JPS647660B2 - - Google Patents

Description

[Detailed description of the invention] The present invention forms an electrostatic latent image on a rotating body, develops it,
The present invention relates to an image forming device that transfers images onto a transfer material.

Conventionally, copying apparatuses include a plurality of process means for copying operations, and these are sequence-controlled at predetermined timings. For example, position detecting means are provided on the path of movement of a reciprocating member for scanning a document, and when the reciprocating member operates these detecting means, the process means assigned to the detecting means is controlled. However, when copying materials of multiple sizes are to be copied according to their size, a large number of detection means are required depending on the size, which complicates the movement path and increases costs. It will also be expensive.

Furthermore, conventional photosensitive drums have stopped at fixed positions. As a result, the photosensitive drum is used unevenly, resulting in a shortened lifespan, and the effects of corona charging and neutralization, as well as the effects of dirt and light leakage caused by the cleaner while the photosensitive drum is stopped, can accumulate in the same area. In some cases, the same portion of the photoreceptor may be physically deformed by the cleaner being pressed against the drum.

The present invention has been made in view of the above points, and utilizes the advantage of a reusable endless photosensitive rotating body that a latent image can be formed from any position on the rotating body. The purpose is to prevent the accumulation of negative effects on the image forming apparatus and to enable good image formation. Specifically, a reusable endless photosensitive rotary member, a latent image formed on the rotary member, and the latent image developed, Transfer the developed image to a transfer material,
a plurality of process means for cleaning the rotary body; a driving means for rotating the rotary body for latent image formation, development, transfer, and cleaning; and a size signal indicating the size of a transfer material to which an image is transferred from the rotary body. a size signal generating means for generating a clock signal, a counting means for counting a clock signal generated synchronously with the rotation of the rotating body, and a process for forming the latent image based on the size signal from the size signal generating means. and a control means for controlling the driving means based on the count output of the counting means, and the control means causes the rotating body to forwardly rotate before forming the latent image, The driving means is controlled to stop or rotate the rotation body after the transfer is completed based on the count output, and the drive means is controlled to stop the rotation body based on the count output. Alternatively, in order to stop the apparatus at a different position after the post-rotation, the counting means, which is reset at the timing when the power is turned on to the apparatus or after the end of forming the latent image, counts a number different from the number corresponding to one revolution of the rotating body. The present invention provides an image forming apparatus that stops the rotation of the rotating body by the driving means when the count ends.

This makes it possible to stop the rotating body at different positions, so the rotating body can be used evenly to form latent images without being biased, taking advantage of the advantage that latent images can be formed from any position on the endless photosensitive rotating body. This contributes to extending the life of the rotating body, and also prevents the influence of corona charging on the rotating body while it is stopped, the pressure of the cleaner, etc. from accumulating on the same part of the rotating body, and eliminates the effects of these. This enables good image formation.

Hereinafter, the present invention will be explained in detail according to examples.

(Overview) The apparatus of this embodiment uses an endless photoreceptor and a more effective control method. When an endless photoreceptor is used, the return time of the document table or optical system becomes a total loss time. Therefore, in order to increase copying efficiency, the above-mentioned quick reversal is indispensable, and in addition, regarding the control of the copying cycle, it is necessary to change the home position of the drum for each rotation of the photosensitive drum, as in the case of conventional edged photosensitive drums. Controlling the installation cycle is extremely wasteful.

For this reason, this apparatus employs a drum having an endless photoreceptor, and also has a pulse generator at regular intervals corresponding to the rotation of the photoreceptor drum from the photoreceptor drum drive device, and generates pulses at regular intervals corresponding to the rotation of the photoreceptor drum. Each cycle is controlled by a counter device.

For example, the clock pulse generator described above may be used for drum 1.
It is configured to generate 15.75 pulses per rotation. By doing this, the drum can make one complete revolution and slightly overturn when the counter counts 16 clock pulses.

This eliminates the unprocessed portion of the photoreceptor before and after the copying cycle in the pre- or post-processing steps described below, and therefore allows the copying process to be started from any part of the photoreceptor, which is an advantage of the endless drum. make it possible.

(Pre-treatment) 1. Pre-exposure: The photoreceptor has different photosensitivity characteristics depending on its prior history of light irradiation, and therefore the sensitivity of the photosensitive plate is different between the first copy and the second copy.

Therefore, by uniformly exposing the photoreceptor to light prior to forming a latent image on the photoreceptor, the characteristics of the photoreceptor become the same between the first sheet and subsequent copies due to the fatigue effect of the photoreceptor.

2 Furthermore, as described below, if the copy is left unattended after copying,
Toner may adhere to the contact area between the cleaning blade and the photoreceptor, which may require cleaning prior to the copying cycle.

(Post-processing) Since the photoreceptor is charged at high voltage with various potentials, the surface potential and polarity of each part of the photoreceptor are different. If left in this state, the characteristics of the drum will be adversely affected, so the copy cycle At the end of the process, it is desirable to remove static electricity from the surface using, for example, AC corona.

Furthermore, if the drum is stopped at a fixed home position, such as a conventional edged photoreceptor, the stopping position is always fixed, so the effects of corona charging will accumulate in the same area, and the drum cleaner Since the photoreceptor is pressed against the drum under considerable pressure, it is inevitable that the same portion of the photoreceptor will undergo physical deformation. However, by generating an appropriate clock pulse per rotation of the drum,
It is possible to avoid the above-mentioned cumulative effect of the stop position and start position of the drum changing from moment to moment, and it is also possible to use the drum evenly over the entire length of the photoreceptor, contributing to a longer life of the photoreceptor. In addition, the copying cycle is not controlled by rotating the drum or by controlling means related to this as in the past.
This is performed using a reversal signal from the document table or optical system that corresponds to the copy size as a reference, and a combination of this, a clock pulse, and a counter.The clock pulse counter can also be reset when the document table or optical system's reversal signal or post-rotation is completed. We aim to improve reliability by using a digital circuit with an effective circuit method such as a clock count (by switching the clock count according to the copy size as necessary) and a clock count at the exit of the fuser. An extremely simple and effective circuit is used as a jam detection means for monitoring delayed accumulation of copy paper based on the signal from the provided copy paper detector.

Furthermore, even if the power switch is turned off during the post-processing period, a means for retaining the power until the post-processing is completed is provided by a non-contact circuit, and the entire control circuit also uses non-contact type elements. In combination with the digital circuit, reliability can be increased and lifespan can be extended.

In addition, instead of the microswitch that has been conventionally used in many devices of this type, a non-contact type position detection device using a magnetic detection element is often used. These are used for the liquid level detection device, clock pulse generator, copy command button, document platen home position, paper feed start timing signal generation position, B5 size inversion position, A4 size inversion position, and B4 size inversion position. By using this in a device that attaches a magnet to all movable parts and detects changes in magnetic flux density due to the movement of the magnet at a specific position using the Hall effect or the effect of changes in resistance of semiconductors due to magnetism, the following can be achieved. You can get the effect. First of all, compared to position detection devices using contact type elements such as micro switches, reed relays, contact type elements, or pairs of light emitting elements that use light as a medium, there are no contact failures, rough installation accuracy, or toner etc. By having advantages against contamination, reliability can be improved and lifespan can be extended. Furthermore, as will be described later, in this embodiment, since a digital IC is applied to the control circuit, one of the advantages is that the above-mentioned device, which serves as a source for generating various signals, does not cause the rotary phenomenon. This circuit also uses a digital IC to make it smaller and more reliable than conventional relay-based control circuits, as well as to increase its flexibility for complex sequences.

Furthermore, the reliability of the switching elements for energizing each terminal element in accordance with a control signal is improved by using semiconductor switching elements such as thyristors and transistors instead of the conventional relay-based switching elements. As is well known, digital ICs and semiconductor switching elements have a great effect on relays by freeing them from the drawbacks of relays, such as contact failure, large size, and high cost. The present invention uses non-contact non-contact type elements and other solid-state elements as described above to more effectively combine these elements as a control circuit in each of the circuits shown below, thereby solving some of the problems unique to conventional copying machines. It is possible to solve this problem and to construct a more reliable copying machine control circuit.

(Explanation of Operation of Apparatus) Next, the operation of the copying machine will be explained with reference to FIGS. 1 and 2.

The copying machine of this embodiment employs a digital circuit and is controlled by clock pulses, thereby making it possible to fully utilize the features of this machine as will be described later.

First, when the main switch 10 is turned on, a very short time (approximately 1 second in this case) has elapsed due to the controller being reset and other electrical systems starting up due to the use of a digital circuit. 15 starts rotating. As mentioned above, this is approximately 16 times per rotation of the photosensitive drum.
A clock pulse generation mechanism is provided in a part of the drive system so as to generate clock pulses of 100 times. When the photosensitive drum 15 begins to rotate, the drum rotates approximately once for 16 clock pulses (hereinafter referred to as 16CPetc). This can be considered a step before starting the copying process, and is intended to obtain a high-quality copy when the copying process begins. If the copy button 13 is not turned on, the photosensitive drum will continue to rotate once and then stop.
If you turn it ON, the copying process will begin. First, the photosensitive drum 15 rotates by an amount of 16 CP plus 4 CP when the copy button is turned on, and then the original platen 2 with the original placed on the original platen glass 5 starts to be illuminated by the illumination lamp 16 and its image is imaged on the drum 15 at the exposure section 19 by the reflecting mirror 17 and the in-mirror lens 18.

The surface of the photosensitive drum 15, that is, the photosensitive layer covered with a transparent insulating layer, is first charged to + by a corona current from a positive charger 21 supplied with a high voltage of + from a high voltage power supply 20.

Subsequently, when reaching the exposure section 19, the image of the subject illuminated by the illumination lamp 16 is slit-exposed onto the photosensitive drum 15, as described above. At the same time, AC high voltage is being supplied from the high voltage electric wire 20. AC charging is performed by an AC charger 22. Then, a high-contrast electrostatic latent image is formed on the drum surface by full-face exposure using the full-face exposure lamp 23, and the next development process begins. The developing device 24 includes a container 26 into which a developing solution 25 is placed, a pump 27 that stirs the developing solution and pushes it up to the developing electrode section.
In order to remove any fog in the image developed on the developing electrode 28 and the drum, the roller 29 rotates very close to the drum, one of which is grounded. Development electrode 28
The electrostatic latent image formed on the photosensitive drum 15 is developed by the toner in the developer 25 pushed up onto the developing electrode 28 by the pump 27. and visualized.

Next, the photosensitive drum 15 is charged with a high voltage from the high voltage power source 20 by the post charger 30, and the excess developer on the photosensitive drum 15 is squeezed out without disturbing the image. Next, the transfer paper 7 fed from the paper feed section is transferred to the photosensitive drum 15.
The image on the photosensitive drum 15 is transferred onto the transfer paper 7 by an electric field generated by a high voltage from the power supply 20 by the transfer charger 31. After the transfer, the transfer paper 7 is separated by a separation belt 32 and guided to a drying and fixing section 33. The remaining toner developer on the photosensitive drum 15 is wiped off by the edge portion 35 of the blade cleaner 34 that is pressed against it, and the next cycle is repeated again. The developer wiped with the blade cleaner 34 is transferred to the photosensitive drum 1.
5 is guided to the developing device 24 through grooves 36 provided at both ends of the film (FIG. 3) and used again for development.

Here, turn on the main switch 10 mentioned earlier, the drum will rotate by an amount equivalent to 16CP, and the 16CP+
To explain why the document table 2 starts moving only after the drum has rotated by 4CP, this machine uses an endless type photosensitive drum, and therefore, no surface of the photosensitive drum can be used for image formation. I am now able to contribute. Therefore, when it comes to increasing the number of copies per unit time by eliminating unnecessary rotations as much as possible, first of all, if some toner remains in the blade cleaner edge portion 35 during the first rotation of the drum, the machine is This is because, in the worst case, the photosensitive drum may dry out and become stuck to the drum if it is not used for a week or 10 days, and in that case, it is necessary to clean the photosensitive drum before forming a latent image.

Next is 4CP, which is because in the copying process mentioned earlier, there is a + charging process etc. before the slit exposure, and in addition, the cleaner edge part mentioned above is added to the first sheet. This is because the machine will be more reliable if you avoid it when it is peepy.

Next, the transfer paper 7 is stored in a cassette 6 and is removably mounted by fitting the cassette 6 into the paper feed section at the lower left of the machine. Various cassettes are prepared according to the sizes of several types of transfer paper, and can be easily replaced as necessary.

The transfer paper 7 is placed on a middle plate 37 inside the cassette 6, and as the spring 38 pushes the middle plate 37 upward, the transfer paper 7 is always pressed against separation claws 39 provided on both sides of the tip of the cassette 6. ing. At this time, by appropriately selecting the spring constant of the spring 38, the force with which the transfer paper 7 is pressed against the paper feed roller 40 during paper feeding is made almost constant, regardless of the amount of transfer paper 7 in the cassette 6. .

When the document table reaches a predetermined position, an actuation piece fixed to the document table issues a signal that activates the detection means on the main body, and the constantly rotating paper feed roller 40 descends to feed the cassette 6. The transfer paper is connected to the uppermost transfer paper in the paper cassette 6, and the transfer paper is separated one sheet by the movement of the separation claw 39 and sent out from the cassette 6. However, the nearby register rollers 41 and 42 stop at the same time as the paper feed roller 40 descends, so the transfer paper 7 sent out from the cassette 6 remains in contact with the contact portion of the register rollers 41 and 42. A slack is created between the guides 43 and 44. Then, when the paper feed roller is about to rise, the register rollers 41 and 42 rotate again at the leading edge of the image on the photosensitive drum, and the transfer paper 7 is transferred to the photosensitive drum 15.
It is sent at a speed that matches the circumferential speed of.

As mentioned above, the transfer paper 7 is attached to the photosensitive drum 1.
5, the image on the drum 15 is transferred onto the transfer paper 7 by the transfer charger 31, and after the transfer, the transfer paper 7 is separated from the drum 15 by the separation belt 32, passes through the dry fixing section 33, and is transferred. The toner on the paper 7 is fixed and discharged onto a discharge tray 47 by discharge rollers 45 and 46.

Next, the operation for copying will be explained with reference to FIGS. 2 and 3. Place the document to be copied on the platen glass 5 with its leading edge aligned with the leading edge A of the glass, press it with the cover 3 (Fig. 2), and press the copy button 13 (Fig. 2). starts rotating and at the same time starts operating. The original table 2 moves to the left in FIG. 1 in synchronization with the circumferential speed of the photosensitive drum 15 in response to a document table start signal after 4CP from the black pulse generating mechanism, and performs slit exposure. When the exposure is completed, the original platen 2 will be placed depending on the size of the paper in the cassette.
In response to the signal from itself, the document table 2 stops moving to the left and immediately returns to the opposite direction, that is, to the right. The time required for this return is loss time during copying, so it is desirable that it be short. In this machine, the return speed is approximately four times the forward speed to increase copying efficiency. Since the return speed is high as described above, a shock is likely to occur when stopping, but in this machine, the shock is absorbed by a brake mechanism, which will be described later, and the document table 2 is quickly stopped at a predetermined position. Even when a large number of copies are to be made continuously from the same document, this can be easily done by using a counting device (not shown) that is linked to the P button 13. The counting device detects the movement of the original platen 2, performs counting, and holds the switch element until the set number of sheets has been counted, so that a large number of copies can be made.

The original platen restart command during continuous copying is sent to the original platen 2.
1CP after stops at the predetermined home position
It is carried out by. This is to ensure that the document table 2 moves smoothly when it starts moving forward. You can also restart from any drum surface. Further, the copying machine of this embodiment is capable of making copies of various sizes from the maximum B4 size to the minimum B5 size. In such a case, if the document table 2 were to move a distance of B4, which is the maximum copy size, for any copy size, the number of copies per unit time would be small, resulting in a large time loss. Therefore, this copier supports various copy sizes (for example, A4,
B5), it has a plurality of document table reversal signal generating members 48 (FIG. 4), and the copying cycle is changed in accordance with each copying size, thereby increasing copying efficiency.

The above-mentioned differences in cycles depending on the copy size are determined by signals from the cassettes 6 for each size.

Next, the suspension state and restart after copying is completed will be described. If the power is left on after all copying operations have been completed, the photosensitive drum 15 will constantly rotate, and if the high-voltage power is on, this is not desirable in terms of the durability of the photosensitive drum 15 and the blade cleaner 34. Therefore, in the copying machine of this embodiment, when a certain copying operation is completed and the next copying operation is not performed even after a certain period of time has passed, the main switch 10 is turned off.
Even if is NO, the drum automatically stops and enters a pause state. During this time, the transferred transfer paper 7 is discharged outside the machine, and the photosensitive drum 1
The time period is set longer than the time required to clean the entire surface of No. 5. To perform copying during this pause state, press the copy button 13 of the operation unit 9, and everything will return to the state before the pause, and after 4CP, the document table 2 will start moving forward. This copying machine enters the hibernation state 26CP after the document table reversal command in the final copying process.

(Description of Structure of Apparatus) Next, the specific structure of the copying machine according to this embodiment will be explained.

In FIG. 3, reference numerals 49 and 50 are front and rear frames, which are strongly constructed by a stay (not shown) and a bottom plate 51 that connect the two frames.

A drum shaft fixing member 52 made of alloy casting is fixed approximately at the center of the rear frame 50.
A drum shaft 53 is fixed to.

As shown in FIG. 3, the drum shaft fixing member 52 is fixed to the frame 50 at the rear with a large interval, so that it has sufficient strength against the weight and other forces of the drum 15 even in a substantially cantilevered state. It is composed of A drum gear 56 is rotatably supported on the drum shaft 53 via bearings 54 and 55. A bearing pusher fitting 57 is fixed to the drum shaft 53 with a set screw, and is held down to prevent the drum gear 56 and bearings 54, 55 from coming off when the drum 15 is removed as described later. The other end of the drum shaft 53 (the right end in FIG. 3) is held substantially horizontally by a support plate 58. The support plate 58 is positioned by two positioning pins so that the drum can be removed as described later, and is removably fixed to the frame 49 by two wing nuts. The support plate 58 has a thrust holding member 59 that is movable in the thrust direction, and a spring 60 pushes the bearing 61 stored in the drum to the left in FIG. It looks like it doesn't exist. The photosensitive drum includes a drum 62, a front flange 63,
It is formed by a rear flange 64, a guide pipe 65, two rods 66, and bearings 61 and 67 press-fitted into the front and rear flanges 63 and 64, and the drum 62 is sandwiched between the front and rear flanges 63 and 64 and tightened with the rods 66. Can be assembled. The guide pipe 65 is for guiding the drum to be easily attached and detached along the drum shaft 54. The rear flange 64 has a hole that can engage with a drive pin 68 fixed to the drum gear 56, and the two engage to rotate the drum. By supporting the drum quasi-cantilevered as described above, the drum is compactly constructed and easily assembled and disassembled while providing sufficient strength. By fixing the drum shaft 53 to the machine body and configuring it with a hollow pipe, a heating element 69 is installed inside the drum shaft 53 to keep the photoreceptor at a constant temperature, thereby preventing moisture from condensing on the drum surface at times of high humidity. Furthermore, it is possible to obtain high-quality images in a low-temperature environment.

A guide rail 70 is provided at the upper end of the rear frame 50.
and control signal magnetic sensing elements 48A, 48B, 4
Members 73 and 74 for attaching 8C, 71 and 72 are fixed (FIGS. 3 and 4). Further, guide rollers 75 and 76 as shown in FIG. 3 are installed at the upper end of the front frame 49, and cooperate with the guide rail 70 to cause the document table 2 to smoothly reciprocate. The document table has a front angle 78 and a rear angle 77 connected by a stay to form a frame body,
It has sufficient rigidity to withstand various forces such as forward movement, backward movement, and reversal. A transparent glass 5 is placed in the center of the frame, and other pages of the book are placed on the front side of the frame (the left end in Figure 1) when copying a book, etc., so that the entire page to be copied is placed well on the glass surface. The document table 2 is constituted by a case 4 provided for close contact.

The rear guardrail 70 is a lower rail 79 fixed to the rear frame 50 via mounting members 73 and 74.
The upper rail 81 is fixed to the rear angle 77 of the document table, and the retainer has a metal ball 80 which is positioned between the upper and lower rails and is rotatably held. and the position in the front-rear direction (left and right in FIG. 3). Further, the reciprocating movement of the document table is controlled by the metal ball 8.
0 rolling motion. On the other hand, the protruding portion 3 of the document table front angle 78 is sandwiched between the lower guide roller 76 and the upper guide roller 75, thereby regulating the vertical position of the document table. The guide rollers 75 and 76 are rotatably held by shafts 82 and 83, which are fixed to a mounting plate 84 and firmly held by the front frame 49.

As mentioned above, the rear guide rail 70 regulates the vertical and front-back (left-right in FIG. 3) position, and the guide rollers 75 and 76 regulate the front angle of the document platen only in the vertical direction. As a result, the reciprocating movement of the document table can be performed very smoothly regardless of manufacturing errors or assembly errors of the machine.

Magnetic detection elements 48A, 71, 72, 78B, and 48C are fixed to the guide rail mounting bases 73 and 74, and the magnet 1 attached to the document table 2
61 and 162 sequentially issue control signals. When the copy button is pressed and the document table 2 starts moving forward, the magnet 161 and the element 71 first issue a paper feeding command. The document table further moves forward, and when the exposure of each copy size (B5, A4, B4) is completed and the magnet 161 reaches above the element 48A, 48B, or 48C, a reversal command is issued, and the document table 2 moves from the forward movement to the backward movement. Move to. As the backward motion progresses and the magnet 162 reaches the element 72, the document table 2 is stopped at a predetermined position in response to a stop command. The size switching command is issued by the cassette 6.

The driving relationship will be explained with reference to FIGS. 5, 9, and 10.

The main motor _M1 is driven by a sprocket wheel 85 via a chain 86 and a sprocket wheel 87 to drive a drum drive shaft 89 to which a gear 88 meshing with the drum gear 56 is fixed at one end. Chain 86 further drives a sprocket wheel 90 which is rotatably mounted on the shaft of electromagnetic clutch 94. 94
A rudder wheel 143 is fixed to the shaft of the electromagnetic clutch on the back side. A rudder wheel 143 in FIG. 10 is connected to a rudder wheel 141 fixed to the output shaft of a clutch motor 95 by a rudder chain 142. A winding drum 91 is attached to the other end of the electromagnetic clutch shaft, and a document plate drive wire 92 is wound several times around the drum 91. Both ends of the wire are guided by guide pulleys 93, and the document plate drive wire 92 is guided by guide pulleys 93. It is fixed to the tip and rear end of the angle 77.

The above electromagnetic clutch 94 and clutch motor 95
By switching and driving the winding drum 91 in the forward and reverse directions, the document table 2 is reciprocated. A gear 96 is fixed to the drum drive shaft 89,
The drive of the main motor M ₁ is transmitted via a gear 97 to a gear 99 fixed to a paper feed roller drive shaft 98 . The main motor _M1 is driven by the gear 9.
One drives a gear 101 through a gear 100 integrally fixed to the clutch 9, and further drives register rollers 41, 42 through a clutch 102.
Also, the gears 100 are engaged with each other, and the clutch 13
A paper feed roller control cam 139 is driven via the roller 7. A drum gear 56 (FIG. 3) engages with a gear 105 fixed to a separation shaft 104 to drive a separation roller 106. Separation shaft 104
A rudder wheel 107 is fixed to the other end, and a rudder chain 108 and a rudder wheel 10
The discharge rollers 110 and 111 are driven through the rollers 9. A gear 113 is integrally fixed to a sprocket wheel 112 driven from a sprocket wheel 85 attached to the main motor _M1 via a chain 86, and the gear 113 is connected to a clock pulse generating magnet 163 (see FIG. 4). ) engages with the gear 115 fixed to the arm 114 holding the magnet, rotates the magnet, and rotates the main motor _M1 by means of the magnetic detection element 164 (FIG. 4) fixed to the rear frame 50 and the magnet. Generates regularly spaced clock pulses synchronized with speed.

Reference numeral 138 in FIG. 4 indicates a paper feed control unit. When the copy button 13 is pressed and the document table 2 moves forward and reaches a predetermined position, a paper feed signal is output, and the constantly rotating paper feed roller 40 is activated. Descending cassette 6
Feed out one sheet of transfer paper inside. Register roller 4 being stopped at the same time as paper feed roller 40 is lowered
When the leading edge of the transfer paper hits the guide 116,
A transfer paper loop is formed between 117 and 117 (Fig. 1). Then, the paper feed roller 40 rises, and the register roller 4
1 and 42 rotate again, and the transfer paper 7 is transferred to the photosensitive drum 1.
It is sent into the machine at a speed that matches the circumferential speed of No. 5.

The document table moves forward and backward by the drive system as described above, but in the copying machine of the embodiment, the copying efficiency is improved.
That is, in order to reduce the loss time during the backward movement, the speed of the backward movement is approximately four times that of the forward movement (approximately 200 mm/sec). In order to stop the document table, which moves at such a high speed, at a predetermined position on the machine body without applying a shock, this machine has a lock mechanism as shown in FIG. 12. The lock mechanism basically consists of a combination of a one-way clutch and a brake, and the solid line in FIG. 4 indicates the position of the lock lever on the document table and in the stopped state. Rear angle 77 that constitutes document table 2
A pin 155 fixed to the lock lever 153 engages with a notch 154 of the lock lever 153. Now, when the document table 2 starts to move forward (rightward in FIG.
, and rotates clockwise in FIG. 12.
At this time, since the one-way clutch 156 is in the releasing direction, the brake disc 157 remains stopped, and the brake disc 157 and the brake shoe 158,
The frictional force caused by 159 does not act as resistance to the movement of document table 2. When the document table further continues to move forward, the lock lever 153 stops at the broken line position. When the document table 2 is in a predetermined position and a reversal command is issued, the document table stops forward movement and starts backward movement, heading toward the stop position at about four times the forward movement speed. Pin 155 is in lock lever notch 154
When the lock lever 153 is rotated counterclockwise from the broken line position to the solid line position, the brake disc 157 is rotated counterclockwise via the one-way crack 156. The brake disc 157 is sandwiched between brake shoes 158 and 159, and pressure is applied by a spring 160, and this frictional force absorbs the inertia of the document table without giving a large shock to the document table. It can be stopped. With this structure, there is almost no load on the document table when it starts, and sufficient braking can be applied when it stops.

1 and 3, a developing device of a copying machine according to an embodiment will be described in detail. In FIG. 1, the developer 25 stored in the developer tank 26 is supplied between the photosensitive drum 15 and the developing electrode 28 by a pump 27, and the latent image on the photosensitive drum 15 is developed with toner. become After development, fog is removed from the surface of the drum by a fog removing roller 29 disposed close to the drum surface. The fog removing roller 29 is rotated by a drive source (not shown) at a speed relative to the surface of the photosensitive plate, and the surface of the fog removing roller is constantly cleaned by a cleaning member 118. Scraper 11 located behind the fog removing roller 29
9 comes into pressure contact with the photoreceptor and removes the developer from the surface of the photosensitive plate corresponding to the separation belt, thereby preventing staining of the separation belt.

As described above, the transfer paper 7 that is sent out from the cassette, transfers the image on the photosensitive drum, and is separated from the photosensitive drum is led to the fixing section where it is dried and fixed by heat from the hot plate. In FIGS. 4 and 8, a cross flow fan 120 is fixed to the rear frame 50, and a first suction port 121 of the fan 120 engages with a conveying section 122 and is formed by a duct plate 123 and a hot plate 124. Air is sucked in through the opening C through the duct, and this airflow assists separation by the separation belt 32 and improves the adhesion of the transfer paper to the hot plate. Further, the second suction port 125 is not engaged with the conveying section and performs suction from the outside.

An air outlet 126 of the cross flow fan 120 is guided onto the heating plate through an air duct 128 located above the hot plate 124 and fixed to the upper cover 127, and contributes to feeding and drying the transfer paper. As mentioned above, by performing suction and spraying with a single fan, it is effective for downsizing and reducing the cost of the device, and by forming a semi-circulating system, the surface of the transfer paper is not covered with saturated steam and is dried. is also good.

Next, we will discuss the operation when paper feeding is defective. The copying machine of this embodiment has a jam detection means for checking whether the transfer paper has completed a predetermined process (feeding, transfer, separation, fixing) and has been ejected outside the machine within a predetermined time. During the above process, the transfer paper stopped due to an accident,
The system is configured to stop the machine if it is not discharged outside the machine after a predetermined period of time to prevent accidents such as fire. In FIG. 1, 129 is a light emitting element, 130
is a light receiving element, which determines the presence or absence of a jam by counting a predetermined number of pulses from the clock pulse generation mechanism in response to a document table inversion command and detecting the presence or absence of a transfer sheet, the details of which will be described later. Therefore, since the pulse count for jam determination is started following the exposure scan, there is no need for a circuit to select the output, compared to the case where the count results are repeatedly output as the drum rotates. . When a jam is detected, the fuser heater is turned off and the main motor M is stopped, so the drum 15 is stopped, but the document table 2 is stopped after returning to a predetermined position (home position). When the machine is stopped, the upper cover 127, which can be opened about the hinge 131 in FIG. 1, is opened substantially vertically together with the duct 128.
In this state, nothing remains on the hot plate 124, and if a jam occurs in the fixing section, the transfer paper can be easily removed by hand by opening the upper cover 127. Next, the main body 1 of the transfer paper conveying section including the hot plate 124
22 is rotatably supported by a shaft 132 together with a separating section including a separating belt 32 and the like, and is normally held in a fixed position by a locking mechanism 133.
By opening the lock mechanism and removing the lock mechanism, it rotates counterclockwise around the shaft 132, and the transfer paper path after the register rollers 41 and 42 is opened.
Jammed transfer paper can be easily removed by hand. At this time, the separation belt 32 is connected to the photosensitive drum 1.
It is also easy to remove the jammed transfer paper from the separating section.

After removing the jammed transfer paper, the jam release operation is performed and the upper cover 127 is closed, thereby restoring the entire machine to its original state. Even if an attempt is made to close the upper cover 127 without carrying out the jam release operation, the upper cover will not close, the door switch 134 (FIGS. 6 and 7) will not work, and the machine will not come into operation. Further safety is ensured by performing the confirmation operation as described above. Next, a method of attaching the cassette 6 to the main body 1 will be described with reference to FIG. Cassette stand 144 fixed to the aircraft body
Place the foot part 145 of the cassette 6 on top and push the cassette into the inside of the machine so that the protruding part 14 at the bottom of the cassette
The cassette 6 is pressed into a predetermined position by a spring 149 having a roller 148 such that the cassette 6 contacts the positioning plate 147 of the cassette stand. At this time, the cam 150 provided on the side wall of the cassette and the micro switches 151, 1 installed on the cassette stand 144
52 outputs a cassette loading signal and a size switching signal. The document holding cover provided on the document table is fixed to the document table with screws 135, 136 (FIG. 2), and can be easily removed when it is desired to copy a large three-dimensional object.

The paper ejection tray 47 is located behind the paper ejection rollers 46 and 45 (slightly upward as shown in FIG. 2). The tray portion 47b is rotated to an approximately vertical position and fixed. With the above configuration, the cassette 6 can be easily attached and detached without removing the entire paper discharge tray 47 from the machine body.

As shown in FIG. 3, since the guide rail 70 is installed in a horizontal position, dust and foreign matter are not accumulated on the runner portion 70a, and the movement of the document table 2 is always smooth. Further, when the document table 2 reaches a predetermined position, the guide rails 70 are all under the document table 2, which is effective from the standpoint of safety and dustproofing.

Next, a sequence control circuit using a digital IC will be explained.

(Reset circuit) The circuit shown in Figure 14-a generates a signal (hereinafter referred to as STOP) that commands to stop the copying operation of the copying machine when the transfer paper is jammed or a spark discharge occurs in the charger, and to reset the entire circuit when the power is turned on. ), and Figure 14-b is its time chart. In FIG. 14-a, an inverted signal of a signal (hereinafter referred to as JAM) output from a transfer paper jam detection circuit, which will be described later, when a jam occurs is sent from a terminal 201 to one input terminal of a three-input AND gate 207. Added. However, here, for example, the signal "XYZ" is a signal at a level that is considered a high level signal or logic "1" when the event it means occurs, and a low level signal or logic "0" when the event does not occur. This means that the signal is at a certain level, and below, each level is simply written as 1 and 0. Also, it is expressed as a signal having a level completely opposite to that of an inverted signal. Further, the circuit 202 is a circuit that outputs 1 when a spark discharge occurs in the charger.Detailed explanation will be omitted here, but the signal will be hereinafter referred to as DISCH.This DISCH is input from the terminal 203 and is sent via the inverter 204. is applied to the other input terminal of gate 207. Further, the circuit 205 is a circuit that generates a signal to reset the necessary parts of other digital circuits to the initial state before starting when the power is turned on, and outputs 0 for a certain period of time TR from the time of power-on, and when the specified period of time has elapsed. TR for a certain period of time in the circuit that outputs the second one
This is a timer circuit that is usually extremely short, does not require high accuracy, and can be easily designed by a person skilled in the art, so the details will be omitted.

Hereinafter, this output will be expressed as WUP. This WUP
is input from terminal 206 and applied to the other input terminal of gate 207. Therefore, as shown in Figure 14-b, the input signals from terminals 201, 203, and 206 are respectively 201', 203', and 206';
If the output of the inverter 204, that is, the inverted signal of 203' is 204', the output of the gate 207 is 202', 204',
206' is 0, it becomes 0, that is, JAM becomes 1 or DISCH
When becomes 1 or WUP is 0, it becomes 0 and is output from terminal 208, causing other necessary circuits to be reset at this time. obey,
By detecting a jam or an abnormality in the charger, the control circuit can quickly bring it into a stable state of inoperability. The reason for outputting an inverted signal of STOP as the reset signal here is because it is convenient for the signal to be 0 when resetting in the following circuit.

(Pre-rotation circuit) Next, a circuit that generates a signal (hereinafter referred to as INTR) to perform pre-rotation when the power is turned on is installed in section 15-a.
As shown in the figure. First, the D-type edge-triggered flip-flop 214 will be explained. This flip-flop has a CP input terminal of 0.
When a rising pulse waveform moving from to 1 is added,
The same signal as the digital signal currently being applied to the input terminal D is output from the output terminal Q, until the next rising signal is applied to the CP terminal again.
The output state is maintained, but when 0 is added to the input terminal or 0 is added to the input terminal, regardless of the state of each input terminal of CP and D,
The Q output becomes 1 and 0 in each case and holds it. Further, the output terminal is a terminal that outputs an inverted signal of the Q output. Below, I will write a flip-flop with this function as an FF. In the FF 241, first, the power supply voltage Vcc 213 is applied to the D terminal. Vcc is a level that is regarded as 1 as a digital signal in the circuit. Also, the terminal has STOP
is applied from terminal 208. Therefore, first, 0 is added to the terminal for the time TR from when the power is turned on, so 1 is output from the terminal and this state is maintained. A signal 16CP indicating that a little more than one revolution has been made is applied from the terminal 211 to the CP terminal, and when this 16CP rises, the terminal becomes 0. The output of this terminal is two more inputs.
is applied to one input terminal of the NAND gate 215, and is applied to the other input terminal. Therefore, the output of the gate 215 becomes 0 for the period when the terminal output 214' is 1 minus the period TR from the time of power-on, as shown in FIG. 216' of time chart No. 15-b. It is output from the terminal 216 as an inverted signal of the output INTR indicating that the pre-rotation is to be performed.
Therefore, since INTR is not output during the reset period TR, together with the initialization by the timer, the desired operation after power-on does not feel abnormal. Also, when the charger is abnormal, it remains 0, so even after TR
INTR is not output. Therefore, since the main motor is driven only in normal conditions, safety and reliability are high. Incidentally, since the rotation stop position due to the INTR of 16CP is different from the initial position as described above, it is possible to prevent the accumulation of harmful effects on the drum due to the cleaning blade and the charger. The reason for outputting the inverted signal here is that it is convenient for subsequent circuits. Also, No. 15-b
In the figure, 211' and 208' are the terminals 21, respectively.
1,208.

(Counting means) Next, the clock pulse counter circuit is
The time chart will be explained with reference to FIGS. 16-b and 16-c. First, the circuit 221 is a clock pulse generator, which detects periodic changes in magnetic field strength using a magnetosensitive element, generates a pulse according to the output of the element, and uses it as a clock pulse. Fig. 163) is synchronized with the rotation of the photosensitive drum (Fig. 1, 15) and uses a Hall effect that is fixed at a specific position.
64 periodically to generate a panel-shaped output as the output of the magnetic sensing element. The circuit 231 is a well-known binary counter that is triggered when a falling signal from 1 to 0 is continuously applied to the CP input terminal as a clock pulse, and the output terminal A receives a 1/2 clock pulse.
An output with a frequency divided into 1/4 is generated at output terminal B, an output with a frequency divided into 1/8 is generated at output terminal C, and an output with a frequency divided into 1/16 is generated at output terminal D. That is,
These outputs are shown in Fig. 16-b 231'A, respectively.
231'B, 231'C, and 231'D. However, in FIG. 16-b, 222' is the clock pulse generator 221 in FIG. 16-a.
This signal is input from the output terminal 222 of the counter 231 and is applied to the CP terminal of the counter 231 via the inverter 230, so that the rising edge of the signal 222' becomes the trigger point. Note that the clock pulse signal at terminal 222 is hereinafter written as CLCK. Furthermore, when 1 is added to the CLEAR input terminal of the counter 231,
All of the output terminals A, B, C, and D become 0, and the state at this time is exactly the same as when the 0th and 16th clock pulses are applied, as shown in FIG. 16-b. Also, unless 1 is added to the CLEAR terminal, the output state repeats the 0th to 15th states, and in the following explanation, when 1 is added to the CLEAR terminal, clock pulses corresponding to the 0th and 16th states are applied. 16th clock pulse is applied. In Figure 16-a, the CLEAR terminal of the counter 231 has
Three types of reset signals are applied to effectively operate other circuits: First, a reset signal from the terminal 208 is applied to one input terminal of the three-input NAND gate 225 as a reset signal when the power is turned on, and a signal CBBP (details will be described later) indicating that the original platen (Fig. 1, 2) or the reverse position has been reached. An inverted signal of 1) is applied from terminal 223 to another input terminal of gate 225. gate 225
A pulse signal indicating the end of post-rotation is applied to the other input terminal of , which can be created as follows. First, a signal indicating that the rear rotation is in progress.
The inverted signal of the LRT (details will be described later) is first applied directly from the terminal 224 to one input terminal of the two-input AND gate 242, and then applied to the inverter 2
27, 228, 229 to other input terminals. At this time, as shown in Figure 16-c,
The signal 224' at the terminal 224 and the output 229' of the inverter 229 are in an inverted relationship, but since the signal 29' passes through three inverters, there is a delay in the signal compared to the signal 224'. If this delay time is TD, the output signal of the gate 242 is
As shown in the figure, 242' is TD time 1 from the falling edge of LRT, that is, the rising edge of signal 224' to the falling edge of signal 229'. After this, a signal indicating the end of rotation (hereinafter referred to as LRTEP) is output from the terminal 243 to other circuits, and further to the inverter 2.
26 to gate 225. Therefore, it becomes a reset signal. The output signal 225' of the gate 225 is STOP, CBBP,
When either LRTEP becomes 1, the counter 231 output as 1 is reset (cleared). Next, the outputs of the counter 231 are further combined as follows. First, the two-input AND gate 235 has
A D terminal inverted output via the inverter 234 of the C terminal output and the D terminal output is applied to each input terminal,
In addition, the two-input AND gate 236 includes the gate 23
5 and the B terminal output are added to each input terminal, and the C terminal inverted output and the D terminal output via the inverter 233 of the B terminal output and the C terminal output are applied to the three-input AND gate 237. In addition, the three-input AND gate 238 has B, C,
Each terminal output of D is connected to an inverter 232,
An inverted output via 233, 234 is applied to each input terminal. Therefore, the output of each AND gate is output to gate 235 as shown in FIG. 16-b.
The output 239' of the gate 236 becomes period 1 of the fourth to seventh clock pulses, and the output 249' of the gate 236 becomes the period 1 of the fourth to seventh clock pulses.
0' is the period 1 of the 6th to 7th clock pulse, the output 241' of the gate 237 is the period 1 of the 10th to 11th clock pulse, and the output 211' of the gate 238 is the period 1 of the 16th (0th) clock pulse.
This is period 1 of the first clock pulse, and is output as 4CP, 6CP, 10CP, and 16CP signals from terminals 239, 240, 241, and 211, respectively. In this embodiment, 15.75 clock pulses are generated per rotation of the drum. This is true in the 16-bit counting method mentioned above.
By counting 16 clock pulses, you can effectively tell that the drum has completed approximately one revolution.

(Size Circuit) Next, the copy size signal generation circuit will be explained with reference to FIG. In this embodiment, in order to improve the time efficiency of the copying process, an endless photosensitive drum is used as described above, and control is performed according to each copy size. Each copy size is automatically determined as soon as the transfer paper cassette is inserted into the main body. Specifically, the circuit shown in Figure 17 determines whether there is no cassette, B4 size cassette, or A4 size cassette.
Four types of status are distinguished: size cassette and B5 size cassette.

In Fig. 17, micro switches 246, 24
7 are both in the open state (when no cassette is inserted), and at this time, the output sections 246' and 247' are connected to the power supply voltage Vcc via resistors 248 and 249, respectively, so they are in the signal state of 1. , by inserting the cassette, each micro switch 246, 2
47 is switched and turned ON, the output section 24
6' and 247' are connected to the zero potential part GND (earth) and have a signal state of 0. In this embodiment, when a B4 size cassette is inserted, the micro switch 247 is turned on, and when an A4 size cassette is inserted, the micro switch 247 is turned on.
46 is switched to the ON state, and when a B5 size cassette is further inserted, the micro switch 24
6,247 are both switched to the ON state. Here, to the two-input AND gate 252, the signals at the output sections 246' and 247' of the microswitch are applied to each input terminal, and to the two-input AND gate 253, the signals at the output section 247' and the signal at the output section 246' are applied. A signal via an inverter 251 is applied to each input terminal, and a two-input AND gate 2
The signal at the output section 246' and the signal via the inverter 250 at the output section 247' are applied to the 2-input AND gate 255.
A signal via 251 is applied. Therefore, the output of gate 252 is 1 when no cassette is inserted, and the no cassette signal (hereinafter referred to as
CEP) and gate 25
The output of 3 is 1 when a B4 size cassette is inserted.
This is the B4 size copy signal (hereinafter written as B4C)
is output from terminal 257 as
The output of gate 54 and the output of gate 255 are each A4.
Size copy signal (hereinafter written as A4C) B5 size copy signal (hereinafter written as B5C) as terminal 25
It is output from 8,259.

(Copy execution command circuit) Next, copy execution command signal (hereinafter written as CCMD)
The generating circuit is shown in FIG. First, the circuit 261 is
Similarly to the circuit 221 in Figure 16-a, when the copying machine user presses the copy button (Figure 2, 13) using a magnet and a Hall element, the magnet moves and the resulting change in magnetic field strength occurs. This is a circuit that has the output of a Hall element that detects using the Hall effect, performs electromagnetic conversion, and generates an output of 1 when the copy button is pressed.
This output is input as a COP from a terminal 264 and is added to one input terminal of a four-input AND gate 270. Further, the circuit 262 is a circuit that outputs 1 as LEP when the developer becomes low in the developing device (FIG. 1 24).
Similar to 61, a pair of magnet and Hall element is used. This output LEP is applied from terminal 265 via inverter 267 to another input terminal of gate 270. Further, the circuit 263 is
This is a circuit that outputs 1 as PEP when there is no paper left in the cassette. In this embodiment, the lamp and the CdS photosensitive element are made to face each other, and the paper in the cassette is interposed between them. Therefore, when the paper runs out, the light emitted from the lamp is strongly irradiated onto the CdS, and this circuit detects the presence or absence of paper. When the paper runs out, this output becomes 1 as a PEP signal and is sent from the terminal 266 to the inverter 268. to another input terminal of gate 270 via . Furthermore, CEP generated from the circuit of FIG. 17 and output from terminal 256 is applied to another input terminal of gate 270 via inverter 269. Therefore, the output of the gate 270 is that the copy button is pressed and CCP becomes 1, the developer is filled and LEP becomes 0, and there is transfer paper in the cassette so PEP becomes 0 and the cassette itself is loaded. becomes 1 when CEP is 0,
It is output from terminal 271 as CCMD.

(Copy execution signal generation circuit) Next, a signal indicating that a copy operation is in progress.
FIG. 19 shows a circuit that generates CEXC (hereinafter simply referred to as CEXC). The signal CEXC starts when the copying machine starts moving forward to copy the first page after the copying machine is powered on, and after the last copy is completed, as will be explained in detail later. This is the signal for period 1 when the post-rotation ends, and terminal 2 is first
From 76, the document table advance command signal CBFOR is applied to the S terminal of FF 281 via inverter 282. Therefore, as will be described later, the FF 281, which has been reset in advance by a 0 signal when the power is turned on, has an output Q of 1 when the first document table advance command signal CBFOR becomes 1, and is output from the terminal 283 as CEXC. In addition, since the signals including the reset signal, jam detection signal, and charger abnormality signal when the power is turned on are applied from the terminal 208 to one input terminal of the two-input AND gate 280, when the signal becomes 0, the output of the gate 280 also becomes 0. , Since this output is further applied to the R terminal of FF281, the output Q becomes 0 and CEXC is stopped. Also FF
The reset of 281 is further inputted from terminal 243. This is also done by the LRTEP signal going to 1. As explained in Figures 16-a and 16-c, LRTEP is a signal that becomes 1 only during the time TD at the end of the post-rotation, and is a signal that becomes 1 from the terminal 243 with two input NAND
It is applied to one input terminal of gate 279. In addition, the other input terminal of the gate 279 has a terminal 271.
Since the CCMD signal is applied from the inverter 278, LRTEP is inverted and applied to the gate 280 only when CCMD is 0;
This is to prevent CEXC from being reset even if the copy button is pressed during post-rotation and CCMD becomes 1, and as will be described later, even if LRT falls at this time.

(Pre-exposure strong illuminance lighting circuit) Next, a pre-exposure strong illuminance lighting command signal BRIGHT (hereinafter simply referred to as BRIGHT) generation circuit is shown in FIG. As described above, in order to improve the efficiency of the copying process in this embodiment, the following photosensitive drum (hereinafter simply referred to as drum) rotation sequence is set up.

This copier is powered on and each circuit goes up to WUP.
After being reset by a signal, the drum rotates once as a forward rotation, and if the copy button is not pressed at this time, the drum stops rotating and enters a rest state. In this pause state, when the copy button is pressed and CCMD becomes 1, the fluorescent light is used to avoid the cleaning blade (Fig. After waiting 4 clocks to wait for the delay in lighting time of the lamp, the document table is started to move forward, and when forming the latent image of this first copy, the drum is exposed to light just before the primary charger (Fig. 1, 21). is applied to compensate for differences in the state of the drum photosensitive layer during continuous copying. However, this exposure (hereinafter referred to as pre-exposure) remains dark even when copying the second and subsequent sheets, but the circuit shown in Figure 20 uses this as a signal to turn on the pre-exposure strongly when copying the first sheet.
This is a circuit that generates the BRIGHT signal. first
As described in the CEXC generation circuit (FIG. 19), the state where CCMD is 1 and CEXC is 0 appears only immediately before the first copy is executed. CCMD
The signal is from the terminal 271 to the two-input NAND gate 29
CEXC is applied to one input terminal of gate 2 from terminal 283 through inverter 289.
93 is applied to the other input terminal. Therefore this
When CEXC is 0 and CCMD is 1, the output of gate 293 becomes 0, which is added to the terminal of FF295, and the output Q of FF295 becomes 1, making terminal 29
8 is output as a BRIGHT signal.
The pre-exposure illuminance, which has become strong when the BRIGHT signal becomes 1, must be returned to weak illumination after the drum has rotated approximately once in order to achieve the above-mentioned purpose. Therefore, in the case of A4 size copy or B4 copy, when the signal A4BP (details will be described later), which indicates that the document table has reached the A4 size inversion position, becomes 1, and in the case of B5 size copy, the document table is A4
The document glass will not reach the reverse size position.
When the B5 size inversion position is reached, the counter 231 in FIG. By this, the high intensity irradiation of the pre-exposure is stopped. In the circuit, terminal 2
The A4BP signal from 87 is applied to the terminal of FF 295 via inverter 291 and three-input AND gate 297. Therefore, when A4BP becomes 1, 0 is added to the terminal, FF 295 is reset, and the output Q becomes 0. Also, A4BP is not 1 and 4CP
When the signal rises, this signal is transferred from terminal 288 to FF2.
Since it is added to the CP terminal of the FF 95 and the D terminal is connected to GND (earth), the output Q of the FF 295 becomes 0. Here, as a signal for resetting the FF295, two input NAND signals are sent from STOP and CEXC from the terminal 283 via the inverter 289.
CCMD is inverted and applied to one input terminal of gate 294, and CCMD is applied to the other input terminal from terminal 271 via inverter 292. The outputs of the gates 294 are applied to the terminals of the FF 295 via gates 297, respectively. This means that STOP, which is the reset signal when the power is turned on, is
The purpose is to reset FF295, and
CCMD is 1 and CEXC is 0,
After setting FF295 (output Q to 1),
Even if 4CP rises and CBFOR rises, if CCMD becomes 0 before CEXC rises, the document table will not move and copying will not be performed, so at this time the pre-exposure should be returned to strong illumination again. CEXC is 0
Then, CCMD becomes 0 and is reset by the output of gate 294. Here, 4CP trust is B5
It is applied to the CP terminal in order to reset the FF295 during size copying, but even if the 4CP signal rises after CCMD becomes 1, as will be described later, the document platen advance command signal CBFOR will be set to 1 by the rise of 4CP.
Therefore, CEXC rises when CBFOR rises, so CEXC remains 0 immediately after 4CP rises, and at this time, FF295 rises due to the rise of 4CP.
is not reset.

(Rear rotation command circuit) Next, the rear rotation command signal LRT generation circuit is connected to the 21st -
Fig. 21-b shows and explains the time chart of Fig. 21-a. In this embodiment, the post-rotation is performed after the developed latent image formed on the photosensitive drum in the final copying process is transferred to the transfer paper, and ends after the drum has rotated approximately one revolution. First FF305
is reset when the power is turned on by a signal applied from the terminal 208 to the terminal via the two-input AND gate 304, and the Q output and the output become 0 and 1, respectively. Next, a 10CP signal is applied to the CP terminal from the terminal 241 to the FF 305, but this signal becomes 1 during forward rotation and when the document table is moving forward.
This occurs at the time when the transfer is completed after the document table reaches the inversion position and the counter 231 in FIG. 16-a is reset. Therefore, first, input CEXC from terminal 283 to the D terminal of FF305, AND
In addition to one input terminal of gate 303, terminal 27
The inverted signal of CBFOR is applied from 6 to another input terminal via inverter 301, and then FF30
FF30 by adding the output of 5 to another input terminal and adding the output of gate 303.
5 is set and the Q output becomes 1 because CEXC
This occurs only when CBFOR is 1, CBFOR is 0, and LRT is 0, and the FF 305 is in a state where it can be turned off by 10CP generated at the time when the transfer is completed. However, FF3 is connected from the terminal 271 through the gate 304.
Since CCMD is inverted and applied to the 05 terminal, FF305 is actually set as follows.
When CCMD runs out and becomes 0 (when the copy button is turned off), that is, when the last copy is being made. This also applies to FF305
is set, LRT is 1, and the copy button is pressed while performing post-rotation.
When CCMD becomes 1, backward rotation is stopped at that point and the vehicle starts moving forward. It resumes forward movement without requiring 4 clocks. Further, after the 10CP signal rises to 1, 10CP rises again when 16 clock pulses are generated, as described in the explanation of FIG. 16-a. Therefore, during this time, the drum rotates approximately one revolution, and at this time, the output of FF 305 applied to gate 303 is 0, and since the D terminal is 0, the output Q of FF 305 is reset to 0. rotation ends. still,
The output Q of the FF 305 is outputted to other circuits from terminals 306 and 224 as LRT, respectively. A time chart is shown in Figure 21-b. Signals 208', 271', 276', 283'241',
306' are terminals 208, 271, 276, respectively.
In the signal waveform at 283, 241, 306, 2
After continuous copying of sheets, 10CP signal rises and LRT
The figure shows an example of a case in which one sheet of paper is copied again after rotation.

(Original platen reciprocating circuit) Next, the document platen forward and backward command signal generation circuit is connected to the second
It is shown and explained in Figure 2. First, to explain the document table movement sequence, forward rotation is performed after the power is turned on, but after the forward rotation is completed (at this time, CEXC is still 0).
However, the document table where CCMD becomes 1 is 4.
Wait for clock pulse time and then start moving forward. With these four clocks, it is possible to form an image while avoiding the portion of the first drum facing the cleaner. B5, A4, B4
When it reaches each reversal position, it starts moving backwards and returns to the original platen home position (starting position).
However, in this embodiment, if the document table is not at the home position, the document table cannot be started, but when the power is turned on, the document table automatically moves to the home position.

In this embodiment, the position detecting device for these document tables uses a pair of magnet and Hall element, similar to the clock pulse generator shown in FIG. 16-a. That is, a magnet is attached to the document table, and a Hall element fixed to the main body detects changes in the magnetic field strength due to the movement of the magnet, so that the document table is moved to the home position B5,
A signal indicating that the reversal position has been reached for each copy size of A4 and B4 is generated. Second
In the circuit shown in Figure 2, a signal CBHP is sent from the terminal 311 to indicate that the document table is at the home position.
(hereinafter written as CBHP) is a two-input AND gate 315
From the terminal 271 added to one input terminal of
CCMD is applied to other input terminals. Therefore, when the document table is in the home position, CCMD is 1.
Then, the output of gate 315 becomes 1, and FF3
It is added to the D terminal of 24. Also, from the terminal 222 to one input terminal of the two-input NAND gate 316
CLCK signal is applied to the other input terminal.
Since CEXC is added from 83, when CEXC is 1, the gate 316 outputs an inverted signal of CLCK. Furthermore, in the two-input NAND gate 319, the 4CP signal from the terminal 288 is applied to one input terminal, and the CEXC is applied to the other input terminal via the inverter 318, so when CEXC is 0, the 4CP signal is inverted from the gate 319. is output.
The outputs of these gates 316 and 319 are further three inputs.
It is applied to the input terminal of the NAND gate 317, and the output of the FF 324 is further applied to the input terminal of the gate 317. Therefore, when the FF 324 is 1, the CLCK or 4CP signal is outputted from the gate 317 via the gates 316 and 319, respectively, and applied to the CP terminal of the FF 324. Therefore, when copying the first sheet, that is, when CEXC is 0,
When CCMD and CBHP become 1, the FF 324 is set at the rising edge of the 4CP signal, and the output Q becomes 1, which is output from the terminal 276 as a manuscript table advance command CBFOR (hereinafter simply referred to as CBFOR). Therefore, even after the forward rotation of 4CP, the presence of the P command and the document table being at the home position are the conditions for moving forward.
Therefore, the displacement of the document table during pre-rotation can be monitored, allowing accurate image formation.

In addition, when copying the second and subsequent sheets, CEXC is already set to 1 at this time, so when the document table returns to the home position and CBHP becomes 1, CBFOR is set by the rising edge of the next input CLCK signal. 1 and the document table moves forward. Therefore, since forward movement is not immediately resumed only by detecting the home position, smooth forward movement can be started. Furthermore, the advantage of endless exposure, which allows restarting from any drum surface, is not lost. In addition, since the start of advance for the first and second sheets is controlled using different methods, the advantage of being able to evenly expose an image at any position on the drum surface is not lost, and the pre-rotation time before the start of forward movement for the first sheet is reduced by 2. Coupled with the fact that the information is not added after the first copy, the time required for repeated copying can be extremely shortened. Next, the document table is reversed using the three-input AND gate 322.
The output of is passed through the two-input AND gate 323,
This is done by adding it to the terminal of FF324. That is, in the case of B5 size copy, the B5C signal is applied as 1 to one input terminal of the two-input NAND gate 320 from the terminal 257, and the B5BP is
It is applied from terminal 312 to the other input terminal. Therefore, at this time, when B5BP becomes 1, gate 3
Invert via 20, 322, 323 and FF32
4 and resets the FF324.
In the case of A4 size copy, it is exactly the same as 258,2.
The A4C and A4BP signals respectively input from 87 are applied to each input terminal of a two-input NAND gate 321, and the output is further applied to one input terminal of a gate 322. In addition, in the case of B4 size, terminal 31
3, B4BP is inverted and applied to the other input terminal of gate 322 via inverter 327. Therefore, each original platen reversal signal is inverted via gates 322 and 323 and applied to the R terminal of FF 324, and at this time, the output becomes 1, and the original platen reverse command signal CBREV is sent via a two-input AND gate 325. (hereinafter simply written as CBREV) is output from the terminal 326 to other circuits. However, when the document table returns to the home position at gate 325 and CBHP becomes 1, 0 is applied to one input terminal via inverter 314.
CBREV becomes 0 and reverse movement stops. If the document table is not at the home position when the power is turned on, it is automatically moved to that position by the output applied to the gate 325 via the inverter 314 and the output of the reset FF 124, together with the CBREV.
This is because. Therefore, it is possible to automatically move to the home position until just before the forward movement starts. Note that STOP is also connected to FF from terminal 208 through gate 323 like other circuits.
324 R terminal. Therefore, when an abnormality is detected in the charger, forward movement is stopped and the movement is switched to reverse, so that no defective images are produced unnecessarily. Further, the output of the gate 322 is an inverted signal of the document table inversion position signal, and is outputted from the terminal 223 to other circuits. Figure 22-b shows a time chart of 311', 222', 322', 311', 222', 322', and
The signal waveforms shown at 276' and 326' are respectively
Compatible with CBHP, CLCK, , CBFOR, and CBREV.

(Paper feed circuit) Next, paper feed start command signal PFSD (hereinafter simply
Figure 23 shows the generation circuit (written as PFSD). In the figure, from the terminal 331, a signal indicating that the document table has reached a specific position is generated by the magnet 161 and the element 71, using means completely similar to the document table reversal position detection means shown in FIG. 22-a. This is input as the paper feed timing signal PFSP.
It is applied to one input terminal of AND gate 332. Other input terminals of gate 332 include terminal 27
Since CBFOR is added from 6, if the PFSP is input as 1 while the document table is moving forward, the gate 33
The output of 2 becomes 1, which is output from the terminal 336 as PFSD. Further, in this embodiment, the PFSD signal and each copy size signal are added to each input terminal of a two-input AND circuit, and the output thereof is used as a count signal for the number of copies. That is, in Figure 23
B5C, A4C, B4C are terminals 259 and 25 respectively
8,257, two-input AND gate 3
In addition to one input terminal of 33, 334, 335, the output of each gate is B5COUNT, A4COUNT, B4COUNT from terminals 337, 338, 339, respectively.
is output as

(Jam Detection Circuit) Next, we will discuss the circuit for detecting the occurrence of abnormal conveyance of transfer paper in the copying process, that is, extreme delays, binding in the conveyance path, etc. (hereinafter simply referred to as jam).
The circuit diagram and time chart are shown in Figures a, b, and c for explanation. First, in Figure 24-a, the generation process was explained from the terminal 223 in Figure 22-a.
The CBBP signal is input and applied to the SD terminal of the FF344 as a set signal. Therefore, when becomes 0, the output Q of the FF 344 becomes 1, and this signal is further applied to one input terminal of the two-input NAND gate 345. Also, the other input terminal of the gate 345 receives a jam timing signal from the terminal 342.
JTP (hereinafter simply referred to as JTP) is added. this
JTP is the time when the leading edge of the transfer paper reaches a specific position in a predetermined path after the transfer process and the drying/fixing process are completed. This is a pulse signal that is generated after a period of time including a margin of
Set FF346. That is, the output Q of FF346
becomes 1 and outputs the jam signal JAM to terminal 3.
43. Note that the inverted JAM signal is output from the output of the FF 346, that is, the terminal 201, to other circuits. If the transfer paper is conveyed normally, the signal PDP (hereinafter simply referred to as PDP) from the paper detection device at the specific position is transmitted to the terminal 34.
1 is added to the CP terminal of FF344 and the D terminal is
Since it is connected to GND (earth) and becomes 0,
When the PDP signal rises from 0 to 1, FF3
The output Q of 44 becomes 0, and at gate 345
Even if JTP becomes 1, the output does not become 0 and FF346
is not set. In the time chart of FIG. 24-c, part A shows the signal waveforms during normal transport, and part B shows the signal waveforms when a jam occurs. However, signal waveforms 223', 341', 342', 344', 34
3' are the signal waveforms of the PDP, JTP, Q output of FF344, and Q output (JAM) of FF346, respectively. Incidentally, a broken line portion in the signal 341' indicates a case where the transfer paper does not reach the specific position or the arrival is extremely delayed.

In this embodiment, the paper detecting means at the specific position uses a pair of a lamp and a CdS photosensitive element, similar to the paper detecting device described in connection with the PEP signal generating circuit of FIG. 18.

Next, regarding the JTP generation circuit described above, the circuit shown in FIG. 24-b was used in this embodiment. In this embodiment, as shown in FIG. 16-a, the clock pulse counter 231 is reset at the document table inversion position, and after that, the leading edge of the transfer paper reaches the specific position by normal conveyance. ,
10CP each for B5, A4, and B4 sizes,
This is approximately one second before the 6CP and 4CP signals are generated, and therefore, each count signal is used as a jam timing signal. That is, as shown in Figure 24-b, the A4C signal from the terminal 258 is a two-input NAND
The 6CP signal from terminal 240 is applied to one input terminal of gate 348 and to the other input terminal. Therefore, the output of gate 348 is 6CP signal inverted and 3 inputs only in case of A4 size copy.
It is applied to one input terminal of NAND gate 350. Also, in the case of B4 size copy, terminal 257,
B4C and 4CP are input from 239 respectively, two inputs
It is applied to the input terminal of NAND gate 349 and the output of gate 349 is applied to another input terminal of gate 350. Further, the 10CP signal is inverted via an inverter 347 and applied to another input terminal of the gate 350. Therefore, gate 3
50 output, 4CP for B4 size copy,
10CP signal appears and in case of A4 size copy
6CP and 10CP signals appear, and in the case of B5 size copy, only the 10CP signal appears, and from terminal 342
Output as a JTP signal. Note that, apart from this embodiment, the JTP signal may also be generated regardless of the copy size, for example, when the document table starts moving forward or after a certain period of time has elapsed from the time when the paper feed start timing pulse is generated. In this way, since the clock pulse count for forming the jam timing signal is started by detecting the position of the document table, there is no need to select the output compared to the case where the count results are repeatedly output as the drum rotates.

(Energization control circuit) Next, the aforementioned control signals are appropriately combined to control the energization switching element in order to energize each terminal element according to the process conditions of the copying process. When a pulse transformer is used as a triax and a triax ignition circuit, an output circuit is used, an example of which is shown in FIG. Figure 25 shows an example of a signal generation circuit that controls the energization of the main motor (M in Figure 5).
Terminals 271, 283, 2 are connected to drive the main motor when any one of them becomes 1.
16, respectively.

Three input OR of COMD, CEXC, INTR signals
In addition to each input terminal of the gate 408, the output of the gate 408 is further connected to a two-input AND gate 409.
is added to one input terminal. In addition, an unstable multivibrator circuit 40 is connected to the other input terminal of the gate 409.
By applying the output signal OSC from 2, the output of gate 409 produces an output from circuit 402 only when the output of gate 408 is 1, switching the energization from terminal 411 to the main motor. It is amplified and added to the pulse transformer in the triac's ignition circuit.

(Electrification Switching Circuit) The digital circuit that is the main part of the control circuit has been explained above, including sequence control. Next, FIG. 26 shows a circuit that switches the current applied to each terminal element according to the output of the control circuit. Shown below. In the figure, P is an AC input power supply, RL ₁ , RL ₂ , RL ₃ are each terminal element, G ₁ , G ₂ , G ₃ are triaxes for switching the current to each terminal element, T ₁ , T ₂ ,
_T3 is a trigger pulse generated from a normal triax trigger generation circuit (not shown).
It is generated in accordance with a signal from the control circuit (for example, FIG. 25). Further, S ₁ and S ₂ are two moving main switches. Therefore,
RL ₁ receives a trigger signal until the specified sequence is completed, regardless of whether the main switch is ON or OFF.
Electricity can be applied by the occurrence of T ₁ . still,
In this example circuit, RL ₁ includes the main motor, high voltage AC output, etc. RL ₂ also has main switches S ₁ and S ₂
When is turned ON, a trigger voltage is applied to g 2 via S ₂ and resistor R ₂ , making G ₂ conductive _and allowing electricity to flow.Furthermore, even if the main switch is turned OFF, the trigger voltage from the control circuit will not be activated. As long as the signal T ₂ is generated, RL ₂ continues to be energized, and in this circuit example corresponds to a power transformer for maintaining the control function. Furthermore, in RL ₃ , the main switch remains OFF even if the trigger signal T ₃ from the control circuit is generated.
When this happens, power supply stops, and this example circuit includes the fuser heater and the like. Here, by including the power transformer of the power supply circuit for applying power supply voltage to the control circuit in RL ₂ , the control circuit can be operated even when the main switches S ₁ and S ₂ are turned off. It is necessary to put it in the state. Note that the power supply circuit and trigger pulse generation circuit may be ordinary ones. Further, other associated circuits that are not directly related to the present invention are common and have been omitted for the sake of simplifying the explanation.

In addition, in Figure 26-a, if it is necessary to cut both sides of the input power supply of each terminal element included in RL ₃ , the connection of point t may be changed from point u to point s, and RL ₂ As shown in Figure 26-b, the current-carrying circuit is connected to one line L ₁ from the AC input power source P with S ₁ ,
Connect one terminal of each of S ₂ and make S ₁ a conductive path to each terminal element corresponding to the pair _of RL ₃ and G ₃ ,
Even if we supply the trigger voltage to g ₂ through R ₂ from
The above effects can be obtained.

In addition, here we will use a switch to directly turn on and off the power.
Although we have described the case where S ₃ and S ₁ are in the on state, it is convenient to use these switches S ₃ and S ₄ as door switches for the case of the copying machine. In other words, when performing jam removal after detecting a jam, opening the door shuts off this switch and turns off the voltage applied to switching elements G ₁ , G ₂ , and G ₃ , thereby cutting off conduction to all loads and control circuits. enough to ensure safety.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view of the copying device, Fig. 2 is an external perspective view thereof, Fig. 3 is a longitudinal sectional side view of Fig. 1, and Fig. 4 is a longitudinal sectional view of the copying device.
5 are sectional views and perspective views showing the driving relationship of the copying device, FIGS. 6 and 7 are partial sectional views showing the operation of the safety device, and FIG. 8 is a perspective view showing the fixing device.
FIG. 9 is a sectional view showing the paper feeder drive section, FIG. 10 is a perspective view showing the document table drive section, FIG. 11 is a perspective view showing the cassette, and FIGS. 12 and 13 are the document table stop device. 14a is the reset command signal generation circuit, FIG. 14b is its time chart, FIG. 15a is the pre-rotation signal generation circuit, FIG. 15b is its time chart, and FIG. 16a is the clock. Figure 16b is a time chart thereof, Figure 16c is a waveform diagram for clearing the counter, Figure 17 is a copy size signal generation circuit,
8 shows a copy execution command signal generation circuit, FIG. 19 shows a copy execution signal generation circuit, FIG. 20 shows a pre-exposure strong illuminance lighting command signal generation circuit, FIG. 21a shows a post-rotation command signal generation circuit, and FIG. 22b is the time chart, FIG. 22a is the document table, forward and backward command signal generation circuit, FIG. 22b is the time chart, FIG. 23 is the paper feed start command signal generation circuit, and FIG.
Figure a is a jam occurrence detection circuit, Figure 24b is a jam timing signal generation circuit, Figure 24c is a time chart thereof, Figure 25 is a signal generation circuit for controlling conduction, Figures 26a and 26 Figure b is a circuit that switches conduction to each terminal, 48
A, 48B, 48C, 71, 72 are magnetic sensing elements, 161, 162 are magnets, and in Fig. 22-a, CBHP: document platen home position signal, CCMD: copy execution command signal, CLCK: clock pulse signal, CEXC: copy execution Medium signal, 4CP: Counter pulse signal, 324: Binary counter,
CBFOR: Document plate forward command signal, CBREV: Document plate backward command signal, B5C, A4C: Cassette size signal, B5BP, A4BP, B4BP: Document plate position detection signal, CBBP: Document plate reverse position signal, STOP: Reset signal. .

Claims (1)

[Scope of Claims] 1. A reusable endless photosensitive rotating body, forming a latent image on the rotating body and developing the latent image,
a plurality of process means for transferring the developed image onto a transfer material and cleaning the rotary body; a driving means for rotating the rotary body for latent image formation, development, transfer, and cleaning; a size signal generating means for generating a size signal indicating the size of the transfer material to be transferred; a counting means for counting a clock signal generated synchronously with the rotation of the rotating body; and a size signal from the size signal generating means. control means for controlling the process means for forming the latent image based on the count output of the counting means, and control means for controlling the driving means based on the count output of the counting means, the control means controlling the rotating body to form the latent image. controlling the driving means to cause forward rotation, stop the forward rotation based on the count output, or cause backward rotation after the transfer is completed, and stop the backward rotation based on the count output; In order to stop the rotating body at a different position after the pre-rotation or after the post-rotation, the counting means, which is reset at the timing after the power is turned on to the apparatus or after the latent image formation is completed, counts the number of revolutions of the rotary body once. An image forming apparatus characterized in that the rotation of the rotating body by the driving means is stopped when counting of a number different from the number corresponding to .