JPH01176737A - Image formation apparatus - Google Patents

Abstract

PURPOSE:To install a large-capacity paper feed cassette in a simple constitution by providing a through hole in a paper push-up plate of the large-capacity paper feed cassette incorporating paper push-up means, whereby no-paper state can be detected by a reflex type sensor of the apparatus main body side. CONSTITUTION:When a large-capacity paper feed cassette 7 is installed on an apparatus main body 1, paper is taken out in the same manner as paper in an upper standard cassette 6 by a take-out roller 45 capable of oscillating up and down. When the height of paper is decreased to a designated sensor position, a paper push-up plate 302 is gradually raised according to the amount of taken-out paper by a driving motor, while spring force of a spring 303 a little larger than the loading weight of paper to be pushed up is reduced to continue taking out paper in the same manner as paper in the standard cassette 6. Subsequently, when the cassette is put in the no-paper state, the state is detected by a reflex type sensor 11 provided on the bottom portion of the apparatus main body 1 through a through hole 403 provided in the paper push-up plate 302. Thus, the large-capacity paper feed cassette can be installed in a simple constitution.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an image forming apparatus such as an electronic copying machine,
In particular, the present invention relates to an image forming apparatus that has an improved function of feeding paper into the main body of the apparatus.

(Prior Art) Normally, in a PPC copying machine, a device is used to feed paper into the main body of the device, which has built-in image forming process configuration means such as charging, development, transfer, cleaning, and fixing, depending on the size of the paper. At the same time, paper feed cassettes are installed in multiple stages above and below in each loading section of the main body of the device, and sheets of frequently used sizes are separately stored in a large capacity paper feed device, and this large capacity paper feed device is connected to the device. There are some that are attached to the main body.

(Problems to be Solved by the Invention) Conventionally, in particular, when a large-capacity paper feeder is attached to the main body of the apparatus, the large-capacity paper feeder itself has become large and can be installed in a wide area. Not only does it require more space, but the capacity of the drive system that pushes the paper up like an elevator increases, and it consumes a lot of power.Furthermore, the large-capacity paper feeder also requires a separate sensor to detect "out of paper." However, there was a problem in that it was inevitably expensive.

The present invention was made under the above circumstances.

The purpose is to provide a small and inexpensive image forming apparatus that has a simple configuration and can be equipped with a large capacity paper feed cassette.

[Structure of the invention] (Means for solving problems) In order to solve the above-mentioned problems, the present invention has been made.

A device that has built-in image forming process components such as charging, development, transfer, cleaning, and fixing, and consists of a standard cassette that stores a normal amount of paper and a large-capacity cassette that stores a large amount of paper. An image forming apparatus is provided with a paper feeding means, and the sheets in the standard cassette and the large-capacity cassette are taken out one by one by a paper take-out means consisting of a take-out roller provided in each mounting section, the image forming apparatus comprising: The cassette has a built-in paper pushing means that operates to push up the paper when the height of the paper stored in the large-capacity cassette becomes lower than the height of the normal amount of paper stored in the standard cassette. The paper push-up means has a paper push-up plate that pushes up the paper stored in the large-capacity cassette with the push-up force of a spring and the driving force of a drive motor via a deceleration means, and The push-up plate is provided with a through hole corresponding to a reflective sensor installed at the bottom of the apparatus main body, so that it is possible to detect the "one paper out" state.

(Function) That is, by having the above configuration, the present invention has the following features:
It is possible to downsize a large-capacity paper feed cassette, reduce the capacity of the drive motor, etc., reduce power consumption, and there is no paper in the large-capacity cassette. It is no longer necessary to install a sensor to detect the status, and the reflective sensor allows you to detect "no paper" even when the paper push-up board in the large-capacity cassette is at top dead center.
It becomes possible to easily detect the state.

(Embodiment) The present invention will be described in detail below with reference to an illustrated embodiment.

FIG. 1 shows the overall appearance of an electronic copying machine as an image forming apparatus according to the present invention, and FIG. 2 shows its internal structure, where 1 is the main body of the apparatus. Inside this device body 1,
Image forming process configuration means 2 such as charging, development, transfer, cleaning, and fixing are built in, and on the top side, it is possible to set an original on the original placing glass 3, or to set the original on the original placing glass 3. An automatic document supply/discharge unit 4, which will be described later, is provided for discharging documents, and an operation panel 5 is further disposed on the front edge of the upper surface thereof.

On the right side of the apparatus main body 1, there are a first paper feed cassette (hereinafter referred to as a standard cassette) 6 containing paper P such as plain paper to be supplied to the image forming process configuration means 2; Two paper feed cassettes (hereinafter referred to as large capacity cassettes) 7 are removably inserted into two upper and lower stages, respectively, and a paper feed means 8 is installed. The paper storage height H2 of the lower large-capacity cassette 7 is higher than that of the upper standard cassette 6.
(Hl<H2), and on the left side thereof, a paper feed tray 9 for collecting fixed sheets P is installed.

The apparatus main body 1 is composed of an upper unit 1a and a lower unit 1b, and as shown in FIG. A paper feed means 8 and a paper feed tray 9 each consisting of a large-capacity cassette 6 and a large-capacity cassette 7 are installed.

Further, in the image forming process configuration means 2, a drum-shaped photoreceptor 20 as an image bearing member is arranged approximately in the center of the upper unit 1a, and a drum-shaped photoreceptor 20 is arranged around the photoreceptor 20 along its rotation direction. Charging device 21, erasing device 22. Exposure section 23a as exposure device 23, developing device! ! 24. Transfer device 25. A peeling device 26, a cleaning device 27, a static eliminator 28, etc. are arranged in order, while paper P automatically fed from the paper feeding means 8 along the inner bottom of the upper unit 1a or a standard cassette is provided. The paper P manually fed from the manual paper feed table 30 which also serves as the cover of No. A paper transport path 33 leading to the paper discharge tray 9 via a roller pair 32 is formed, and an aligning roller pair 34 is provided on the upstream side of the image transfer section 31 of this paper transport path 33, and an aligning roller pair 34 is provided on the downstream side thereof. A fixing device 35 is arranged in each of the.

On the other hand, a first take-out roller 41 that is attached to a swingable first arm 40 and takes out sheets of paper P one by one is located near the mounting portion of the m-semi-cassette 6 that constitutes the paper feed means 8. A first conveyance roller 42a and a first conveyance roller 42a receive the sheet P taken out through the takeout roller 41 and feed it into a first branch conveyance path 33a forming the upstream side of the sheet conveyance path 33. A first sheet separating and conveying means 42 consisting of a separating roller 42b is provided, and also separates the sheets P manually fed from the manual sheet feed tray 30 which also serves as the cover of the standard cassette 6. A certain first conveyance roller 4'2a and a first separation roller 42b
A manual feed roller 43 is provided to feed the paper into the first branch conveyance path 33a through a gap between the paper and the paper.

Also, in the vicinity of the mounted portion of the large-capacity cassette 7, there is a second take-out roller 45 that is attached to a swingable second arm 44 and takes out sheets P one by one, and a second branch conveyance path 3 that receives the taken out paper P and forms the upstream side of the paper conveyance path 33;
3b, the second conveying roller 46a and the first
A second paper separation and conveyance means 46 is provided, which includes a separation roller 46b, and a paper-out detection switch 5 is installed at the mounting portion of each of the standard cassettes 6 and large-capacity cassettes 7.
0, and a paper size detection switch 51 which also serves to detect the presence or absence of a cassette.

Further, in the figure, reference numeral 52 denotes a paper sensor, and this paper sensor 52 is installed at the confluence of the first and second branch conveyance paths 33a and 33b, that is, near the upstream side of the aligning roller pair 34. The paper P from the standard cassette 6 or the large-capacity cassette 7 transported via the first or second paper separation and transport means 42, 46 can be detected.

Further, the exposure device 23 uses an exposure lamp 61 surrounded by a reflector 60 to illuminate the back of the original set on the original glass 3 provided on the top surface of the main body 1.
The reflected light from the document surface is reflected by the first mirror 62.
, the second mirror 63 and the third mirror 64 in order to the lens 65, and then the light transmitted through the lens 65 is guided to the fourth mirror 66, the fifth mirror 67, and the sixth mirror 68.
The photoreceptor is guided to the photoreceptor 20 through the following sequentially.

Then, the exposure lamp 6 surrounded by the reflector 60
1 and the first mirror 62 are mounted on a first carriage 69 that is reciprocally movable along the lower surface of the document placement glass 3, and the second mirror 63 and the third mirror 64 are The first and second carriages 69 and 70 are respectively mounted on second carriages 70 that move in the same direction at half the speed of the carriage 69, and in the state shown in FIG. By moving it in the right direction, the document sheet set on the document placing glass 3 is scanned, and an image corresponding to the document sheet is slit-exposed onto the photoreceptor 20.

The first carriage 69 is equipped with a spotting unit 71 for specifying, for example, an area where there is a document stain when copying is desired with that area erased.

The developing device 24 is composed of an upper developing unit 75 for color development and a lower developing unit 76 for black development, each of which is of a magnetic brush type and equipped with developing rollers 77 and 78. By selectively bringing the .78 close to each other and rotating them, it is possible to selectively develop black or other colors, such as red.

Furthermore, the cleaning device 1127 brings the cleaning blade 80 into contact with the photoreceptor 20 to scrape off the developer (toner) remaining on the photoreceptor 20, and also removes the scraped developer. It is configured to be discharged out of the casing 82 via an auger 81 and collected into a collection box (not shown).

The fixing device 35 has a heating roller 86 containing a heater lamp 85 and a pressure roller 87 that is urged to be in constant pressure contact with the heating roller 86, and these are surrounded by upper and lower casings 88 and 89. In addition, the pair of paper ejection rollers 32 and the paper ejection switch 90 are integrated near the downstream side thereof.

Further, the charging device 21. Transfer device 25 and peeling device 2
6 is each composed of a corona discharge device,
The charging device 21 irradiates the photoconductor 20 with light from a static elimination lamp 95 via a green filter 96, and the erasing device 22 has a large number of LEDs arranged along the longitudinal direction of the photoconductor 20, and It is possible to erase charges in a portion corresponding to a region specified by the unit 71.

Note that in the upper part of the fixing device 35 in the apparatus main body 1,
A cooling fan 55 and a sub-main motor 56 are disposed, and a conveyance belt 57 forming a part of the paper conveyance path 33 is disposed between the peeling device 26 and the fixing device 35. High voltage transformers 58 are arranged below the belt 57, that is, at the bottom of the upper unit 1a. In the drawing, reference numeral 59 denotes a document stacking table on which a document tray in the automatic document supply/discharge unit device 4, which will be described later, is stacked.

That is, the automatic document supply/discharge unit device 4 includes a separation unit 100 that constitutes a separation means for feeding, separating, and conveying the documents stacked on the document stacking table 59, and a separation unit 100 adjacent to the separation unit 100. The separating unit 100 is configured to stack originals to be transported on a document stacking table 59 and separate and invert the originals. The transport unit 200 is the separation unit 100
The document sheet ejected from the main body 1 is conveyed to an exposure position on the document placement glass 3 of the apparatus main body 1, and the document sheet after copying is discharged and stacked on the document ejection table 201. The separation unit 100 and the transport unit 200 are independent from each other, and the transport unit 200 can be opened and closed to facilitate the removal of document jams and the copying of thick originals such as books. It has become. Moreover, the separation unit 100 is.

It is attached on the device main body 1.

As shown in detail in FIG. 3, the separation unit 100 constituting the above-mentioned automatic document supply/discharge unit device 4 has a base 101 attached to the device main body 1 to which the document loading table 59 is attached at one end. A pickup roller 103 is fixed via a bracket 102 and is a take-out roller on the downstream side of the document loading table 59 on the base 101.
, a separation roller 104 and a paper feed roller 105 paired with the separation roller 104 are provided in this order, and the pickup roller 103 takes out the uppermost document sheet stacked on the document stacking table 59 one by one, and performs the separation and feeding process. Paper roller pair 10
4.105, and a first pair of aligning rollers 106 is provided on the downstream side of the pair of separating/feeding rollers 104 and 105.
The document separated in step 04 is further conveyed to the downstream side.

And as mentioned above. First aligning roller pair 106
A second aligning roller pair 107 is provided downstream of the second aligning roller pair 107.
is for conveying the document conveyed from the first pair of aligning rollers 106 or the document conveyed from the reversing path mechanism described later to the conveying unit 200 side, and one reversing roller is provided at the upper position. A paper path mechanism 110 is provided.

This reversing paper path mechanism 110 is connected to a transport unit 2 which will be described later.
Three outer paper guides 111°, 112, and 113 and two inner paper guides form a curved paper path path for guiding and reversing the document reversely conveyed from the 00 paper path mechanism.
It is composed of two paper guides 114 and 115, and three pairs of transport rollers 116 to 118 provided on a curved paper path path formed by each of these paper guides 111 to 115. ~11
5 is divided into parts to improve jam handling and ease of assembly, and each of the three pairs of conveying rollers 116
118 are arranged so that the conveyance performance of the one-curve paper bus is ensured.

Furthermore, a gate 120 is provided downstream of the second pair of aligning rollers 107 described above, and this gate 120 is used during paper conveyance from the one-separation unit 100 to the conveyance unit 200 side, which will be described later, and during document reversal. The paper conveyance from the conveyance unit 200 to the separation unit 100 can be switched and guided and controlled.

Further, in the figure, reference numeral 121 denotes a document detecting means 122 provided in the same phase as the pickup roller 103 to detect whether or not a document is stacked on the document stacking table 59 and to control the operation of the separation unit 100. 123 and 124 are document detection sensors installed on the conveyance path between the pair of separating/feeding rollers 104 and 105, which separate and feed the document one by one, and the first pair of aligning rollers 106; First and second aligning rollers installed separately on the conveyance path between the first and second aligning roller pairs 106 and 107, respectively.
This first jam detection means 1 is a jam detection means.
23 is designed to detect jams, document width, document length, etc. of the document conveyed from the pair of separating/feeding rollers 104 and 105 and the first pair of aligning rollers 106; The second jam detecting means 124 is configured to detect a jam in the document conveyed from the first pair of aligning rollers 106 and a jam in the document conveyed from the reversing paper path mechanism 110. Reference numeral 125 in FIG. 1 indicates a third jam detecting means installed on the curved paper path of the reversing paper path mechanism 110 to detect a jam of a document that is reversed once.

As shown in detail in FIG. 4, the transport unit 200 includes a single paper bus mechanism 210,
0 transports the original transported from the separation unit 100 to the exposure position on the original placing glass 3 of the apparatus main body 1, and transfers the original after copying to the original ejection table 201.
A conveyance belt 211 that conveys the paper to the side or reversely conveys it to the reversing paper path mechanism 110 of the separation unit 100, and first and second belt rollers 212 and 213 that drive this conveyance belt 211 by a drive system (not shown). Four sets of presser rollers 214 to 21 for ensuring that the conveyance belt 211 contacts the document placement glass 3 of the apparatus main body 1
7, and a paper guide 2 forming an ejection path so as to guide the original after copying to the original ejection table 201 side.
18, and a discharge roller 219 that conveys the documents on the discharge path by the paper guide 218 to the document discharge table 201 and discharges and accumulates them.

Reference numeral 220 in the figure is a document stopper for stopping the document conveyed by the conveyance belt 211 at an exposure start position on the document placement glass 3 of a predetermined copying apparatus unit 1-1.

Next, to explain the operation of the automatic document supply/discharge unit described above, first, when copying a single-sided document, when the document tray is set on the document stacking table 59 of the separation unit 100,
This "document present" state is detected by the document detecting means 121. In this condition.

When the copy button on the operation panel 6'2 of the copying apparatus main body 1 is pressed, the originals stacked on the original loading table 59 are picked up by the pickup roller 103 inside the separation unit 100, which rotates and descends, and the originals are separated and separated. The paper is fed to feed rollers 104.105, and these roller pairs 104.
With 105 rotations.

For example, the documents on the two-sheet tray 111 are separated one by one and sent to the downstream side. When the leading edge of the document is detected by the document detection sensor 122 installed in front of the first aligning roller pair 106, after a certain period of time, the first and second aligning roller pairs 106, 107
starts rotating and sends the original to the transport unit 200 side. At this time.

Said first and second aligning roller pair 106.10
7, the conveyor belt 2 of the conveyor unit 200
11 is driven, and the document sent from the separation unit 100 is conveyed onto the document placement glass 3 of the apparatus main body 1 by the drive of this conveyor belt 211, and this document is moved by the document stopper 220 onto the document placement glass 3 of the apparatus main body 1. is stopped at a predetermined exposure start position on the document placement glass 3. In this state, the apparatus main body 1 operates and starts copying the original. Then, the completion of such a copying process is completed by the apparatus main body 1.
When the copying operation is completed, the above-mentioned conveyor belt 211 is driven again, and the document that is stationary on the document placement glass 3 of the apparatus main body 1 is transferred to the pager guide 218 and the ejection roller 219. The documents are discharged onto the document discharge table 201 via the document discharge table 201 and accumulated thereon, whereby one normal document copy is performed.

In addition, during double-sided copying of a document, the document is conveyed in the same manner as in the case of single-sided document copying described above, and when the copying of the first surface of the document is completed, the gate 120 on the separation unit 100 side is activated by the switching drive of a solenoid (not shown) to convey the document. belt 21
1, the conveyor belt 211 is driven in the opposite direction to convey the document backwards to the reversing paper path mechanism 110 that constitutes the separation unit 100 and reverse it. When the leading edge of the paper passes through the paper path path and is detected by the second jam detection means 124, the conveyor belt 211 is driven in the forward direction again after a certain period of time in synchronization with this detection operation. , said second
The aligning roller pair 107 starts rotating and conveys the original onto the original placing glass 3 of the apparatus main body 1, and in this way, the second surface, which is the back side of the original, is again moved by the original stopper 220 to the apparatus main body. The second copying process is performed by stopping at a predetermined exposure start position on the first document placement glass 3, and when copying the first surface of the document, The original stopped at the exposure start position is reversed again and copied.

However, the operation of the apparatus main body 1 having the above-mentioned configuration is as follows.

Document loading table 59 of the document automatic supply and discharge unit device 4
After setting the original tray, the original is set on the original placing glass 3 from the automatic original supply/discharge unit device 4 by operating the operation panel 5. Meanwhile, in this state, the photoreceptor 20 rotates, and the photoreceptor 20 is uniformly charged by the charging bag v121.Next, with the exposure lamp 61 of the exposure device 23 turned on, the first carriage 69 and the second By moving the carriage 70 from the left to the right in the figure along the lower surface of the document placement glass 3, the document tray set on the document placement glass 3 is scanned and exposed to slit light, and is exposed to the yK document. A corresponding electrostatic latent image is formed on the photoreceptor 20.

The electrostatic latent image thus formed on the photoreceptor 20 is developed and visualized by either the upper developing unit 75 or the lower developing unit 76 of the developing device 24. In synchronization with the image forming operation, paper P automatically taken out from the standard cassette 6 or large-capacity cassette 7, or paper P manually fed from the manual paper feed table 30 on the top of the standard cassette 6 is placed between the aligning rollers. 34 to the image transfer section 31, and transfers the developer image previously formed on the photoreceptor 20 to the transfer device 2.
The image is transferred onto the paper P by the action of 5.

Next, the sheet P after the developer image has been transferred is peeled off from the photoreceptor 20 by the peeling device 26 and sent to the fixing device 35 via the conveyor belt 57 that constitutes a part of the sheet conveyance path 33. After the developer image is melted and fixed on the paper P, it is discharged onto the paper discharge tray 9 via a pair of paper discharge rollers 32, and the developer image on the paper P is The developer remaining on the photoconductor 20 after the transfer and peeling is scraped off and cleaned by the cleaning blade 80 of the cleaning device 27, and then the developer facing the static eliminator 28 is removed so that light can be applied to the photoconductor 20. The electrostatic memory is removed by the irradiation, thereby bringing the photoreceptor 20 into a normal state in which the next copying operation can be performed.

By the way, the large-capacity cassette 7 constituting the above-mentioned paper feeding means 8 has a built-in paper pushing means 300 according to the present invention, and this paper pushing means 300 is shown in FIGS. 5 to 12. The configuration is as shown in .

That is, as shown in FIGS. 5 to 7, the paper pusher 300 is a paper pusher provided on the inner bottom surface of the large-capacity cassette 7 via a rotation shaft 301 so as to be able to push up the paper upward and downward. A lifting plate 302, a spring 303 that supports the sheet lifting plate 302 from below and urges it upward with a predetermined lifting force, and the sheet lifting plate 302 is raised and lowered with the urging force of the spring 303. A link lever 304 to be moved, an idle gear 307 that is coaxially provided with a pinion gear 305 that engages with a gear 304a provided at one end of this link lever 304 via a one-way clutch 306, and a worm wheel 307a of this idle gear 307. The one-way clutch is composed of a worm gear 308 that meshes with the worm gear 308, a drive motor 309 that rotationally drives the worm gear 308, and a battery 401 connected to the drive motor 309 via a control circuit 400 and whose power source is a dry battery. 306 is a paper push-up plate 30
2, the pinion gear 305 can be rotated freely in the downward direction of paper P, and can be kept locked in the upward direction, while the spring 303 is slightly stronger than the loaded weight of the paper P to be pushed up. As a result, the drive motor 309 gradually drives the paper push-up plate 302 upward while loosening the spring force of the spring 303, thereby reducing the load applied to the drive motor 309. This makes it possible to reduce power consumption. At this time, the worm gear 3
08 allows a large reduction ratio to be achieved, making the whole system more compact.Moreover, since the worm gear 308 is used, the drive motor 309 does not rotate in the reverse direction due to the spring force of the spring 303. It is possible to lock the raised plate 302 at an appropriate raised position.

Further, as shown in FIGS. 6 and 8, the height H2 of the paper P stored in the large capacity cassette 7 is set to a height H2.
A paper height position displacement/detection sensor 402 is installed to detect the position IIl, and this paper height position detection sensor 402 is set to 0N-OFF as shown in FIG.
It has a hysteresis characteristic between the two, and the 0N-OFF position differs depending on the direction in which the sensor enters, thereby making it possible to detect the height position of the paper P with one sensor. .

Furthermore, as shown in FIGS. 6, 10, and 11,
The paper push-up plate 302 of the large-capacity cassette 7 has through holes 40.
3 is provided, and this through hole 403 is.

Corresponding to the reflective sensor 11 installed at the bottom of the apparatus main body 1, it is arranged so that it can detect the state of ``no paper'' even when the paper pushing plate 302 is at the top dead center. It is not necessary to install a sensor to detect the "out of paper" state on the capacity cassette 7 side, and since the sensor position distance is small even at the top dead center of the paper push-up plate 302, detection can be easily performed. ing.

That is, when the above-mentioned large-capacity cassette 7 is attached to the attachment part of the apparatus main body 1, as shown in FIG. The paper P is taken out in the same way as in the upper standard cassette 6 by vertically swinging the arm 44 of the paper taking out means (see Fig. 12), and as shown in Fig. 13, the height of the paper is increased. , when the installation height Hm of the paper height position detection sensor 402 is reached, the paper height position detection sensor 402 is turned on, the drive motor 309 is driven, and the paper push-up plate 302 is driven as shown in FIG. While loosening the spring force of the spring 303, which has a spring force slightly stronger than the loaded weight of the paper P to be pushed up, the paper is gradually driven upward according to the amount of paper taken out. This makes it possible to take out P.

Furthermore, FIG. 15 shows a state in which the standard cassette 6 is attached to the attachment part of the large-capacity cassette 7 of the apparatus main body 1, and as shown in FIG. 16, the insertion end side of the standard cassette 6 is A guide member 601 is provided on the side, and the guide member 601 is guided and supported by a support guide member (not shown) provided at the mounting portion of the large-capacity cassette 7 of the apparatus main body 1, so that the standard cassette 6 can be mounted. It is what it is. Further, 404 in the figure indicates the large-capacity cassette 7.
A display means consisting of an LED lamp installed on the top side of the
This display means 404 is connected to the battery 40 (not shown).
The battery 401 is connected to a means for detecting whether or not the battery 401 has a certain capacity, and when the capacity of the battery 401 falls below a certain capacity, a message to that effect can be displayed and checked.

[Effects of the Invention] As is clear from the above description, according to the present invention, one normal amount of paper can be stored in an apparatus main body in which image forming process constituent means such as charging, developing, transferring, cleaning, and fixing are built-in. A paper feeding means consisting of a standard cassette for storing a large capacity of paper and a large capacity cassette for storing a large capacity of paper, and a paper feed means for taking out the paper in the standard cassette and the large capacity cassette at respective loading parts. The image forming apparatus is configured to take out sheets one by one by a take-out means, and the large-capacity cassette has a height of the sheets stored in the large-capacity cassette in a normal amount that can be accommodated in a standard force set. A built-in paper pushing means operates to push up the paper when the height of the paper becomes lower than the height of the paper, and this paper pushing means pushes up the paper stored in the large capacity cassette with the pushing force of the spring and decelerates the paper. The paper has a paper push-up plate that is pushed up by the driving force of the drive motor, and this paper push-up plate is provided with a through hole that corresponds to a reflective sensor installed at the bottom of the device main body. Since the configuration is such that it is possible to detect the "absent" state, it is possible to downsize a large-capacity paper feed cassette, and it is also possible to reduce the capacity of the drive motor. In addition, it is no longer necessary to install a sensor on the large-capacity cassette side to detect the "out of paper" condition.Moreover, the 1-reflection sensor eliminates the need for a sensor to detect the "out of paper" condition, and even when the paper push-up board in the large-capacity cassette is at the top dead center, there is no paper left. This has an excellent effect in that the state can be easily detected.

[Brief explanation of the drawing]

FIG. 1 is an external view showing the overall configuration of an electronic copying machine as an image forming apparatus according to the present invention, FIG. 2 is a schematic longitudinal sectional front view, and FIG. 4 is a schematic explanatory diagram showing an enlarged view of the conveyance unit of the automatic document feed/discharge unit device; FIG. Figure 6 is a partially cutaway perspective view of a large capacity cassette;
The figure is a sectional view of the main part of the paper pushing means, and Figures 8 and 9 show the installation state and detection operation state of a paper height position detection sensor that detects the height of paper installed in a large-capacity cassette, respectively. Explanatory diagrams, Figures 10 and 11 are explanatory diagrams of a detection means for detecting the "out of paper" state of a large-capacity cassette.
Figures 2 to 14 are explanatory diagrams showing the state of paper removal;
5 and 16 are explanatory diagrams showing the state in which a standard cassette is attached to the large-capacity cassette attachment portion of the main body of the apparatus. DESCRIPTION OF SYMBOLS 1... Apparatus body, 2... Image forming process configuration means, 6... Standard cassette (first paper feed cassette), 7...
・Large capacity cassette (second paper feed cassette), 8...paper feed means, 11...reflective sensor, 41...first paper take-out means (take-out roller) 45
...Second paper take-out means (take-out roller) 300.
...Paper push-up means, 302...Paper push-up plate. 303...Spring, 403...Through hole, P...Paper. Applicant's agent Patent attorney Takehiko Suzue Figure 1, 8, Figure 9

Claims (1)

[Claims] A device that has built-in image forming process components such as charging, development, transfer, cleaning, and fixing, and consists of a standard cassette that stores a normal amount of paper and a large-capacity cassette that stores a large amount of paper. An image forming apparatus is provided with a paper feeding means, and the sheets in the standard cassette and the large-capacity cassette are taken out one by one by a paper take-out means consisting of a take-out roller provided in each mounting section, the image forming apparatus comprising: The cassette has a built-in paper pushing means that operates to push up the paper when the height of the paper stored in the large-capacity cassette becomes lower than the height of the normal amount of paper stored in the standard cassette. The paper push-up means has a paper push-up plate that pushes up the paper stored in the large-capacity cassette with the push-up force of a spring and the driving force of a drive motor via a deceleration means, and An image forming apparatus characterized in that a push-up plate is provided with a through hole corresponding to a reflective sensor installed at the bottom of the apparatus main body, so that a "paper out" state can be detected.