JP2000275948A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device where an image can always be formed stably and that is superior in durability by preventing beforehand generation of various nonconformities arising with increase of deteriorated toner with lowered fluidity or static charge characteristic when the ratio of the deteriorated toner is increased within the toner due to repeated developing. SOLUTION: In this image forming device, a toner containing chamber 27 to contain toner that is non magnetic and one component, a developing cartridge 36 provided with a developing roll 22 and a layer thickness restriction blade 23 and a photoreceptor drum 21 are provided to be able to be separated and a toner empty sensor detecting toner empty in a state where the toner is remaining at least in the developing cartridge 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a laser printer.

[0002]

2. Description of the Related Art Generally, an image forming apparatus such as a laser printer using a non-magnetic one-component toner includes a toner accommodating chamber for accommodating toner, and a developing roller for carrying toner supplied from the toner accommodating chamber. A layer thickness regulating blade disposed on the side of the developing roller and forming a thin layer of toner on the developing roller; and a photosensitive drum disposed opposite the developing roller and forming an electrostatic latent image. Provided.

The layer thickness regulating blade is pressed against the surface of the developing roller, and the toner supplied from the toner storage chamber is rubbed between the layer thickness regulating blade and the developing roller to be sufficiently charged. While being carried on the developing roller as a thin layer having a constant thickness. On the other hand, the electrostatic latent image is formed by uniformly charging the surface of the photosensitive drum with a charger and then irradiating the surface with a laser beam based on predetermined image data by a laser light emitting device by high-speed scanning. ing. Then, development is performed by selectively transferring the charged toner when the charged toner is opposed to the electrostatic latent image.

[0004]

However, when developing such a non-magnetic one-component toner, most of the charging of the toner is performed by frictional contact between the layer thickness regulating blade and the developing roller. Therefore, in order to uniformly charge the toner, it is necessary to strongly press the layer thickness regulating blade against the developing roller and rub the toner strongly. on the other hand,
When the toner is strongly rubbed, external additives such as silica externally added to the toner are buried in the base particles of the toner, so that the fluidity is reduced or the chargeability is reduced. . Therefore, the toner that has not been subjected to the development thereafter will be subjected to the development again by the developing roller, but as such development is repeated,
The proportion of the deteriorated toner having reduced fluidity or chargeability in the toner increases steadily with the consumption of the toner, for example, due to poor fluidity, filming occurs on the photosensitive drum, Alternatively, image roughness may occur, and due to poor charging properties,
As the image density increases, character collapse occurs, or fogging occurs due to the generation of reverse polarity toner.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for refining a deteriorated toner having reduced fluidity and chargeability by repeating development. An object of the present invention is to provide an image forming apparatus capable of always stably forming an image and having excellent durability by preventing various problems caused by the increase even if the ratio increases.

[0006]

In order to achieve the above object, the present invention is directed to a developer accommodating chamber for accommodating a non-magnetic one-component developer, and a developer carrying member for carrying the developer. And a developing device having a layer thickness regulating member for forming a thin layer of the developer on the developer carrier, and a photoreceptor on which an electrostatic latent image is formed, wherein the developer is provided by the layer thickness regulating member. An image forming apparatus configured to form a visible image by causing a thin layer of the developer formed on a carrier to face the photoconductor on which an electrostatic latent image is formed; And a photoreceptor is provided so as to be separable, and further includes a developer remaining amount detecting unit that detects a limit at which the developer can be consumed when at least the developer remains in the developing device. It is characterized by having.

According to such a configuration, the developer is rubbed when the developer is formed as a thin layer on the developer carrying member by the layer thickness regulating member, so that the fluidity and the chargeability are reduced.
As the development is repeated, the ratio of the deteriorated developer having reduced fluidity or chargeability in the developer increases steadily with the consumption of the developer. Detects a limit at which the developer can be consumed in a state where at least the developer remains in the developing device.

[0008] The invention described in claim 2 is the first invention.
The present invention is characterized in that the developer carrier and the photoreceptor are arranged in contact with each other via a thin layer of the developer.

According to such a configuration, a visible image is formed by the thin layer of the developer formed on the developer carrier by the layer thickness regulating member coming into contact with the electrostatic latent image.

[0010] Further, the invention according to claim 3 is based on claim 1.
3. The invention according to claim 2, wherein the developing device includes a developing chamber for housing the developer carrier and the layer thickness regulating member, and the developer housing chamber and the developing chamber are provided in the developer housing chamber. The developer present in the developing chamber and the developer present in the developing chamber are communicated with each other through an opening through which the developer can pass through each other. Is configured to detect a limit at which the developer can be consumed in a state where the developer remains.

According to such a configuration, the developer existing in the developer accommodating chamber and the developer existing in the developing chamber can move back and forth through the opening. In a state where at least the developer remains in the developer accommodating chamber, that is, while the developer existing in the developer accommodating chamber and the developer existing in the developing chamber can come and go with each other, the developer is Detect the limits that can be consumed.

The invention described in claim 4 is the same as the invention described in claim 3.
Wherein the developer is a polymerized toner obtained by polymerizing a polymerizable monomer.

When the developer is a polymerized toner obtained by polymerizing a polymerizable monomer, the fluidity is extremely good because the particle diameter is uniform and close to a true sphere, as compared with a pulverized toner.

The invention described in claim 5 is the third invention.
Or in the invention according to 4, wherein the developer remaining amount detecting means is configured such that, in a state where the amount of the developer remaining in the developer accommodating chamber with respect to the amount of the developer remaining in the developing chamber is the same or larger, It is characterized in that it is configured to detect a limit at which the developer can be consumed.

According to such a configuration, the developer remaining amount detecting means performs the developing when the amount of the developer remaining in the developer accommodating chamber with respect to the amount of the developer remaining in the developing chamber is the same or larger. Detect the limit at which the agent can be consumed.

The invention described in claim 6 is the third invention.
In the invention according to any one of the first to fifth aspects, the developer remaining amount detecting unit includes an optical sensor including a light receiving unit and a light emitting unit, and the light receiving unit and the light emitting unit are provided in the developer accommodating chamber. The developer is accommodated in the developer accommodating chamber, and is disposed to face each other with respect to the volume of the developer that can exist in the developing chamber, and the developer is interposed between the light receiving unit and the light emitting unit. It is characterized in that the developer accommodating chamber, which is lower than the developer accommodating chamber, is provided at a position where the volume of the developer accommodating chamber is the same or larger.

According to this configuration, the limit of the amount of the developer that can be consumed when the amount of the developer stored in the developer storage chamber is equal to or larger than the amount of the developer existing in the development chamber is limited. Is detected.

[0018]

FIG. 1 is a side sectional view showing a main part of an embodiment of a laser printer as an image forming apparatus according to the present invention. In FIG. 1, a laser printer 1 includes a feeder unit 4 for supplying paper 3 and an image forming unit 5 for forming a predetermined image on the supplied paper 3 in a main body casing 2. .

The feeder unit 4 includes the main casing 2.
Paper tray 100 detachably mounted on the bottom of the paper tray
A sheet pressing plate 6 provided in the sheet feeding tray 100;
Paper feed roller 7 and paper feed pad 8 provided above one end of paper feed tray 100, and registration roller 9 provided downstream of paper feed roller 7 in the transport direction of paper 3.
And

The sheet pressing plate 6 is capable of stacking the sheets 3 in a stacked manner. The end farther from the paper feed roller 7 is swingably supported, and the end closer to the paper feed roller 7 is vertically movable. And is urged upward by a spring (not shown) from the back side. Therefore, as the stacking amount of the sheet 3 increases, the sheet pressing plate 6 is rotated downward against the urging force of the spring with the end remote from the sheet feeding roller 7 as a fulcrum. The paper feed roller 7 and the paper feed pad 8 are disposed to face each other, and the paper feed pad 8 is moved by a spring 10 disposed on the back side of the paper feed pad 8.
Is pressed toward the paper feed roller 7. The uppermost sheet 3 on the sheet pressing plate 6 is pressed from the back side of the sheet pressing plate 6 toward the sheet feeding roller 7 by a spring (not shown), and the sheet feeding roller 7 is rotated by the rotation of the sheet feeding roller 7. After being sandwiched between the pads 8, the sheet is fed one by one. The registration roller 9 includes two rollers on the driving side and the driven side. The registration roller 9 sends the sheet 3 sent from the sheet feeding roller 7 to the image forming unit 5 after a predetermined registration.

The image forming unit 5 includes a scanner unit 11, a developing unit 12, a fixing unit 13, and the like.

The scanner unit 11 is provided at an upper part in the main body casing 2 and has a laser emitting unit (not shown),
It includes a polygon mirror 14, which is driven to rotate, lenses 15 and 16, reflection mirrors 17, 18 and 19, and the like.
A laser beam based on predetermined image data emitted from the laser emitting section is indicated by a chain line as shown by a polygon mirror 14, a lens 15, reflection mirrors 17 and 18, and a lens 1
6. The light passes through or is reflected by the reflecting mirror 19 in this order to irradiate the surface of the photosensitive drum 21 of the developing unit 12 described later by high-speed scanning.

FIG. 2 is a side sectional view showing the developing unit 12 in an enlarged manner. Next, based on FIG.
2 will be described. In FIG. 2, a developing unit 12 is disposed below the scanner unit 11 and is detachably mounted on the main body casing 2.
0, a photosensitive drum 21 as a photosensitive member, a developing cartridge 36 as a developing device, a scorotron type charger 25,
A transfer roller 26 and the like are provided. Developing cartridge 3
6 is removably mounted on the drum cartridge 20 so that the developing cartridge 36 can be separated from the photosensitive drum 21 and the like.

In the developing cartridge 36, a developing chamber 51 accommodating the developing roller 22 as a developer carrying member, a layer thickness regulating blade 23 as a layer thickness regulating member and a supply roller 24, and a developer accommodating toner. It is partitioned into a toner storage chamber 27 as a storage chamber. The developing chamber 51 and the toner storage chamber 27 are partitioned by an upper partition wall 53 and a lower partition wall 54, and between the upper partition wall 53 and the lower partition wall 54 in the width direction. A substantially rectangular opening 52 extending is formed. This opening 5
Reference numeral 2 denotes the toner existing in the toner storage chamber 27 and the developing chamber 51.
Are open so that the toner existing in the toner storage chamber 27 and the toner existing in the developing chamber 51 can pass through the opening 52.
Are able to go back and forth through each other.

In the toner storage chamber 27, as a developer,
A positively chargeable non-magnetic one-component toner having an electrical insulating property is contained. If a positively charged toner is used, development can be performed on the positively charged photosensitive drum 21. That is, when a negatively charged toner is used, the photosensitive drum 21 needs to be negatively charged. For example, the photosensitive drum 21 is negatively charged in a non-contact state using a scorotron type charger 25. In this case, a large amount of ozone is generated, and in order to prevent the generation of ozone, if charging is performed using a conductive roller, a brush, or the like in a state of contact, uneven charging on the photosensitive drum 21 is caused. May occur. On the other hand, when the photosensitive drum 21 is positively charged, generation of ozone is extremely small even when the photosensitive drum 21 is charged in a non-contact state using the scorotron charger 25.
In addition, charging can be performed uniformly without charging unevenness. Therefore, by using a positively charged toner,
Ozone generation is small, and uniform development can be achieved.

The toner may be a polymerizable monomer, for example, a styrene monomer such as styrene, or an acrylic resin such as acrylic acid, alkyl (C1 to C4) acrylate, or alkyl (C1 to C4) methacrylate. To a styrene-acrylic spherical resin obtained by copolymerizing a monomer by a known polymerization method such as suspension polymerization, a coloring agent such as carbon black, a charge control agent such as nigrosine, and a wax are added. As a main component, a polymerized toner obtained by adding toner additives such as silica to toner base particles having a particle diameter of about 6 to 10 μm as a main component is used. Such a polymerized toner has a uniform particle diameter and is close to a true sphere as compared with a pulverized toner, and therefore has extremely good fluidity. Further, in this toner, fluidity and charge stability are improved by externally adding an external additive such as silica. In this embodiment, two types of silica to be externally added are used, one having a BET specific surface area of 200 and the other having a BET specific surface area of 50. BET specific surface area 5
The silica having a large particle of 0 prevents the small particle of silica from being embedded in the base particle.

The toner in the toner storage chamber 27 is
The toner is agitated by an agitator 29 supported on a rotating shaft 28 provided at the center of the toner storage chamber 27, and is discharged to a developing chamber 51 through an opening 52.

In the developing chamber 51, on the side close to the opening 52,
The supply roller 24 is disposed rotatably in the direction of the arrow (counterclockwise), and the developing roller 22 is disposed opposite to the supply roller 24 so as to be rotatable in the direction of the arrow (counterclockwise). ing. The supply roller 24 and the developing roller 22 are in contact with each other so that each of them is compressed to some extent.

The supply roller 24 has a metal roller shaft,
A roller made of a conductive foam material is covered. The developing roller 22 has a metal roller shaft covered with a roller made of a conductive rubber material. More specifically, the roller portion of the developing roller 22 has a coating layer of urethane rubber or silicone rubber containing fluorine on the surface of a roller body made of conductive urethane rubber or silicone rubber containing fine carbon particles or the like. Coated. By coating the surface of the developing roller 22 with a coat layer of urethane rubber or silicone rubber containing negatively chargeable fluorine, the positive chargeability of the toner carried on the surface is improved. Can be. A bias is applied to the developing roller 22 so that a potential difference is generated between the developing roller 22 and the photosensitive drum 21, and the resistance from the axis to the surface is about 10 ⁴ to 10 ⁸ Ω. Have been.

In the vicinity of the developing roller 22, a layer thickness regulating blade 23 is provided. The layer thickness regulating blade 23 has a blade body 37 made of a metal leaf spring material.
And a semicircular pressing portion 38 provided at the tip end of the blade main body 37 as a contact portion made of insulating silicone rubber. An end of the blade main body 37 opposite to the pressing portion 38 is provided. , Is supported by the developing cartridge 36 near the developing roller 22, and the pressing portion 3
8 is the developing roller 22 due to the elastic force of the blade body 37.
It is configured to be pressed against the top.

The toner discharged from the opening 52 into the developing chamber 51 is supplied to the developing roller 22 by the rotation of the supply roller 24. At this time, the friction between the supply roller 24 and the developing roller 22 becomes positive. The charged toner further supplied to the developing roller 22 enters between the pressing portion 38 of the layer thickness regulating blade 23 and the developing roller 22 with the rotation of the developing roller 22, and this layer The developing roller 22 is rubbed between the pressing portion 38 of the thickness regulating blade 23 and the developing roller 22, is sufficiently triboelectrically charged, and is carried on the developing roller 22 as a thin layer having a constant thickness. The thickness regulating blade 23
The toner rubbed between the pressing portion 38 and the developing roller 22 may have an external additive such as silica externally added to the toner embedded in the toner base particles, resulting in reduced fluidity. Alternatively, the chargeability is reduced. Further, a part of the toner carried on the developing roller 22 is used for the development, but the others are returned to the inside of the developing chamber 51 again without being used for the development.

On the other hand, the photosensitive drum 21 is
Are arranged rotatably in the direction of the arrow (clockwise) in a state of being in contact with the developing roller 22 in an opposing manner. The photosensitive drum 21 has a drum main body grounded and a surface formed of a positively chargeable material such as an organic photoreceptor containing polycarbonate as a main component. Further, the scorotron type charger 25 is connected to the photosensitive drum 2.
Above 1, they are arranged at predetermined intervals. The scorotron charger 25 is a scorotron charger for positive charging that generates corona discharge from a charging wire such as tungsten, and is configured to uniformly positively charge the surface of the photosensitive drum 21. Have been.

The surface of the photosensitive drum 21 is uniformly positively charged by the scorotron charger 25, and is then exposed by high-speed scanning of a laser beam from the scanner unit 11 to form an electrostatic latent image based on predetermined image data. An image is formed. Then, by the rotation of the developing roller 22, the toner that is carried on the developing roller 22 and is positively charged,
When the photosensitive drum 21 faces and contacts the photosensitive drum 21, the photosensitive drum 2
1 is selectively transferred to a portion of the electrostatic latent image formed on the surface of the photosensitive drum 21, that is, a portion of the uniformly positively charged photosensitive drum 21, which is exposed to a laser beam and has a reduced potential. Thus, a visible image is formed, whereby development (reversal development) is achieved. At this time, since a positively charged toner carried on the developing roller 22 contacts the photosensitive drum 21 to form a visible image, a reliable and accurate image is formed on the electrostatic latent image. A visible image can be formed.

Below the photosensitive drum 21, a transfer roller 26 facing the photosensitive drum 21 is disposed rotatably in the direction of the arrow (counterclockwise). Transfer roller 26
In FIG. 1, a metal roller shaft is covered with a roller made of a conductive rubber material, and a predetermined transfer bias is applied. Therefore, the toner developed on the photosensitive drum 21 is transferred to the sheet 3 while the sheet 3 passes between the photosensitive drum 21 and the transfer roller 26.

The fixing unit 13 is, as shown in FIG.
A heating roller 32, a pressing roller 31 pressed by the heating roller 32, and a pair of transport rollers 33 provided downstream of the heating roller 32 and the pressing roller 31; It has.
The heating roller 32 is made of metal and includes a halogen lamp for heating. The heating roller 32 transfers the toner transferred onto the sheet 3 in the developing unit 12 while the sheet 3 passes between the heating roller 32 and the pressing roller 31. Then, the sheet 3 is conveyed to a pair of sheet discharge rollers 34 by the conveying rollers 33. A pair of paper discharge rollers 34
Is discharged onto a paper discharge tray 35 by the paper discharge rollers 34.

In the laser printer 1, the toner remaining on the photosensitive drum 21 after the transfer of the visible image is collected by a so-called cleaner-less method. That is, in the cleanerless method, the toner remaining on the photosensitive drum 21 after the visible image is transferred is
First, the photosensitive drum 21 rotates to face the scorotron-type charger 25, and the scorotron-type charger 25 uniformly charges the photosensitive drum 21. Then, the photosensitive drum 21 rotates to face the developing roller 22. Developing roller 2
2, the toner is collected by the developing roller 22.

According to such a cleanerless recovery method, the toner remaining on the photosensitive drum 21, that is, the toner is rubbed between the pressing portion 38 of the layer thickness regulating blade 23 and the developing roller 22, and the fluidity is reduced. Or the deteriorated toner whose chargeability has been reduced returns to the inside of the developing chamber 51 again.

Therefore, in such a laser printer 1, as the image forming operation is repeated, the developing chamber 51
In the inside, the deteriorated toner (as described above, the toner that is not used for development after being rubbed between the pressing portion 38 of the layer thickness regulating blade 23 and the developing roller 22 or the developing chamber 51 is filled in the developing chamber 51 by a cleanerless method). The ratio of the returned toner) increases steadily with the consumption of the toner. For example, filming occurs on the photosensitive drum 21 due to poor fluidity, or the image quality is reduced. Cause roughness, and due to poor chargeability,
The image density is increased, which may cause character collapse or fog due to the generation of reverse polarity toner.

Therefore, in the present embodiment, in the above-described configuration, in a state where at least the toner remains in the developing cartridge 36, the limit that the toner can be consumed,
That is, the toner empty sensor 55 is provided as a developer remaining amount detecting means for detecting the toner empty. The toner empty sensor 55 detects that the toner remains in the toner storage chamber 27 at least and the amount of the toner remaining in the toner storage chamber 27 is equal to or larger than the amount of the toner remaining in the developing chamber 51. It is configured to detect empty.

That is, the toner empty sensor 5
5 is composed of an optical sensor having a light emitting section 60 having a light emitting element and a light receiving section 61 having a light receiving element. As shown in FIGS. 2 and 3, the light emitting section 60 and the light receiving section 6 are provided.
Reference numeral 1 denotes an outer side of a pair of light transmitting windows 58 and 59 provided opposite to both side walls 56 and 57 in the toner storage chamber 27 of the developing cartridge 36 so as to face the light transmitting windows 58 and 59, respectively. It is arranged.

The light transmitting windows 58 and 59 are provided on both side walls 56 and 57 of the toner storage chamber 27, and are configured so that the surfaces thereof can be wiped by rotating the cleaner 39. Further, the light transmission windows 58 and 59 are provided with a volume of toner that can exist in the developing chamber 51 (in FIG. The volume of the chamber 27 is indicated by an imaginary line 63), and is provided at a position where the volume is the same or larger. Such a position is appropriately determined by the volumes of the developing chamber 51 and the toner storage chamber 27.

The light emitting unit 60 and the light receiving unit 61
It is supported by a frame (not shown) of the main body case 2 so as to face the pair of light transmission windows 58 and 59 provided at such positions. Accordingly, the empty sensor 55 determines that the amount of toner remaining in the toner storage chamber 27 with respect to the amount of toner remaining in the developing chamber 51 is
In the same or more states, toner empty can be detected.

The toner empty sensor 55 is provided as shown in FIG.
As shown in the control system, while the amount of toner in the toner storage chamber 27 is large, the light emitted from the light emitting unit 60 is blocked by the toner in the toner storage chamber 27, so that the light is not received by the light receiving unit 61. Absent. Therefore, the output of the light receiving unit 61 based on the received light cannot be obtained. However, the toner storage chamber 2
In the case where the amount of toner 7 decreases, the light emitted from the light emitting unit 60 reaches the light receiving unit 61 every time the toner in the toner storage chamber 27 is stirred by the agitator 29. An output corresponding to the amount of received light is obtained. For example, the output of the light receiving section 61 can be obtained in the form of a pulse signal, and the pulse width is set to be wider as the toner amount is smaller. The output of the light receiving section 61 is monitored by the CPU 67 via the I / O 66 in the control section 65 as control means shown in FIG. The CPU 67 has a ROM 68 in which a program is stored.
And a RAM 69 used for storing data and the like. The CPU 67 measures the width of the pulse signal output from the light receiving unit 61 via the I / O 66 according to the program stored in the ROM 68, and stores the measured width in the RAM 69. ,
It is determined whether the stored pulse width value has exceeded a predetermined threshold value. When it is determined that the value of the pulse width has exceeded the predetermined threshold, the CPU 67
The detection of toner empty is output via O66, and a display urging replacement of the developing cartridge 36 is displayed on the display panel 70.

By providing such a toner empty sensor 55, even if the ratio of the deteriorated toner in the toner in the developing cartridge 36 increases steadily with the consumption of the toner as the image forming operation is repeated, the developing Since toner empty is detected in a state where the toner remains in the cartridge 36, compared to a case where the toner is consumed until the toner is exhausted, when the toner is developed with a small percentage of the deteriorated toner, It can be replaced with new toner.

That is, the toner remaining immediately before consumption is the deteriorated toner (as described above, the toner which is not used for development after being rubbed between the pressing portion 38 of the layer thickness regulating blade 23 and the developing roller 22). And the ratio of the toner returned to the developing chamber 51 by the cleanerless method) is considerably high, and if the toner is developed with such toner, filming occurs on the photosensitive drum 21. However, if the toner is replaced with a new toner when the toner remains in the developing cartridge 36, at least the toner is not developed by the remaining toner immediately before the toner is consumed. It is possible to always stably form an image without generating the image and improve the durability of the apparatus.

In particular, in the present embodiment, since the developing cartridge 36 and the photosensitive drum 21 are provided so as to be separable, the toner empty sensor 55 detects that the toner remains in the developing cartridge 36, In other words, if only the developing cartridge 36 is replaced with a new one at the time when the ratio of the deteriorated toner is still being developed with the small toner, the trouble caused by the deteriorated toner is less likely to be given to the photosensitive drum 21. Therefore, the use of the photosensitive drum 21 can be continued as it is. Therefore, the life of the photosensitive drum 21 can be extended, and the running cost can be significantly reduced while reducing the number of waste components.

In this embodiment, the developing chamber 5
1 and the toner storage chamber 27, the opening 52 opened between the toner storage chamber 27 and the toner existing in the toner storage chamber 27.
1, and the toner empty sensor 55 detects the toner empty in a state where the toner remains in the toner storage chamber 27 in such a state. .

That is, first, the toner existing in the toner storage chamber 27 and the toner existing in the developing chamber 51 can be moved back and forth through the opening 52.
Not only the unused toner in the toner chamber 27 can move to the developing chamber 51, but also the toner that has deteriorated in the developing chamber 51 can move to the toner chamber 27. Therefore, the deteriorated toner can be prevented from staying in the developing chamber 51, and the deteriorated toner can be repeatedly
And can be effectively prevented from being rapidly deteriorated by being rubbed by the pressing portion 38 and the developing roller 22.
The increase in the ratio of the deteriorated toner in the developing chamber 51 can be reduced.

In this manner, the toner storage chamber 27
Even in a state where the toner existing in the developing chamber 51 and the toner existing in the developing chamber 51 can move back and forth, the amount of the toner existing in the developing chamber 51 that returns to the toner storage chamber 27 with the consumption of the toner is small. When there is no toner in the toner storage chamber 27, in other words, when the toner does not remain in the toner storage chamber 27, as described above, the toner stays only in the developing chamber 51 and causes rapid deterioration. Therefore, the toner empty sensor 55 is in a state where the toner remains in the toner storage chamber 27, that is, while the toner existing in the toner storage chamber 27 and the toner existing in the developing chamber 51 can move back and forth. In addition, the toner empty is detected to prevent the toner from staying only in the developing chamber 51,
It is intended to stably form an image at all times and to improve the durability of the apparatus. In addition, in the present embodiment, since the polymerized toner having extremely good fluidity is used, the developing roller 22 and the supply roller 24 are used.
As a result, the toner in the developing chamber 51 circulates, and as a result, the toner existing in the toner storage chamber 27 and the toner existing in the developing chamber 51 move more smoothly. The stagnation only in the chamber 51 is further prevented.

Further, the empty sensor 55 is provided in the toner storage chamber 27, and its light receiving portion 60 and light emitting portion 61
Is provided at a position where the detectable volume of the toner in the toner storage chamber 27 is equal to or larger than the detectable volume of the toner in the developing chamber 51. When the amount of toner present in the developing chamber 51 with respect to the amount of toner stored is equal to or greater than the amount, the toner empty is detected. Therefore, at the time when the toner is developed with the toner having a small percentage of deteriorated toner, the toner can be replaced with new toner, and an image can be formed more stably.
The durability of the device can be improved. Further, in the present embodiment, the light emitting unit 60 and the light receiving unit 61 are arranged to face each other in the toner storage chamber 27, and the volume in the toner storage chamber 27 is the same as the volume of the toner that can exist in the developing chamber 51. Since the detection is performed by a configuration in which each of them is provided only at a position larger than or larger than that, the cost is reduced by simplifying the configuration.

In the present embodiment, since the developing roller 22 and the photosensitive drum 21 are opposed to each other in contact with each other, filming due to the deteriorated toner on the photosensitive drum 21 is likely to occur. By the detection of the toner empty sensor 55 as described above, only the developing cartridge 36 can be replaced with a new one at the time when the ratio of the deteriorated toner is still developed with the small toner. The photosensitive drum 21 can be used for a longer time while effectively preventing the occurrence.

Further, in the present embodiment, the light receiving portion 60 and the light emitting portion 61 of the toner empty sensor 55 are set to have a volume equal to or larger than the volume of the toner that can exist in the developing chamber 51 in the toner developing chamber 27. However, the position is not particularly limited as long as the position can be detected at least in a state where the toner remains in the developing cartridge 36. For example, the position is provided in the developing chamber 51. Alternatively, it may be provided at a position other than the above position in the toner developing chamber 27.
Further, in the present embodiment, an optical sensor including the light receiving unit 60 and the light emitting unit 61 is used as the developer remaining amount detecting unit. However, for example, the rotation resistance of the agitator 29 may be detected. Alternatively, an electrode may be provided at a predetermined position where it can come into contact with the toner, and the resistance value may be detected. Further, in the present embodiment, a display urging the replacement of the developing cartridge 36 is displayed on the display panel 70 after the detection, but for example, the apparatus may be stopped after the detection, or an external personal computer may be used. May be transmitted to the personal computer to perform predetermined processing such as display and stop.

In this embodiment, a positively charged toner is used. However, a negatively charged toner may be used, and a pulverized toner may be used instead of the polymerized toner.

[0054]

EXPERIMENTAL EXAMPLES The present invention will be described more specifically with reference to the following experimental examples, but the present invention is not limited to the following experimental examples. 1) Image Forming Apparatus A laser printer having the following configuration was used as the image forming apparatus.

The basic configuration is the same as that of the laser printer 1 described above.

Developing cartridge: Replaceable separately from drum cartridge Developing roller: Conductive urethane rubber roller with fluorine-based surface coating layer formed Supply roller: Conductive foamed urethane rubber Layer thickness regulating blade: Diameter for leaf spring 3.5 mm semi-cylindrical silicone rubber integrally molded Toner: Non-magnetic one-component toner, styrene-acryl copolymer spherical resin obtained by suspension polymerization, nigrosine as a charge control agent, Carbon and other waxes are added as a coloring agent, and silica having a BET specific surface area of 200 and 50 is externally added as an external additive.

However, silica has been subjected to a well-known surface treatment such as a silicone oil and a silane coupling agent.

Printing conditions: At a printing speed of 20 ppm (10 cm / sec as the peripheral speed of the photosensitive drum), intermittent printing of two sheets per minute was performed on the entire surface with a printing area ratio of 4%. 2) Evaluation First, prior to the evaluation, under the above printing conditions, 10
It was confirmed that the consumption amount of toner per 00 sheets was 25 g, and the remaining amount of toner in the toner cartridge when the toner in the toner storage chamber was exhausted was about 30 g.

In the developing cartridge, 125 g (equivalent to 5,000 sheets) and the toner corresponding to the remaining amount of toner shown in Table 1 were added in addition to the toner.
An endurance test for printing 000 sheets was performed. When printing of 5,000 sheets was completed, only the developing cartridge was replaced (the photosensitive drum was left as it was), a zip pattern of one dot and two spaces on the entire surface was printed, and the presence or absence of filming of the photosensitive drum was evaluated. With respect to the photosensitive drum having no filming, the durability test for printing 5,000 sheets was continued as it was, and the durability test was repeated until filming occurred. Table 1 shows the results. The presence or absence of filming of the photosensitive drum was determined based on whether or not vertical stripe-shaped density unevenness occurred in the zip pattern.

[0060]

[Table 1]

As is clear from Table 1, the life of the photosensitive drum can be extended by replacing the developing cartridge with the toner remaining in the developing cartridge. In other words, when the toner is completely used (toner remaining amount is 0), the life of the photosensitive drum and the developing cartridge become the same, and it is not meaningful to use separate cartridges. You can see that it is extended. In particular, when 60 g of the toner remains in the developing cartridge, no filming occurs up to 40,000 sheets. Therefore, the remaining toner in the toner storage chamber is equal to or more than the remaining toner in the developing chamber. It will be understood that the life of the photosensitive drum can be significantly extended if the toner cartridge is replaced during the process.

[0062]

As described above, according to the first aspect of the present invention, as the development is repeated, the ratio of the deteriorated developer whose fluidity or chargeability is reduced in the developer is increased. The developer remaining amount detecting means detects a limit at which the developer can be consumed in a state where the developer remains at least in the developing device. Therefore, compared to the case where the developer is consumed until the developer runs out, the developer can be replaced with a new developer at the point of time when the development is performed with the developer occupying a small percentage of the deteriorated developer. Therefore, an image can always be stably formed, and the durability of the apparatus can be improved.

That is, the developer remaining immediately before consumption has a considerably high proportion of deteriorated developer, and by being developed with such a developer, filming occurs on the photosensitive member, Alternatively, various problems such as image roughness, character collapse due to high image density, and fogging due to the generation of reverse polarity toner occur.
If the developer is replaced with a new developer at least at the time when the developer remains in the developing device, at least the developer is not developed by the remaining developer immediately before being consumed, and various problems as described above are solved. It is possible to always stably form an image without generation, and to improve the durability of the apparatus.

In particular, in the present invention, since the developing device and the photoreceptor are provided so as to be separable, the state where at least the developer remains in the developing device by the detection of the developer remaining amount detecting means, In other words, if the developer is replaced with a new one only when the developer is still developing with a small percentage of the deteriorated developer, the problem caused by the deteriorated developer is less likely to be given to the photoconductor. And the use of the photoreceptor can be continued as it is. Accordingly, the life of the photoconductor can be extended, and the running cost can be significantly reduced while reducing the number of waste components.

According to the second aspect of the present invention, the visible image is formed by the thin layer of the developer formed on the developer carrier by the layer thickness regulating member coming into contact with the electrostatic latent image. Therefore, a reliable and accurate visible image can be formed on the electrostatic latent image.

Further, in such a configuration, since the developer carrier and the photosensitive member are in contact with each other, filming due to the deteriorated developer is likely to occur on the photosensitive member. At the point where the ratio of deteriorated developer is still being developed with a small amount of developer, only the developing device can be replaced with a new one. Can be used longer.

According to the third aspect of the present invention, the developer existing in the developer accommodating chamber and the developer existing in the developing chamber can move back and forth through the opening. Not only the unused developer in the storage chamber can move to the development chamber, but also the deteriorated developer rubbed by the layer thickness regulating member and the developer carrier in the development chamber can move to the developer storage chamber. . Therefore, it is possible to prevent the deteriorated developer from staying in the developing chamber, and to effectively prevent the deteriorated developer from being repeatedly rubbed by the layer thickness regulating member and the developer carrier and rapidly deteriorated. In addition, it is possible to reduce the increase in the ratio of the deteriorated developer in the developing chamber, thereby always achieving stable image formation.

In this manner, even in a state where the developer existing in the developer accommodating chamber and the developer existing in the developing chamber can move back and forth with each other, the developing chamber is consumed with the consumption of the developer. In a state where the amount of the developer existing in the developer storage chamber is not large enough to return to the developer storage chamber, in other words, in a state where the developer does not remain in the developer storage chamber, as described above, the developer is stored only in the development chamber. It stays and causes rapid deterioration. For this reason, the developer remaining amount detecting unit is in a state where at least the developer remains in the developer accommodating chamber, that is, the developer existing in the developer accommodating chamber and the developer existing in the developing chamber come and go with each other. If it is possible to detect the limit of the amount of the developer that can be consumed while it is possible, the developer can be prevented from staying only in the developing chamber, and as a result, an image can be always stably formed. And the durability of the device can be improved.

According to the fourth aspect of the present invention, by using the polymerized toner having extremely good fluidity, the flow of the developer existing in the developer accommodating chamber and the developer existing in the developing chamber can be improved. It can be performed smoothly, and the developer can be further prevented from staying only in the developing chamber.

According to the fifth aspect of the invention, the developer remaining amount detecting means determines whether the amount of the developer remaining in the developer accommodating chamber is equal to or less than the amount of the developer remaining in the developing chamber. Since the limit at which the developer can be consumed is detected in a larger number of states, the developer can be replaced with a new one at the time when the developer is further developed with a smaller percentage of the deteriorated developer. Therefore, an image can be formed more stably and the durability of the apparatus can be improved.

According to the sixth aspect of the present invention, the developer can be consumed when the amount of the developer accommodated in the developer accommodating chamber is equal to or larger than the amount of the developer existing in the developing chamber. Since the limit is detected by the optical sensor, a new developer can be exchanged for a new developer when the developer is further developed with a smaller percentage of deteriorated developer, and an image can be formed more stably. And the durability of the device can be improved.

Further, the light-emitting portion and the light-receiving portion of the optical sensor are arranged to face each other with the developer contained in the developer containing chamber interposed therebetween.
Since the detection can be performed by a configuration in which each of the developer accommodating chambers is provided at a position where the volume of the developer accommodating chamber is the same or larger, the cost can be reduced by simplifying the configuration.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a main part of an embodiment of a laser printer including a developing device of the present invention.

FIG. 2 is an enlarged side sectional view showing a developing unit.

FIG. 3 is an explanatory diagram illustrating a schematic configuration of a toner empty sensor and a control system.

DESCRIPTION OF REFERENCE NUMERALS 1 laser printer 21 photosensitive drum 22 developing roller 23 layer thickness regulating blade 38 pressing part 27 toner storage chamber 36 developing cartridge 51 developing chamber 52 opening

Claims (6)

[Claims] 1. A developer accommodating chamber for accommodating a non-magnetic one-component developer, a developer carrier for carrying a developer, and a layer thickness regulating member for forming a thin layer of the developer on the developer carrier. And a photoreceptor on which an electrostatic latent image is formed. An electrostatic latent image is formed on the thin layer of the developer formed on the developer carrier by the layer thickness regulating member. An image forming apparatus configured to form a visible image by being opposed to the photosensitive member, wherein the developing device and the photosensitive member are provided so as to be separable, and the developing device is provided in the developing device. An image forming apparatus comprising: a developer remaining amount detecting unit that detects a limit at which the developer can be consumed in a state where at least the developer remains. 2. The image forming apparatus according to claim 1, wherein the developer carrier and the photoconductor are disposed in contact with each other via a thin layer of the developer. apparatus. 3. The developing device includes a developing chamber for accommodating the developer carrying member and the layer thickness regulating member, wherein the developer accommodating chamber and the developing chamber are present in the developer accommodating chamber. The developer and the developer present in the developing chamber are communicated with each other through an opening through which the developer can pass. The developer remaining amount detecting unit is configured such that the developer remains in at least the developer accommodating chamber. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to detect a limit at which the developer can be consumed in a state in which the developer is consumed. 4. 4. The image forming apparatus according to claim 3, wherein the developer is a polymerized toner obtained by polymerizing a polymerizable monomer. 5. The developer remaining amount detecting means, wherein the amount of the developer remaining in the developer accommodating chamber with respect to the amount of the developer remaining in the developing chamber is the same or larger,
The image forming apparatus according to claim 3, wherein the image forming apparatus is configured to detect a limit at which the developer can be consumed. 6. The developer remaining amount detecting unit includes an optical sensor having a light receiving unit and a light emitting unit, wherein the light receiving unit and the light emitting unit are provided in the developer accommodating chamber.
The developer is accommodated in the developer accommodating chamber with the developer accommodated therebetween, and is interposed between the light receiving unit and the light emitting unit with respect to the volume of the developer that can exist in the developing chamber. 6. The developer storage chamber according to claim 3, wherein a volume of the developer storage chamber, which is lower than a part of the developer storage chamber, is provided to be the same or larger. Image forming device.