward the light receiving element, while, when the contact protrusion 82 is brought into contact with the contact pawl portion 95 and causes the light blocking portion 96 to rotate upward, the detection light emitted from the light emitting element toward the light receiving element is received by the light receiving element (see fig. 4B).

3. Detecting operation of a new developer cartridge

Next, a method of determining whether the developer cartridge 30 mounted in the main casing 2 is new or old and determining the maximum number of sheets to be printed using the developer cartridge 30 will be described.

(a) Case of two contact bumps

As shown in fig. 4A, first, the front cover 7 is opened, and then the process cartridge 20 with the new developer cartridge 30 thereon is inserted into the main casing 2 through the access opening 6 in the direction a. Alternatively, the front cover 7 may be opened, and a new developer cartridge 30 may be inserted through the access opening 6 and mounted to the process cartridge 20 already mounted in the main casing 2.

As shown in fig. 4A to 4F, two contact projections 82 are provided on the sensor gear 70 in the developer cartridge 30.

When the developer cartridge 30 is mounted in the main casing 2, the actuator 91 is in its normal state, and the protrusion 84 of the front contact projection 82 that moves downward is in contact with the contact pawl portion 95 of the actuator 91 at the detection position. As a result, as shown in fig. 4B, the actuator 91 rotates about the cylindrical insertion portion 94 against the urging force of the tension spring 97 so that the contact pawl portion 95 of the actuator 91 rotates downward and the light blocking portion 96 rotates upward in the direction B. Therefore, the light receiving element receives the detection light from the optical sensor 92, and the detection light is blocked by the light blocking portion 96 in advance when the actuator 91 is in its normal state.

At this time, the optical sensor 92 transmits a reception signal to the CPU90 based on the received light. The CPU90 recognizes the reception signal as the first reception signal and resets a counter that counts the number of printing sheets.

Also, when the developer cartridge 30 is mounted in the main casing 2, a coupling insertion portion (not shown) that transmits a driving force from the motor 59 provided in the main casing 2 is inserted into the coupling receiving portion 72 of the input gear 65 in the developer cartridge 30. As a result, the driving force from the motor 59 drives the input gear 65 of the gear mechanism 63, the supply roller drive gear 66, the developing roller drive gear 67, the intermediate gear 68, the agitator drive gear 69, and the sensor gear 70.

Next, when the developer cartridge 30 is mounted in the main casing 2, the CPU90 starts the warm-up operation of the idle agitator 45.

In this idling operation, the CPU90 drives the motor 59 provided in the main casing 2. The driving force of the motor 59 is input from the coupling insertion portion to the input gear 65 of the developer cartridge 30 through the coupling receiving portion 72 and drives the input gear 65 to rotate. At this time, the supply roller drive gear 66 meshed with the input gear 65 is driven to rotate. The rotation of the supply roller shaft 48 sequentially rotates the supply roller 37. Then, the developing roller drive gear 67 meshed with the input gear 65 is driven to rotate, and the rotation of the developing roller shaft 50 sequentially rotates the developing roller 38. Also, the intermediate gear 68, which is meshed with the input gear 65 through the external teeth 74, is driven to rotate, causing the internal teeth 75 formed integrally with the external teeth 74 to rotate. When the internal teeth 75 of the intermediate gear 68 rotate, the agitator drive gear 69, which is meshed with the internal teeth 75 via the internal teeth 76, is driven to rotate. Rotation of the agitator rotating shaft 43 rotates the agitator 45, agitating the toner in the toner containing chamber 41 and generating a flow of the toner.

When the agitator drive gear 69 is driven to rotate by the internal teeth 76, the external teeth 77 integrally formed with the internal teeth 76 also rotate. Therefore, since the toothed portion 80 of the sensor gear 70 is meshed with the external teeth 77, the sensor gear 70 is also driven to rotate. The sensor gear 70 rotates a predetermined amount from the start position to the stop position.

In other words, the sensor gear 70 is driven to rotate in the direction C only when the toothed portion 80 meshes with the external teeth 77 of the agitator drive gear 69, and the sensor gear 70 stops when the sensor gear 70 is driven to rotate about one and a half turns in a single direction about the sensor gear support shaft 78 corresponding to the toothed portion 80 formed on the semi-circumferential surface of the main sensor gear portion 79. After stopping, the main sensor gear portion 79 is held in a stopped state together with the sensor gear support shaft 78 by frictional resistance.

With this structure, when the developer cartridge 30 is mounted in the main casing 2 for the first time and the sensor gear 70 is driven to rotate for the first time, the protruding portion 84 on the contact projection 82 on the front face of the sensor gear 70 comes into contact with the contact pawl portion 95 and moves in the same direction as the contact pawl portion 95 moves in the contact point moving direction, i.e., the direction from the top to the bottom, as shown in fig. 4B. When sliding in the same direction and passing over and separating from the contact pawl portion 95, the projection 84 further presses the contact pawl portion 95 as shown in fig. 4C. Therefore, when the contact between the protrusion 84 and the contact pawl portion 95 is removed, the urging force of the tension spring 97 causes the actuator 91 to rotate about the cylindrical insertion portion 94 in the direction D so that the contact pawl portion 95 moves upward and the light blocking portion 96 moves downward until the actuator 91 returns to the normal state. At this time, the light blocking section 96 blocks again the detection light of the optical sensor 92 that has been received by the light receiving element.

When the sensor gear 70 is further driven to rotate, the projecting portion 84 of the lower contact protrusion 82 then comes into contact with the contact pawl portion 95 of the actuator 91 in the normal state in the detection position downward direction, as shown in fig. 4D. As shown in fig. 4E, the actuator 91 is again urged to rotate about the insertion portion 94 against the urging force of the tension spring 97 so that the contact pawl portion 95 moves downward and the light blocking portion 96 moves upward. As a result, the light receiving element receives the detection light of the optical sensor 92. The optical sensor 92 transmits a reception signal to the CPU90 based on the reception light. The CPU90 recognizes the received signal as a second received signal.

Then, the protruding portion 84 further press-contacts the pawl portion 95 as the protruding portion 84 slides along the contact pawl portion 95 and then passes through and separates from the contact pawl portion 95, as shown in fig. 4F. Therefore, when the contact between the protruding portion 84 and the contact pawl portion 95 is broken, the urging force of the tension spring 97 causes the actuator 91 to rotate about the insertion portion 94 so that the contact pawl portion 95 moves upward and the light blocking portion 96 moves downward until the actuator 91 returns to its normal state. At this time, the light blocking portion 96 blocks again the detection light of the optical sensor 92 that has been received by the light receiving unit.

Then, the toothed portion 80 of the sensor gear 70 is separated from the external teeth 77 of the agitator drive gear 69, and the rotation of the sensor gear 70 is stopped. At this time, the warm-up operation including the idling operation is ended.

During the idle operation, the CPU90 determines whether the developer cartridge 30 is a new product based on whether the received signal is input from the optical sensor 92, and determines the maximum number of sheets to be printed by the developer cartridge 30 based on the input number of received signals.

More specifically, in the example shown in fig. 4A to 4F, as described above, the CPU90 determines that the developer cartridge 30 is new based on the recognized first reception signal.

Also, the CPU90 associates the input number of received signals with information on the maximum number printed. Specifically, for example, when two reception signals are input, the CPU90 associates this number with a maximum of 6000 sheets to be printed. When a reception signal is input, the CPU90 associates this number with a maximum of 3000 sheets to be printed.

In the above example described from fig. 4A to 4F, the CPU90 recognizes the first and second reception signals during the idling operation. Since the two reception signals are recognized, the CPU90 determines that the maximum number of sheets printed with the developer cartridge 30 is 6000.

Therefore, when the developer cartridge 30 is mounted in the example of fig. 4A to 4F, the CPU90 determines that the developer cartridge 30 is new and determines that the maximum number of sheets to be printed using the developer cartridge 30 is 6000. When the actual number of printed sheets is detected by the sheet discharge sensor 60 after the developer cartridge 30 is mounted to be about 6000, the CPU90 displays a toner-out alarm on a control panel or the like (not shown).

However, if a new developer cartridge 30 mounted in the main casing 2 is later temporarily removed to clear a jam or the like and then reinstalled, the sensor gear 70 remains in a stopped state with the toothed portion 80 in a position not to mesh with the external teeth 77 of the agitator drive gear 69 (see fig. 4F). Therefore, when the developer cartridge 30 is reloaded, the sensor gear 70 is not driven to rotate when the CPU90 performs the idling operation, and therefore, neither of the contact protrusions 82 passes through the detection position of the actuator 91. Therefore, the optical sensor 92 does not input a reception signal to the CPU 90. Thereby preventing the CPU90 from misinterpreting the refilled developer cartridge 30 (old developer cartridge) as a new product, enabling the CPU90 to continue to compare the originally determined maximum number of sheets printed when the developer cartridge 30 was determined to be new with the actual number of sheets printed from then on.

(b) One contact bump condition

As shown in fig. 5A, first, the cover 7 is opened, and then the process cartridge 20 with the new developer cartridge 30 thereon is inserted into the main casing 2 through the access opening 6. Alternatively, the front cover 7 may be opened, and a new developer cartridge 30 may be inserted through the access opening 6 and mounted to the process cartridge 20 already mounted in the main casing 2.

As shown in fig. 5A to 5D, a single contact projection 82 is provided on the sensor gear 70 in the developer cartridge 30. This single contact projection 82 corresponds to the leading contact projection 82 of the two contact projections 82 shown in fig. 4A to 4F. Therefore, the contact projection 82 at the rear in fig. 4A to 4F is not provided in the example of fig. 5A to 5D.

When the developer cartridge 30 is mounted in the main casing 2, the actuator 91 is in its normal state, and the protruding portion 84 of the downwardly moving leading contact projection 82 is in contact with the contact pawl portion 95 of the actuator 91 at the detection position. As a result, as shown in fig. 5B, the actuator 91 rotates about the insertion portion 94 against the urging force of the tension spring 97 so that the contact pawl portion 95 of the actuator 91 rotates downward and the light blocking portion 96 rotates upward. Therefore, the light receiving element receives the detection light from the optical sensor 92, and the detection light is blocked by the light blocking portion 96 in advance when the actuator 91 is in its normal state.

At this time, the optical sensor 92 transmits a reception signal to the CPU90 based on the received light. The CPU90 recognizes the return signal as the first reception signal and resets a counter that counts the number of printed sheets.

Also, when the developer cartridge 30 is mounted in the main casing 2, a coupling insertion portion (not shown) that transmits a driving force from the motor 59 provided in the main casing 2 is inserted into the coupling accommodation portion 72 of the input gear 65 in the developer cartridge 30. As a result, the driving force from the motor 59 drives the input gear 65 of the gear mechanism 63, the supply roller drive gear 66, the developing roller drive gear 67, the intermediate gear 68, the agitator drive gear 69, and the sensor gear 70.

Next, when the developer cartridge 30 is mounted in the main casing 2, the CPU90 starts the warm-up operation of the idle agitator 45.

In this idle rotation operation, the sensor gear 70 is driven to rotate only when the toothed portion 80 meshes with the external teeth 77 of the agitator drive gear 69 as described above. Therefore, the sensor gear 70 stops when the sensor gear 70 is driven to rotate about one and a half turns in a single direction about the sensor gear support shaft 78 corresponding to the toothed portion 80 formed on the semi-circumferential surface of the main sensor gear portion 79. After stopping, the main sensor gear portion 79 and the sensor gear support shaft 78 are held in a stopped state by frictional resistance.

With this structure, when the developer cartridge 30 is mounted in the main casing 2 for the first time and the sensor gear 70 is driven to rotate for the first time, the protruding portion 84 on the contact projection 82 on the front face of the sensor gear 70 comes into contact with the contact pawl portion 95 and moves in the same direction as the direction in which the contact pawl portion 95 moves at the contact point, i.e., the direction from the top to the bottom, as shown in fig. 5B. The protruding portion 84 further presses the contact pawl portion 95 while sliding in the same direction, and then passes through and separates from the contact pawl portion 95, as shown in fig. 5C. Therefore, when the contact between the protrusion 84 and the contact pawl portion 95 is removed, the urging force of the tension spring 97 causes the actuator 91 to rotate about the insertion portion 94 so that the contact pawl portion 95 moves upward and the light blocking portion 96 moves downward until the actuator 91 returns to the normal state. At this time, the light blocking section 96 blocks again the detection light of the optical sensor 92 that has been received by the light receiving element.

Then, the toothed portion 80 of the sensor gear 70 is separated from the external teeth 77 of the agitator drive gear 69, and the rotation of the sensor gear 70 is stopped. At this time, the warm-up operation including the idling operation is ended.

During the idle operation, as described above, the CPU90 determines whether the developer cartridge 30 is a new product based on whether the reception signal is input from the optical sensor 92, and determines the maximum number of sheets to be printed by the developer cartridge 30 based on the input number of reception signals.

More specifically, in the example shown in fig. 5A to 5D, the CPU90 determines that the developer cartridge 30 is new based on the recognized first reception signal.

In the example from fig. 5A to 5D, the CPU90 recognizes the first reception signal during the idling operation. Since only one received signal is recognized, the CPU90 determines that the maximum number of sheets printed with the developer cartridge 30 is 3000.

Therefore, when the developer cartridge 30 is mounted in the example of fig. 5A to 5D, the CPU90 determines that the developer cartridge 30 is new and that the maximum number of sheets to be printed with the developer cartridge 30 is 3000. When the actual number of printing sheets approaches 3000 detected by the sheet discharge sensor 60 after the developer cartridge 30 is mounted, the CPU90 displays a toner-out alarm on a control panel or the like (not shown).

However, if a new developer cartridge 30 mounted in the main casing 2 is later temporarily removed to clear a jam or the like and then reassembled, the sensor gear 70 is still kept in a stopped state with the toothed portion 80 in a position not to mesh with the external teeth 77 of the agitator drive gear 69 (see fig. 5D). Therefore, when the developer cartridge 30 is reloaded, the sensor gear 70 is not driven to rotate, the CPU90 performs an idling operation, and therefore, the contact protrusion 82 does not pass through the detection position of the actuator 91. Therefore, the optical sensor 92 does not input the reception signal to the CPU90, thereby preventing the CPU90 from erroneously determining that the refilled developer cartridge 30 (old developer cartridge) is a new product, so that the CPU90 can continue to compare the previously determined maximum number of sheets printed when the developer cartridge 30 is determined to be new with the actual number of sheets printed from then on.

4. Effect of method of detecting New developer Cartridge

In the above-described laser printer 1, when the developer cartridge 30 is mounted in the main casing 2, the motor 59 drives the sensor gear 70 to rotate exactly one and a half turns from the start position to the end position. When the sensor gear 70 is driven, the contact protrusion 82 moves circumferentially and passes through the detection position of the actuator 91. The optical sensor 92 detects the passage of the contact protrusion 82. The CPU90 determines whether the developer cartridge 30 is new based on whether the optical sensor 92 detects the contact projection 82. The laser printer 1 capable of determining whether the developer cartridge 30 is new can be manufactured with a simple configuration at a reduced production cost.

Also, since the contact pawl portion 95 of the actuator 91 allows passage of the contact protrusion 82 when detecting passage of the contact protrusion 82, the laser printer 1 may be provided with a plurality of contact protrusions 82 and may allow the plurality of contact protrusions 82 to pass through the contact pawl portion 95. As a result, based on whether the optical sensor 92 detects the plurality of contact protrusions 82, the CPU90 can determine whether the developer cartridge 30 is a new product when the developer cartridge 30 is a new product and can determine the maximum number of sheets to be printed using the developer cartridge 30.

Moreover, since the contact protrusion 82 is disposed on the sensor gear 70 so as to be opposed to the midpoint of the toothed portion 80, the toothed portion 80 can be configured to reliably pass through the detection position by driving the sensor gear 70 by a smaller amount than when the contact protrusion 82 is opposed to the end of the toothed portion 80.

Also, since the protruding portion 84 of the contact protrusion 82 moves circumferentially in the same direction in which the protruding portion 84 contacts the contact pawl portion 95 of the actuator 91, that is, the protruding portion 84 moves when the contact protrusion 82 is pushed, the protruding portion 84 can easily continue to move in the same direction after contacting the contact pawl portion 95. Therefore, the laser printer 1 having this structure reliably ensures contact between the protruding portion 84 and the contact pawl portion 95.

In the above-described laser printer 1, the protruding portion 84 comes into contact with the insertion portion 94 when the developer cartridge 30 is first mounted in the main casing 2. Therefore, even before the motor 59 performs the idling operation, the protruding portion 84 can be placed in contact with the contact pawl portion 95. Therefore, when the optical sensor 92 detects this contact, the CPU90 can determine whether the developer cartridge 30 is new without the need for the motor 59 to drive the sensor gear 70 to rotate.

Further, since the sensor gear 70 is constituted by a missing tooth gear having a toothed portion 80 and a missing tooth portion 81, the driving force from the motor 59 is transmitted to rotate the sensor gear 70 when the toothed portion 80 opposes the agitator drive gear 69 and is not transmitted to rotate the sensor gear 70 when the missing tooth portion 81 opposes the agitator drive gear 69, thereby stopping the rotation of the sensor gear 70 at this time. Therefore, the sensor gear 70 can be reliably driven by a predetermined driving amount from the start of rotation to the end of rotation.

To ensure reliable engagement between the sensor gear 70 and the external teeth 77, the developer cartridge 30 further includes a coil spring 85 that urges the sensor gear 70 toward the external teeth 77 of the agitator drive gear 69. Therefore, the sensor gear 70 is reliably driven by the driving force of the motor 59 through the external teeth 77 of the agitator driving gear 69. By ensuring that the sensor gear 70 is reliably driven. When the developer cartridge 30 is determined to be new, the CPU90 can reliably determine the maximum number of sheets to be printed with the developer cartridge 30.

In the above-described laser printer 1, the information on the maximum number of sheets to be printed with the developer cartridge 30 is set to coincide with the number of the contact projections 82 provided in the developer cartridge 30. Therefore, based on the number of the contact projections 82 (the inputted reception signal amount) detected by the optical sensor 92, the CPU90 can easily and reliably determine the maximum number of sheets to be printed with the developer cartridge 30. Therefore, even when the toner amount corresponding to the maximum paper printed differs from that in the developer cartridge 30, the CPU90 can reliably determine the life of the developer cartridge 30 to ensure that the developer cartridge 30 is replaced at a precise time.

Since the CPU90 in the laser printer 1 of the present preferred embodiment can determine whether the mounted developer cartridge 30 is new based on whether the optical sensor 92 detects the contact projection 82 in the developer cartridge 30, the laser printer 1 of the present preferred embodiment can easily and reliably determine whether the developer cartridge 30 is old or new. Therefore, the laser printer 1 can reliably determine that the developer cartridge 30 has reached the end of its life from the time the developer cartridge 30 is determined to be new.

5. Variations of contact bumps

In the preferred embodiment described above, the number of contact projections 82 is associated with the maximum number of sheets to be printed using the developer cartridge 30. However, the top width of the contact projection 82 (including the circumferential width of the top of the projection 84) may also be associated with the maximum number of sheets to be printed with the developer cartridge 30, as shown in fig. 5A to 5D and 6A to 6C.

Specifically, as shown in fig. 6A to 6C, for example, the contact projection 82 formed with a wider top may be associated with displaying information of printing of up to 6000 sheets of paper. As shown in fig. 5A to 5D, the contact protrusion 82 formed with a narrower top may be associated with displaying information of printing up to 3000 sheets of paper.

The CPU90 can also determine the maximum amount of printing paper based on the length from the point in time when the motor 59 is first driven to receive a signal to the input time input from the optical sensor 92.

Therefore, in the idle rotation operation shown in fig. 5A to 5D, when the sensor gear 70 is driven to rotate for the first time, the protruding portion 84 of the contact protrusion 82 comes into contact with the contact pawl portion 95, as shown in fig. 5B. When the protruding portion 84 slides along the contact pawl portion 95, the optical sensor 92 inputs a reception signal to the CPU90 for a short time corresponding to the time required for the protruding portion 84 to pass through the contact pawl portion 95.

In the idle rotation operation shown in fig. 6A to 6C, when the sensor gear 70 is driven to rotate for the first time, the protruding portion 84 of the contact protrusion 82 comes into contact with the contact pawl portion 95 of the actuator 91, as shown in fig. 6A. However, since the projection 84 in the example of fig. 6A to 6C has a larger circumferential length, the projection 84 slides along the contact pawl portion 95 for a longer period of time, as shown in fig. 6B. Therefore, the optical sensor 92 inputs the reception signal to the CPU90 for a longer time relative to the time required for the protrusion 84 to pass through the contact pawl portion 95, as shown in fig. 6C.

In this way, the CPU90 can determine the maximum amount of paper to print with the developer cartridge 30 based on the input time of the received signal. For example, the CPU90 can determine that the maximum amount of paper printed is 3000 when the input time is short and the CPU90 can determine that the maximum amount of paper printed is 6000 when the input time is long.

With this structure, the CPU90 can determine the maximum number of sheets to be printed by different developer cartridges based on the length of time that the optical sensor 92 detects the contact protrusion 82, simply by modifying the width of the top of the contact protrusion 82 of the different developer cartridges without providing a plurality of contact protrusions 82.

6. Variation of the relationship between the number of contact bumps and the maximum number of sheets printed

In the above preferred embodiment, two contact protrusions 82 are associated with the maximum number of 6000 sheets of paper for display printing, and one contact protrusion 82 is associated with the maximum number of 3000 sheets of paper for display printing. However, the opposite relationship is also possible. In other words, one contact bump 82 may be associated with the maximum number of 6000 sheets of paper for which printing is displayed, and two contact bumps 82 may be associated with the maximum number of 3000 sheets of paper for which printing is displayed.

Next, a new product determination process for determining whether the developer cartridge 30 is new and determining the maximum number of sheets to be printed using the developer cartridge 30 using such a relationship will be described in detail with reference to fig. 7 to 10. Fig. 7 is a block diagram of a control system showing a new product determination process. Fig. 8 is a table stored in the ROM shown in fig. 7. Fig. 9 is a time chart of a new product determination process. Fig. 10 is a flowchart showing the steps of the new product determination process.

As shown in fig. 7, the control system includes an ASIC101 that controls the respective areas of the laser printer 1; the motor 59 and the optical sensor 92 described above, and a front cover open/close sensor 102 connected to the ASIC 101.

The ASIC101 controls the motor 59 when the CPU90 executes various programs.

The optical sensor 92 inputs the above-described reception signal to the CPU90 through the ASIC 101.

The front cover open/close sensor 102 is constituted by a switch (not shown) that is opened by contact with the front cover 7. The front cover open/close sensor 102 is opened when the front cover 7 is closed from the open position, and a close detection signal is input to the CPU90 via the ASIC 101.

The control system also includes ROM104, RAM105, NVRAM106, and CPU90, all connected to ASIC101 via bus 103.

The ROM104 stores various programs executed by the CPU90, such as an image forming program that performs an image forming process, a new product determining program that performs a new product determining process, and a motor rotational speed determining program that performs a motor rotational speed determining process when necessary. The ROM104 also stores a table 107 that associates the toner capacity and the number of detections of the developer cartridge 30 and is referred to in the new product determination process.

In the table 107 shown in fig. 8, the detection number corresponds to the number of times the optical sensor 92 detects the contact projection 82 and receives a signal input to the CPU 90. As shown in fig. 8, the detection number (hereinafter referred to as detection amount) "1" corresponds to "high capacity" and the detection number "2" corresponds to "low capacity". Here, "high capacity" shows that the developer cartridge 30 mounted in the main casing 2 has high capacity toner capable of printing up to 6000 sheets of paper (hereinafter referred to as "high-capacity developer cartridge"). The "low capacity" shows that the developer cartridge 30 mounted in the main casing 2 has a low toner capacity (hereinafter referred to as "low-capacity developer cartridge") capable of printing up to 3000 sheets.

The RAM105 temporarily stores values and the like used when the CPU90 executes various programs. The NVRAM106 stores data showing the presence of a reception signal input from the optical sensor 92, the length of the reception signal time (see fig. 9), the number of input reception signals (detection number), and the like.

With this control system, the CPU90 executes a new product determination program stored in the ROM104 to implement a new product determination process. In this process, the ASIC101 controls the respective areas of the laser printer 1.

As described above, in the new product determining process, the developer cartridge 30 having the single contact projection 82 is a high-capacity developer cartridge that contains effective toner for printing up to 6000 sheets. The developer cartridge 30 provided with 2 contact protrusions 82 is a low-capacity developer cartridge that contains effective toner for printing up to 3000 sheets.

Fig. 9 is a diagram showing the on/off time of the optical sensor 92 when the developer cartridges mounted in the optical sensor 92 are a new high-capacity developer cartridge, a new low-capacity developer cartridge, and an old developer cartridge.

As described above, when a new high-capacity developer cartridge is mounted in the main casing 2, the protruding portion 84 of the contact projection 82 comes into contact with the contact pawl portion 95 of the actuator 91 at the detection position at the moment when the new cartridge is mounted. When the protruding portion 84 comes into contact with the contact pawl portion 95, the actuator 91 rotates, opening the optical sensor 92. In other words, the optical sensor 92 inputs a reception signal to the CPU 90.

At this time, the CPU90 controls the motor 59 to drive at full speed, and starts the idling operation. As a result, the protruding portion 84 further presses the contact pawl portion 95 when sliding in the same direction, and then separates from the contact pawl portion 95. At this time, the actuator 91 rotates backward to its normal state, closing the optical sensor 92 (in other words, the reception signal input to the CPU90 is interrupted). When the motor 59 is driven at full speed, the elapsed time from the start of the idling operation to when the optical sensor 92 is turned off is 0.3 seconds.

Therefore, when a new high-capacity developer cartridge is mounted in the main casing 2, the optical sensor 92 is turned on and off only once (receives light once). Therefore, a predetermined time (0.3 seconds in the present preferred embodiment) in which the state continues in a predetermined interval (e.g., 5 seconds) from the moment when the motor 59 is initially driven is counted as one detection. This is true in the following description.

As described above, when a new low-content developer cartridge is mounted in the main casing 2, the protruding portion 84 of the leading contact projection 82 comes into contact with the contact pawl portion 95 of the actuator 91 at the detection position at the moment when the new cartridge is mounted. When the protruding portion 84 comes into contact with the contact pawl portion 95, the actuator 91 rotates, opening the optical sensor 92.

At this time, the CPU90 controls the motor 59 to drive at full speed, and starts the idling operation. As a result, the front projection 84 further presses the contact pawl portion 95 when sliding in the same direction, and then separates from the contact pawl portion 95. At this time, the actuator 91 rotates backward to its normal state, turning off the optical sensor 92. When the motor 59 is driven at full speed, the elapsed time from the start of the idling operation to when the optical sensor 92 is turned off is 0.3 seconds.

Then, the protruding portion 84 of the slave contact protrusion 82 comes into contact with the contact pawl portion 95 of the actuator 91 in the normal state. As a result, the actuator 91 rotates and the optical sensor 92 is opened again. When the motor 59 is driven at full speed, the elapsed time from the moment when the optical sensor 92 is turned off until the optical sensor 92 is turned on again is 1.1 seconds (i.e., 1.4 seconds from the start of the idling operation until the optical sensor 92 is turned on again when the motor 59 is driven at full speed).

When brought into sliding contact with the contact pawl portion 95, the rear projection portion 84 further press-contacts the contact pawl portion 95. Then, the protrusion 84 is separated from the contact pawl portion 95, allowing the actuator 91 to rotate backward to its normal state, and finally closing the optical sensor 92. When the motor 59 is driven at full speed, the elapsed time from when the optical sensor 92 is turned on again to when the optical sensor 92 is turned off again is 0.3 seconds (i.e., 1.7 seconds from the start of the idling operation to when the motor 59 is driven at full speed to when the optical sensor 92 is turned off again).

Therefore, when a new low-content developer cartridge is mounted in the main casing 2, the detection number of the optical sensor 92 (the number of times the optical sensor 92 receives light) is 2.

As described above, when the old developer cartridge (old high-content developer cartridge or old low-content developer cartridge) is mounted in the main casing 2, the sensor gear 70 is kept in the stopped state. Therefore, since the contact protrusion 82 does not pass through the detection position of the actuator 91, the optical sensor 92 is maintained in the closed state.

Therefore, the detection number of the optical sensor 92 is 0 when the old developer cartridge is mounted in the main casing 2.

Next, a new product determination process performed by the CPU90 will be explained with reference to fig. 10. In step S1 in fig. 10, the CPU90 determines whether the power is on or the front cover open/close sensor 102 has input a close detection signal to the CPU 90. If the power is not turned on or the CPU90 does not receive the off detection signal (S1: NO), the process returns to the main routine (not shown) and the determination in S1 continues. However, if the power has been turned on or the CPU90 has received the off detection signal (S1: YES), the CPU90 starts the idling operation as described above in S2.

As described above, first, the front cover 7 is opened, and the developer cartridge 30 is inserted into the main casing 2 through the access opening 6. Then, the front cover 7 is closed, at which time the front cover open/close sensor 102 is opened and a close detection signal is input to the CPU 90. At this time, the idling operation in S2 starts.

After the start of the idling operation, the CPU90 determines in S3 whether the idling operation has ended. If the idling operation is not ended (S3: no), that is, when the idling operation is performed, the CPU90 determines whether the optical sensor 92 is on (whether the optical sensor 92 is receiving a signal) in S4. If the optical sensor 92 is on (S4: YES), the CPU90 measures the time of the on process of the optical sensor 92 (hereinafter referred to as "on time of the optical sensor 92") in S5. The on time of the optical sensor 92 is continuously measured during the idling operation when the optical sensor 92 is turned on, and the measured time is stored in the NVRAM106 (S3: no, S4: yes, S5).

However, when the optical sensor 92 is off (S4: No), the CPU90 determines in S6 whether the on time of the optical sensor 92 is 0.3 seconds or more. If the on time of the optical sensor 92 exceeds 0.3 seconds (S6: YES), the contact protrusion 82 has come into contact with the contact pawl portion 95 at the contact position, as described above. Therefore, the CPU90 determines that the reception signal has been input and increases the number of detections stored in the NVRAM106 in S7. In S8 the CPU90 clears the measured hitting time of the optical sensor 92 from the NVRAM 106.

However, if the on time of the optical sensor 92 is less than 0.3 seconds (S6: NO), the CPU90 determines whether the input signal is a disturbance caused by contact between the contact protrusion 82 and the contact pawl portion 95. Therefore, the CPU90 not only does not increase the number of detections in S7, but also clears the measurement time stored in the NVRAM 106.

After clearing the measured on time of the optical sensor 92 in S8, the CPU90 returns to S3 to determine again whether the idling operation has ended. If the idle operation has not been ended (S3: NO), the CPU90 repeats the above steps.

When the developer cartridge 30 mounted in the main casing 2 is a used developer cartridge, the on/off detection number of the optical sensor 92 is "0" in the idle rotation operation. Therefore, in this state, the detection number never increases in S7, and the detection number remains "0" when the idling operation ends.

When the developer cartridge 30 mounted in the main casing 2 is a new high-capacity developer cartridge, the developer cartridge 30 has one contact projection 82. Therefore, as shown in fig. 9, the on/off detection number of the optical sensor 92 is "1" in the idle operation. Therefore, the detection number is increased once in S7, and the detection number is kept at "1" when the idling operation ends.

If the developer cartridge 30 mounted in the main casing 2 is a new low-content developer cartridge, the developer cartridge 30 has two contact projections 82. Therefore, as shown in fig. 9, the on/off detection operation of the optical sensor 92 is detected twice in the idle operation. Therefore, the detection number is never increased twice in S7, and the detection number is kept at "2" when the idling operation ends.

When the idling operation has ended (S3: yes), the CPU90 determines whether the optical sensor 92 is on in S9. For example, if the optical sensor 92 is on (S9: YES), the detection number is not counted correctly because the contact projection 82 is kept in contact with the contact pawl portion 95. In this case, the CPU90 determines in S10 that an error has occurred in the new product determination process and returns to the main routine. If the CPU90 determines that an error has occurred in the new product determination process, the CPU90 displays information reflecting the information on a control panel or the like.

However, if the optical sensor 92 is off (S9: NO), the CPU90 determines that the detected number has been correctly counted and determines whether the detected number is "0" in S11. If the detection number is "0" (S11: YES), the CPU90 determines that the mounted cartridge is an old developer cartridge in S12 and returns to the main routine. When the CPU90 determines that the mounted cartridge is an old developer cartridge, the CPU90 continues to compare the maximum number of sheets printed with the cartridge when the cartridge is new with the number of sheets actually printed since the cartridge was determined to be new, as described above.

However, if the test number is not "0" (S11: NO), the CPU90 determines whether the test number is "1" in S13. If the number of tests is "1" (S13: YES), the CPU90 refers to the table 107 stored in the ROM104 in S14, and determines that the mounted cartridge is a new high-content developer cartridge because the data showing "high content" in the table 107 is associated with the number of tests "1". Then, the CPU90 returns to the main routine. As described above, when the CPU90 determines that the mounted cartridge is a new high-content developer cartridge, the CPU90 determines that the developer cartridge 30 is new and the maximum number of 6000 sheets can be printed using the developer cartridge 30. Therefore, the CPU90 displays the toner-out alarm on the control panel or the like when it is detected by the paper discharge sensor 60 that the maximum number of actually printed sheets from when the developer cartridge 30 was first mounted exceeds 6000.

If the test number is not "1" (S13: NO), the CPU90 determines whether the test number is "2" in S15. If the number of tests is "2" (S15: YES), the CPU90 refers to the table 107 stored in the ROM104 in S16, and determines that the mounted cartridge is a new low-content developer cartridge because the data showing "low content" in the table 107 is associated with the number of tests "2". Then, the CPU90 returns to the main routine. As described above, when the CPU90 determines that the mounted cartridge is a new low-content developer cartridge, the CPU90 determines that the developer cartridge 30 is new and the maximum number of 3000 sheets can be printed using the developer cartridge 30. Therefore, the CPU90 displays the toner-out alarm on the control panel or the like when it is detected by the paper discharge sensor 60 that the maximum number of actually printed sheets from when the developer cartridge 30 was first mounted exceeds 3000.

However, when the detection number is not "2" (S15: No), that is, when the detection number is "3" or more, the detection number is not listed in the table 107. In this case, the CPU90 determines in S14 that the cartridge is "high-capacity" and thus a new high-capacity developer cartridge, and the CPU90 returns to the main routine. When the CPU90 determines that the mounted cartridge is a new high-content developer cartridge, the CPU90 determines that the developer cartridge 30 is new and that the maximum amount of 6000 sheets can be printed using the developer cartridge 30. Therefore, the CPU90 displays the toner-out alarm on the control panel or the like when it is detected by the paper discharge sensor 60 that the maximum number of actually printed sheets from when the developer cartridge 30 was first mounted exceeds 6000.

Since the on/off detection number of the optical sensor 92 generally increases more when the number of the contact projections 82 increases, there is a risk that the CPU90 misses the detection signal input from the optical sensor 92 and determines that the detection number is less than the actual on/off detection number in the new product determination process. Therefore, when the two contact projections 82 are provided, there is a possibility that the CPU90 mistakenly recognizes the on/off detection number of the optical sensor 92 as "1" instead of "2" due to the missing detection signal.

For example, when a high-capacity developer cartridge having two contact projections 82 is mounted, the CPU90 should determine that the optical sensor 92 is turned on and off twice. However, as described above, if the CPU90 misses a received signal, and it is mistaken that the on/off detection number is "1". The CPU90 will determine that the maximum number of sheets printed using the high-volume developer cartridge is 3000 rather than 6000.

In this case, the CPU90 displays a toner-out alarm on a control panel or the like when it is detected by the paper-discharge sensor 60 that the maximum number of actually printed sheets from when the developer cartridge 30 was initially mounted in the main casing 2 approaches 3000, prompting the user to replace the developer cartridge. Therefore, the developer cartridge 30 is to be replaced when a large amount of unused toner remains in the high-capacity developer cartridge.

However, according to the new product determining process of the present preferred embodiment, the developer cartridge having one contact projection 82 corresponds to the high-capacity developer cartridge, thereby reducing the risk that the CPU90 misunderstands that the on/off detection number of the optical sensor 92 is larger than when the high-capacity developer cartridge is two optical sensors 92 as described above. Therefore, this method can prevent the developer cartridge 30 from being replaced when a large amount of unused toner remains in the developer cartridge 30 as described above.

Since the two cartridges of the contact projection 82 correspond to the low-volume developer cartridge in the present new product determination process, if the CPU90 misses the detection signal as described above, there is a risk that the CPU90 determines that the maximum sheet number to be printed with the low-volume developer cartridge is 6000 instead of 3000. The laser printer 1 of the present preferred embodiment, however, has the toner sensor that determines the actual amount of toner remaining in the toner-accommodating chamber 41 as described above. Therefore, when the actual amount of remaining toner becomes low, the CPU90 will display a toner-out alarm on the control panel or the like based on the determination of the toner sensor. Therefore, even if the CPU90 mistakenly believes that the maximum sheet number printed with the low-content developer cartridge is 6000, the CPU90 will display a toner-out warning when the actual number of printed sheets approaches 3000 based on the determination of the toner sensor, although the warning will not be displayed based on the actual amount of printing detected by the sheet discharge sensor 60.

Also, when the CPU90 determines in S15 of the new product checking process that the detected amount is not "2" (S15: no), that is, the detected number corresponds to a number other than the detected numbers listed in table 107, the CPU90 determines in S14 that the cartridge is a new high-content developer cartridge. Therefore, if the CPU90 misunderstands that the input disturbing signal is a reception signal, resulting in the detection number exceeding the detection number listed in the table 107, the CPU90 associates the number with "high capacity", thereby preventing the developer cartridge 30 from being replaced when a large amount of unused toner remains in the high-capacity developer cartridge.

In the above description, if the number of tests is not "2" in S15 (S15: no), that is, if the number of tests exceeds the number of tests listed in table 107, the CPU90 determines in S14 that the developer cartridge is a high-content developer cartridge. However, as shown in S17 in fig. 11, the CPU90 may determine that an error has occurred in the new product determination process, instead of determining that the cartridge is a high-content developer cartridge, and may return to the main routine. After determining that an error has occurred in the new product determination process, the CPU90 displays an error message on a control panel or the like.

The flowchart in fig. 11 has the same steps as the flowchart in fig. 10 except for the above-described variations.

In the present preferred embodiment described above, the motor 59 is driven to rotate at full speed during the idling operation, i.e., the operation of detecting the passage of the contact protrusion 82 with the optical sensor 92, which is the same speed as that used in image formation. However, the motor 59 may also be driven at a lower speed during the idling operation than during the image forming. By driving the motor 59 at a lower speed such as a half speed, the accuracy of the CPU90 in determining the number of on/off detections of the optical sensor 92 can be improved.

Fig. 12 is a flowchart showing steps in the motor rotation speed determination process performed by the CPU90 during the idling operation. This process is implemented as step 2a, as shown in fig. 14. The motor speed determination process is stored in the ROM104 as a motor speed determination program for driving the motor 59 at half speed during the idling operation.

As shown in the motor rotation speed determination process of fig. 12, the CPU90 determines in S31 whether an instruction to rotate the drive motor 59 to perform an image forming operation, an idling operation, or the like has been issued. If no command is issued to drive the motor 59 (S31: NO), the CPU90 returns to the main routine, and the determination in S31 is repeatedly carried out.

However, if a command has been issued to the motor 59 (S31: YES), the CPU90 determines whether or not the power has been turned on or off and whether or not a detection signal has been input to the CPU90 in S32. If the power has not been turned on and the off detection signal has not been input to the CPU90 (S32: no), the motor 59 is driven to rotate to perform the image forming operation. In this case, the CPU90 drives the motor 59 at full speed in S33, and then returns to the main routine.

However, if the power has been turned on or the off detection signal has been input to the CPU90 (S32: YES), the idling operation as described above is started. In this case, the CPU90 drives the motor 59 to rotate at half speed in S34, and then returns to the main routine.

Fig. 13 is a time chart of the new product determination process when the motor 59 is driven to rotate at half speed. Fig. 14 is a flowchart showing the steps of the new product determination process when the motor 59 is driven to rotate at half speed.

As shown in fig. 13, when a new high-content developer cartridge is mounted in the main casing 2, as described above, the optical sensor 92 is turned on at the same time as the new cartridge is mounted. After the optical sensor 92 is turned off, the CPU90 drives the motor 59 at half speed. When the motor 59 is driven at half speed, the time from the start of the idling operation to the moment when the optical sensor 92 is turned off is 0.6 seconds.

As described above, when a new low-content developer cartridge is mounted in the main casing 2, the optical sensor 92 is turned on at the same time as the new cartridge is mounted. After the optical sensor 92 is turned off, the CPU90 drives the motor 59 at half speed. When the motor 59 is driven at half speed, the time from the start of the idling operation to the moment when the optical sensor 92 is turned off is 0.6 seconds.

Then, the optical sensor 92 is turned on again. When the motor 59 is driven at half speed, the time from when the optical sensor 92 is turned off to when the optical sensor 92 is turned on again is 2.2 seconds (2.8 seconds from the start of the idling operation to the moment when the optical sensor 92 is turned on again).

The optical sensor 92 is turned off again. When the motor 59 is driven at half speed, the time from the moment when the optical sensor 92 is turned on again to when the optical sensor 92 is turned off again is 0.6 seconds (3.4 seconds from the start of the idling operation to when the optical sensor 92 is turned off again).

As described above, the optical sensor 92 is kept in the closed state when the old developer cartridge is mounted in the main casing 2.

Next, referring to fig. 14, a new product determination process that is implemented when the motor 59 is driven at half speed will be explained. The steps in the new product determination process in fig. 14 are the same as those in the flowchart in fig. 10 except for step 6. In step 6 of fig. 10 described above, the CPU90 determines whether the time of the opening process of the optical sensor 92 exceeds 0.3 seconds, whereas in fig. 14 the CPU90 determines whether the time has exceeded 0.6 seconds.

Specifically, since the optical sensor 92 is kept on for a longer time while the motor 59 is driven at the half speed, the CPU90 determines whether the on time of the optical sensor 92 has exceeded 0.6 seconds in the new product determination process of fig. 14. If the on time exceeds 0.6 seconds (S6: YES), the CPU90 determines that the recycle signal has been input and increments the number of tests in S7. In S8 the CPU90 clears the on time of the optical sensor 92 stored in the NVRAM 106. However, if the on time of the optical sensor 92 is less than 0.6 seconds (S6: NO), the CPU90 determines that the signal is caused by interference. Therefore, the CPU90 not only does not increase the number of detections in S7, but also clears the measurement time stored in the NVRAM106 in S8.

By driving the motor 59 at half speed in the idling operation, the optical sensor 92 can detect the passage of the contact protrusion 82 with higher accuracy. Therefore, the CPU90 can determine with higher accuracy when a reception signal is input from the optical sensor 92. As a result, the CPU90 can reliably determine whether the mounted cartridge is a high-content developer cartridge or a low-content developer cartridge.

In the present preferred embodiment described above, the developer cartridge 30 is provided separately from the process frame 27, and the photosensitive drum 28 is provided in the process frame 27. However, it is apparent that the developer cartridge according to the present invention may be integrally formed with the process frame 27.

While the invention has been described in terms of specific embodiments, it will be apparent to those skilled in the art that various changes can be made without departing from the scope of the invention.

For example, the present invention is applicable not only to a monochrome image forming apparatus in which one developer cartridge can be mounted, but also to a color image forming apparatus in which four cartridges respectively accommodating yellow, magenta, cyan, and black toners can be mounted.

Claims (19)

1. An image forming apparatus, comprising:

a main housing;

a developer cartridge accommodating a developer and detachable from the main casing;

a motor generating a driving force;

a driving member disposed in the developer cartridge and capable of being driven by the motor from a start position to an end position by a predetermined amount when the developer cartridge is mounted in the main casing;

a moving member provided in the developer cartridge and associated with the driving member so as to be movable together with the driving member;

an information detecting portion that detects the moving member and outputs a detection result when the moving member moves together with the driving member; and

a controller that obtains information about the developer cartridge based on a detection result output from the information detecting portion,

the information on the developer cartridge is information indicating whether the developer cartridge is a new product and the maximum number of recording media on which images can be formed using the developer accommodated in the developer cartridge when the developer cartridge is a new product.

2. The image forming apparatus according to claim 1, wherein the information detecting portion includes a contact member contactable with the moving member, wherein the moving member moves so as to push the contact member.

3. The image forming apparatus according to claim 2, wherein the contact member is in contact with the moving member when the developer cartridge is mounted in the main housing.

4. The image forming apparatus according to claim 1, wherein the driving member includes a gear with missing teeth having a toothed portion that transmits the driving force from the motor, and a non-toothed portion that does not transmit the driving force from the motor.

5. The image forming apparatus according to claim 4, wherein the developer cartridge includes a transmission gear that transmits the driving force from the motor when the developer cartridge is mounted in the main casing, and the gear with teeth missing meshes with the transmission gear.

6. The image forming apparatus according to claim 5, wherein the developer cartridge further comprises an urging member that urges the missing-tooth gear toward the transfer gear to be engaged with the transfer gear.

7. The image forming apparatus as claimed in claim 1, wherein a plurality of moving members are provided in association with the driving member.

8. The image forming apparatus according to claim 1, wherein one or more moving members are provided in association with the driving member, the number of the moving members indicating a maximum amount of information on a recording medium on which an image can be formed using the developer accommodated in the developer cartridge when the developer cartridge is a new product, and the controller decodes the maximum amount of information on the recording medium on which an image can be formed using the developer accommodated in the developer cartridge when the developer cartridge is a new product, based on the number of the moving members detected by the information detecting portion.

9. The image forming apparatus according to claim 1, wherein a width of the moving member in a moving direction thereof indicates a maximum amount of information using a recording medium on which an image can be formed by the developer accommodated in the developer cartridge when the developer cartridge is a new product, and in the process of the information detecting section detecting the moving member, the controller decodes the maximum amount of information using the recording medium on which an image can be formed by the developer accommodated in the developer cartridge when the developer cartridge is a new product, based on the detection time.

10. The image forming apparatus as claimed in claim 1, further comprising:

wherein a first number of the moving members are provided when the amount of the developer accommodated in the developer cartridge is a first amount, and a second number of the moving members larger than the first number are provided when the amount of the developer accommodated in the developer cartridge is a second amount smaller than the first amount; and

the controller determines that the developer accommodated in the developer cartridge is a first amount when the number of detections of the moving member detected by the information detecting portion corresponds to a first number and determines that the developer accommodated in the developer cartridge is a second amount when the number of detections of the moving member corresponds to a second number.

11. The image forming apparatus according to claim 10, further comprising a storage storing a table associating the first number and the second number with a detection number corresponding to the first number and a detection number corresponding to the second number, respectively, wherein the controller refers to the storage and determines the amount of the developer contained in the developer cartridge to be the first number when the detection number is not among the detection numbers listed in the table.

12. The image forming apparatus as claimed in claim 10, wherein a speed at which the motor moves the moving member during the operation of detecting the moving member by the information detecting portion is lower than a speed used during image formation.

13. A developer cartridge detachably mountable to an image forming apparatus including an information detecting portion and a controller, characterized by comprising:

a driving member capable of being driven from an initial position to an end position when the developer cartridge is mounted in the image forming apparatus; and

a plurality of contact projections provided in association with the driving member so as to be movable together with the driving member, the plurality of contact projections passing through positions where the plurality of contact projections contact the information detecting portion when the driving member is driven from an initial position to an end position when the developer cartridge is mounted in the image forming apparatus, the plurality of contact projections being detected by the information detecting portion and outputting a detection result when the plurality of contact projections move together with the driving member; obtaining, by the controller, information about the developer cartridge based on a detection result output from the information detecting portion.

14. The developer cartridge according to claim 13, wherein the drive member comprises an edentulous gear having a toothed portion that receives drive force from a motor in the image forming apparatus and a non-toothed portion that does not receive drive force from the motor.

15. A developer cartridge detachably mountable to an image forming apparatus including an information detecting portion and a controller, characterized by comprising:

a toothless gear capable of being driven from an initial position to an end position when the developer cartridge is mounted in the image forming apparatus, the toothless gear being formed with a toothed portion that receives a driving force from a motor, and a toothless portion that does not receive the driving force from the motor; and

a plurality of contact projections movable together with the toothless gear, the plurality of contact projections being provided at positions detected by the information detecting portion when the toothless gear is driven by the motor, information on the developer cartridge being obtained by the controller based on a detection result output from the information detecting portion.

16. The developer cartridge according to claim 15, further comprising a transfer gear that meshes with the gear having no teeth.

17. The developer cartridge according to claim 16, further comprising an urging member that urges the toothless gear toward the transfer gear.

18. The developer cartridge according to claim 17, wherein when the urging member urges the toothless gear toward the transfer gear, an end of the toothed portion engages the transfer gear.

19. The developer cartridge according to claim 15, wherein a plurality of contact projections are provided in association with the toothless gear, the plurality of contact projections having end portions arranged on a predetermined circle.