HK1068170B - Image forming apparatus - Google Patents

Description

Image forming apparatus with a plurality of image forming units

Technical Field

The present invention relates to an image forming apparatus including a recording medium storing section.

Background

In laser printers and copiers, there is a photosensitive element that is charged in an image forming unit. In the image forming unit, an electrostatic latent image is formed on a photosensitive element by exposure to a laser beam or a Light Emitting Diode (LED) beam. The latent image is developed (a) with a developing medium such as toner, transferred from the photosensitive element to a recording medium such as paper (b), and then heated and completely transferred to the recording medium (c) with a fixing device. With this method, an image is formed on the recording medium.

Such an image forming apparatus includes a process unit for forming respective portions integrally for image formation and a developing cartridge accommodating a developing medium. The process unit and the developing cartridge are detachably attached to the image forming apparatus, facilitating the process and maintenance of the image forming apparatus. A paper cassette for storing recording paper on which an image is formed is also attached to the image forming apparatus.

The paper tray and the processing unit are independently removed from or inserted into the laser printer because they are placed in different places. However, it is preferable to take out and insert the paper tray and the process unit from the front of the laser printer in view of user convenience. In japanese patent laid-open No. 2000-250378, there is provided a paper tray which is located at a lower portion of a body and is connected from a front face of the body. When the front cover located in front of the body is rotated downward to sufficiently open the inside, the processing unit is taken out of or inserted into the body.

However, when a jam occurs, both the paper tray and the process unit should be removed in order to clear the jam. Since the paper tray and the front cover are configured differently from each other, the paper tray may not be opened due to interference generated by the front cover when the front cover is opened. Thus, the paper tray and the front cover cannot be simultaneously opened, and it is difficult to remove the paper jam. In addition, if the front cover and the paper tray are simultaneously kept open by one device, a different operation is required to open them, which affects the convenience of the user.

Disclosure of Invention

Therefore, the present invention provides, among other devices, an image forming apparatus in which a cover portion for blocking opening of a storage portion of an exchange unit is provided in a recording medium storage member so that the storage portion is opened or closed in accordance with loading and unloading of the recording medium storage member.

According to one embodiment of the present invention, the present invention includes a housing having a first opening and a second opening; a receiving portion formed on the body, wherein the first opening communicates with the receiving portion; a replacement unit detachably connected to the accommodating portion through the first opening; a paper tray accommodating portion formed on the body, wherein the second opening communicates with the paper tray accommodating portion; and a paper tray disposed in the paper tray accommodating portion and movable between a first position and a second position with respect to the body, wherein the paper tray further includes a fixing portion in which a recording medium is fixed; and a cover portion that covers the first opening when the paper tray is in the first position.

According to another embodiment of the present invention, the present invention includes a housing having a first opening and a second opening; a process cartridge (processcartridge) detachably coupled to the body and passing through the first opening; and a paper tray movable between a first position and a second position relative to the second opening of the body, wherein an outer wall of the paper tray covers the first opening when the paper tray is in the first position.

Drawings

Embodiments of the invention are described in detail below with reference to the following drawings, in which:

fig. 1 is a perspective view showing an appearance of a laser printer 1 according to the present invention.

Fig. 2 is a sectional view of the general structure of the laser printer 1 according to the present invention.

Fig. 3 is a sectional view of the paper tray viewed from the direction of the attached arrows along the broken line I-I in fig. 2 when the cover 100 is pulled open.

Fig. 4 is a sectional view taken along the broken line I-I in fig. 2, viewed in the direction of the attached arrows.

Fig. 5 is a sectional view showing attachment and detachment of the drum core 17a and the developing cartridge 17 b.

Fig. 6 is a perspective view of the laser printer 1 for manual sheet feeding printing.

Fig. 7 is a sectional view showing the paper tray when the cover 100 is pulled open to replenish the paper 3.

Fig. 8 is a perspective view showing the paper tray when the cover 100 is pulled open to replenish the paper 3.

Fig. 9 is a sectional view showing the paper tray when the cover 100 is pulled open to mount the process cartridge 17.

Fig. 10 is a perspective view showing the paper tray when the cover 100 is pulled open to mount the process cartridge 17.

Fig. 11 is a perspective view showing an external appearance of a laser printer 201 according to the present invention.

Fig. 12 is a perspective view showing the paper tray 230 of the laser printer 201 opened.

Fig. 13 is a sectional view of the general structure of a laser printer 201 according to the present invention.

Fig. 14 is a sectional view showing one structure of the locking mechanism of the sheet tray 230.

Fig. 15 is a sectional view showing the structure of the locking mechanism of the sheet tray 230.

Fig. 16 is a sectional view showing the paper tray when the cover 200 is pulled open.

Fig. 17 is a perspective view showing the sheet tray when the cover 200 is pulled open to replenish the sheet 3.

Fig. 18 is a perspective view showing the paper tray when the cover 200 is pulled open to mount the process cartridge 17.

Fig. 19 is a sectional view showing the paper tray when the cover 200 is pulled open and the paper tray 230 is in an open state.

Fig. 20 is a perspective view showing the paper tray when the cover 200 is pulled open and the paper tray 230 is in an open state.

Fig. 21 is a perspective view showing an external appearance of a laser printer 301 according to the present invention.

Fig. 22 is a perspective view of the laser printer 301 according to the present invention with the cover plate portion 310 opened.

Fig. 23 is a sectional view of the general structure of a laser printer 301 according to the present invention.

Fig. 24 is a cross-sectional view of one locking mechanism of the cover portion 310.

Fig. 25 is a cross-sectional view of the locking mechanism of the cover portion 310.

Fig. 26 is a sectional view of the locking mechanism of the cover portion 310.

Fig. 27 is a sectional view showing the paper tray when the cover 300 is pulled open.

Fig. 28 is a perspective view showing the sheet tray when the cover 300 is pulled open to replenish the sheet 3.

Fig. 29 is a perspective view showing the paper tray when the cover 300 is pulled open to mount the process cartridge 17.

Fig. 30 is a sectional view showing the cover portion 310 opened when the paper tray is not pulled open and the cover 300 is pulled open.

Fig. 31 is a perspective view showing the cover plate portion 310 opened when the paper tray is not pulled and the cover 300 is pulled.

Fig. 32 is a sectional view showing the paper tray when the cover 300 is pulled open and the cover plate portion 310 is in an open state.

Fig. 33 is a perspective view showing the paper tray when the cover 300 is pulled open and the cover plate portion 310 is in an open state.

Fig. 34 is a perspective view showing an external appearance of a laser printer 401 according to the present invention.

Fig. 35 is a perspective view showing the paper tray 430 of the laser printer 401 opened.

Fig. 36 is a perspective view showing the cover plate portion 410 of the laser printer 401 opened.

Fig. 37 is a sectional view of the general structure of a laser printer 401 according to the present invention.

Fig. 38 is a sectional view showing the paper tray when the cover 400 is pulled open.

Fig. 39 is a perspective view showing the sheet tray when the cover 400 is pulled open to replenish the sheet 3.

Fig. 40 is a perspective view showing the sheet tray when the cover 400 is pulled open to mount the process cartridge 17.

Fig. 41 is a sectional view showing the cover portion 410 opened when the paper tray is not pulled and the cover 400 is pulled.

Fig. 42 is a perspective view showing the cover plate portion 410 opened when the paper tray is not pulled and the cover 400 is pulled.

Fig. 43 is a sectional view showing the paper tray when the cover 400 is pulled open and the cover portion 410 is in an open state.

Fig. 44 is a perspective view showing the paper tray when the cover 400 is pulled open and the cover plate portion 410 is in an open state.

Fig. 45 is a sectional view showing the paper tray when the cover 400 is pulled open and the paper tray 430 is in an open state.

Fig. 46 is a perspective view showing the paper tray when the cover 400 is pulled open and the paper tray 430 is in an open state.

Fig. 47 is a sectional view of the entire structure of the laser printer 401.

Fig. 48 is a sectional view seen from the direction of the attached arrows along the broken line II-II in fig. 47.

Fig. 49 is a sectional view showing a modification of the drive force transmission mechanism, which is viewed from the direction of the attached arrow along the broken line II-II in fig. 47.

Fig. 50 is a perspective view of the laser printer 1 on which the image reading device 501 is mounted.

Fig. 51 is a perspective view of the laser printer 1 on which the image reading device 501 is mounted when replenishing the sheet 3.

Fig. 52 is a perspective view showing the attachment and detachment of the process cartridge 17 in the laser printer 1 to which the image reading apparatus 501 is attached.

Detailed Description

Hereinafter, a first preferred embodiment of an image forming apparatus employing the present invention will be described with reference to the accompanying drawings. First, the overall structure of a laser printer 1 as an example of an image forming apparatus of the first embodiment will be described with reference to fig. 1 to 5. In the following drawings, the-Z direction represents the front side of the laser printer, the-X direction represents the left side, the + X direction represents the right side, the + Z direction represents the rear side, the + Y direction represents the upper side, and the-Y direction represents the bottom side.

As shown in fig. 1, the laser printer 1 of the first embodiment has a substantially rectangular solid shape. The cover portion 110 is disposed in front of the body 2 of the laser printer 1. The cover portion 110 covers the opening of the accommodating portion 55 designed to detachably place the process cartridge 17. The cover portion 110 is a substantially rectangular plate-like member which completely covers the front of the laser printer 1 as viewed from the front, and which has gripping portions (holding ports) 112, 113 at upper and lower intermediate edge portions thereof for opening and closing the cover portion 110. The cover portion 110 further includes a slit opening 111 which is located substantially at the middle of the cover portion 110 in the up-down direction, and is a long and narrow opening formed on the left and right for inserting the sheet 3 in manual sheet feeding printing.

As shown in fig. 2, a box-like sheet tray portion 120 for storing sheets 3 is detachably attached to the lower portion 56 of the body 2. The paper tray portion 120 can be taken out from the front side of the body 2. The sheet tray portion 120 includes a sheet holding portion (sheet holding portion) that holds sheets 3 stacked therein. The sheet fixing portion has a pressing plate 122 that causes the sheet 3 to press against a sheet feeding roller 8 provided at the bottom inside the body 2. The platen 122 is pivotally supported at its distal end from the paper feed roller 8 at the bottom of the paper tray portion 120 so that the platen can move vertically at its end closest to the paper feed roller 8. The platen 122 is urged toward the sheet-feeding roller 8 from its reverse, or bottom, by a spring 123.

The cover portion 110 is fixed to the front of the paper tray portion 120 such that its surface is perpendicular to the bottom of the paper tray portion 120. The paper tray portion 120 and the cover portion 110 constitute a paper tray with the cover 100. The cover portion 110 is loaded or unloaded from the body 2 according to the forward and backward movement of the paper tray 120. The cover portion 110 opens and closes the opening of the accommodating portion 55, and when the paper tray with the cover 100 is mounted, it serves as a decorative plate in front of the laser printer 1.

Between the cover portion 110 and the sheet fixing portion in the sheet tray portion 120, there is provided a passage opening 121 which penetrates the sheet tray portion 120 in the up-down direction (in the Y direction in fig. 2). The passage opening 121 is a narrow passage extending in the width direction (in the X direction in fig. 1) of the sheet tray portion 120, and forms a part of a sheet conveying path so that the sheet 3a stored in the lower sheet tray 150 is conveyed into the body 2 when forming an image on the sheet 3 a.

The grip portions 112, 113 are grooves provided at the upper end (toward the + Y direction) and the lower end (toward the-Y direction) of the cover portion 110, respectively, so that a user can put fingers in or grip it to slide the paper tray with the cover 100 toward the front side (-Z direction). The shutter plate 114 is provided on the rear side (+ Z direction) of the grip portion 112, and a known optical sensor 2a is further provided on the body 2 to detect whether light is blocked by the shutter plate 114. When the paper tray with the cover 100 is loaded into the body 2, the cover portion 110 closes the accommodating portion 55, and the shutter plate 114 blocks light emitted from the photosensor 2a so that the light receiving portion (1 light receiving portion) (not shown) does not receive light. When the paper tray with the cover 100 is not connected to the body 2, the light is not blocked. The state in which the cover portion 110 is opened and closed can be detected using a signal of the photo sensor. Further, the optical sensor 2a can also detect the state of loading and unloading the paper tray section 120 integrated with the cover plate section 110.

The opening of the slit opening 111 provided substantially at the height center of the cover portion 110 allows the paper 3b to be printed to be manually inserted through the slit opening 111 so that the leading end edge of the paper 3b reaches the nip portion between the resist rollers 12 when manual feed printing is performed. The slit opening also forms a part of the conveying path P.

As shown in fig. 3, the paper tray with the cover 100 can slide in and out of the body 2 in the Z direction, so that both side surfaces 124 (in the X direction) of the paper tray portion 120 are slidably supported by the inner walls on both sides of the body 2. Stoppers 2b are provided on inner walls of both sides of the body 2 for positioning and temporarily fixing the paper tray with the cover 100 when the paper tray with the cover 100 is loaded. The stopper 2b is a rod-like member supported in such a manner as to swing in the X-axis direction in both side surfaces of the body 2. The brake 2b is provided with mutually opposed bosses 2c on its free end. The spring 2d behind each boss 2c pushes the stopper 2b so that the bosses 2c protrude from openings of both side inner walls of the body 2.

The recessed portions 125 are provided on both side surfaces of the paper tray portion 120 near the cover plate portion 110. As shown in fig. 4, when the paper tray with the cover 100 is placed in the body 2, the bosses 2c of the stopper 2b are engaged with the corresponding recessed portions 125, and the paper tray with the cover 100 is thereby positioned and temporarily fixed. The bosses 2c are spherical at their respective ends, and the recessed portion 125 is bowl-shaped. Thus, when the X-axis force applied to each recess 125 of the corresponding stopper 2b is larger than the urging force of each spring 2d (in other words, the force of fixing the paper tray), the paper tray with the cover 100 can be pulled out.

As shown in fig. 2, above the paper cassette 120 in the body 2, a circuit board 39 for electrically controlling the laser printer is disposed, which is equipped with a control circuit board and a main circuit board. A carriage 40 that guides the conveyance of the sheet 3 covers the upper portion of the circuit board 39. The upper surface of the sheet feeding frame 40 forms a part 40a of the conveying path, which is disposed substantially upstream of the conveying roller 30 in the middle; a portion 40b is also formed, which is downstream of the transfer roll 30. The sheet feeding tray 40 also forms a part of the sheet conveying path P so that the sheet 3 supplied from the sheet cassette portion 120 by the sheet feeding rollers is guided into the fixing unit 18. The resist roller 12 is provided on the conveying path 40a, where the feed timing of the sheet 3 to be printed can be adjusted.

The image forming portion is composed of a scanner unit 16, a process cartridge 17, and a fixing unit 18. The scanning unit 16 is disposed below the delivery table 46 in the body 2, and has a laser light generating portion (not shown) that emits laser light; a rotating polygon mirror 20 for scanning the laser light emitted from the laser light generating section in a main scanning direction; an f θ lens 21 stabilizing a scanning speed of the polygon mirror 20 for scanning the laser light; a cylindrical lens 22 for correcting an angle error of the optical surface in a sub-scanning direction when laser light is irradiated onto a photosensitive drum 27 for forming an image, and mirrors 23, 24 for reflecting the laser light and changing an optical path thereof. The scanner unit 16 is designed such that the laser light emitted from the laser light generating section based on the print data passes through or is reflected by optical devices, which are, in the order indicated by broken lines in fig. 2: a polygon mirror 20, an f θ lens 21, a cylindrical lens 22, and reflecting mirrors 23, 24. Thus, the laser beam is directed to the surface of the photosensitive drum 27 in the process cartridge 17.

The process cartridge 17 in the image forming portion includes a drum core 17a and a developing cartridge 17b, which is detachable from the drum core 17a, and is placed in an accommodating portion 55 formed between the scanner unit 16 and the sheet feeding tray 40. The drum core 17a includes a photosensitive drum 27, a scorotron charger 29, and a cleaning roller 28. The developing cartridge 17b includes a developing roller 31, a paper feed roller 33, and a toner hopper 34.

The photosensitive drum 27 in the drum core 17a is arranged so as to contact the developing roller 31 and rotate in the arrow direction (clockwise direction) in fig. 2. The photosensitive drum 27 is a positively charged photosensitive member formed by covering a positively charged photosensitive member on a conductive material base layer in which a charge generating material is dispersed. When the photosensitive drum 27 is irradiated with a laser beam, electric charges are generated in the charge generating material due to the laser adsorption. The electric charge is transferred to the surface of the photosensitive drum 27 and the conductive material base layer in the charge transfer layer, and the surface potential charged on the scorotron charger 29 is canceled. Therefore, a potential difference is generated between the potential of the portion irradiated with the laser beam and the potential of the portion not irradiated with the laser beam. The laser beam is controlled based on the print data, so that an electrostatic latent image is formed.

The Scorotron charger 29 is disposed above and apart from the photosensitive drum 27 at a position opposite to the photosensitive drum 27 by a predetermined distance. The Scorotron charger 29 generates a corona discharge through a discharge wire, such as made of tungsten. When printing is performed, a bias is applied to the Scorotron charger 29 so that the surface of the photosensitive drum 27 is uniformly positively charged.

When the developing cartridge 17b is attached to the drum core 17a, as shown in fig. 5, the developing cartridge 17b is fitted and fixed to the bottom surface of the drum core 17a, and the photosensitive drum 27 in the drum core 17a is disposed opposite to the developing roller 31 in the developing drum 17 b. As shown in fig. 2, they are arranged in the image forming portion of the process cartridge 17 such that the photosensitive drum 27 is opposite to the transfer roller 30. In this case, the developing roller 31 is disposed downstream of the Scorotron charger 29 in terms of the rotational direction of the photosensitive drum 27 (clockwise in the drawing), and rotates in the direction indicated by the arrow (counterclockwise in the drawing). The developing roller 31 is made by covering a conductive rubber material on a metal shaft, and receives a developing bias (developing bias) when performing printing.

The ink supply roller 33 is rotatably disposed on one side of the developing roller 31 and opposite to the photosensitive drum 27, and is in contact with the developing roller 31 so as to be pressed against the developing roller 31 for deformation. The ink supply roller 33 is made of a metal roller shaft and a roller formed of a conductive foam material, and the metal roller shaft is covered with the roller. The ink supply roller 33 is designed to charge toner supplied to the developing roller by friction. For this reason, the ink supply roller 33 is set to rotate in the arrow direction (counterclockwise in fig. 2), which is the same direction as the developing roller 31.

The toner hopper 34 is disposed on one side of the ink supply roller 33, and contains therein a developing medium to be supplied to the developing roller 31 through the ink supply roller 33. In this embodiment, a positively charged non-magnetic single component toner is used as the developing medium. The toner is a polymer toner obtained by copolymerization of a styrene-based monomer such as styrene and an acrylic-based monomer such as acrylic acid, alkyl (C1-C4) acrylate, and alkyl (C1-C4) methacrylate, using a known polymerization method such as suspension polymerization. Such polymer toner has a spherical particle shape and a particle size of about 6 to 10 μm. Colorants such as carbon black and waxes are added to the polymer toner. An external additive such as silica is further added to the polymer toner to improve fluidity.

The toner hopper 34 is internally divided into two chambers, each equipped with an agitator 36. The agitator 36 is a substantially net-shaped plate-shaped member which extends in the axial direction and rotates about an axis at one end in the clockwise direction shown in fig. 2, so that the thin sheet member 35 attached to the other end of the agitator 36 sweeps on the inner wall of the toner hopper 34 to agitate the toner contained in the toner hopper 34.

The cleaning roller 28 is disposed on one side of the photosensitive drum 27, which is located upstream of the charger 29 in terms of the rotational direction of the photosensitive drum 27. In printing, by applying a cleaning bias (cleaning bias), the cleaning roller 28 electrically adsorbs the toner remaining on the surface of the photosensitive drum 27 without transferring to the paper, so that these toners are electrostatically adsorbed on the surface of the cleaning roller 28. When printing is not performed, a potential different in direction is generated by applying a reverse cleaning bias so that toner is attracted from the cleaning roller 28 onto the photosensitive drum 27, and the cleaning roller 28 causes toner to adhere to the surface of the photosensitive drum 27. The toner returned from the cleaning roller 28 to the photosensitive drum 27 is collected by the developing roller 31.

The transfer roller 30 is disposed downstream of the developing roller 31 and below the photosensitive drum 27 in the rotational direction of the photosensitive drum 27. The transfer roller 30 is rotatably supported in the body 2 in the arrow direction (counterclockwise) so as to fit in a recessed portion of the upper surface of the sheet feeding frame 40. The transfer roller 30 is made by coating a roller formed of an ion conductive rubber material on a metal roller shaft, and is structured so as to receive a transfer bias (transfer bias) when printing is performed. The transfer bias is a bias applied to the transfer roller 30 so that a potential difference is generated in a direction such that the toner electrostatically adhering to the surface of the photosensitive drum 27 is electrically attracted to the surface of the transfer roller 30.

The fixing unit 18 includes a fixing roller 41 diagonally disposed downstream of the process cartridge 17 and a pressure roller 42 that presses the fixing roller 41. The fixing roller 41 is formed by coating a fluorinated resin on a hollow aluminum tube and sintering, and it has a halogen lamp 41a for heating the inside of the roller. The pressure roller 42 is a roller formed by coating a roller made of low-hardness silicone rubber on a metal shaft, and a tube made of fluorinated resin on the roller. Since the shaft of the pressure roller 42 is pushed up by a spring (not shown), the pressure roller 42 is pressed against the fixing roller 41. In the fixing unit 18, the toner transferred to the sheet 3 in the process cartridge 17 is melted and fixed on the sheet 3 because of being heated while the sheet 3 passes through a gap portion between the fixing roller 41 and the pressure roller 42, and then the sheet 3 is sent to the delivery path 44.

The sheet delivery path 44 is provided at the rear of the body 2 (left side in fig. 2), which is a half arc upward along the rear of the body 2, so that the sheet 3 fed from the fixing unit 18 at the lower rear of the body 2 is drawn to a sheet delivery table 46 at the upper portion of the body 2. The sheet discharge roller 45 is provided at the downstream end of the sheet discharge path 44, and feeds the sheet 3 to the sheet receiving table 46.

The lower paper tray 150 is detachably attached to the laser printer 1 below the paper tray with the cover 100, and is used to load the paper 3a other than the paper 3. The lower tray 150 is constituted by a tray portion 170 for loading the stacked sheets 3a and a front panel 160 as a decorative panel at the front of the laser printer 1. The paper tray portion 170 is supported in such a manner that side surfaces (in the front-to-rear direction in the drawing) of both sides of the paper tray portion 170 can slide along support walls (not shown) extending downward from both sides of the body 2 and connected thereto. The paper tray portion 170 can move forward and backward so that the paper tray portion 170 can be attached to and detached from the front of the body 2.

A paper feed roller 174 is provided at a front end portion of the paper tray portion 170 of the lower paper tray 150. Like the paper tray with the cover 100, the paper tray portion 170 is provided with a pressing plate 172 and a spring 173 that applies an urging force to the pressing plate 172 from the back thereof. Thus, the stacked sheet 3a is pressed against the sheet feeding roller 174. To pull the sheet 3a to the path 121 of the paper cassette with the cover 100, a paper feed path 171 is provided along the outer periphery of the paper feed roller 174. The paper feed path 171 and the path 121 form a part of the paper transport path P, whereby the paper 3a is drawn to the resist roller 12. At the lower end of the front panel 160, a grip portion 161 is provided so that a user can grip it to install and remove the paper tray 150, like the paper tray with the cover 100.

Referring to fig. 2 to 6, the operation of the laser printer 1 at the time of printing is briefly explained. Fig. 6 is a perspective view of the laser printer 1 for manual sheet feeding printing. When printing is started based on print data received from a host computer (not shown), the paper 3 is fed to the resist roller 12 by friction force as the paper feed roller 8 rotates.

In the scanner unit 16, a laser generating section (not shown) generates a laser beam according to a laser driving signal generated based on print data, and the laser beam is irradiated onto the polygon mirror 20. The polygon mirror 20 scans the incident laser beam in the main scanning direction (perpendicular to the conveying direction of the sheet 3) and then guides it to the f θ lens 21. The f θ lens 21 converts the laser beam scanned at a constant angular velocity into a laser beam to be scanned at a constant velocity. Then, the laser beam is converged on the cylindrical lens 22, and is guided to the surface of the photosensitive drum 27 by the mirrors 23, 24 to form an image.

The photosensitive drum 27 is charged by a Scorotron charger 29 so that the surface potential is, for example, about 1000V. The photosensitive drum 27 rotating in the direction of the arrow (clockwise in fig. 2) is irradiated with a laser beam. The laser beam emitted in the main scanning direction is such that it is incident on a portion where an image is formed and is not incident on a portion where an image is not formed. At the portion irradiated with the laser beam (exposed portion), the surface potential drops to, for example, 200V. By the rotation of the photosensitive drum 27, the laser beam is also irradiated in the sub-scanning direction (the direction in which the sheet 3 is conveyed), and an invisible image, i.e., a latent image, is electrically formed between the exposed portion on the surface of the photosensitive drum 27 and the portion (unexposed portion) that is not irradiated with the laser beam.

Toner in the toner hopper 34 is supplied to the ink supply roller 33 by rotating the agitator 36, and is supplied to the developing roller 31 by the rotation of the ink supply roller 33. At this time, the toner is positively charged between the supply roller 33 and the developing roller 31 due to the friction, forms a thin layer of a predetermined thickness, and adheres to the developing roller 31. By the rotation of the developing roller 31, the positively charged toner carried by the developing roller 31 comes into contact with the photosensitive drum 27 and is transferred onto the electrostatic latent image formed on the surface of the photosensitive drum 27. That is, the potential of the developing roller 31 is lower than the potential of the unexposed portion (+1000V) and higher than the potential of the exposed portion (+200V), so the toner is selectively transferred to the exposed portion having a low potential. Thus, a visible image, which is an image of the developing medium obtained by the toner, is formed on the surface of the photosensitive drum 27.

The resist roller 12 blocks the sheet 3, and feeds the sheet 3 when the leading edge of the visible image formed on the surface of the rotating photosensitive drum 27 is aligned with the leading edge of the sheet 3. When the sheet 3 passes through the photosensitive drum 27 and the transfer roller 30, a constant negative current is applied to the transfer roller 30, so that the potential of the transfer roller 30 is reduced to, for example, -1000V, lower than the potential of the exposed portion (+ 200V). Thus, the visible image formed on the surface of the photosensitive drum 27 is transferred to the sheet 3.

The sheet 3 to which the toner has been transferred is sent to the fixing unit 18. The fixing unit 18 heats and pressurizes the sheet 3 at a temperature of about 200 c, supplied by a fixing roller 41, and a pressure roller 42, so that the toner melts on the sheet 3 to form an external image. The fixing roller 41 and the pressure roller 42 are grounded through respective diodes, which are arranged such that the surface potential of the pressure roller 42 is lower than that of the fixing roller 41. In this way, the toner positively charged on the side of the sheet 3 opposite to the fixing roller 41 is electrically attracted toward the pressure roller 42 by the pressure roller 42 through the sheet 3, thereby preventing image deformation occurring when the toner is attracted toward the fixing roller 41 in fixing.

The sheet 3 on which the toner is melted and fixed by the fixing unit 18 is conveyed along the sheet discharge path 44, is discharged to the sheet receiving table 46 by the sheet discharge roller 45, and has the print surface facing downward. Similarly, the next printed sheet 3 is stacked with the print surface facing downward on the sheet delivery table 46. In this way, the user can obtain the printed sheets 3 in the order of printing.

For manual feed printing, as shown in fig. 6, the paper 3a is inserted into the slit opening 111 of the cover portion 100. When the resistance is felt by the inserted sheet 3a, the leading edge of the sheet 3a reaches the gap portion between the resistance rollers 12 shown in fig. 2. In this state, if the above-described print job is executed, the user can obtain the printed sheet 3 b.

The replenishment of the paper 3 and the insertion and removal of the process cartridge 17 in the laser printer 1 are explained below with reference to fig. 7 to 10. Fig. 7 is a sectional view of the laser printer 1 in which the paper cassette with the cover 100 is pulled out from the body 2 to replenish the paper 3. Fig. 8 is a perspective view of the laser printer 1 in which the paper cassette with the cover 100 is pulled out from the body 2 to replenish the paper 3. Fig. 9 is a sectional view of the laser printer 1 in which the paper cassette with the cover 100 is pulled out from the body 2 to insert and remove the process cartridge 17. Fig. 10 is a perspective view of the laser printer 1 in which the paper cassette with the cover 100 is pulled out from the body 2 to insert and remove the process cartridge 17.

As shown in fig. 7 and 8, when the sheet 3 is placed in the sheet tray portion 120, the sheet tray with the cover 100 is pulled out from the body 2, exposing the sheet tray portion 120. As described above, the paper tray portion 120 is supported by the inner walls of both sides of the body 2, and when the user applies a sufficient force to fix the paper tray in the-Z direction against the stopper 2b (fig. 3), the paper tray with the cover 100 can be pulled out. The user can grasp either one of the grip portions 112, 113 to pull out the paper tray with the cover 100. The paper tray portion 120 is exposed so that paper can be put in. When the paper tray with the cover 100 is pulled out, the light receiving portion of the photo sensor 2a blocked by the shutter plate 114 receives light, and it is detected that the paper tray with the cover 100 is in the open position. When the sheet tray with the cover 100 is moved in the + Z direction until the sheet tray portion 120 is temporarily locked so that the stopper 2b is engaged with the recessed portion 125, the shutter plate 114 of the cover portion 110 blocks the light of the photosensor 2a of the body 2, detecting that the sheet tray with the cover 100 is in the closed position.

When insertion and removal of the process cartridge 17 as shown in fig. 9 and 10 are performed, the sheet tray with the cover 100 is pulled out like the supplementary sheet 3. As described above, the user can grasp either of the grip portions 112, 113 to pull out the paper tray with the cover 100, exposing the paper tray portion 120. When the cover plate portion 110 combined with the paper tray portion 120 is separated from the body 2, the opening of the accommodating portion 55 is opened. The optical sensor 2a detects that the opening of the accommodating portion 55 is opened. When the paper tray with the cover 100 is pulled out so that the distance between the cover plate portion 110 and the body 2 is larger than the size of the process cartridge 17, the process cartridge 17 can be inserted and removed. As described above, when the paper tray with the cover 100 is loaded into the body 2, the optical sensor 2a detects that the opening of the accommodating portion 55 is closed.

A second embodiment of an image forming apparatus embodying the present invention is explained below. First, referring to fig. 11 to 15, an overall structure of a laser printer 201 as an example of an image forming apparatus of the second embodiment is explained. Fig. 11 is a perspective view showing an appearance of a laser printer 201 according to the second embodiment. Fig. 12 is a perspective view of the laser printer 201 with the paper tray 230 in the open position. Fig. 13 is a sectional view showing a schematic configuration of the laser printer 201. Fig. 14 is a sectional view of the locking mechanism of the sheet tray 230. Fig. 15 is a sectional view of the locking mechanism of the sheet tray 230.

As shown in fig. 11, the laser printer 201 includes a cover plate portion 210 similar to the cover plate portion 110 of the laser printer 1, an openable paper tray 230, and a paper feed unit 240 (fig. 12). A grip portion 213 for opening and closing the cover portion 210 is provided in the middle of the lower end of the cover portion 210 when viewed from the front. Side walls (in the X-axis direction) of both sides of the cover portion 210 are provided as sheet tray supporting portions 210a, each extending forward except for the lower portion. The sheet tray 230 in the closed state is fixed between the sheet tray support sections 210 such that the front face (XY plane) thereof is substantially parallel to the front face of the cover section 210. A grip portion 235 (to be described later) is provided at an upper end intermediate portion of the front surface of the sheet tray 230. The grip portion 231 is disposed at a middle position of the top surface of the sheet tray 230, and is flush with the top surface of the laser printer 201, close to the grip portion 235. The grip portion 231 is designed to be grasped by a user to rotate the sheet tray downward about the shaft 234 (fig. 13) to open the sheet tray 230.

As shown in fig. 12, when the sheet tray 230 is in the open position, the slit opening 211 provided on the cover plate portion 210 is exposed. The tray 233 is disposed inside the sheet tray 230. The tray 233 may be extended so as to place the sheet 3b thereon for a single manual feed. The paper feed unit arrangement 240 is disposed in a middle portion above the slit opening 211. The locking piece 232 protrudes inward at the upper left corner of the paper tray 230, and it is engaged with the locking piece engaging portion 215 provided near the upper left corner of the cover plate portion 210 when the paper tray 230 is closed. The locking piece 232 and the locking piece engaging portion 215 engage with each other to form a locking mechanism (fig. 14 and 15).

As shown in fig. 13, like the cover portion 110, the cover portion 210 is fixed to the front of the sheet tray portion 120, and the sheet tray portion 120 and the cover portion 210 constitute a sheet tray with a cover 200. According to the back-and-forth movement (in the Z-axis direction) of the paper tray 120, the cover plate portion 210 is loaded into or pulled out from the body 2, thereby opening and closing the opening of the accommodating portion 55, as in the case of the first embodiment.

A shaft 234 incorporated in a shaft hole (not shown) of the sheet tray 230 protrudes from the sheet tray support section 210a of each side of the cover plate section 210 at a position near the lower end portion. The sheet tray 230 is pivoted on a shaft 234 so that the slit opening 211 can be opened and closed. When the paper tray 230 is in the open position, the tray 233 can be extended in the-Z direction. At this time, the end of the tray 233 facing the + Z direction is connected to the slit opening 211, and the sheet 3b placed on the tray 233 is ready to be inserted into the slit opening 211.

The paper feed unit 240 is disposed above the slit opening 211 and is configured to drive a paper feed roller 241 for feeding the paper 3b placed on the tray 233 into the slit opening 211 during printing. The force for driving the paper feeding roller 241 is transmitted from the body 2. The driving force transmission mechanism will be described later.

When the sheet tray 230 is closed, it is held in a closed state by a lock mechanism. As shown in fig. 14, when the openable sheet tray 230 pivoted by the shaft 234 is closed, the locking piece 232 is engaged with the locking piece engaging portion 215 provided on the cover plate portion 210. As shown in fig. 15, when opening and closing the sheet tray 230, the user grasps the grip portion 231 and moves in the-Z direction. At this time, the flexible locking piece 232 is deformed along the shape of the locking piece coupling portion 215, and the restoring force of the deformed locking piece 232 is tensioned, so that the paper tray 230 is held in the closed position to be coupled with the locking piece coupling portion 215, as shown in fig. 14.

When the paper tray 230 is opened, the component force in the Z-axis direction required to maintain the lock piece 232 in the current state of fig. 13 is set smaller than the component force in the Z-axis direction to fix the paper tray with the cover 200, which is positioned and temporarily fixed in the machine body 2 by the paper tray portion 120. In other words, the paper tray with the cover 200 is not opened or closed by the opening and closing of the paper tray 230. Although the locking piece 232 is a flexible protruding portion, a force applying member such as a spring may be additionally used, as in the case of temporarily fixing the paper tray portion 120.

Other mechanisms and printing operations in the laser printer 201 are similar to those of the laser printer 1, and the lower paper tray 150 can be loaded into the bottom of the laser printer 201.

The replenishment of the paper 3 and the insertion and removal of the process cartridge 17 in the laser printer 201 are explained below with reference to fig. 16 to 20. Fig. 16 is a sectional view of the laser printer 201 in which the paper cassette with the cover 200 is pulled out from the body 2 to replenish the paper 3. Fig. 17 is a perspective view of the laser printer 201 in which the paper cassette with the cover 200 is pulled out from the body 2 to replenish the paper 3. Fig. 18 is a perspective view of the laser printer 201 in which the paper tray with the cover 200 is pulled out from the body 2 to insert and remove the process cartridge 17. Fig. 19 is a sectional view of the laser printer 201 in which the paper cassette with the cover 200 is pulled out from the body 2 to insert and remove the process cartridge 17. Fig. 20 is a perspective view of the laser printer 201 in which the paper tray 230 with the cover 200 is in an open state and the paper tray is pulled out of the body.

As shown in fig. 16 to 18, when the sheet 3 is put into the sheet tray portion 120 or the process cartridge 17 is inserted into the body 2, the user pulls out the sheet tray with the cover 200 from the body 2 of the laser printer 201 in the-Z direction by using the grip portion 213 provided at the lower edge of the cover portion 120. When the sheet 3 is placed in the sheet tray portion 120, the sheet tray with the cover 100 is pulled out from the body 2, exposing the sheet tray portion 120. When the paper tray with the cover 200 is pulled out, the opening of the accommodating portion 55 for placing the process cartridge 17 is also opened. As in the above case, when the paper tray with the cover 200 is pulled out so that the distance between the cover portion 210 and the body 2 is larger than the size of the process cartridge 17, the process cartridge 17 can be inserted and removed without being affected by the cover portion 210. When the paper tray with the cover 200 is attached to and detached from the body 2 as described above, the optical sensor 2a detects the state of the paper tray with the cover 200.

As shown in fig. 19 and 20, in the laser printer 201, even when the paper tray 230 is opened, the paper tray with the cover 200 can be pulled out. When the paper tray 230 is closed, the paper tray with the cover 200 can be pulled out by grasping the grip portion 213. However, when the sheet tray 230 is opened, the grip portion 213 is located at the rear lower portion of the sheet tray 230, and it is difficult to grip the grip portion 213. However, since the grip portion 235 provided at the front upper end of the paper tray 230 is located at the front end of the laser printer 201, there is no problem in gripping the paper tray with the cover 200. Thus, when the user grasps the grip portion 235 and pulls the paper tray with the cover 200 in the Z-axis direction, the cover portion 210 is pulled by the shaft 234, and the paper tray portion 120 integrated with the cover portion 210 is pulled. That is, the paper tray with the cover 200 can be pulled out.

A third embodiment of an image forming apparatus embodying the present invention is explained below. First, referring to fig. 21 to 23, an overall structure of a laser printer 301 as an example of an image forming apparatus of the third embodiment is explained. Fig. 21 is a perspective view showing an external appearance of a laser printer 301 according to the third embodiment. Fig. 22 is a perspective view of the laser printer 301 with the cover plate portion 310 opened. Fig. 23 is a sectional view showing a schematic configuration of the laser printer 301. Fig. 24 is a cross-sectional view of the locking mechanism of the cover portion 310. Fig. 25 is a cross-sectional view of the locking mechanism of the cover portion 310. Fig. 26 is a sectional view of the locking mechanism of the cover portion 310.

As shown in fig. 21, in the laser printer 301, a cover portion 310 that blocks the opening (fig. 23) of the housing portion 55 is located above the front panel 130 as a decorative plate located in front of the paper deck portion 120 (fig. 23), which is the same as that used in the first and second embodiments. The cover portion 310 is supported at the front panel 130 so that it can be opened and closed. A grip portion 131 for opening and closing the paper tray portion 120 is provided at a lower end intermediate portion of the front panel 130 when viewed from the front. A long and narrow opening formed on the left and right for inserting the sheet of paper 3b at the time of manual feed printing, i.e., a slit opening 311, is provided at a lower end position on the cover plate portion 310, as in the case of the first embodiment. A grip portion 315 (described later) is provided at an upper end intermediate portion of the cover plate portion 310. The grip portion 312 is disposed at a middle position of the top surface of the cover plate portion 310, and is flush with the top surface of the laser printer 301, close to the grip portion 315. The gripping portion 312 is designed to be grasped by a user when opening the cover portion 310, causing the cover portion to rotate downward about an axis 314 (fig. 23).

As shown in fig. 22, when the cover portion 310 is opened, the opening of the accommodating portion 55 for placing the process cartridge 17 is opened. The shaft 314 (fig. 23) combined with the shaft hole 310a (fig. 24) of the cover part 310 is provided with a locking mechanism to prevent the cover part 310 from being opened or closed accidentally. The locking mechanism of the cover portion 310 will be described later.

As shown in fig. 23, a front panel 130 as a decorative panel is fixed to the front of the paper tray portion 120. The length of the front panel 130 in the up-down direction (Y-axis direction) is slightly larger than the thickness of the paper tray portion 120. The front panel 130 includes support portions 132 (both ends in the left-right direction of the laser printer 301) protruding upward from both ends. A shaft 314 inserted into the shaft hole 310a (fig. 24) of the cover plate portion 310 protrudes from each support portion 132. Accordingly, the cover portion 310 may be rotated at an upper portion of the front panel 130. When the user grasps the grip portion 312 and moves it downward, the opening of the accommodating portion 55 for placing the process cartridge 17 is opened.

For manual feed printing, a single sheet of paper 3b (fig. 21) is inserted into a slit opening 311 provided above a shaft 314 of the cover portion 310, as in the case of the slit opening 111 in the first embodiment.

When the opening of the accommodating portion 55 is opened and closed with the movement of the cover portion 310, the opened and closed state of the cover portion 310 is maintained by the locking mechanism. As shown in fig. 24, the locking mechanism of the cover portion 310 is composed of a shaft 314 coupled to the shaft hole 310a of the cover portion 310 and a locking bar 313 having one end fixed to the cover portion 310. The shaft 314 is provided with two notches 314a, 314 b. When the cover portion 310 is closed, a protrusion 313a provided on the other end of the lock lever 313 is engaged with the notch 314 a.

As shown in fig. 25, when the cover portion 310 is opened, the engagement of the protrusion 313a of the lock lever 313 fixed to the cover portion 310 with the notch 314a moved relative to the cover portion 310 is released, the protrusion 313a abuts on the circumference of the shaft 314, and the lock lever 313 is bent. As shown in fig. 26, when the cover portion 310 is completely opened, the protrusion 313a of the lock lever 313 is combined with the notch 314b of the shaft 314, and the bending of the lock lever 313 is eliminated. The protrusion 313a of the lock lever 313 attempts to remain engaged with the notch 314a or 314b by the stress based on the bending of the lock lever 313, and the cover portion 310 is thereby maintained in the opened or closed state.

The paper tray portion 120 having the front panel 130 and the cover plate portion 310 constitute a paper tray having the cover 300. Other mechanisms and printing operations in the laser printer 301 are similar to those of the laser printer 1, and the lower paper tray 150 can be loaded into the bottom of the laser printer 301.

The replenishment of the paper 3 and the insertion and removal of the process cartridge 17 in the laser printer 301 are explained below with reference to fig. 27 to 33. Fig. 27 is a sectional view of the laser printer 301 in which the paper cassette with the cover 300 is pulled out from the body 2 to replenish the paper 3. Fig. 28 is a perspective view of the laser printer 301 in which the paper cassette with the cover 300 is pulled out from the body 2 to replenish the paper 3. Fig. 29 is a perspective view of the laser printer 301 in which the paper tray with the cover 300 is pulled out from the body 2 to insert and remove the process cartridge 17. Fig. 30 is a sectional view of the laser printer 301 in which the cover plate portion 310 is opened and the paper tray with the cover 300 is not pulled out from the body 2. Fig. 31 is a perspective view of the laser printer 301 in which the cover plate portion 310 is opened and the paper tray with the cover 300 is not pulled out from the body 2. Fig. 32 is a sectional view of the laser printer 301 in which the paper cassette with the cover 300 is pulled out of the body 2 and the cover plate portion 310 is opened. Fig. 33 is a perspective view of the laser printer 301 in which the paper cassette with the cover 300 is pulled out of the body 2 and the cover plate portion 310 is opened.

As shown in fig. 27 to 29, when sheets 3 are replenished into the sheet tray portion 120, or the process cartridge 17 is taken out or inserted into the body 2, the user pulls out the sheet tray with the cover 300 in the-Z direction from the body 2 of the laser printer 301 by using the grip portion 131 provided at the lower edge of the front panel 13. When the paper tray with the cover 300 is pulled out, the cover plate portion 310 does not fall off at its free end because the locking mechanism maintains the positional state of the cover plate portion 310. Thus, if the paper tray with the cover 300 is kept standing upright in the machine body 2 for loading or unloading, the optical sensor 2a detects that the cover portion 310 is in an open or closed state.

As shown in fig. 30 and 31, the laser printer 301 is configured such that the process cartridge 17 can be inserted into or removed from the body 2 only by opening the cover portion 310 without pulling out the paper tray with the cover 300 from the body 2. When the user grasps the grip portion 312 of the cover portion 310 and rotates the cover portion 310 downward, the cover portion 310 rotating about the shaft 314 is opened, and the opening of the receiving portion 55 is opened. In this state, the user can insert or remove the process cartridge 17 in the body 2. When the cover portion 310 is opened, the component force in the Z-axis direction required to maintain the cover portion 310 is set smaller than the component force in the Z-axis direction to fix a paper tray with the cover 300, which is positioned and temporarily fixed in the machine body 2 by the paper tray portion 120. In other words, the paper tray with the cover 300 is not opened or closed by the opening and closing of the cover portion 310.

As shown in fig. 32 and 33, in the laser printer 301, even when the cover plate portion 310 is opened, the paper cassette with the cover 300 can be pulled out. For example, the user may replenish the paper 3 after inserting and removing the process cartridge 17. At this time, the sheet tray with the cover 300 is pulled out of the body 2 by grasping the grip portion 315 and pulling in the-Z direction, so that the sheet tray portion 120 is exposed. Thus, the paper tray with the cover 300 can be pulled out of the body 2 without using the grip portion 131 located behind and below the cover portion 310. It should be appreciated that when the cover part 310 is opened, it is difficult to grasp the grip part 131 because the cover part 310 is positioned above the grip part 131 as shown in fig. 30 and 32.

A fourth embodiment of an image forming apparatus embodying the present invention is explained below. First, referring to fig. 34 to 37, an overall structure of a laser printer 401 as an example of an image forming apparatus of the fourth embodiment is explained. Fig. 34 is a perspective view showing an external appearance of a laser printer 401 according to the fourth embodiment. Fig. 35 is a perspective view of the laser printer 401 with the paper tray 430 open. Fig. 36 is a perspective view of the laser printer 401 with the cover plate portion 410 opened. Fig. 37 is a sectional view of a schematic configuration of the laser printer 401.

As shown in fig. 34, the laser printer 401 includes a cover plate portion 410 having the same structure as the cover plate portion 310 in the laser printer 301 of the third embodiment, an openable paper tray 430, and a paper feed unit 440 (fig. 35). A grip portion 131 for pulling and pushing the paper tray portion 120 open is provided at a middle portion of a lower end of the front panel 130 when viewed from the front.

Lateral (X-axis direction) side walls of the cover portion 410 are supported on the front panel 130, as in the case of the cover portion 310. The side wall is provided as a sheet tray support section 410a extending forward. The closed sheet tray 430 is fixed between the sheet tray support sections 410a such that the front face thereof is parallel to the front face of the cover plate section 410. A grip portion 435 (described later) is provided at an intermediate portion of the upper end of the sheet tray 430. The grip portion 432 is disposed at a middle position of the top surface of the paper tray 430, and is flush with the top surface of the laser printer 401, close to the grip portion 435. The grip portion 432 is designed to be grasped by a user to rotate the paper tray 430 pivoted on the shaft 434 (fig. 37) downward to be opened. A similar grip portion 412 is provided on the top surface of the cover plate portion 410.

As shown in fig. 35, when the sheet tray 430 is opened, the slit 411 on the cover plate portion 410 is exposed. The tray 433 is disposed inside the sheet tray 430. The tray 433 is extensible so that the sheet 3 can be placed thereon for a single manual feed. A paper feed unit arrangement 440 is provided in the middle portion above the slit 433.

As shown in fig. 36, the rotation axis of the cover plate portion 410 is coaxial with the rotation axis 434 (fig. 37) of the sheet tray 430. When the cover portion 410 is opened, the opening of the accommodating portion 55 for placing the process cartridge 17 is opened. When the grip portion 412 is gripped with its free end moved downward, the free end of the cover portion 410 is moved downward, and the sheet tray 430 is opened. The paper tray 430 is provided with the same locking mechanism (not shown) as that used for the paper tray 230 in the second embodiment. The cover portion 410 is provided with the same locking mechanism (not shown) as that used in the third embodiment for the shaft 434. Thus, the cover plate portion 410 and the sheet tray 430 can be independently opened and can be independently maintained in an opened or closed state.

When the paper tray 430 and the cover plate portion 410 are opened, the component force in the Z-axis direction required to maintain the current state of the locking mechanism is set smaller than the component force in the Z-axis direction to fix the paper tray with the cover 400, which is positioned and temporarily fixed in the machine body 2 by the paper tray portion 120. In other words, the paper tray with the cover 400 is not opened or closed by the paper tray 430 or the cover plate portion 410 being opened and closed. If the structure of the locking mechanism is such that the force required to open the paper tray 430 is smaller than the force required to open the cover plate portion 410, the cover plate portion 410 is not opened or closed by the opening and closing of the paper tray 430.

As shown in fig. 37, a front panel 130 as a decorative panel is fixed to the front of the paper tray portion 120, as described above. On both sides of the upper portion of the front panel 130, support portions 132 are provided, from which the cover plate portion 410 and the shaft 434 of the sheet tray 430 protrude. With this structure, the cover portion 410 and the tray 430 can be rotated independently without interfering with each other. Even when one of them applies tension to the shaft 434 by opening or closing, the other is not affected.

When the cover portion 410 is opened, the opening of the accommodating portion 55 for placing the process cartridge 17 is opened. The grip portion 412 is located at the free end of the cover portion 410 so that the user can easily force open the cover portion 410. As in the case of the cover portion 410, a grip portion 432 is provided at the free end of the sheet tray 430, and thus is easily opened. When the sheet tray 430 is opened, the tray 433 placed in the sheet tray 430 is stretched and unfolded in the-Z direction so that the slit 411 of the cover portion 410 is opened to be connected to the tray 433. A paper feed unit 440 is provided above the slit 411, and in printing, the paper 3a placed on the tray 433 is fed one by one through the slit 411 to the image forming portion by a paper feed roller 441, as in the case of the second embodiment.

The cover plate portion 120 having the front panel 130 and the cover plate portion 410 having the paper tray 430 constitute a paper cassette with the cover 400. The driving force for driving the paper feeding roller 411 is transmitted from the machine body 2. The driving force transmission mechanism will be described later. Other mechanisms and printing operations in the laser printer 401 are similar to those of the laser printer 1, and the lower paper tray 150 can be loaded into the bottom of the laser printer 201.

The replenishment of the paper 3 and the insertion and removal of the process cartridge 17 in the laser printer 401 are explained below with reference to fig. 38 to 46. Fig. 38 is a sectional view of the laser printer 401 in which the paper tray with the cover 400 is pulled out from the body 2. Fig. 39 is a perspective view of the laser printer 401 in which the paper cassette with the cover 400 is pulled out from the body 2 to replenish the paper 3. Fig. 40 is a perspective view of the laser printer 401 in which the paper tray with the cover 400 is pulled out from the body 2 to insert and remove the process cartridge 17. Fig. 41 is a sectional view of the laser printer 401 in which the cover plate portion 410 is opened and the paper tray with the cover 400 is not pulled out from the body 2. Fig. 42 is a perspective view of the laser printer 401 in which the cover plate portion 410 is opened and the paper tray with the cover 400 is not pulled out from the body 2. Fig. 43 is a sectional view of the laser printer 401 in which the paper cassette with the cover 400 is pulled out from the body 2 and the cover plate portion 410 is opened. Fig. 44 is a perspective view of the laser printer 401 in which the paper cassette with the cover 400 is pulled out of the body 2 and the cover plate portion 410 is opened. Fig. 45 is a sectional view of the laser printer 401 in which the paper tray with the cover 400 is pulled out of the body 2 and the paper tray 430 is opened. Fig. 46 is a perspective view of the laser printer 401 in which the paper tray with the cover 400 is pulled out of the body 2 and the paper tray 430 is opened.

As shown in fig. 38 to 40, when the sheet 3 is put into the sheet tray portion 120 or when the process cartridge 17 is inserted into the body 2, the sheet tray with the cover 400 is pulled out from the body 2 of the laser printer 401 by the grip portion 131 provided at the lower edge of the front panel 130 in the-Z direction, as in the case of the third embodiment. When the paper tray with the cover 400 is pulled out, the cover plate portion 410 and the paper tray 430 do not fall off at the free ends thereof because their respective locking mechanisms maintain the positional states of the cover plate portion 410 and the paper tray 430. Thus, if the paper tray with the cover 400 is loaded or unloaded while remaining upright in the body 2, the optical sensor 2a detects that the paper tray with the cover 400 is in an open or closed state.

As shown in fig. 41 and 42, the laser printer 401 is structured such that the process cartridge 17 can be inserted into or taken out of the body 2 without pulling out the paper tray with the cover 400 from the body 2 by opening the cover portion 410, as in the case of the third embodiment. When the grip portion 412 is grasped to move it downward at the free end, the cover portion 410 is opened.

As shown in fig. 43 and 44, the structure of the laser printer 401 makes it possible to pull out the paper tray with the cover 400 when the cover plate portion 410 is opened, as in the case of the third embodiment. Thus, even during the process of inserting and removing the process cartridge 17, the sheets 3 can be easily replenished, and it is only necessary to grasp the grip portion 435 to pull out the sheet cassette with the cover 400 from the body 2.

As shown in fig. 45 and 46, the laser printer 401 is structured so that, even when the paper tray 430 is kept unfolded to place the paper 3 thereon for the manual sheet feeding printing of a single sheet, the replenishment of the paper 3 and the insertion and removal of the process cartridge 17 can be performed without closing the paper tray 430, as is the case with the second embodiment.

The laser printers 201 and 401 in the second and fourth embodiments are provided with paper feed units 240 and 440, respectively. The force to drive the paper feeding rollers 241 and 441 is transmitted from a driving source provided in the body 2 through a power transmission member such as a gear, and then the paper feeding units 240 and 440 are driven. However, since the paper cassettes with the covers 200 and 400 are pushed in and pulled out in the machine body 2, for example, transmission of the driving force is performed when gears provided on the paper cassettes with the covers 200 and 400 are engaged with gears connected to a driving motor as a driving source in the machine body 2. A driving force transmission mechanism for transmitting a driving force will be described below.

Fig. 47 is a sectional view showing a schematic configuration of the laser printer 401. Fig. 48 is a sectional view taken along the broken line II-II in fig. 47. Fig. 49 shows a modification of the drive force transmission mechanism, which is viewed from the arrow direction along the broken line II-II in fig. 47. Since the driving force transmission mechanism of the laser printer 201 is the same in structure as that of the laser printer 401, the laser printer 401 will be described here as an example.

As shown in fig. 47, the driving force transmission mechanism is composed of a driving force transmission unit 480, and the driving force transmission unit 480 includes a gear 450 provided on the body 2, a gear 460 provided on the paper tray with the cover 400, and a shaft 442 connected to a paper feed roller 441 (fig. 48). The gear 450 is a gear disposed at a plurality of gear discharge ends (disposaend) that mesh with a drive motor (not shown) of the laser printer 401. As shown in fig. 48, a gear 460 is provided in the paper tray with the cover 400, a shaft 442 is a rotation shaft of the paper feed roller 441, and is also a rotation shaft of the gear 460, and the paper feed roller 441 rotates in accordance with the rotation of the gear 460. The gear 450 is located at the front + X direction side end portion of the body 2. The gear 460 is located inside the cover portion 410, and corresponds to the gear 450 when the paper cassette with the cover 400 is inserted into the body 2.

When the paper tray with the cover 400 is inserted into the body 2, the gears 450 and 460 are engaged. When the rotating drive motor drives the gear 450, the driving force is transmitted to the gear 460, and the gear 460 rotates. As the gear 460 rotates, the shaft 442 rotates, and the paper feed roller 441 also rotates. The driving force transmitted from the gear 450 to the gear 460 is not applied in the direction in which the cover plate portion 410 is opened, i.e., the-Z direction. Assuming that the driving force transmitted from the gear 450 to the gear 460 acts in the-Z direction, this force is set sufficiently small for the force required to open the cover plate portion 410.

Since the gears 450 and 460 are exposed when the paper tray with the cover 400 is separated from the body 2, the user may inadvertently touch the gear teeth. Thus, the gears may be damaged or the user's fingers may be stained. To prevent these problems, the gear 450 is disposed in the outer wall of the body 2, and the gear 460 is positioned so as to protrude from the cover portion 410 toward the gear 450, so that they are engaged with each other when the paper cartridge with the cover 400 is inserted into the body 2. In order to prevent damage to the gear 460, protective members 461 having outer circumferences slightly larger than the gear 460 are provided at upper and lower portions of the gear 460 in parallel with a circular plane of the gear 460 such that both axial sides of the gear 460 are sandwiched therebetween. The protective member 461 protrudes from the wall plate surface of the cover plate portion 410.

With this structure, when the gears 450 and 460 are not engaged, since the gear 450 is located in the wall surface of the body 2 and the gear 460 is sandwiched between the protection members 461, the gears 450 and 460 are not easily touched by the user. In this way, damage to the gears 450 and 460 or soiling of the user's fingers may be avoided.

Effects similar to those of the above-described configuration can also be obtained by incorporating the protective members 461 directly on both sides of the gear 460 as shown in fig. 49. Alternatively, the protective member 461 may be coupled to the gear 450. In addition, a driving motor (not shown) that drives the paper feeding roller 41 may be provided at the cover portion 410 such that a controller (not shown) outputs a control current of the driving motor, and when the paper cassette with the cover 400 is inserted into the body 2, contacts on the cover portion 410 and contacts on the body 2 are connected, and a current is supplied to the driving motor through the contacts.

As described above, in the laser printer 1 of the first embodiment, replenishment of the sheets 3 and insertion and removal of the process cartridge 17 can be performed only by leaving the paper tray with the cover 100 in the pulled-out state. When the user supplies paper or takes out the process cartridge 17 from the laser printer 1, the operation is the same for the laser printer 1, thereby improving the ease of use of the laser printer 1. If the sheet tray portion 120 and the cover plate portion 110 are separate parts like a conventional printer, two sensors are required to detect the open/closed states of the sheet tray portion 120 and the cover plate portion 110. However, in the sheet tray with the cover 100, only one optical sensor 2a is used to detect the open/closed states of the sheet tray portion 120 and the cover plate portion 110. In addition, a mechanism for independently opening and closing the cover part 110 may be omitted, reducing the manufacturing cost.

When a jam occurs at the passage opening 121 or at the conveyance path 40a, it is necessary to take out the paper tray portion 120 or the process cartridge 17 from the laser printer 1 to clear the jam. However, both cases can be solved by taking out and inserting the paper tray with the cover 100. In addition, as shown in fig. 9, when the process cartridge 17 is taken out from the laser printer 1 and the paper tray with the cover 100 is completely pulled out, the conveyance path 40a can be seen from outside the body 2 through the accommodating portion 55, and the jam can be easily removed.

The movement of the process cartridge 17 in the accommodating portion 55 is substantially in the horizontal direction and substantially parallel to the direction in which the sheet tray portion 120 is drawn out and loaded. In other words, since the process cartridge 17 and the paper cassette portion 120 do not move in the thickness direction of the body 2, there is no need to provide a space for movement in this direction of the body 2, and therefore, the size of the body 2 in the thickness direction can be reduced. When the process cartridge 17 that moves substantially horizontally in the accommodating portion 55 is taken out from the accommodating portion 55, it moves in the direction opposite to the sheet feeding direction in which the sheet 3 is fed into the conveying path 40 b. Assuming that if the sheet 3 jams at the conveyance path 40b, when the process cartridge 17 is taken out, the frictional force of the process cartridge 17 is applied to the sheet 3, and the sheet 3 slightly retreats from the sheet feeding direction. Thus, the sheet 3 can be easily removed regardless of where in the conveyance path 40b the sheet is jammed.

In the laser printer 201 of the second embodiment, in addition to the effects brought by the first embodiment, the paper tray with the cover 200 can be pulled open even when the paper tray 230 is opened.

In the laser printer 301 of the third embodiment, in addition to the effects brought about by the first embodiment, the process cartridge 17 can be taken out or inserted into the laser printer 301 only by opening the cover portion 310 without pulling out the paper tray with the cover 300. In addition, even when the cover plate portion 310 is opened, the paper tray with the cover 300 can be pulled open.

In the laser printer 401 of the fourth embodiment, in addition to the effects brought by the first and third embodiments, even when the paper tray 430 and the cover plate portion 410 are opened, the paper cassette with the cover 400 can be opened by merely grasping the grip portion 435.

While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, the preferred examples set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined in the following claims. For example, the optical sensor 2a may be replaced with a sensor other than an optical sensor. Instead of using the shutter plate 114, a protrusion for opening and closing may be provided so that the switch is opened and closed by contact of the top of the protrusion. The bend applied to the locking mechanism may also be created using a force member such as a spring or a bending member.

In the third and fourth embodiments, the cover portions 310, 410 are fixed by the locking mechanisms, respectively. Each locking mechanism may be replaced by an element that secures the lock, for example, by depressing a release key to release the lock. Each grip portion may be located anywhere, and a plurality of grip portions may be provided at the opening/closing portion.

In the laser printers 1, 301 of the first and third embodiments, a member such as a cover plate may be provided so as to cover the slit openings 111, 113 when manual paper feed printing is not performed. In the laser printer 301 of the third embodiment, the slit opening 311 may not be provided on the cover portion 310 by utilizing the gap between the cover portion 310 and the front panel 130.

The laser printers 1, 201, 301, and 401 of the first to fourth embodiments can constitute a copying machine or a multifunction device by installing an image reading device that can read an image thereon. For example, as shown in fig. 50, if the image reading device 501 is mounted on the laser printer 1, the function of the laser printer 1 is not affected because only the delivery table 46 is provided on the top of the laser printer 1.

For example, as shown in fig. 50, on the top of the laser printer 1, in addition to the delivery table 46 and the paper tray portion with the cover 100, a partition wall 530 is provided to fix the image reading device 501 thereon. As an example of the image reading apparatus 501, a known flatbed scanner may be used. In such a scanner, a document to be scanned is placed on a flat glass plate 510 facing down, irradiated with a light beam, and the intensity of its reflected light is read by a linear Charge Coupled Device (CCD) in which a large number of CCDs are arranged and then converted into a digital signal.

As shown in fig. 51 and 52, in the laser printer 1, a paper cassette with a cover 100 is pulled out or inserted from the front of the laser printer 1 to replenish the paper 3 and to take out the process cartridge 17. Thus, even if the image reading apparatus 501 is mounted on the laser printer 1, it does not affect the drawing of the paper cassette with the cover 100. When the printed paper 3 is fed out to the delivery table 46, the user can take the paper 3 from the front of the laser printer 1.

In the laser printer 1, the paper tray with the cover 100 and the process cartridge 17 are pulled out of and inserted into the laser printer 1 substantially in parallel with each other and substantially in the horizontal direction. That is, since the movement of the paper tray with the cover 100 and the process cartridge 17 in the laser printer 1 is not in the thickness direction of the laser printer 1, there is no need to provide a space in this direction, so the laser printer 1 can be made lower in profile. Thus, even if the image reading apparatus 501 is mounted thereon, the size of the laser printer 1 as a whole can be reduced.

In the above embodiment, the process cartridge 17 is composed of the drum core 17a and the developing cartridge 17 b. However, it may be a process cartridge in which a drum core and a developing cartridge are combined. The developing cartridge 17b is detachably attached to the drum core 17 a. However, the drum core and the developing cartridge may be provided to be independently detachable from the body 2.

The developing cartridge 17b and the developing roller 31 may be separated from each other so that the developing cartridge 17b and the developing roller 31 are independently detachable from the body 2.

Claims (52)

1. An image forming apparatus, comprising:

a body having a first opening and a second opening;

an accommodating portion formed on the body, wherein the first opening communicates with the accommodating portion;

a replacement unit detachably connected to the accommodation portion through the first opening;

a paper tray accommodating part formed on the machine body, wherein the second opening is communicated with the paper tray accommodating part;

a paper tray disposed in the paper tray accommodating portion and movable between a first position and a second position relative to the machine, wherein the paper tray further comprises:

a fixing portion in which the recording medium is fixed; and

when the paper box is at the first position, the cover plate part of the first opening is shielded,

when the paper tray is placed in the second position, the cover plate partially exposes the first opening to perform insertion and removal operations of the replacement unit.

2. An image forming apparatus according to claim 1, wherein the cover portion extends perpendicularly from the fixing portion.

3. An image forming apparatus according to claim 2, wherein the cover plate portion is formed integrally with the fixing portion.

4. An image forming apparatus according to claim 1, wherein the replacement unit includes a photosensitive member, a charging device, a developing device, and a developer container.

5. An image forming apparatus according to claim 1, wherein the sheet tray is detachable from the sheet tray accommodating portion, and when the sheet tray is detached from the sheet tray accommodating portion, both the first opening and the second opening are exposed.

6. An imaging device according to claim 1, wherein the first opening and the second opening face in a common direction with respect to the body.

7. The imaging apparatus of claim 6, further comprising:

an image scanning device is provided on the body.

8. The imaging apparatus of claim 1, further comprising:

a paper feeding path extending from the fixed portion.

9. The image forming apparatus as claimed in claim 8, wherein at least a part of the sheet feeding path communicates with an outside of the body through the first opening when the sheet tray is in the second position.

10. The image forming apparatus as claimed in claim 8, wherein at least a part of the paper feeding path extends in parallel with a direction in which the exchanging unit is mounted to the accommodating part.

11. The imaging apparatus of claim 10, further comprising:

and a first paper feeding device adjacent to the second opening and conveying the recording medium from the fixed portion to the paper feeding path.

12. The image forming apparatus as claimed in claim 1, wherein the paper tray further comprises:

a slit opening communicating with the paper feed path.

13. An image forming apparatus according to claim 12, wherein the slit opening is formed in the cover portion.

14. An image forming apparatus according to claim 13, wherein the cover portion extends perpendicularly from the fixing portion.

15. The image forming apparatus as claimed in claim 13, wherein the paper tray further comprises:

a cover disposed on the cover portion and movable between an open position and a closed position, the slit opening being exposed when the cover is in the open position; the slit opening is covered when the cover is in the closed position.

16. The imaging apparatus of claim 15, further comprising:

and a second paper feeding device for feeding the recording medium to the paper feeding path through the second opening.

17. The image forming apparatus as claimed in claim 16, wherein the second sheet supplying device is provided at the cover portion.

18. The image forming apparatus as claimed in claim 17, wherein the second paper feeding device feeds the recording medium placed on the cover when the cover is in the open position.

19. The imaging apparatus of claim 18, further comprising:

and a first transfer device provided on the main chassis, transferring the driving force to the second paper supply device.

20. The image forming apparatus as claimed in claim 19, wherein the paper tray further comprises:

and a second conveying device provided on the cover portion, connected to the first conveying device, and conveying the driving force to the second paper feeding device.

21. An image forming apparatus according to claim 20, wherein the first and second conveyors each include a circular gear having a predetermined diameter.

22. The image forming apparatus as claimed in claim 21, wherein at least one of the first and second conveying means further comprises:

and a disk-shaped protective member combined with the gear, and having a diameter larger than that of the gear.

23. The image forming apparatus as claimed in claim 15, wherein the paper tray further comprises:

a lock formed on the cover; and

an engaging member provided on the lid portion, wherein the lock is engaged with the engaging member when the lid is in the closed position.

24. The image forming apparatus as claimed in claim 15, wherein the paper tray further comprises:

a first grip portion formed on the cover for moving the cover to the open position.

25. The image forming apparatus as claimed in claim 15, wherein the paper tray further comprises:

a first recess formed in a top surface of the cover.

26. An image forming apparatus according to claim 24, wherein the paper tray further comprises:

a second grip portion formed on the cover for moving the paper tray to the second position when the cover is in the open position.

27. An image forming apparatus according to claim 25, wherein the paper tray further comprises:

a second recess formed in the outer surface of the cap adjacent the top surface of the cap.

28. An image forming apparatus according to claim 24, wherein the sheet tray further includes a third recess formed in a bottom surface of the cover.

29. The image forming apparatus as claimed in claim 1, wherein the paper tray further comprises:

a support portion provided at the cover portion, which supports the cover portion so that the cover portion is movable between an open position corresponding to the second position of the paper tray and a closed position corresponding to the first position of the paper tray.

30. An imaging device according to claim 29, wherein the support portion is a shaft.

31. An image forming apparatus according to claim 29, wherein when the cover portion is in the closed position, the cover portion is perpendicular to the fixing portion.

32. An image forming apparatus according to claim 31, wherein when the cover is in the open position, the cover portion is parallel to the fixing portion.

33. An imaging device as recited in claim 29, wherein the first opening is exposed when the cover is in the open position.

34. An image forming apparatus according to claim 29, wherein the paper tray further comprises:

a first grip portion formed at the cover portion for moving the cover to the open position.

35. An image forming apparatus according to claim 29, wherein the paper tray further comprises:

a first recess formed in a top surface of the cover portion.

36. An image forming apparatus according to claim 34, wherein the paper tray further comprises:

a second grip portion formed on the cover plate for moving the paper tray to the second position when the cover plate portion is in the open position.

37. An image forming apparatus according to claim 35, wherein the paper tray further comprises:

a second recess formed in the outer surface of the cap adjacent the top surface of the cap.

38. An image forming apparatus according to claim 36, wherein the paper tray further comprises:

a locking portion that holds the cover portion in the open position and the closed position.

39. An image forming apparatus according to claim 36, wherein the paper tray further comprises:

a shaft provided in the cover portion for moving the cover portion between the open position and the closed position; and

a lever coupled to the shaft and maintaining the cover plate portion in the open position or the closed position.

40. An image forming apparatus according to claim 38, wherein the paper tray further comprises:

a slit opening communicating with the paper feed path.

41. An image forming apparatus according to claim 40, wherein the sheet tray further comprises:

a cover disposed on the cover portion and movable between an open position and a closed position, the slit opening being exposed when the cover is in the open position; the slit opening is covered when the cover is in the closed position.

42. An image forming apparatus according to claim 41, wherein the sheet tray further comprises:

and a second paper feeding device for feeding the recording medium to the paper feeding path through the second opening.

43. An image forming apparatus according to claim 42, wherein the second sheet supplying device is provided in the cover portion.

44. An image forming apparatus according to claim 43, wherein the second sheet feeding device feeds the recording medium placed on the cover when the cover is in the open position.

45. The imaging apparatus of claim 44, further comprising:

and a first transfer device provided on the main chassis, transferring the driving force to the second paper supply device.

46. An image forming apparatus according to claim 45, wherein the paper tray further comprises:

and a second conveying device provided at the cover portion, communicating with the first conveying device, and conveying the driving force to the second paper feeding device.

47. An image forming apparatus according to claim 46, wherein the first and second conveyors each include a circular gear having a predetermined diameter.

48. An image forming apparatus according to claim 47, wherein at least one of the first and second conveying means further comprises:

and a disk-shaped protective member combined with the gear, and having a diameter larger than that of the gear.

49. An image forming apparatus according to claim 41, wherein the sheet tray further comprises:

a locking member formed on the cover; and

and a coupling member provided on the cover plate, wherein the locking member is coupled with the coupling member when the cover is in the closed position.

50. The imaging apparatus of claim 1, further comprising:

and a sensor for detecting whether the cover plate of the paper tray is at the second position.

51. The image forming apparatus as claimed in claim 1, wherein a distance between an inner surface of the cover plate portion and an outer surface of the body is larger than a length of the replacing unit when the sheet tray is in the second position.

52. An imaging apparatus, characterized in that it comprises:

a body having a first opening and a second opening;

a process cartridge detachably coupled to the body and passing through the first opening; and a paper tray movable between a first position and a second position relative to the second opening of the body, wherein when the paper tray is in the first position, an outer wall of the paper tray covers the first opening, and when the paper tray is placed in the second position, the cover plate partially exposes the first opening for insertion and removal of the replacement unit.