JPH04367844A - Image forming device - Google Patents

Abstract

PURPOSE:To smoothly turn an original platen in a short distance in the case that the moving speed of the original platen is made higher in an original platen moving system copying machine. CONSTITUTION:An oscillator 26 being the reference of normal-speed movement and an oscillator 27 being the reference of high-speed movement are prepared. When an original platen table 2 is moved in a backward direction, it is moved at the high speed by the oscillator 27. When a slit 12 is detected by a position detecting sensor 9 on the way, a motor 3 is braked in specified timing. At such a time, by switching the oscillators 26 and 27, the moving speed of the original platen table 2 just before the original platen table is turned to a forward direction is decreased to the normal speed.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electronic copying machine with a movable document table.

0002

2. Description of the Related Art As is well known, in electronic copying machines with a movable document table, the document table reciprocates within a specific range during image formation. In this case, the direction and speed of movement of the document table are controlled according to the rotation direction and rotation speed of a motor provided in the main body of the apparatus.

[0003] Furthermore, for example, a sensor is provided to detect the position of the original platen, and the output of this sensor is used to reverse the direction of rotation of the motor at a timing that prevents the original platen from colliding with a stopper, thereby folding the original platen. . In this type of copying machine, one way to increase the number of copies per unit time is to increase the moving speed of the document table.

[0004] However, in the case where the folding of the document table at the end of the range to be moved is controlled using a position detection sensor, it is necessary to change the mounting position of the sensor in accordance with the increase in speed. That is, when the moving speed of the document table is increased, its inertial force increases. Therefore, if the sensors are installed at the same position, there is a high possibility that the document table will collide with the stopper, and a shock absorbing material must be used to avoid this.

[0005]

[Problem to be Solved by the Invention] As mentioned above, conventionally, when trying to increase the moving speed of the document table,
This had the disadvantage of requiring changes to standards and the use of shock absorbing materials.

[0006] Therefore, the present invention aims to change the standard and
It is an object of the present invention to provide an image forming apparatus that can increase the moving speed of a document table without using a shock absorbing material, and can further reduce the size of the entire apparatus. [Structure of the invention]

[0007]

[Means for Solving the Problems] In order to achieve the above-mentioned object, in the image forming apparatus of the present invention, an original image read along with the forward movement of the reciprocating original table is scanned as an image. In the device for forming images on a forming medium, an operating means for continuously performing an image forming operation on a plurality of image forming media by repeatedly moving the document table back and forth, and a repeating reciprocating movement by the operating means a first setting means for setting a moving speed during a forward movement of the document table; and a first setting means for setting a moving speed during a backward movement of the document table, which is repeatedly moved back and forth by the operating means. The second speed is set to a faster speed than the movement speed set by the means.
a setting means, a detection means for detecting a reference position of the document table which is operated in a backward motion at a speed set by the second setting means, and a predetermined period of time elapsed since the detection of the reference position by the detection means. and switching means for switching the moving speed of the document table from the moving speed set by the second setting means to the moving speed set by the first setting means.

[0008]

[Operation] In this invention, by the means described above, it is possible to quickly decelerate to a stable speed where no impact is generated by the stopper immediately before turning, so by using the same sensor position and the same detection timing,
This makes it possible to turn around smoothly and over a short distance.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 5 shows the configuration of a copying machine with a movable document table (electrophotographic process configuration mechanism) according to the image forming apparatus of the present invention.

A photosensitive drum 120 as an image carrier is arranged approximately in the center of the copying machine main body 1, and the photosensitive drum 120 is moved at a copying speed of 100 mm/sec in the direction of arrow c by a drive mechanism (not shown). It is rotated at the same speed as the moving speed of the original platen table 2. Photosensitive drum 120
is made of a negatively chargeable organic photoconductor (OPC), and has a structure in which a charge generation layer and a charge transport layer covering the charge generation layer are formed on the surface of an aluminum cylinder.

Around the photoreceptor drum 120, along the rotational direction thereof, there are provided a charging device 121 as a charging means, a charge removal/exposure device 122 as an electrostatic latent image forming means, and a developing unit 123 as a developing means. , a transfer charger 124 as a transfer means, and a peeling charger 1 as a peeling means.
25, and a cleaner unit 126 as a cleaning means
are arranged in sequence.

The above-mentioned static eliminating/exposure device 122 includes a lamp 1
40, a condensing light transmitting body 143, a reflecting member 148, and a static elimination light opening 149 formed in the reflecting member.

Furthermore, a paper conveyance path 128 is formed within the copying machine main body 1. This conveyance path 128 transports the paper P fed from the paper cassette 102 via the paper feed means 133 and the paper P manually fed from the manual paper feed tray 104 to the photosensitive drum 120 and the charged transfer material. vessel 12
4 and then to the paper discharge tray 103 mounted on the left side of the copying machine main body 1.

Image transfer section 127 of this paper conveyance path 128
An aligning roller pair 129 is arranged on the upstream side, and a fixing unit 130 as a fixing means and a paper ejecting roller pair 131 as a paper ejecting means are arranged on the downstream side. Furthermore, an aligning switch 132 is provided near the aligning roller pair 129.

Note that 135 indicates each charger 121, 124,
125 is an ozone filter that neutralizes the ozone generated, and 136 is a cooling fan unit that prevents the temperature inside the machine from rising. 137 is a toner cartridge installed in the developing unit 123.

As the photosensitive drum 120 rotates in the direction of arrow c, the surface of the photosensitive drum 120 is charged to -700V by the charger 121. The charging device 121 is equipped with a grid 121a, and the voltage of the grid 121a is set to -750V during charging.

The negatively charged photoreceptor drum 120 is uniformly illuminated by a lamp 140 as a bar-shaped light source that constitutes the static eliminating/exposure device 122, and the original document D on the document table 141 made of transparent glass is illuminated by the lamp 140 as a rod-shaped light source constituting the exposure device 122. An electrostatic latent image is formed on the surface of the photoreceptor drum 120 by forming an image by a condensing light transmission member (trade name: Selfoc Lens Array) 143 . Next, the electrostatic latent image on the photoreceptor drum 120 is made visible by being opposed to the developing unit 123 and having positive polarity toner attached thereto.

The developing device unit 123 uses a positive polarity two-component magnetic brush system, and has a developing roller 1 which is a developer conveying means.
44 sleeve 144a is moved in the direction of arrow d by a drive mechanism (not shown) at a faster speed than the photosensitive drum 120 (approximately 3.5 mm).
3 to 3.5 times), and a bias voltage of -200V is applied.

On the other hand, in synchronization with this toner image forming operation, the paper is taken out from the paper feed cassette 102, or the paper is removed from the manual paper feed tray 1.
The paper P manually fed from 04 is sent to the image transfer section 127 via a pair of aligning rollers 129.

The paper P fed into the image transfer section 127 is fed by a pre-transfer guide 145 so as to come into close contact with the surface of the photoreceptor drum 120, and the toner image previously formed on the photoreceptor drum 120 is used for transfer. The image is transferred to the paper P by the negative charging action of the charger 124. Next, the sheet P on which the toner image has been transferred is subjected to AC corona discharge by the peeling charger 125 to neutralize the electrification, so that it is peeled off from the surface of the photoreceptor drum 120 and conveyed through the paper conveyance path 128. , are fed into the fuser unit 130 along the fuser front guide 146. Then, the toner image is melted and fixed onto the paper P by a pair of fixing rollers 147, and after that,
The paper is discharged onto the paper discharge tray 103 via the paper discharge roller pair 131.

The fixing roller pair 147 includes a fuser roller 147a coated with Teflon-based resin on an Al core metal, and a heater 152 built inside, and a press roller 147b made of silicone rubber, and the surface of the fuser roller 147a is negative. Since the press roller 47b is charged with a positive charge, an offset due to contact with the positive polarity toner or staining of the press roller 47b occurs. This equipment uses PT in which carbon black is dispersed.
The fuser roller 147a is coated with FE to lower the resistance of the resin layer, and is grounded by a leaf spring (not shown) to prevent charging. Furthermore, a cleaning member 301 for cleaning the surface of the fuser roller 147a, a holder 302 for holding the cleaning member, a handle portion 303 for attachment and detachment, and the like are installed.

Note that after transferring the toner image onto the paper P,
The residual toner remaining on the photosensitive drum 120 is scraped off by a cleaning blade 126a of the cleaner unit 126. Furthermore, after this, the photosensitive drum 120
The afterimage on the surface is erased by the static eliminating light from the static eliminating/exposure device 122, and the image returns to the initial state. The above-mentioned static elimination light is led out from a static elimination light opening 149 as an opening formed in a reflecting member (hereinafter referred to as a reflector), passes through a static elimination light filter 150, and is converted into an appropriate static elimination light amount and wavelength to be used in the cleaner unit 126. The surface of the photoreceptor drum 120 is irradiated with the light from the static elimination light opening 151 .

Note that the copying machine main body 1 has a paper conveyance path 128.
The upper unit is divided into upper and lower halves with approximately the boundary between The device facing the conveyance path 128 can be exposed. In addition, it is possible to easily remove jammed sheets of paper P, and perform maintenance, inspection, and replacement of equipment. FIG. 1 shows the main parts of the structure of the above-described movable document table copying machine.

That is, this electronic copying machine has an original document that can be moved back and forth in the left and right directions (the forward X direction as a forward movement, the backward X' direction as a backward movement) in the upper part of the main body 1 of the copying machine. A base table 2 is provided.

In this electronic copying machine, one sheet of copy paper is output by one reciprocating movement of the document table 2 in the forward X direction and the backward X' direction. Furthermore, continuous copying, that is, a plurality of copies, can be obtained by reciprocating the document table 2 a plurality of times.

In FIG. 1, a document table 2 is driven by a motor (for example, a DC brushless motor) 3 within a main body 1 of the copying machine. This motor 3 is adapted to rotate in the left-right direction (forward rotation T direction, reverse rotation T' direction).

The driving force of the motor 3 is transmitted via a belt 4, a drive transmission gear 5, a belt 6, and a drive transmission gear 7 to a gear 8 for directly driving the document table 2. In this case, the original platen table 2 is moved in the forward X direction with respect to the forward rotation T direction of the motor 3. Further, the document table table 2 is moved in the backward X' direction with respect to the reverse rotation T' direction of the motor 3.

A position detection sensor 9 is provided at a predetermined position on the upper surface of the copying machine main body 1, for example, corresponding to an image reading section. This position detection sensor is constituted by, for example, a photointerrupter. Further, a microswitch or the like can also be used as a position detection sensor. On the other hand, corresponding to this position detection sensor (photointerrupter) 9, the document table table 2 has slits 10, 11,
12 are provided. The slit 10 is used to detect the movement limit position when the document table table 2 moves in the forward T direction. The slit 11 is used to detect the movement limit position when the document table 2 moves in the backward direction T'.

Furthermore, at the end of the slits 10 and 11, there are stoppers (
(not shown) are provided respectively. These stoppers are arranged at intervals that are longer than the length of the maximum document that can be copied. The slit 12 is used, for example, to detect the home position of the document table 2. FIG. 2 shows a schematic configuration of a control system related to the movement of the document table 2 described above.

That is, this control system includes a microcomputer 21 that controls the entire copying machine, signal conversion sections 22 and 23, a switching section 24, a drive control section 25,
It is composed of oscillators 26 and 27, a drive circuit 28 for driving the motor 3, and the position detection sensor 9 described above.

The signal converting section 22 converts the signal serially transferred from the microcomputer 21 into a parallel signal, and outputs this to the switching section 24 and the drive control section 25. The signal conversion section 23 converts the signal from the drive control section 25 and the output of the position detection sensor 9 into a serial signal, and outputs this to the microcomputer 21.

The switching section 24 selects one of the oscillators 26 and 27 according to the signal from the signal converting section 22, and uses the output of the oscillator as a basic clock to control the drive control section 2.
This is what is output to 5. The oscillator 26 oscillates at a frequency that can be used as a basic clock for moving the document table 2 at a speed necessary for reading the document image, for example.

The oscillator 27 oscillates at a frequency that can be used as a basic clock for speeding up the movement of the document table 2 in the backward X' direction during continuous copying, for example.

The drive control unit 25 controls the drive circuit 28 based on the signal from the signal conversion unit 22 and the basic clock from the switching unit 24, and thereby controls the motor 3 in the normal rotation T direction or It is designed to rotate steadily in the reverse T' direction. The drive control unit 25 also uses a lock signal (MRD) during steady rotation of the motor 3.
Y) is monitored.

In this embodiment, the broken line portions shown in the figure, that is, the signal conversion sections 22 and 23 and the switching section 2
4 and the drive control section 25 are configured with a gate array or the like, and signals are exchanged with the microcomputer 21 by serial transfer. Next, the operation in the above configuration will be explained. 3 and 4 show the flow of processing for turning the document table table 2 from the backward X' direction to the forward X direction during continuous copying.

For example, suppose now that an image forming operation in continuous copying mode has been started. That is, the signal conversion section 22, the switching section 24, and the drive control section 25 are controlled by outputting a signal instructing movement in the forward X direction from the microcomputer 21. In this case, the switching section 2
4 is operated to select the oscillator 26, and the oscillator 26
The output is outputted to the drive control section 25 via the switching section 24. Then, the drive circuit 28 is driven by the drive control section 25, and the motor 3 is rotated in the normal rotation T direction. As a result, the document table table 2 is moved in the forward X direction on the upper surface of the copying machine main body 1 at a constant speed using the output of the oscillator 26 as a basic clock.

As the document table 2 moves in the forward X direction, the image of the document held on the document table 2 is read. Furthermore, in synchronization with this reading, the electrophotographic process configuration mechanism within the copying machine main body 1 is operated, thereby forming (copying) the above-described original image on a sheet of paper.

On the other hand, after a while, the position of the document table 2 being moved in the forward X direction is detected by the position detection sensor 9 as the slit 10 blocks light from the photointerrupter. The detection output of the position detection sensor 9 is sent to the microcomputer 21 via the signal conversion section 23.

Then, a signal for stopping is output from the microcomputer 21, and the signal is sent to the drive control section 25 via the signal conversion section 22.
supplied to As a result, the driving of the drive circuit 28 is stopped, and a brake is applied to the rotation of the motor 3 in the normal rotation T direction. As a result, the movement of the document table 2 in the forward X direction is gradually decelerated. Then, the document table table 2 is finally stopped at a position where no impact occurs with a stopper (not shown).

[0040] The rotation of the motor 3 has completely stopped.
The signal is sent to the microcomputer 21 via the drive control section 25 and the signal conversion section 23, and when this is recognized, the microcomputer 21 outputs a signal instructing movement in the backward X' direction. Thereby, the signal conversion section 22, the switching section 24, and the drive control section 25 are controlled. In this case, the switching section 24 is operated to select the oscillator 27, and the output of the oscillator 27 is outputted to the drive control section 25 via the switching section 24. Then, the drive circuit 28 is driven by the drive control section 25, and the motor 3 is rotated in the reverse direction T'. As a result, the document table table 2 is folded over the upper surface of the copying machine main body 1 in the backward X' direction, and is moved at a constant speed using the output of the oscillator 27 as the basic clock, that is, at a moving speed in the forward X direction. is also moving at high speed. Note that the explanation up to this point is not shown in the drawings for convenience.

After a while, the document table table 2 moving in the backward direction X' is detected by the position detection sensor 9 as the slit 12 blocks light from the photointerrupter. The detection output of the position detection sensor 9 is sent to the microcomputer 21 via the signal conversion section 23. Then,
Control is transferred from the main flow shown in FIG. 3 to the interrupt flow shown in FIG.

In this interrupt flow, first, the count start flag FXCT and the flag FXCTR are set (
FXCT=1, FXCTR=1). Then, a counting operation of a timer (not shown) for measuring the timing of starting braking or speed switching is started. This count value is determined in advance according to various conditions.

[0043] At this point, the moving speed of the document table 2 has been increased in order to increase the speed. Therefore, the conditions (standards) such as the positions of the slit 11 and the position detection sensor 9, and the sizes of the document table table 2 and the copying machine body 1 are not changed, and in addition, the document table table 2 can be moved without changing the conditions (standards) such as the positions of the slit 11 and the position detection sensor 9, and the size of the document table table 2 and the copying machine main body 1. In order to turn back in the forward X direction, the speed of the document table 2 just before turning back can be set to the original speed before speeding up, where no impact occurs.

Normally, when the document table 2 is turned back, the motor 3 starts rotating in the reverse direction T' in response to a reverse command from the microcomputer 21. However, an inertial force acts on the original platen table 2, and there is some time difference between the output of the reversal command and the actual reversal. Therefore, the faster the moving speed of the document table 2 becomes, the longer the moving distance from the output of the reverse rotation command to the turning back becomes longer.

Therefore, in this embodiment, a brake is used to reduce the speed to a speed that does not cause an impact, thereby making it possible to turn around smoothly and over a short distance.

When the counting operation of the timer described above is completed, that is, when it is determined that there is a borrow, the count start flag FXCT is reset (FXCT=0). Further, a switching signal is output from the microcomputer 21 and sent to the switching section 24 via the signal converting section 22. As a result, the switching unit 24 is operated to switch to the oscillator 26, and the output of the oscillator 26 is output to the drive control unit 25. Then, the drive control unit 25 drives the drive circuit 28 so that the motor 3 rotates at a constant speed using the output of the oscillator 26 as a basic clock.

[0047] Also, at this time, the braking operation is started. That is, since the motor 3 has its own inertia force, even if the oscillator is switched, the speed does not become constant immediately. Therefore, a brake is used to reduce the speed of the document table 2 and the motor 3 to speed up the process.

As for the above-mentioned braking method, since a DC brushless motor is used as the motor 3 in this embodiment, a command from the microcomputer 21 is sent to the drive control section 25 via the signal conversion section 22. and motor 3
This is achieved by controlling the current flowing through the

On the other hand, immediately after the start of braking, it is checked whether the rotation of the motor 3 is out of the lock range. That is, the lock signal MRDY during steady rotation of the motor 3 is sent from the drive control section 25 to the microcomputer 21 via the signal conversion section 23 and is constantly monitored. Therefore, when the flag FXCTR is set, by checking the lock signal MRDY described above, the motor 3 is removed from the lock range using the output of the oscillator 27 as the basic clock (MRDY=0).
is detected. When the deviation from this high rotation lock range is detected, the motor 3 with the oscillator 26 as a reference
lock detection flag MRDY2 is set (MRDY2=
1) To be done.

Next, this lock detection flag MRDY2
is set, by the time the slit 11 reaches the position detection sensor 9, the motor 3 has reached the steady rotation range after deceleration, that is, the steady rotation lock range with the output of the oscillator 26 as the basic clock. It is checked whether it has entered or not. And, having entered this steady rotation lock range (
When MRDY=1) is detected, the above-described braking is released and flags FXCTR and MRDY2 are both reset (FXCTR=0, MRDY2=0). As a result, the original platen table 2 continues to move on the upper surface of the copying machine main body 1 at the constant speed before the speed-up. Furthermore, control is returned to the main flow via the interrupt flow.

After that, the slit 11 is connected to the position detection sensor 9.
When detected, the motor 3 is rotated in the normal rotation T direction in the same manner as described above. As a result, the document table table 2 is smoothly folded back and is again moved in the forward X direction on the upper surface of the copying machine main body 1 at a constant speed. and,
The second copy operation is started. In this way, by repeating the reciprocating movement of the document table 2 and the copying operation, continuous copying for the specified number of sheets is performed. As described above, the speed can be quickly decelerated to a stable speed at which no impact is caused by the stopper just before turning around.

That is, the timing of braking and speed switching is determined by the conventional position detection sensor and a specific timer program for the faster movement of the document table table in the backward direction. As a result, when turning back in the forward direction, it is possible to change the direction of movement at a conventional stable speed without any impact caused by the stopper. Therefore, even when trying to speed up continuous copying, it is possible to increase the speed of continuous copying without changing the mounting position of sensors and slits, the size of the document table or the copying machine, and without using shock absorbing materials. The document table can be turned back smoothly and within a very short distance at the detection timing of the detection sensor. In addition, it allows for quick turnarounds over short distances,
By reducing space, it is possible to downsize the device. It should be noted that the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the invention.

[0053]

[Effects of the Invention] As detailed above, according to the present invention, it is possible to increase the moving speed of the document table without changing the specifications or using shock absorbing materials, and moreover, the entire apparatus can be improved. An image forming apparatus that can be downsized can be provided.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing the main parts of a copying machine with a movable document table according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the main parts of the control system.

FIG. 3 is a flowchart shown to explain an overview of the operation.

FIG. 4 is a flowchart similarly shown to explain interrupt processing.

FIG. 5 is a configuration diagram showing the internal mechanism of the copying machine with a movable document table.

[Explanation of symbols]

1...Copying machine main body, 2...Original platen table, 3...Motor, 9
...Position detection sensor, 10, 11, 12...Slit, 21
...Microcomputer (microcomputer), 22, 23...Signal conversion section, 24...Switching section, 25...Drive control section, 26
, 27... Oscillator.

Claims (1)

[Claims] 1. In an image forming apparatus that forms a document image on an image forming medium, which is read as the document table moves back and forth, a plurality of document images are read by repeatedly moving the document table back and forth. an operating means for continuously performing an image forming operation on the image forming medium;
a first setting means for setting a moving speed during a forward movement of the document table which is repeatedly moved back and forth by the operating means; and a moving speed during a backward movement of the document table which is repeatedly moved back and forth by the operation means. a second setting means for setting the moving speed to a speed faster than the moving speed set by the first setting means; and a second setting means for setting the document table to a speed faster than the moving speed set by the first setting means; detecting means for detecting a reference position; and after a predetermined time has elapsed since the detection of the reference position by the detecting means, the moving speed of the document table is changed from the moving speed by the second setting means to the first setting means. 1. An image forming apparatus comprising: switching means for switching to a moving speed according to the present invention.