JP2647993B2 - Paper feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a paper feeding device such as a copying machine or a laser printer,
More specifically, the present invention relates to a sheet feeding device having a sheet feeding tray that can move up and down.

<Prior Art> A conventional paper feeding device, for example, a paper feeding device of a copying machine,
In a configuration in which the vertically movable paper tray is moved down to a drawable position (lower limit position) of the paper cassette by operating a tray switch, the tray switch is turned on to lower the paper tray. In this case, the paper tray is pulled out once, and the above paper tray can be copied at the copyable position (upper limit position) unless it is stored again.
Could not be ascended.

The above operation is the same as the operation when detecting that no paper is placed on the paper feed tray and automatically lowering the tray to a tray withdrawable position.

<Problems to be Solved by the Invention> In the above-mentioned conventional paper feed tray device, when the tray switch is turned on and the paper feed tray is lowered to a drawable position, the paper feed cassette is pulled out and then stored again. Unless otherwise, the paper feed tray could not be raised. Therefore, even when it is not necessary to replenish the sheets, the cassette must always be pulled out, which is very troublesome.

<Means for Solving the Problems> The present invention has been made in view of the above-mentioned drawbacks.

[First Means] As shown in FIGS. 1 to 4 in the first embodiment,
A paper cassette 106 having a paper tray 501 on which a large number of sheets can be placed and which can be moved up and down, and which can be pulled out at a paper feeding section of the apparatus main body; Drive mechanism 506 and the paper feed tray 501
And a tray switch 306 for lowering the paper cassette 106 to a lower limit position Q where the paper cassette 106 can be pulled out, and a paper feed for detecting that the cassette 106 is set at a predetermined position after the paper cassette 106 is pulled out. Cassette detection means
406 and the drive mechanism 506, and in response to the detection signal of the paper feed cassette detecting means 406, raises the paper feed tray 501 so as to always hold the uppermost sheet at a specified position, and raises the tray switch 306. A control means for lowering the paper feed tray to a predetermined position where the paper feed cassette 106 can be pulled out in response to the operation of the paper feed tray. A timer 704 that starts a timing operation when it is lowered to the position, and outputs a signal after the set time is counted;
The sheet detection means 606 for detecting the presence of the upper sheet and the sheet supply cassette detection means 406 do not detect the drawer of the sheet supply cassette 106, and the output signal is output from the timer 704. When the means 606 detects the presence of paper on the paper tray 501, the paper tray 5
The paper feeding device is provided with a lifting means 804 for raising 01.

[Second Means] As shown in FIG. 1, FIG. 2, FIG. 5, and FIG. 6 in the embodiment, a paper feed tray 501 on which a large number of sheets can be placed and which can be moved up and down. And a drive mechanism 506 for vertically moving the paper feed tray 501, and a paper feed tray Switch 30 for lowering to the lower limit position Q where the paper can be pulled out
6 and after the paper cassette 106 is pulled out, the cassette 10
6 controls the drive mechanism 506 to detect that the sheet 6 is set at a predetermined position, and always controls the driving mechanism 506 so that the uppermost sheet is always in the specified position in response to the detection signal of the sheet cassette detection means 406. Paper tray 501
And a control means for lowering the paper feed tray to a predetermined position where the paper feed cassette 106 can be pulled out in response to the operation of the tray switch 306. When the paper feed tray 501 is lowered to a predetermined position, the timer 704 starts a timing operation, and outputs a signal after the set time has been counted. Lifting means 804 for raising the paper feed tray 501 regardless of the presence or absence of paper on the paper feed tray 501 when an output signal is output from the timer 704 without being detected. A paper feeder is provided.

[Third Means] As shown in FIG. 1, FIG. 2, FIG. 7, and FIG. 8 in the embodiment, a paper feed tray 501 on which a large number of sheets can be placed and which can be moved up and down. And a drive mechanism 506 for vertically moving the paper feed tray 501, and a paper feed tray Switch 30 for lowering to the lower limit position Q where the paper can be pulled out
6 and after the paper cassette 106 is pulled out, the cassette 10
6 controls the drive mechanism 506 to detect that the sheet 6 is set at a predetermined position, and always controls the driving mechanism 506 so that the uppermost sheet is always in the specified position in response to the detection signal of the sheet cassette detection means 406. Paper tray 501
And a control means for lowering the paper feed tray to a predetermined position where the paper feed cassette 106 can be pulled out in response to the operation of the tray switch 306. The drawer of the paper cassette 106 is not detected by the paper detection means 606 for detecting the presence of paper on the paper tray 501 and the paper cassette detection means 406. When the presence of a sheet on the sheet 501 is detected, the tray switch 306 is operated to raise the sheet feeding tray 501 to raise the sheet feeding tray 501.
04.

<Operation> [First operation] According to the first means, when the tray switch is set to N to lower the paper feed tray to the lower limit position where the paper feed cassette can be pulled out, the paper feed tray After the descent is stopped, a timer operation is started, and a preset time is measured.

Then, after the timer starts counting, detection is performed by paper detection means for detecting the presence of paper on the paper feed tray, and based on the detection signal, whether or not paper is loaded on the paper feed tray by the control means is determined. Determine whether or not.

If the paper is placed on the paper feed tray and the time count of the timer is completed without pulling out the paper feed cassette, the time-up signal and the paper detection signal are sent to the ascending means. By inputting, a control signal of the tray drive mechanism is output from the raising means, and the tray is raised to the raised position.

[Second operation] According to the second means, when the tray switch is set to N to lower the paper feed tray to the lower limit position where the paper feed cassette can be pulled out, after the paper feed tray is stopped lowering, A timer operation is started, and a preset time is measured.

When the time count of the timer is completed without the sheet cassette being pulled out at all, the time-up signal and the sheet cassette detection signal are input to the ascending means, so that the tray drive is performed from the ascending means. A control signal for the mechanism is output, and the paper feed tray is raised to the upper limit position regardless of the presence or absence of paper on the paper feed tray.

[Third operation] According to the third means, when the tray switch is set to N and the paper feed tray is lowered to the lower limit position where the paper feed cassette can be pulled out, the paper on the paper feed tray is A detection unit and a sheet cassette detection unit. When the sheet cassette is not pulled out and sheets are placed on the sheet tray, the two units are detected. Is input to the raising means and the tray switch is set to N, whereby a control signal of the tray driving mechanism is output from the raising means, and the paper feed tray is raised to the upper limit position.

<Example> An example of the present invention will be described below with reference to the drawings.

First Embodiment FIG. 1 is a cross-sectional view showing one embodiment of a copying machine according to the present invention, FIG. 2 is a schematic cross-sectional view showing the structure of a paper feed tray unit according to the present invention, and FIG. FIG. 4 is a block diagram according to the first embodiment of the present invention, and FIG. 4 is a control flowchart of the first embodiment.

In FIG. 1, at the center of the inside of the copying machine main body 100,
A photoreceptor drum 101 is rotatably installed. Various copying process units as image forming means are provided along with an outer peripheral portion of the photoreceptor drum 101 along with a charging device 102 and a developing device 103, and a fixing device 104 is provided on the left side of FIG. Is installed. A recirculating automatic document feeder 1 is provided on one side of the upper surface of the copying machine main body 100, and a first exposure unit 5 provided vertically below a first document cylinder 20 and a second document cylinder 21 of the device 1 and a 2 exposure section 6
Are provided in parallel on substantially the same plane on the upper end surface of the main body 100. On the other side of the upper surface of the copying machine main body, a third exposure unit 105 corresponding to a book document is provided to constitute an optical system having two systems of exposure systems.

Paper feed cassettes 106A and 106B for copy paper Y are mounted on one side surface of the copying machine main body 100, and paper feed cassettes 106C and 106D are mounted on the lower center. These paper cassettes 106A
Copy paper Y placed in ~ 106D is picked up and fed
8A to 108D, and each paper cassette 10
Paper feed roller rollers 109A to 109D installed on the upper surface of 6A to 106D
Are rotated by the sheet feeding drive motor M8, respectively, so that the sheet feeding path 108A
-108D are fed one by one. The above paper feed paths 108A to 10
8D and a paper feed path 115 from an intermediate tray 113 to be described later are provided with paper transport rollers 107A to 107E, and these transport rollers are rotationally driven by a drive motor M9, so that the copy paper Y Is being fed.

An offset tray 110 is provided on the other side of the copying machine body 100.
A solenoid SOL8 is attached to the offset tray 100, and the solenoid SOL8 is operated for a predetermined time.
When turned on, the offset tray 110 shifts in the direction of the front of the paper in FIG.
When N, a shift operation is performed in the direction of the back of the paper surface, so that the offset tray 110 is configured to be able to receive a plurality of copies of the copy paper Y for some of the originals in a sorted state. A discharge path 111 for discharging the copy sheet Y through the image receiving means and the fixing device 104 to be fed to the offset tray 110 in the copy process, and a copy sheet front / back reverse path branched from the discharge path 111 ( Switchback path) 112 is provided. The copy sheet Y, which has passed through the above-described copy process and the fixing device 104 and has a document copied on one side, is copied according to the copy content desired by the operator.
The sheet is discharged to the offset tray 110 by the following three methods.

(I) The copy sheet Y is discharged to the offset tray 110 through the discharge path 111 as it is.

(Ii) After heading to the discharge path 111, the switchback 112 reverses the image on the other side of the copy sheet Y, and temporarily stops the intermediate tray 113 to convey it to the copy process step again. To be stored.

The paper feed roller 1 that rotates the copy paper Y stacked on the intermediate tray 113 sequentially from the lowermost portion by the motor M14.
The sheet is fed to the re-conveying path 115 by 14 and fed to the copying process step, passes through the fixing device 104, passes through the discharging path 111, and is discharged to the offset tray 110.

(Iii) After going to the discharge route 111, switch back route
After the copy sheet Y is reversed at 112, the copy sheet Y is discharged from the discharge path 111 to the offset tray 110.

In order to enable the above three methods, the discharge route 111
The switchback path 112 has the configuration shown in FIG. That is, the switchback path 112 includes paths 112a and 112b branched from two positions of the discharge path 111, and the paths 112a and 112b.
2b, and a path 112d that branches off from the path 112c and heads toward the intermediate drain 113. Route 1 above
A gate flapper 115 is provided at a branch between the 12a and the discharge path 111,
Gate flapper 116 at the branch point of paths 112a and 112b, path 1
A gate flapper 117 is installed at a branch portion between 12c and 112d, and each is operated by a drive solenoid, and a transport path of the copy sheet Y is automatically selected according to a copy content desired by an operator. A roller 118A is provided near the branch of the paths 112a and 112b.
118B and 118C, and rollers 119A, 119B and 119C near the branch between the paths 112c and 112d.
Is being transported. A reversing roller 120 is installed on a route 112c near the branch between the routes 112a and 112b, and is rotated forward and reverse by a driving motor M11 to reverse the transport direction of the copy sheet Y and to reduce the route 112d of the route 112c. A reversing roller 121 is installed at a position downstream of the branching point, and is rotated forward and reverse by a driving motor M12. Further, a paper output detection sensor S13 is provided near the exit of the discharge path 111, and near the entrance of the path 112a and the path 112c.
Paper inversion sensors S14 and S15, and an intermediate tray entrance sensor S16 near the exit of the path 112d. In the figure, 112A to 122c are transport rollers arranged along the discharge path 111, and 123 is a transport roller arranged in the path 112d. The transport rollers 112A to 122C are used for the copying process step components such as the photosensitive drum 102 and the fixing device 104.
And is driven by the motor M10 in synchronism therewith.

With the above configuration, in the case of the above (i), the path 112a is closed by the gate flap 115, and the copy sheet Y is discharged along the discharge path 111. In the case of (ii), the discharge route 111 is closed by the gate flapper 115 and the switchback route 11 is closed.
The copy sheet Y is guided to the second path 112a, the path 112c is opened by the gate flapper 116, the conveying direction is reversed by the reversing roller 121 through the path 112c, and the path 1 is moved by the gate flapper 117.
12d is opened, and the copy sheet Y is guided to the intermediate tray 113. In the case of (iii), after the copy sheet Y is guided to the path 112c, the conveying direction is reversed by the reversing roller 120, the path 112b is opened by the gate flapper 116, and the discharge path 1 is moved from the path 112b.
Leading to 11.

Next, an optical system provided in the copying machine main body 100 will be described. An optical system including a light source 150 for performing slit exposure on a document surface, mirrors 151A, 151B, 151C, 151D, and a lens 152 above the inside of the copying machine main body 100. The equipment system is installed to be freely scannable. In the optical device system, the light of the light source 150 is irradiated on the image plane of the light source X, and the reflected light is reflected by the mirrors 151A to 151A.
The light is distributed to the surface of the photosensitive drum 101 via the lens 151D and the lens 152. Further, in the optical device system, the first automatic document feeder 1 presents a sheet original X in response to the presentation of the sheet original X.
First exposure unit 5 of document cylinder 20 and second document cylinder
Two systems are used to perform exposure in a stopped state at the second exposure unit 21 and to perform exposure while scanning the optical system when a block document or the like is placed on the third exposure unit 105. The mirror system is driven by the driving motor M13.

The photoconductor is a belt photoconductor, and the upper surface thereof is arranged in parallel with the surface formed by the first, second, and third exposure units.
If the lens is constituted by a self-focusing transmission body array or the like, an image can be formed on the photosensitive member without using a mirror.

In this copying apparatus, a detection sensor is provided in each part, S7 is an optical system second exposure position detection sensor, S8 is an optical system first exposure position detection sensor, S9 is an OC section original leading end position detection sensor, and S10 is A copy sheet hopper exit detection sensor, S11 is a copy sheet pre-transfer detection sensor, S12 is a post-fixation detection sensor, S17 is a sheet presence / absence detection sensor in the intermediate tray, and S18 is an intermediate tray exit detection sensor. Further, although not shown in FIG. 1, in this apparatus, a clutch CLT1 for feeding the original to the first exposure unit 5 and a clutch CLT1 for feeding the original to the second exposure unit 6 are provided in the circulating automatic original feeder. A clutch CLT2 is provided, and a clutch CLT3 for synchronizing the copying paper and the leading edge of the document is provided in the copying machine main body 100.

Depending on the copy contents desired by the operator, a double-sided copying apparatus provided with the above-mentioned circulating automatic document feeder, (i) a single-sided copy sheet obtained by sorting a plurality of copies from a single-sided document; Multiple sheets (iii) Single-sided multiple sheets with multiple copies sorted from double-sided originals (IV) Any one of multiple-sided multiple sheets sorted from double-sided originals can be copied freely by circulating the original multiple times. It is possible.

Also, depending on the copy content desired by the operator, exposure is performed while the sheet document is wound around the document cylinder a plurality of times,
A plurality of copies can be made during one circulation of a sheet document.

In the copying apparatus according to the present invention, the control unit shown in the block diagram of FIG.
And are controlled in relation to each other. That is, each of the above motors
M1 to M14 are connected to the motor driver 200, the clutches CLT1 to CLT3 are connected to the clutch driver 201, and the solenoids SOL1 to SOL8 are connected to the solenoid driver 202.
The control elements used for document transport control, paper transport control, and control of the process unit, such as the control unit 202 and the DC power supply 79, are connected to an interface circuit (I / O) 203, and the detection sensors S1 to S18 are also connected to the interface circuit 203. It is connected to the. The interface circuit 203 is connected to the microcomputer 204, outputs a detection signal from the detection sensor to the microcomputer 204, and controls the driver 2 according to a control signal from the microcomputer 204.
Control operations of 00 to 203 are performed. Microcomputer 204 is RO
The microcomputer 20 is connected to the M205 and the RAM 206, and according to a control program stored in the ROM 205 in advance.
4 controls. The RAM 206 is used as a buffer memory and flags, counters, timers, and other calculation areas necessary for copy control, which will be described later.

Further, the interface circuit 203 is connected to the dimming unit 208 and the copy lamp 209 via the driver 207, and is also connected to the operator operation key 211 and the display driver 212 of the scanning panel 210.
Connected to 213. Further, the interface circuit 203
Are connected to select switches SSW1 to SSW4 described later.

The operation panel 210 has the configuration shown in FIG. 3 and includes a ten key 211-1 for setting the number of copies, a clear key 211-2,
RDH-SELECT key 211-3, ADF key 211 for setting copy conditions
-5, print switch 211-4, slip sheet mode key SET
A display unit 213-1, a COUNT display unit 213-2, four types of copy mode display units 213-3 to 213-6 of RDH, and an ADF mode display unit 2
13-7.

The RDH copy mode display sections 213-3 to 213-6 are used to make a one-sided copy from a one-sided original (SIMPLEX-SIMPLEX), to make a one-sided copy from a one-sided original (SIMPLEX-DUPLEX), and to make a one-sided copy from a two-sided original. (DUPLEX-SIMPLEX),
This indicates four copy modes for duplex copying from a double-sided original (DUPLEX-SUPLEX). Each time the RDHSELECT key 211-3 is pressed once, the lamp is turned on sequentially from the top and turned on. After the lowermost position, it returns to the uppermost position, and automatically returns to the uppermost position in the initial state. The required number of copies is set with the 10 key 211-1, and the set number is displayed on the SET display unit 213-1. When the copying operation is started, the completed number of copies is displayed in the COUNT display section 213.
-2 are sequentially displayed. When the number of SETs and the number of COUNTs match, the machine stops and the SET counter automatically returns to "0 display". The COUNT counter is maintained until the next print switch 211-4 is turned on.

The structure of the sheet cassettes 106A to 106D will be described with reference to FIG.

As shown in FIG. 2, a paper feed cassette removably set in a paper feed port of a body 509 of a copying machine or the like, for example, a paper feed tray 501 of 106B is provided with a motor 502 capable of normal rotation and reverse rotation, Gear group 503 for reducing the power transmitted from the output shaft of 502 One pulley 504 fixed coaxially with the reduction gear of this gear group 503, and the other pulley disposed above the paper feed tray 501 504 and a drive mechanism 506 composed of a wire 505 and the like, which is stretched from one pulley 504 to the side portion 501a of the paper feed tray 501 via the other pulley 504, and connected between the upper limit position P and the lower limit position Q. It is configured to be able to move up and down freely in a stable state horizontally up and down in the A direction or the B direction.

On this paper feed tray 501, a paper group (not shown) in which a large number of papers to be provided for copying are stacked is placed. 501 is going to rise.

At the upper position of the paper feed tray 501, a paper upper limit position control unit (not shown) that controls the upper limit position of the paper group placed on the paper feed tray 501, and the uppermost sheet of the paper group one by one. A paper feed roller 507 as paper feed means capable of feeding out is provided, and the paper feed roller 507 is provided so as to be rotatable in the arrow C direction.

Then, the paper feed roller 501 is fed to the paper feed tray 501.
When the uppermost sheet of the upper group of sheets comes into contact with a predetermined pressure, the upper-limit sheet position detecting means detects the position of the uppermost sheet and operates a limit switch (not shown) to stop the motor 502. On the other hand, when the pressing force of the uppermost sheet on the paper feeding roller 507 is reduced or eliminated by the feeding of the sheet, the uppermost sheet reaches the above-mentioned predetermined pressure with respect to the sheet feeding roller 507 by the paper upper limit position regulating means. The motor 502 is started up to the position, and the paper feed tray 501 is raised in the A direction. Therefore, the upper surface of the paper group placed on the paper feed tray 501 always comes into contact with the paper feed roller 507 with a constant pressing force, and the top sheet of the paper group is pressed by the paper feed roller 507. When the sheets are sequentially fed out one by one, the sheet feeding tray 501 is raised in accordance with the amount of sheet reduction on the sheet feeding tray 501, and the top sheet is always kept at a constant height position.

On the other hand, a lamp or L
A light emitting source 510 such as an ED is provided. This light source 510
It is arranged in an opaque case 511, and is configured so that light from the light emitting source 510 is irradiated directly downward through a small hole 512 formed downward in the case 511.

A light detection device comprising a light receiving element such as a blue cell is provided immediately below the light emitting source 510 at a position below the movable range of the sheet feeding tray 501 and at a position where the lifting and lowering of the sheet feeding tray 501 is not hindered. The container 513 is fixedly mounted on the body 509. The light detector 513 can detect the remaining amount of paper on the paper feed tray 501 based on the amount of light received from the light emitting source 510. That is, when light is emitted from the light emitting source 510, the light detector 513 detects the amount of received light and generates an electrical output signal corresponding to the amount of received light. This light detector 513
The electrical output signal generated from the paper tray 501 is further amplified by, for example, the amplifier 514, whereby the height position of the paper feed tray 501 is detected, and the remaining amount of paper on the paper feed tray 501 can be detected with high accuracy. .

As a method of detecting the remaining amount of paper on the paper feed tray 501 based on the amount of light received by the photodetector 513, for example, as shown in FIG. Output from amplifier 514 of photodetector 513 at voltage V ₀
And the output (voltage Vf) from the amplifier 514 of the photodetector 513 in a state where the paper is fully loaded on the paper feed tray 501, is input to the arithmetic processing unit, and from the upper limit position P of the paper feed tray 501. Vf from the voltage V ₀ is taken a number of equally divided points until the lower limit position Q
Are linearly divided, and a voltage value is stored according to the amount of paper on the paper feed tray 501. This makes it possible to continuously detect the remaining amount of paper on the paper feed tray 501 by an arithmetic process using the interpolation method.

In this case, a standard is set for the light emission amount of the light emission source 510, the input / output characteristics of the photodetector 513, and the input / output characteristics of the amplifier 514,
It is necessary to adjust these characteristic values and the like so as to conform to the above-described standards in accordance with each copying machine or the like. If the input / output characteristics of the current or the voltage corresponding to the amount of received light in the photodetector 513 and the input / output characteristics of the photodetector 513 and the amplifier 514 have a linear regularity, the above calculation process is performed. It will be very simple.

On the other hand, a through hole 501a for passing light emitted from the light emitting source 510 is formed at a position adjacent to the light emitting source 510 in the sheet feeding tray 501, and the sheet feeding tray is located at a position above the light emitting source 510. Another light detector 515 outside the range of motion of 501
Is installed.

As a result, when the amount of paper positioned on the paper feed tray 501 gradually decreases and the paper on the paper feed tray 501 runs out, the paper placed on the paper feed tray 501 is thereby blocked. The through-hole 501a of the paper feed tray 501 that has been opened is opened, and the light emitted from the light emitting source 510 reaches the light detector 515, and the light detector 515 feeds the paper over the entire movable area of the paper feed tray 501. The “paper out” state on the tray 501 can be detected.

The paper feed cassette 106B is provided with a tray switch 306B for lowering the paper feed tray 501 to a position where the paper feed cassette can be pulled out. The tray switches are provided on all of the paper feed trays configured to be able to move the paper feed tray up and down.

The paper feed cassettes 106A to 106D, including the tray drive mechanism 506, are configured to slide on a rail or the like, for example, and to be pulled out.

Further, on the bottom surface of each of the sheet cassettes 106A to 106D, sheet cassette detecting means for detecting a state where the cassette is pulled out and set at a predetermined position, for example, a reflection type optical sensor, or a micro sensor. Switches and the like are provided.

Further, the CPU 204A as the control means is provided with a timer for measuring a preset time, a rising means 804A for outputting a signal for driving the tray drive mechanism 506 by inputting various detection signals, and the like. .

The operation of the sheet feeding device configured as described above will be described with the sheet feeding cassette 106B as an example.

When the paper feed cassette 106B is housed in the copier main body 100 and the paper feed tray 501 is at the upper limit position, that is, at the copyable position, when the tray switch 306B is pressed to N, the N signal of the switch 306B is output. Is sent to the CPU 204A, and the tray drive mechanism 506B corresponding to the switch is driven to lower the paper feed tray 501 to the lower limit position, that is, the cassette drawable position, and stop.

At this time, it is confirmed by the N signal of the tray switch that the paper feed tray 501 has been lowered, and the CPU 204A
The timer 704 built in the printer starts counting from the time when the sheet feeding tray 501 is lowered to the position where the sheet can be pulled out and stopped. Then, a predetermined time set in advance is measured.

After the timer starts counting, the paper tray 50
The sheet detection unit 606B that detects the presence of the sheet on the sheet 1 detects whether or not a sheet is placed on the paper feed tray 501, and outputs a detection signal from the detection unit 606B to the CPU 204.
A, and the CPU 204 determines whether or not a sheet is placed on the sheet tray 501 based on the detection signal.

When paper is placed on the paper feed tray 501,
The sheet cassette detecting means 406B detects the sheet cassette.
Whether or not the paper cassette 106B has been pulled out is detected, and based on the detection signal, the CPU 204 determines whether or not the paper feed cassette 106B has been pulled out.

Then, when the time is completed without the paper cassette being pulled out during the time counting by the timer 704,
The time-up signal of the timer and the detection signal of the paper detection means are input to the lifting means 804A in the CPU 204A, and a control signal for raising the paper feed tray 501 to the upper limit position is sent from the lifting means 804 to the tray driving mechanism. Sent to 506, the tray 501 is raised to the upper limit position, and the uppermost sheet is always held at the specified position.

On the other hand, when the CPU 204A determines that the paper is not placed on the paper feed tray 501 based on the detection result by the paper detection means 606B, the paper feed cassette detection means
Whether or not the sheet cassette 106B has been pulled out is detected by the 406B, and based on a detection signal from the detecting unit 406B,
The CPU 204A determines whether or not the cassette has been pulled out.

When it is determined that the cassette 106B has not been pulled out, until the cassette 106B is pulled out,
The paper feed tray 501 maintains a state where it is stopped at a position where it can be pulled out. When the sheet cassette 106B is pulled out and replenished with sheets, and then the cassette 106B is stored again, the sheet tray 501 moves up to the upper limit position, and always holds the uppermost sheet at the specified position.

Although the paper cassette 106B has been described above, the other paper cassettes 106A, 106C, and 106D have the same configuration and operation principle, and thus description thereof will be omitted.

[Second Embodiment] This embodiment is a modification of the first embodiment with a part of the configuration changed, and most of them are common to the first embodiment. Therefore, the description of the common parts will be omitted here, and the description will focus on the parts unique to the second embodiment.

FIG. 5 is a block diagram according to a second embodiment of the present invention,
FIG. 6 is a flowchart of the control.

In this embodiment, when the tray switch 306 is set to N in FIG. 1, FIG. 2, and FIG. After the stop, a timer 704 for counting a preset time is built in the CPU 204B.

Further, after the sheet cassette 106 is pulled out, a sheet cassette pull-out detecting means 406 for detecting a state where the cassette is set at a predetermined position is provided on the bottom portion of each sheet cassette.

After the timer 704 starts counting, it is determined whether or not the sheet cassette 106 has been pulled out based on the detection signal from the sheet cassette detecting unit 406, and the sheet cassette 106 is not drawn out once. When the time measurement is completed, a time-up signal of the timer 704,
By inputting the detection signal of the paper feed cassette detecting means 406, a tray drive mechanism 406 control signal for raising the paper feed tray 501 to the upper limit position regardless of the presence or absence of paper on the paper feed tray 501 is generated. Output ascent means 804B to CPU
Provided in 204B.

Subsequently, the operation of the present embodiment will be described using the sheet cassette 106B as an example.

When the paper feed cassette 106B is housed in the copier main body 100 and the paper feed tray 501 is at the upper limit position, when the tray switch 306B is pressed to N, the switch 30
The N signal of 6B is sent to the CPU 204B, and the tray driving mechanism 506B corresponding to the switch is driven to drive the sheet feeding tray 50B.
Lower 1 to the lower limit position and stop. At this time, it is confirmed by the N signal of the tray switch 306B that the tray has been lowered, and a timer 704 built in the CPU 204B is used.
However, the timing of the preset predetermined time is started from the time when the sheet feeding tray 501 is lowered to the lower limit position and stopped.

Then, after the timing starts, the sheet cassette detecting means
By 406B, it is detected whether or not the sheet cassette 106B is pulled out, and the detection signal is sent to the CPU 204B to determine whether or not the sheet cassette 106B is pulled out.

The above-described detection and determination are repeated while the timer 704 is counting, and when the timing is completed without pulling out the sheet feeding cassette 106B, the timer 704 is stopped.
And the detection signal of the paper feed cassette detecting means 406B are sent to the raising means 804B in the CPU 204B. Then, a control signal for raising the paper feed tray 501 to the upper limit position is transmitted from the raising means 804B to the tray drive mechanism 506 regardless of the presence or absence of paper on the paper feed tray 501, and the upper limit of the tray 501 is set. To the position,
Always keep the top sheet in the specified position.

The configuration and operation principle of the other sheet cassettes 106A, 106C, and 106D are the same, and thus description thereof is omitted.

[Third Embodiment] This embodiment is a modification of the first embodiment with a part of the configuration changed, and most of the third embodiment is common to the first embodiment. Therefore, the description of the common parts is omitted here, and the description will focus on the parts specific to the third embodiment.

FIG. 7 is a block diagram according to a third embodiment of the present invention,
FIG. 6 is a flowchart of the control.

In this embodiment, the sheet detecting means 606 for detecting whether or not a sheet is placed on the sheet feeding tray 501 in FIGS. 1, 2, and 7 is provided in the sheet feeding cassette 106. Paper cassette detecting means 406 (optical sensor, micro switch, etc.) for detecting the state in which the cassette is set at a predetermined position after the paper cassette 106 is drawn out.
Is provided on the bottom surface of the sheet cassette 106.

Further, when the paper feed tray 501 is lowered by setting the tray switch 306 to N, the detection results of the paper detection means 606 and the paper feed tray detection If the sheet 106 has not been pulled out and sheets are placed on the sheet supply tray 501, the two detection signals are input, and the tray switch 306 is pressed to make the N position. Elevating means 804C for elevating the paper tray 501 to the upper limit position is provided in the CPU 204C.

Subsequently, regarding the operation of the present embodiment, the sheet cassette 106B
Is described as an example.

When the paper feed cassette 106B is housed in the copier main body 100 and the paper feed tray 501 is at the upper limit position, when the tray switch 306B is pressed to N, the switch 30
The N signal of 6B is sent to the CPU 204, and the tray drive mechanism 506B corresponding to the switch is driven to drive the paper feed tray 501.
Is lowered to the lower limit position and stopped.

After the paper feed tray 501 stops, the paper feed cassette detecting means 406B detects whether or not the cassette 106B has been pulled out, and the detection signal is sent to the CPU 204C to determine whether or not the cassette has been pulled out. You.

If the cassette 106B has not been pulled out, the sheet detecting means 606B subsequently causes the sheet tray 50 to be pulled out.
It is detected whether a sheet is placed on 1 or not. Then, the detection signal is sent to the CPU 204C, and it is determined whether or not a sheet is placed. When it is determined that the paper is loaded, the above two detection signals are raised
By inputting the data to 804C and pressing the tray switch 306B, the sheet feed tray 501 is controlled to be raised to the upper limit position.

For the other paper cassettes 106A, 106C, 106D
Since the configuration and operation principle is the same as that of 6B, the description is omitted.

Although the first to third embodiments have been described above, the present invention is not limited to each of the above embodiments, and the object can be achieved by appropriately combining these embodiments.

<Effects> [First Effect] According to the present invention, when the paper feed tray is lowered to a drawable position by operating the tray switch,
If the paper cassette is left without being pulled out with the paper loaded on the paper tray, after a predetermined time,
The tray is automatically raised to a copyable position. Therefore, it is possible to save the trouble of drawing out the cassette and storing it in order to make the copy possible.

[Second Effect] According to the present invention, when the paper feed tray is lowered to the drawable position by operating the tray switch, and if the paper feed tray is left without being pulled out, the paper feed tray becomes Since the sheet is automatically raised to the copy-enabled position after a predetermined time, it is possible to prevent the copying machine from being left for a long time in a copy-impossible state regardless of the presence or absence of a sheet, thereby enabling effective use of the copying machine.

[Third Effect] According to the present invention, when the paper feed tray is lowered to a position where the paper tray can be pulled out by operating the tray switch, the paper is still loaded on the paper feed tray and the paper is fed. When the paper cassette is left without being pulled out, the paper feed tray can be raised to a copyable position by operating the tray switch. Therefore,
When copying is desired, the copying can be quickly performed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a copying machine according to the present invention,
FIG. 2 is a schematic cross-sectional view showing the structure of the paper feeding unit according to the present invention,
FIG. 3 is a block diagram according to the first embodiment of the present invention, and FIG.
FIG. 5 is a control flowchart of the first embodiment of the present invention, FIG. 5 is a block diagram according to the second embodiment of the present invention, FIG. 6 is a control flowchart of the second embodiment of the present invention, 7
FIG. 13 is a block diagram according to a third embodiment of the present invention, and FIG. 8 is a control flowchart diagram of the third embodiment of the present invention. 501: paper feed tray, 306: tray switch, 506: tray drive mechanism, 406: paper feed cassette detection means, 606: paper detection means,
704: Timer.

Claims (3)

(57) [Claims] A sheet cassette which has a sheet tray on which a large number of sheets can be placed and which can be moved up and down, and which can be pulled out from a sheet feeding section of the apparatus main body; And a tray switch for lowering the paper feed tray to a lower limit position where the paper cassette can be pulled out. After the paper cassette is pulled out, the cassette is set at a predetermined position. Paper feed cassette detecting means for detecting that the paper feed tray is controlled to raise the paper feed tray so as to always hold the uppermost sheet at a specified position in response to a detection signal of the paper feed cassette detecting means. A control means for lowering the paper feed tray to a predetermined position where the paper feed cassette can be pulled out in response to the operation of the tray switch. The control means starts a timing operation when the paper feed tray is lowered to a predetermined position, and outputs a signal after a set time is counted. A paper detection means for detecting the presence of paper on the paper feed tray When the paper cassette detecting means detects the presence of paper on the paper feed tray when the drawer of the paper cassette is not detected by the paper cassette detecting means and an output signal is output from the timer, A sheet feeding device comprising: a raising means for raising the sheet feeding tray. A paper cassette having a paper tray on which a large number of papers can be placed and which can be moved up and down, and which can be pulled out at a paper feeding section of the apparatus body; And a tray switch for lowering the paper feed tray to a lower limit position where the paper cassette can be pulled out. After the paper cassette is pulled out, the cassette is set at a predetermined position. Paper feed cassette detecting means for detecting that the paper feed tray is controlled to raise the paper feed tray so as to always hold the uppermost sheet at a specified position in response to a detection signal of the paper feed cassette detecting means. A control means for lowering the paper feed tray to a predetermined position where the paper feed cassette can be pulled out in response to the operation of the tray switch. The control means starts a timing operation when the paper feed tray is lowered to a predetermined position, and outputs a signal after the set time is counted. The paper cassette detection means detects the drawer of the paper cassette. A sheet feeding apparatus, comprising: a rising unit that raises the sheet feeding tray when an output signal is output from the timer, regardless of whether there is a sheet on the sheet feeding tray. 3. A paper cassette which has a paper tray on which a large number of papers can be placed and which can be moved up and down, and which can be pulled out at a paper feeding section of the apparatus main body. And a tray switch for lowering the paper feed tray to a lower limit position where the paper cassette can be pulled out. After the paper cassette is pulled out, the cassette is set at a predetermined position. Paper feed cassette detecting means for detecting that the paper feed tray is controlled to raise the paper feed tray so as to always hold the uppermost sheet at a specified position in response to a detection signal of the paper feed cassette detecting means. A control means for lowering the paper feed tray to a predetermined position where the paper feed cassette can be pulled out in response to the operation of the tray switch. The control means includes a paper detection means for detecting the presence of paper on the paper feed tray, and a drawer of the paper feed cassette not being detected by the paper feed cassette detection means, and the paper detection means A sheet feeding device, comprising: lifting means for raising the sheet feeding tray by operating the tray switch when the presence of a sheet is detected.