JPS63277133A - Image forming device - Google Patents

Abstract

PURPOSE:To enable a paper feeding cassette to be installed/removed also in the direction perpendicular to a paper feeding direction by providing a guide part which has an upwardly curved arc form or which is upwardly inclined, in each of two directions of the paper feeding direction and the direction perpendicular to the paper feeding direction. CONSTITUTION:By depressing a releasing lever 334 and with a lock pin 337 being engaged with an engaging groove 341a, a paper feeding cassette is inserted into a housing case 308. And, an inclined face 341d is brought into contact with a latch part 343a and, as the lock pin 337 comes off of the engaging groove 341a, a stopper part 336a enters, and is lapped on, the engaging part of a frame 324. When the paper feeding cassette is pushed into a defined position, a lock lever 341 rides over and is engaged with a latch claw 343. At the time of drawing out the paper feeding cassette, as the releasing lever 334 is depressed, the lock pin 337 of a latch plate 336 is fitted into the engaging groove 341a while sliding on a guide face 341b and releases locking, also rotating the latch claw 343 to enable the draw out.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus such as a printer, a copying machine, a printing machine, etc., and particularly to a method for storing paper stored in a paper feeding cassette detachably attached to a paper feeding unit thereof. 6 Concerning the detection piece for detecting the presence or absence of a detection piece Conventionally, image forming devices such as various printers, copiers, printing machines, etc. are generally used with a removable paper feed cassette attached to the paper feed unit. .

When the attached paper feed cassette runs out of paper, a function is provided to detect and notify the paper out.

As a mechanism for detecting the presence or absence of paper in such a paper feed cassette, for example, as shown in FIG. It has a guide part 160C, and the support part 180a is connected to the pin 361.
The tip of the detection piece 160 rotatably supported by a fixed part (not shown) is brought into contact with the top surface of the paper 301 placed on the bottom of the paper feed cassette (not shown). be.

When the paper 301 in the paper feed cassette runs out, the tip of the detection piece 160 falls into the bottomless hole and rotates greatly, and the protruding piece 180b formed at the rear end becomes the photo sensor. Paper end sensor '5
The light enters the detection groove 320a of No. 20 and blocks the light, thereby detecting the paper breakage.

However, such conventional detection pieces only have a guide section with an upwardly curved arc-shaped tip provided in the paper feeding direction, so the paper feeding cassette cannot be moved in a direction perpendicular to the paper feeding direction. (in the direction of arrow M), even if a notch is provided on the side wall of the paper cassette to allow the detection piece to escape, if the paper cassette is fully loaded with paper and is inserted, the paper will fall at the tip of the detection piece. There is a problem in that the paper or the detection piece may be damaged by hitting the side of the detector.

Purpose This invention has been made in view of the above points, and is an image forming apparatus having a detection piece for detecting the presence or absence of paper in a paper feed cassette as described above. The purpose of the present invention is to enable the paper feed cassette to be attached and detached in both directions.

Structure In order to achieve the above object, the present invention brings the tip of a detection piece rotatably attached to a fixed part into contact with paper in a paper feed cassette that is detachably attached to a paper feeder part. In image forming apparatuses such as printers, copiers, printing machines, etc., in which the presence or absence of paper in a paper feed cassette is detected based on the rotational position of the detection piece, there is a sensor at the tip of the detection piece in the paper feeding direction and orthogonal thereto. The guide section is provided with an arcuate shape or an upwardly inclined guide section in two directions.

[Margin below]

Hereinafter, a detailed explanation will be given based on one embodiment of the present invention.

FIG. 1 is an external perspective view showing an example of a laser printer as an image forming apparatus embodying the present invention.

This laser printer is connected to a host (not shown), such as a word processor or personal computer.

Based on image information and other control information provided by character codes and image data from various information processing devices such as office computers, data processors, workstations, and image editing processing devices, printing is performed on various types of paper such as sheet paper and envelopes. It has the function of forming (printing) images.

This laser printer consists of a main body that can be divided into an upper unit 1 and a lower unit 2, an optional tray 9 that is an automatic paper feeder installed at the bottom of the lower unit 2, and a cover 3 of the upper unit 1. Inner and lower unit 2
Inside the cover 4, a mechanism for forming an image and a control unit for controlling this mechanism are housed, the details of which will be described later, and automatic and manual paper feeding from the paper feed tray 13 is possible. It is equipped with a paper feeding mechanism, and by installing the optional tray 9, three-way paper feeding becomes possible.

The cover 3 of the upper unit 1 has an operation panel 5 attached to the front, and a font cartridge insertion slot 6 at the back of the right side.
It forms an emulation card insertion lower, and further forms an upper paper ejection tray 8 for storing ejected paper in a part of the upper part.

The operation panel 5 includes a rotary type paper size selection switch 10 for instructing the paper size to this printer, and a switch for selecting the paper feed tray between the lower unit (main body side) 2 and the optional tray 9. , a group of switches 11 for giving various other instructions, and a display device 12 consisting of a light emitting diode (LED) etc. for displaying various error statuses such as photoconductor replacement, paper end, jam, toner end, etc., paper size, etc. ing. The font cartridge insertion slot 6 is for inserting a font cartridge having RAM or ROM that stores character fonts, and the emulation card insertion lower is used to connect the host and this printer depending on the type of host. This is for inserting an emulation card to ensure consistency.

In addition, a paper feed tray 13 for placing and holding paper is removably installed on the right side of the lower unit 2, and furthermore, on the left side of the front side, the paper output direction is set to the outside of the printer to the left (in the direction of arrow A) and to the upper tray. A paper discharge switching knob 14 for switching to one of the paper trays 8 is provided.

These upper unit 1 and lower unit 2 are hinged on the back side, and are fixedly held together by a locking mechanism on the front side, and locked by pushing up the lock lever knob 15 protruding from the front side of the cover 3. The mechanism is released and the upper unit 1 can be rotated and lifted from the lower unit 2 to facilitate maintenance work and parts replacement.

In addition, a paper feed cassette 300 is inserted into the optional tray 9, and a recess 363 for a handle is formed in the center of the front surface, and a release lever 334 for unlocking is provided to protrude from the fan-shaped opening 330. It is being

370 is a power indicator lamp of the option tray, and a green LED lights up when the power is turned on.

FIG. 2 is a configuration diagram showing an image forming mechanism section and a paper feeding device section of this laser printer.

This laser printer uses a drum-shaped photoreceptor (op
c drum) 21 is rotated in the direction of the arrow by a main motor (not shown).

At this time, first, the surface of the photoreceptor 21 is uniformly charged by electric discharge from the charge wire 23 stretched parallel to the photoreceptor 21 on the charger 22, and then the laser writing device 2
4, a laser beam modulated according to a written image from a semiconductor laser (not shown) is transmitted to a polygon motor 10.
5 rotates the polygon mirror 106, mirror 1
07 and the photoreceptor 2 through the cylindrical lens 108.
The laser beam (scanning beam) scans the photoreceptor 21 in the axial direction and sub-scans it by rotating the photoreceptor 21 itself in the direction of the arrow. A corresponding electrostatic latent image is formed.

Then, toner 27 is attached to the electrostatic latent image on the photoreceptor 21 by the developing device 26, and the toner image is visualized as a toner image. This developing device 26 includes a toner replenishing roller 2 that rotates toner 27 contained in a toner storage tank 28 in the direction of the arrow.
9 replenishes the developing roller 30, and with the toner layer thickness control blade 32 regulating the toner layer thickness on the surface of the developing roller 30 to a constant thickness, the developing roller 30 is moved in the direction of the arrow while lightly touching the photoreceptor 21. Rotate to toner 2
This is a contact development type developing device in which the photoreceptor 7 is deposited on the photoreceptor 21.

The developing device 26 includes an agitation plate 33 for agitating the toner 27 contained in the toner storage tank 28, and a toner cartridge 34 mounted on the top.

On the other hand, when printing is started by selecting the main body side (paper feed tray 13) with the paper feed tray selection switch on the operation panel 5, the paper feed device section detects the The uppermost sheet of paper 36 is separated by a paper feed roller 37 and friction pad 38 that rotate in the direction of the arrow, passes through the upper part of a paper guide 80 bent into a deformed U-shape, and is transferred to an upper conveyance roller. 39 and the lower conveyance roller 40, and is further conveyed to the conveyance surface 41 by these upper conveyance roller 39 and lower conveyance roller 40.
is conveyed to the transfer position via.

Then, this paper is brought into contact with the photoreceptor 21 at the transfer position to be superimposed on the toner image, and a predetermined voltage is applied to the transfer charger 43 at a predetermined timing to attract the toner toward the paper, and the toner is placed on the photoreceptor 21. Transfer the toner image onto paper.

Immediately after this transfer process is completed, the photoconductor 21 is irradiated through the paper and the paper by a static elimination lamp 44 made of a light emitting diode (LED) disposed on the downstream side of the transfer charger 43, and the residual charge on the photoconductor 21 and the paper are removed. Charges on the paper as it passes are removed, and the paper is separated from the photoreceptor 21 by its own weight.

After that, the paper that has been separated by its own weight from the photoconductor 21 is transferred to the conveying surface 47.
It is sent between the heating roller 50 and pressure roller 51 of the fixing device 48 via the fixing device 48 .

A heater 52 is provided inside the heating roller 50 to heat the surface, and the heating roller 50 and pressure roller 51 heat and press the paper and toner image, thereby melting the toner image onto the paper. Take root. Note that the heating roller 5
0 has a surface made of a conductive material such as Teflon mixed with carbon as a roller base, and the stackability after paper ejection is improved by removing the charge on the paper during fixing.

This fixed paper is peeled off from the heating roller 50 by a peeling claw 53 and sent to a paper discharge roller 55. A paper ejection switching claw 56 is provided at a downstream position of the paper ejection roller 55. This paper ejection switching knob 5 is the paper ejection switching knob 1 shown in Figure 1.
4, by rotating the paper discharge switching knob 14, the paper discharge switching claw 56 is rotated between the position shown by the solid line and the position shown by the broken line.

When the paper ejection switching claw 56 is in the position shown by the solid line, the paper ejected from the paper ejection roller 55 passes through the conveyance path 60 formed by the paper ejection guide member 57 and the paper ejection guide members 58 and 59. Upper paper ejection roller 6 in the reversed state
1, the paper is ejected onto the upper paper ejection tray 8 (face-down paper ejection).

Further, when the paper ejection switching claw 5 is at the position shown by the broken line, the paper ejected from the paper ejection roller 55 remains at the arrow A.
Paper is ejected in the direction (face-up ejection).

Note that you are free to select any paper ejection mode, but
Face-down paper ejection, which is stacked with pages, is suitable for plain paper, and face-up paper ejection, which is stacked with reverse pages, is suitable not only for plain paper, but also for paper that is relatively dusty, such as envelopes. .

In addition, when the paper 36 is placed on the paper feed tray 13 and you want to manually print a sheet of paper 36' of a different size, for example, the paper 36' can be mounted on the paper feed tray 13 so that it can be opened and closed. When the paper 36' is inserted into the upper part of the manual feed guide 13a that has been inserted, the pressure of the paper feed roller 37 on the paper 36 is temporarily released, and then the pressure is pressed again to start printing. 3
6' is conveyed to the transfer position by the paper feed roller 37 passing over the paper guide 80, and from the second sheet onward, the sheets 36 in the paper feed tray 13 are conveyed to the transfer position in the same manner as in the above case. After the predetermined fixing process is performed, the paper ejection roller 55
is discharged from.

Furthermore, when printing is started by selecting "optional tray" with the paper feed tray selection switch on the operation panel 5, the paper feed cassette 300 is moved by the paper feed device provided in the option tray 9, details of which will be described later. The sheets 301 inside are fed out one by one by the rotation of the feed roller 302 in the direction of the arrow and the frictional force of the friction pad 303, and are forcibly reversed along the arc-shaped guide portion 304a of the turn cover 304. The lower conveyance roller 39 and the lower conveyance roller 40 pass through the conveyance path formed by the upper guide plate 305 and the paper guide stay 306, and then pass through the conveyance path between the paper guide 80 on the lower unit 2 side and the lower paper guide 307. The paper is then fed into the nip portion of the paper feed tray 13, and thereafter transported to a predetermined transfer position in the same way as when paper is fed from the paper feed tray 13.

After the paper is fed by any of the methods described above, the photoreceptor 21 that has completed the transfer process is cleaned of toner remaining on the surface by the cleaning blade 63, and is ready for the next image forming process. Be prepared. Further, the residual toner removed from the photoreceptor 21 is sent into a toner collection tank 65 by a toner collection roller 64 and collected.

Further, an electrical chassis 74 is provided at the upper part of the cover 3 of the upper unit 1, and therein is a main control board 75 which constitutes a main controller which is a control section of this laser printer, and a character control board 75 which constitutes a character controller. Board 7B is installed.

Further, in FIG. 2, 71 is an ozone blower fan, 72 is a suction fan unit, 171 is a registration sensor that detects when the paper is fed to the position where it hits the upper and lower conveyance rollers 39 and 40, and 172 is a fixing sensor. 173 is a toner over sensor; 174 is a paper end sensor that detects the presence or absence of paper on paper feed tray 13; 175 is a latch that detects the operating state of latching solenoid 145; sensor, 17
7 is a fixing temperature sensor.

Further, 520 is a paper end sensor of the optional tray, which detects the presence or absence of paper in the paper feed cassette 300 by the filler 36.
Detected by rotation of 0.

Next, the option tray 9 will be explained in detail with reference to FIG. 3 and subsequent figures.

As shown in FIG. 3, the optional tray 9 has an insertion slot in the lower part of the storage case 308 into which the paper feed cassette 300 can be inserted and removed in the direction of arrow B (direction perpendicular to the paper feed direction). 308a, and the lower end of the turn cover 304 is pivotally attached to the front side of the right side so that it can be opened and closed in the direction of arrow C, and DC1! A power supply unit 309 for supplying pressure and a control board 310 equipped with a microcomputer for controlling various types of option trays are fixedly installed.

In addition, a boss portion 308 that serves as a mounting seat is provided on the top surface 308b of the case, which is slightly lower than the height of the peripheral edge of the storage case 308.
A plurality of brackets c are formed at intervals, and the bracket 3
12 are fixed vertically to the rear bottom, and above them are a front upper plate 311, a rear upper plate 313.
A plurality of tapping screws 323 are attached to each rear cover 314.
It is installed by.

The option tray 9 is positioned with respect to the lower unit 2 using positioning protrusions 322, 3 fixedly protruding upward from the top surface of the front and rear upper plates 311 and 313.
22 is fitted into a corresponding positioning hole (not shown) provided on the lower unit 2 side.

In addition, on the rear surface 308d of the storage case 308, as shown in FIG. 4, an AC input socket 315° for supplying power to the option tray 9, a fuse holder 316 for storing a fuse for protecting the circuit from overcurrent,
An AC cable 317 that connects to a connector (not shown) provided on the lower unit 2 on the main body side to supply power to the main body side, and a microcomputer provided on the main body side, for example, whether the optional tray 9 is installed. An interface cable 318 is provided for serially transmitting a signal to periodically send a signal to confirm whether the
Power switch 319 for turning on and off C power supply
is provided.

Furthermore, as clearly shown in FIG. 4, the storage case 3
08 is a paper end sensor 32 that detects the presence or absence of paper.
0. A cassette size sensor 321 (both photo sensors) detects the various paper sizes in the paper feed cassette 3i00 and whether or not the cassette itself is installed, and a pulse sensor 32 detects the positive rotation speed of the feed motor 325, which will be described later.
Each of the 7 sensors is arranged at a predetermined position.

At a position in the paper feeding direction adjacent to the turn cover 304, the above-mentioned upper guide plate 305 and paper guide plate 306 are arranged so that one of the two ends thereof is spaced at a required interval suitable for conveying the paper between them. It is fixed to the storage case 508 via a frame 324, and the frame 32
A feed motor 325, which is a DC motor, is fixedly mounted on the output shaft of the feed motor 325 with its output shaft facing in the horizontal direction, and a feed roller 302 (second
The feed roller shaft 326 to which the feed roller shaft 326 (see Figures 1 and 5) is fixed is connected to the drive gear 329. They are rotatably connected via a paper feed gear 328, so that the feed roller shaft 326 is decelerated in synchronization with the rotation of the feed motor 325, and the feed roller 302 is rotated in the direction indicated by the arrow in FIG. .

Next, the peripheral portion of the turn cover 304 will be described in detail with reference to FIGS. 5 to 8.

As shown in FIG. 5, the turn cover 304 is rotatably mounted in the direction of arrow C by fitting pivot shafts 504b formed on both sides of the lower end (only one side is shown) into the storage case 308.
A large number (7 in this example) formed in an arc shape on the left edge of the inside upper part.
A guide portion 304a is formed by aligning ribs 304c spaced apart from each other.

One of the ribs 304c is attached to the storage case 308 as shown in FIG. 6(A) when the turn cover 304 is closed.
The cover sensor 35 is a photosensor fixed on the bottom of the
The positional relationship is such that it is inserted into the detection groove 352a of No. 2,
The cover sensor 352 has a rib 304 in this detection groove 352a.
c is inserted, and the open/closed state of the cover is detected. When the rib 304c is separated from the detection groove 352a as shown in FIG. 6(b), the open state of the cover is detected by the passage of light, and the sheet feeding operation is disabled.

Further, L-shaped pieces 353, which are paper pull-out members, are attached to the side surface of the turn cover 304, with bent portions 353a at the tips thereof facing each other inward, and their positions are as shown in FIG. When the turn cover 304 is closed (in the state of use 71), the bent portion 353a is located inside the outer diameter of the feed roller 302.

Therefore, under normal use, the paper cassette 3
Guide part '504a of turn cover 304 from inside 00
The paper 301 fed by the feed roller 302 passes between the upper guide plate 305 and the paper guide stay 30B without interfering with the L-shaped piece 353, and
The lower conveying roller 3
9 and the lower conveyance roller 40.

In the unlikely event that an abnormal condition occurs and the paper 301 jams, the paper 301 will stop at the position shown in FIG.
If paper is not fed from the paper shown in the figure) first, turn cover 30
4 is opened in the direction of the arrow as shown in FIG.
Since the jammed paper is engaged with both sides of the feed roller 302 and pulled out in a direction away from the feed roller 302, the jammed paper can be easily taken out.

Note that this L-shaped piece 353 can be installed in the paper width direction at a position where it can hold the minimum width paper to be used. It can be attached movably according to the turn cover 504, or this L-shaped piece can be formed integrally with the turn cover 504 in advance.

Next, details of the paper feed cassette 300 will be explained with reference to FIG. 9.

The paper feed cassette 300 inserted into the option tray 9 occupies approximately half of the area at the bottom of a rectangular parallelepiped cassette case 354 with an open top, as shown in a perspective view from the rear side in FIG. Hinge parts 555a, 355a in which a bottom plate 355 of the same size is formed on both side ends of one edge part.
(only one side is shown) is pivotally supported on both sides of the cassette case 354 so as to be rotatable in the direction of arrow E, and a space is provided in the front wall portion 354a on the operation side, and the upper part is covered with a lid 348. A cassette lock mechanism'5 is connected to a latch plate 336 protruding from the rear wall 354C through a shaft 333 pivotally supported at the bottom of the cassette.
57, and the wall 354b on the paper take-out side is connected to the rear wall 3.
Thicker than 54c.

The butt holder is biased upward by a spring and includes a friction pad 303 whose upper edge is arched and has many shallow ribs formed at intervals, and whose central portion is cut out to prevent double feeding of paper. It is attached to.

Furthermore, paper edge guides 351a and 331b for guiding the front screen of paper stored in the cassette case 354 are provided inside the front and rear walls 354a and 354c.
are provided facing each other, and a bottom plate 355 at the bottom of the cassette is provided.
Insert holes a, b, and c (c is the back fence 33
9 is inserted, so it is not visible), and a back fence 339 that guides the rear side of the paper is inserted therein. And the latch plate 3 of the rear wall portion 354c
An insertion groove 354d is formed on the upper edge adjacent to 36, into which the cassette size detection plate 352 is inserted and attached.

The cassette lock mechanism 357 is pivotally supported at the bottom of the cassette case 354, as shown in FIG.

A release lever 33 is attached to one end (front operation side) of the long shaft 333 that reaches from the front wall 354a to the rear wall 354c.
4 is fixedly installed, and an operating knob 334b is fixedly installed at the tip thereof, and one end of a coil spring 335 is locked to a locking claw 334a formed at the top, and the other end is locked to the front wall 354a of the cassette case. The release lever 334 is always urged to rotate in the direction of arrow F.

On the other hand, a latch plate 33 is formed in a fan shape on the other end side of the shaft 333, and has a stopper part 336a formed at the upper end.
6 is fixedly installed, and the stopper part 336a on the plate surface
A lock pin 337 is fixed perpendicularly to and parallel to the shaft 333 near the outer peripheral edge away from the shaft 333 . Therefore, the latch plate 336 is configured to rotate in conjunction with the movement of the release lever 334 in the direction of arrow F or in the opposite direction.

A support piece 338 with a plate surface parallel to the latch plate 7136 is fixed to the bottom of the cassette case 354 in the vicinity of the latch plate 7136, and a support pin 3i40 is fixed to the upper part of the support piece 338 parallel to the shaft 333.

The bent intermediate portion of the L-shaped lock lever 341 is rotatably supported by the support pin 340.

The lock lever 341 is always urged to rotate in the direction of arrow G by a spring 342 that is engaged with the support pin 340 between it and the support piece 538.
A locking groove 341a is formed on the side of the lock pin 337.
When the lock lever 341 is rotated in the direction opposite to the arrow F from the position shown in FIG. (state shown).

Note that the latch plate 336 is attached to the frame 324 (fourth
The positional relationship with the lock lever 341 is shown in FIG.
In the situation shown in b).

The stopper part 336a is the locking part of the frame '524!
124a, and when the latch plate 336 is at its maximum rotational position in the direction of arrow F in FIG. 10 (the state after inserting the cassette), the locking portion 3
24a so that the paper feed cassette 300 cannot be pulled out from the storage case 308.

In addition, as shown in FIG. 12 when viewed from the direction of arrow H in FIG. is pivoted to the jetty part 308e of the storage case 308, and is in a positional relationship in which it abuts against the V-shaped bent latch part 343a of the latch pawl 343, which is allowed to rotate only in the direction of the arrow.

Note that the latch pawl 343 is urged to rotate in the direction opposite to the direction indicated by the arrow by a coil spring 344.

Furthermore, approximately at the center of the shaft 333, there is a
Pressure plate: 5i4 as shown in Figure 0)
5 is fixed, for example, by a screw, and the shaft 3
An L-shaped support plate 346 on which a support part 346a is rotatably supported is attached to the outside in the axial direction of the pressure plate 33, and its flat part faces the flat part of the pressure play 1-345. .

Approximately midway in the plate width direction of the left vertical surface 346b of the support plate 346, the cassette case side holder is connected to the seat 354e, and the spring holder is held upward by a coil spring 358 that is engaged via the seat 347. A pad holder 351 is attached to the pad holder 351, which is biased by the pad holder 351 and supported by a pin 349 so as to be able to rotate slightly with respect to the vertical surface 346b.

The friction pad 303 is made of, for example, cork material with a large coefficient of friction, and the pad holder 351
It is integrally fixed on the top surface of the unit by adhesive or the like.

Also, the maximum rotation angle θMAI of the pressure plate 345
is determined by the position where the upper part of the operating knob 334b of the release lever 334 abuts the end of the lever opening 330 of the front wall 354a, and the pressure plate 345 is regulated so as not to rotate more than necessary. There is.

Then, the release lever 334 is pushed down in the direction opposite to the arrow F in FIG. When inserted from the direction of arrow J in FIG. 12, the inclined surface 341d of the lock lever 341 comes into contact with the latch portion 343a of the latch pawl 343 as shown in FIG. The latch plate 336 rotates slightly against the biasing force of the spring 342 in the direction opposite to the direction indicated by G, and the lock pin 337 disengages from the locking groove 341a.
The stopper portion 336a enters into the locking portion 324a of the frame 324 and wraps therein.

Therefore, even if you try to pull out the paper feed cassette 300 from the storage case 30B in this state, the latch plate 33
6 is locked and cannot be done.

At this time, as the latch plate 336 rotates, the pressure plate 345 also rotates via the shaft 333, so the bottom plate 355 is pushed up as shown in FIG. 13, and as shown in FIG. Then, the top of the paper 301 placed thereon is pressed against the feed roller 302.

When the paper feed cassette 300 is pushed into a predetermined position, the lock lever 341 passes over the latch pawl 343 and is firmly locked, as shown in FIG. 14(B).

When pulling out the paper feed cassette 300, push down the release lever 334 in the direction opposite to arrow F in FIG.
While the lock pin 337 of the latch plate 336 slides on the guide surface 341b of the lock lever 341, the locking groove 3
41a and the latch plate 336 returns to the state shown in FIG. 11(a), the lock is released and the latch claw 34
3 also rotates in the working direction as shown in FIG. 14(c), so that it can be pulled out.

Next, the mechanism for detecting the cassette size will be explained in detail with reference to FIGS. 15 and 16.

This optional tray 9 is 1, for example, A4. It is possible to use paper of different sizes, such as 1-gal, letter, etc., and a cassette size detection plate (with a detection part of different shape as shown in Fig. 15), which is prepared in advance according to each paper size, is used.
332A to 332C (hereinafter simply referred to as "detection plates") are used.

To explain the detection plate 332A as a representative example, 1. For example, a thin steel plate (magnetic plate) is bent into a U-shape to form a detection part 332a for paper size identification at the bottom, and its width is narrower than the intermediate base part 332b. Insert portions '562Q are provided at both ends of the base portion 332b.

332d, and a bent part 332e for preventing reverse insertion is formed at the upper part with the same width as the base part 332b, and the height of the bent part 332e is made lower than that of the detecting part 332a.

As shown in FIG. 15, this detection plate 3152A is for A4 size, and the detection part 332a thereof is formed to have the widest width, and the detection part 332a of the detection plate 332B for legal size is half the width and is opposite. The detection portion 332a of the letter size detection plate 332C is formed to be offset to the left side.
It is also half the width and is offset to the right.

In addition, a cassette case 354 into which these detection plates 332 (332A to 332C are collectively referred to) is inserted.
A rubber magnet tape 359, which is an elastic magnet, is attached to the side insertion groove 354d using an adhesive or the like.

To attach this detection plate 332 to the cassette case 354, as shown in FIG.
Insert portions 332G at both ends of the base 332b with a facing downward.
, 332d into the insertion groove 354d formed in the cassette case 354 and press firmly. As a result, the detection portion 332a of the detection plate 332 is lowered and positioned until it comes into contact with the groove bottom portion 354f.

The inserted detection plate 332 is attracted to the back surface of the base 3i52b by the magnetic force of the rubber magnetic tape 359, and
Because it is tightly pressed due to its elasticity, the paper feed cassette 3
Even when attaching and detaching the 00, it is securely held without falling.

In addition, if you accidentally try to insert the detection plate 332 with the detection part 332a facing upward, the bent part 332e for preventing reverse insertion will get in the way and prevent you from inserting it into the insertion groove 354d. This reliably prevents the detection plate from being inserted in the opposite direction.

Note that the bent part for preventing reverse insertion does not necessarily have to be formed on the entire edge of the detection plate on the side where the detection part is not formed.
They may be formed at least at positions corresponding to the insertion portions 552a and 352d.

Further, instead of the rubber magnetic tape, a rigid magnet may be attached to the wall surface of the insertion groove via an elastic body.

When the paper feed cassette 300 is inserted and set in the storage case 308 to a predetermined position, the cassette size sensor 321 shown in FIG.
The cassette size (paper size) is detected by detecting the difference in shape of a by a combination of light transmission and blocking.

For example, as shown in FIG. 16A, the cassette size sensor 321 includes two sets of photosensors, each consisting of a light emitting diode LED1 and a phototransistor PT1, and a light emitting diode LED8 and a phototransistor PT2. They are arranged facing each other on both sides of the left side.

This cassette size sensor 321 is connected to the aforementioned control board 310, and each phototransistor PT□, PT has a pull-up resistor R1, R,
+5V power is applied to the collector through the emitter, and the emitter is grounded.

The detection signals Si and S2 on the collector side are respectively input to the CPU in the control board 310 via trigger inverters.

Therefore, when each phototransistor PT, PI3 receives light from the light emitting diode LED, LED2 and turns on, the detection signal S,, S2 becomes low level "L", and the light from the light emitting diode LED1°LED is detected. Board 53
When it is blocked by the second detection unit 3″62a and turned off,
The detection signal 5itS2 becomes high level "H".

The relationship between the combination of the detection signals S, S2, and H, the presence or absence of a cassette, and the cassette size is as shown in FIG. 16B, and the CPU determines this.

Next, the paper end detection relationship will be explained in detail with reference to FIGS. 17 and 18.

At the top of the bottom plate 355, a support part 360a is attached with a pin 361 in the direction of the arrow in FIG. A projecting piece 360b formed at the rear end and projecting upward is arranged so as to go in and out of the detection groove 320a of the paper end sensor 320, which is a photosensor.

As shown in FIG. 18, the tip of the filler 360 has an upward curve in two directions perpendicular to the feeding direction of the paper 301 (arrow L) and the attachment/detachment direction of the paper feed cassette 500 (arrow M). Arc-shaped curved surface part (slope may be used) 3i80c to 360e
, and the free height of each tip part is 3
55 is set to be higher than the top surface position when the pressure plate 345 is at the maximum rotation angle θmax (approximately the same position as the top surface of the paper when fully loaded with paper in the bottom-down state). There is.

Therefore, even if you accidentally insert the paper feed cassette 300 fully loaded with paper into the storage case 508 with the bottom plate 355 raised or lowered, the filler 360 will have its curved portion 360d aligned with the bottom plate. 355 or the upper surface of the paper and rises, so there is no risk of breakage.

When the paper '501 is on the top of the bottom plate 355, the filler 360 is lifted, so the projecting piece 3 at the rear end
60b is located outside the detection groove 320a of the paper end sensor 320, the sensor enters the transmitting state, the paper 301 is controlled to be transported, and when the paper runs out, the tip of the filler 360 lowers and the protruding piece 360b detects the paper end. Since the paper is inserted into the groove 320a to block light, the feeding operation of the paper is stopped.

FIG. 19 is a cross-sectional view showing the vicinity of the paper curl press mounting portion of the optional tray.

A paper curl presser 362 made of a thin elastic plate material such as Mylar is attached to the upper surface 308e of the storage case 308 near the feed roller 302 of the optional tray 9, and the upper surface 355C in an arched manner and is fixed so as to be lightly pressed by the elasticity of the material itself.

Note that the paper curl presser 362 is provided with inclined portions 382a at both front ends, as shown in FIG. 20, in order to prevent damage to itself and to prevent the upper end of the paper from shifting when the cassette 300 is attached or removed. At the same time, the strength of the waist is kept to the minimum necessary to suppress the curling of the paper.

Therefore, in this optional tray 9, the cassette 3
For example, when the paper 301 is fully loaded and the paper 301 is warped and curled on both sides, the uppermost paper is held firm by the paper curl presser 362 so that it does not affect the paper feeding of the feed roller 302. To hold down the curls,
It is possible to prevent the curled paper from coming into contact with the feed roller 302 and curling up, or from jamming, skewing, etc. caused by the curling of the paper during conveyance.

FIG. 21 is a block diagram showing a schematic configuration of the electrical system of the main body of this laser printer.

First, to explain the power supply system, a commercial power source is connected to the power input section 122 via the socket into which the AC plug 121 or the AC cable 317 of the optional tray 9 is inserted.
Input the power supply voltage to .

This power input section 122 removes noise from the input voltage through a main switch 123 and a noise filter 124, and then disconnects the main power when the upper unit 1 is separated from the lower unit 2 and lifted. The power is supplied to the main controller power supply unit 126 via the interrotator switch 125, and directly to the character controller power supply unit 127.

The main controller power supply unit 126 includes a noise filter 130, a constant voltage circuit 131 that converts input voltage from AC/DC to generate a constant voltage, and a heating roller 50 shown in FIG. 1 for controlling the fixing temperature of the fixing device 48. A high-speed solid-state relay (SSR) as a switching element to control on/off the power supply to the heater 52 provided inside.
132 mag.

The character controller power supply unit 127 includes a noise filter 133, a constant voltage circuit 134 that converts input voltage from AC/DC to generate a constant voltage, and the like.

Then, ffi for the main controller [unit 126
, a main controller 135 formed on the main control board 75 (FIG. 2), a power back (charging/developing power back) 137 for the charging charger 22 and developing bias, and a power back (transfer power back) 138 for the transfer charger 43. and a driver for the main motor 139, a crystal oscillator for generating a reference signal for constant speed control,
Power supply voltage is supplied to a main motor unit 140 including an encoder, a power circuit, a servo circuit, etc., a group of various operating devices 141, an ozone blower fan 71, a suction fan (not shown), a heater 52 of the fixing device, and the like.

Further, the character controller power supply unit 127 supplies a power supply voltage to the character controller 136 formed on the character control board 76 (FIG. 2).

Note that the various operating equipment group 141 includes a paper feed roller 37 (second
A paper feed clutch 142 for controlling the rotation of the lower conveyance roller 40, a paper conveyance latch 143 for controlling the rotation of the lower conveyance roller 40, and a total counter for counting up a total counter (not shown) that displays the number of prints. It is composed of a solenoid 144 and a latching solenoid 145 provided in the suction fan unit 72.

Next, the control system will be described.

The character controller 136 has an interface 151 with the computer HT, and a microcomputer (hereinafter simply referred to as rC) consisting of an MPU, ROM, RAM, r/○, etc.
PUJ) consists of 152 mag.

The interface 151 is in charge of receiving character information sent from the host HT, sending status information to the host HT, and the like.

The CPU 152 converts the character information received from the host HT via the interface 151 into character font information using the font cartridge (or internal font cartridge) 153 installed via the font cartridge insertion slot 6, and converts it into character font information. Controller 1
35 and takes in instruction information from each switch of the switch group 11 of the operation panel 5 (FIG. 1), and also controls the lighting of the display 12A forming the display group 12.

The main controller 135 has a video interface 161 interposed between it and the character controller 136, and a microcomputer (hereinafter simply referred to as rcPUJ) 162, which includes an MPU, ROM, RAM, and/or etc.
, a write control section 163, a display driver 164, a synchronization detection circuit 165, a polygon motor driver 166, and the like.

The video interface 161 is in charge of sending and receiving character font information from the character controller 136 and transmitting a clock signal that serves as a reference for controlling the character controller 136.

The CPU 152 generates a clock signal from a built-in clock oscillator, and performs charging, exposure, and development using a built-in timer that operates based on the internal clock.

Controls the timing of image forming processes such as transfer, paper feeding, and fixing.

Further, based on the image clock (pixel clock) from the write control unit 163, the CPU 182 sends write data corresponding to the character font information received from the character controller 136 to the write control unit 163 to write the image. .

Furthermore, this CPU 182 controls the lighting of each display 12B forming the display group 12 provided on the operation panel 5 via the display driver 184, and also takes in size selection information from the paper size selection switch 10.

This CPU 162 is the charging/developing power pack 1.
37. Transfer power pack 138. Main motor driver 140. Various operating equipment group 141 and fixing control 5SR1
32 etc. is also controlled. In addition, each resist sensor 171 is made of a transmission type photo sensor or the like. Paper discharge sensor 172.
Toner over sensor 173. Paper end sensor 17
4. Various detection information from a latch sensor 175, a toner end sensor 176 consisting of a microswitch, etc., a fixing temperature sensor 177 consisting of a thermistor, etc. are also input.

Here, the mounting position of each sensor is shown in FIG. 2. Although the toner end sensor 176 is not shown in FIG.
8 and detects when there is no toner.

Next, to explain the write control unit 163, the CPU
Based on the write data from the laser writing device 182, the laser diode of the laser writing device 24 is driven and controlled by the LDW moving part 180 to emit a laser beam according to the writing data, and the laser beam is also incident from the laser writing device 24 via the optical fiber 112. The synchronization detection circuit 16
The driving start timing of the laser diode of the laser writing device 24 is controlled according to the synchronization detection signal output from the laser writing device 24.

Furthermore, the drive control of the polygon motor 105 of the laser writing device 24, that is, the rotation of the polygon mirror 106 is controlled via the polygon motor driver 166.

Note that within this main controller 135, two voltage conversion circuits 178 and 179 each consisting of a three-terminal regulator, a DC/DC converter, etc. are provided. These voltage conversion circuits 178 and 179 generate various voltages.

Figure 22 shows the optional tray 9 of this laser printer.
The schematic configuration of the electrical system is shown below.

When the plug of the power cord from the commercial power source is inserted into the AC input socket 315, power is supplied to the power supply unit 309 via the fuse and power switch 319. In addition, before passing through the power switch 319, the AC cable 3 branches off and passes through the terminal block 371.
By outputting this power to the main body 17 and inserting the plug into the AC input socket of the main body, power is also supplied to the main body 1 through the optional tray 9.

By doing so, it is not necessary to provide the main body with a 3-pin AC power outlet, which is expensive due to safety standards, and the cost becomes low.

The power supply unit 509 steps down the input AC 100V using a transformer, rectifies and smoothes it, and outputs two types of DC voltage terminals V1 (e.g. +5V) and +v2 (e.g. +5V) with different voltages.
15v) to the control board 310.

The control board 310 is a microcomputer (C
PU), an input/output interface, a feed motor driver, a communication buffer, etc., and includes the aforementioned feed motor 325, power indicator lamp 370, and various sensors, that is, the paper end sensor 3.
20. Cassette size sensor 321. Cover sensor 35
2. A pulse sensor 327 and a dip switch 372 for self-test are also connected.

Furthermore, an interface cable 318 is connected to this control board 310, and by inserting the plug at the end of the cable into the socket of the main body, it is connected to the main controller 135 of the main body described above, and the interface cable 318 is connected to the main controller 135 of the main body described above, and the interface cable 318 is connected to the main controller 135 of the main body described above. Serial communication can be performed between CPU1B2 and the CPU in this control board 310.

The main controller 135 of the main body takes initiative in this communication, and is performed by sending a command and having the control board 310 on the option tray 9 side return a response.

The command consists of 1 byte, and includes a command to start and stop paper feeding, a command to notify that the option tray is in a non-selected state or a selected state, and a request to notify the state of the option tray 9. There is a command (which is constantly sent at 1 second intervals).

The response from the optional tray side also consists of 1 byte, and the contents of the response that informs the status are ready (paper feeding is possible or not), hardware error (CPU error, etc.), and motor error (failure of feed motor 325). , cover open (turn cover 304
(open/close status), paper information (paper size and paper end)
These pieces of information are transmitted using 1 bit for each byte (2 bits for paper information only).

This information is used by the main controller 135 of the main body, and error information is displayed on the error display section of the display 12 of the operation panel 5 in FIG.

The control board 310 in FIG. 22 also drives and controls the feed motor 325 based on paper feed start and stop commands from the main body, but by counting clock signals from the pulse sensor 327.
Check the rotation speed of the feed motor 325 and control the stop timing.

The pulse sensor 327 is operated by the rotation of a slit disk attached to the shaft of the feed motor 325.
A pulse signal is output from the phototransistor by intermittent ED light.

Also, the feed motor 325 causes the feed roller 3 to
02 to feed the sheets of paper in the cassette 300 one by one, and with the leading end in contact with the upper and lower transport rollers 39 and 40 in FIG. 2, the feed motor 325 is stopped to free the feed roller 302. Conveyance rollers 39 and 40 enable conveyance at a predetermined timing.

However, when the paper end sensor 320 detects the paper end, the last paper has been fed, so the paper is not only sandwiched between the feed roller 302 and the friction pad 303 but also between the feed roller 502 and the
The transport roller 355 also stops being directly sandwiched by the friction pad 355d provided at the center of the front end of the bottom plate 355 shown in the figure, and a large frictional force acts on the transport roller 355.
Even if 9.40 is started, the paper cannot be conveyed immediately, and the transferred image may become misaligned due to unsmooth movement.

Therefore, when the paper end sensor '520 detects the paper end, the feed roller 302 is rotated a predetermined amount and then given a certain additional rotation until the last paper is fed at least to the position where it comes out of the friction pad 355d. I'm trying to stop it.

In the above embodiment, an example in which the present invention was implemented in a laser printer was described, but it can also be applied to other copying machines,
It can also be implemented in an image forming apparatus such as a printing machine.

Effects As described above, according to the present invention, in an image forming apparatus having a detection piece for detecting the presence or absence of paper in the paper feed cassette, the paper feed cassette can also be inserted in a direction perpendicular to the paper feed direction. Can be attached and detached.

[Brief explanation of drawings]

Fig. 1 is an external perspective view showing an example of an image forming apparatus embodying the present invention, Fig. 2 is a configuration diagram showing the groove section and paper feeder section of the image forming apparatus, and Figs. 3 and 4 are the same. FIG. 5 is a perspective view showing different front and back views of the optional tray, and FIG. 5 is a perspective view showing the peripheral part of the turn cover. 6(a) and 6(b) are side views showing the turn cover in the closed and open states, respectively. FIGS. 7 and 8 are side views showing the state before and after removing jammed paper in the paper conveyance section. FIG. 9 is a front view partially cut away showing different states during ejection; FIG. 9 is a perspective view of the paper feed cassette seen from the rear side; FIG.
The figure is a perspective view showing the cassette lock mechanism. Figures 11 (a) and 11 (b) are front views showing different states to explain the positional relationship between the latch plate and the frame, Figure 12 is a view seen from the direction of arrow H in Figure 10, and Figure 13 is a A cross-sectional view showing the vicinity of the pressure plate of the optional tray! Figures 14 (a) to (c) are explanatory diagrams showing different stages of engagement between the lock lever and the latch pawl, respectively. Figures 15 and 16 are diagrams showing different types of cassette size detection plates and Figure 18A is a circuit diagram showing an example of the cassette size sensor and the detection signal input section in the control board; Figure 16B is the combination of the detection signals of the cassette size sensor, the presence or absence of a cassette, and the cassette. An explanatory diagram showing the relationship with the size, Figures 17 and 18 are a front view and a perspective view showing a part of the periphery of the detection device that detects the paper end, respectively, and Figures 19 and 20 are the paper curl. 21 is a block diagram showing the schematic configuration of the electrical system of the main body of this embodiment; FIG. 2 is a block diagram showing a schematic configuration of the electrical system of the optional tray. FIGS. 2 and 3 are perspective views showing an example of a conventional mechanism for detecting the presence or absence of paper in a paper feed cassette. 1... Upper unit 2... Lower unit 5.
・・Operation panel 8・Upper paper output tray 9・
...Optional tray 13...Paper feed tray 21.
... Photoreceptor 22 ... Charger 24
...Laser writing device 26...Developing device 43...
・Transfer charger 48...Fixing device 135...
Main controller 136...Character controller 300...Paper feed cassette 301...Paper 302
... Feed roller 303 ... Friction pad 304 ... Turn cover 308 ... Storage case 310 ... Control board 320 ... Paper end sensor 321 ... Cassette size sensor 325 ... Feed motor 327 ...Pulse sensors 332A to 332C...Cassette size detection plate 345
... Pressure plate 352 ... Cover sensor 356 ... L-shaped piece (paper drawer member) 354 ... Cassette case 355 ... Bottom plate 3
57...Cassette lock mechanism 360...Filler (detection piece) Fig. 5 Fig. 6 (a) (b) Fig. 7 Fig. 8 Fig. 13 Fig. 15 Fig. 332A 3328 332C Fig. 16A Fig. 168 Figure 17 Figure 18 Figure 19 Figure 20 362α Figure 23 Procedural amendment (white side, June 12, 1988, Japanese Patent Application No. 112970-1982, Title of invention Image forming device 3, Person making the amendment) Relationship to the case Patent applicant Ricoh Co., Ltd. 1-3-6 (674) Nakamagome, Ota-ku, Tokyo, Agent (Telephone: 986-23'80)
1-20-5 Higashiikebukuro, Toshima-ku, Tokyo (1) Detailed description of the invention in the specification (2) Brief description of the drawings in the specification (3) Drawing 6, contents of amendments (1) Description "Display unit 12" on page 6, line 18 is corrected to "display unit group 12." (2) In the same book, page 17, line 11, "interface cable 318" is corrected to "r interface cable 318." (3) “Figure 1” in page 37, line 10 of the same book was changed to “Figure 2 J.
I am corrected. (4) In the same book, page 49, line 14, ``each different stage'' is corrected to ``each different stage.'' (5) "Figure 12" and "Figure 15" of the drawings are corrected as shown in the attached corrected drawings. Above Figure 12 Corrected drawing Figure 15

Claims (1)

[Claims] 1. The tip of the detection piece rotatably attached to the fixed part is brought into contact with the paper in the paper feed cassette that is detachably attached to the paper feed unit, and the In an image forming apparatus such as a printer, a copying machine, or a printing machine configured to detect the presence or absence of paper in the paper feed cassette, a tip of the detection piece is provided in two directions: a paper feed direction and a direction perpendicular thereto. An image forming apparatus characterized by having a guide section having an upwardly curved arc shape or an upwardly inclined guide section.