JPS61294463A - Paper feed timing control device of copying machine - Google Patents

Abstract

PURPOSE:To execute copying to a roughly exact position by providing a means for deciding whether it is correct or not in accordance with whether an intrinsic delay time which is read is within a prescribed range or not, and a means for setting a prescribed time which has been stored in advance, as a control use delay time. CONSTITUTION:When a power source of a copying machine is on, an intrinsic delay time is inputted to a register A from a RAM, whether this value is '00H' or not, and in case of '00H', it is decided that a data transfer has not been executed, a prescribed time which has been set in advance is inputted to the register A, this value is converted to a hexadecimal number and the operation is returned to a main routine. In case the value of A is not '00H', only a numerical value of the first digit is inputted to a register B, and whether this number is a number of '0'-9 or not is decided. When it is normal, a transfer value from the RAM is converted to a hexadecimal number an used as a delay time control value. Even in case when a transfer of the intrinsic delay time is not correct when the power source is on, or in case when the intrinsic delay time data which has been stored is incorrect, an average delay time by its copying machine is set automatically, and copying is executed. In such a way, an influence to a copying work, caused by an error can be suppressed to the minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device that controls the transfer position of a toner image formed on a photoreceptor onto a sheet of paper based on the paper feeding timing.

<Prior art and its drawbacks> FIG. 3 shows a schematic structure of a general copying machine.

A photoreceptor drum 1 is installed approximately at the center inside the copying machine body, and around this there are chargers 2 for copying processes.
Developing device 3. Transfer charger4. Cleaner 5. A static elimination charger 6 and a static elimination lamp 7 are provided. A glass plate document table 8 on which a document is placed is installed on the top surface of the copying machine body, and an optical system 9 is installed below the document table 8 to transmit reflected light from the document to the photosensitive drum 1. . The reflected light of the image is reflected from the charger 2. Light enters between the developing devices 3.

A paper cassette 1-10 is inserted into the lower right of the copying machine body, and a paper feed roller 1 is inserted above the tip of the paper cassette 10.
1 is installed. A paper transport path is provided at the bottom of the main body of the copying machine, and paper is fed into this paper transport path from the tip of the paper cassette. This paper conveyance path includes PS rollers 12. It consists of a paper guide 14, a wL transport belt 15, etc., and a fixing device 16 is installed on the left side of the transport belt 15. The PS roller 12 temporarily stops the leading edge of the paper fed from the paper cassette 10. On the left side of the fixing device 16, there is a paper output tray 1 for storing the paper ejected from the fixing device 16.
A discharge roller 17 for discharging the paper to the paper 8 is installed. A paper sensor 13 is installed in front of the PS roller 12 on the paper transport path to detect when the paper has been transported to this position.

In the copying machine configured as described above, when the copying process is started, scanning of the document table 8 and rotation of the photosensitive drum 1 are started, and at the same time, one of the uppermost sheets of paper stored in the paper cassette 10 is fed. It is sent onto the conveyance path by the rollers 11 and conveyed to the position of the PS roller 12 (point P).

By scanning the original by the optical system 9 and rotating the photoreceptor drum 1, an image of the original on the original platen 8 is exposed on the surface of the photoreceptor drum 1 at a point Q. Immediately before the photoreceptor moving to the position of point Q, it is uniformly charged by the charger 2, and the electric charge is removed in accordance with the amount of exposure to form an electrostatic latent image. As the photoreceptor drum (3) rotates, this electrostatic latent image is developed into a toner image by the developing device 3. This toner image is transferred to the transfer charger 4.
The image is transferred to the copy paper by corona discharge of opposite polarity from the transfer charger at a position '11 (point R) opposite to the image.

Here, in order to copy the position accurately, it is necessary to feed the leading edge of the original image and the leading edge of the paper to point R at the same time. However, if the paper fed from the paper cassette 10 onto the transport path is If paper is directly fed to point R without stopping once, the toner image will reach point R after a considerable amount of time has passed after the paper reaches point R. Therefore, an image is transferred to the paper with a very late delay in the copying direction. The start of rotation (sheet feeding) of the PS roller 12 must be delayed until exposure has progressed to some extent.

In order to correct this misalignment, in a typical copying machine, the paper is kept waiting at the position of the PS roller 12 until the copying process has progressed to a point where the paper can be started, so that the leading edge of the copied image is aligned with the leading edge of the paper. A method is adopted in which paper feeding is started when the paper has moved to a position where matching can be achieved.

The time during which the paper is kept waiting at point P as described above is called the delay time. Although there is a rough guideline value for this delay time depending on the model of the copying machine, the optimum value varies depending on the model due to variations in the operation of the PS roller 12, etc. The value is stored in the control unit. The optimum value is called the inherent delay time of the copying machine.

In order to perform the above-mentioned sheet feeding timing control, the copying machine is equipped with a control section as shown in FIG. This control unit is the CPU
20 and a ROM 21 connected to the CPU 20 and storing programs and the like. The CPU 20 includes a RAM 22 for storing specific delay time, mode setting data, etc. A paper sensor 13 is connected. Said R.A.
The M22 is backed up by a battery 23 so that its memory is not lost even when the power is turned off. Furthermore, a photo sensor 2 is connected to the interrupt terminal INT of the CPU 20.
4 is connected. This photosensor 24 is connected to the rotating plate 2
Every time the slit 5 is detected, it outputs “H” and the CPU2
0 to perform the interrupt routine. This rotating plate 25 has slits at equal intervals and is configured to rotate in synchronization with the rotation of the photosensitive drum 1.

The interval between the slits is determined by the photo sensor 24 passage period T when the photoreceptor drum 1 is rotating at a constant speed, and the pulse period T is determined by the process speed (the speed at which the surface of the photoreceptor drum 1 is exposed), for example. If the speed is 100 mm/s and the resolution of tip adjustment is 0.5 fins, then T = 0.5/100 = 5 subs.

Therefore, the inherent delay time stored in the RAM 22 is not stored in seconds, but after the permission signal is input to the CPU 20 (when the paper is conveyed to point P and the paper sensor 13
The number of pulses from when the PS roller 12 is turned on until the PS roller 12 is turned on is stored. For example, after inputting the permission signal, 250
The inherent delay time that turns on the ps crawler 2 in ms is stored as the number of pulses "50". Further, this data is stored as 1-byte data in which the 10th digit of a decimal number is stored in the upper 4 bits and the 1st digit is stored in the lower 4 bits. Therefore, the memory contents are 100 ways from OO to 99,
When converted to time, the inherent delay time is stored in 0.005 second increments of Os~0.4955.

FIG. 2 shows an interrupt routine for controlling the feeding timing of the leading edge of paper during the copying process in the copying machine. This operation is performed every time the photosensor 24 outputs "■(" to the interrupt terminal INT of the CPU 20. When the copying process is started and the photosensitive drum 1 starts rotating, the rotating plate 25 also rotates in synchronization with the rotation. The slit begins to rotate and begins to cross the photosensor 24.When the photosensor 24 detects the slit and outputs "Fr", C
The PU 20 jumps to step n10 (hereinafter, step ni is simply referred to as ni). In n10, paper is point P
It is determined whether or not the sheet sensor 13 is turned on (permission signal turned on).

If it is not turned on, it is assumed that the delay time has not yet entered, and a control delay time C (inherent delay time) is set in the subtraction count register D, and the process returns to the main routine.

If the paper sensor 13 is on, the paper moves to the PS roller 1.
2 position (point P) and is in a standby state (delay time) to synchronize with the image on the photoreceptor door chimney, so the delay time is measured by subtracting 1 from the subtraction counter D (nil) . If the subtraction counter D becomes 0'' as a result of the nil operation, turn on the PS roller 12 and start feeding the paper to the transfer position (14). If it does not become 0, it is still within the delay time. Therefore, the program returns to the main routine.

In this way, the paper feeding timing is controlled to be optimal, but if the inherent delay time changes to an incorrect value due to static electricity, etc. (so-called memory corruption), or changes to a different value during transfer to the CPU. If the image changes, the image on the copied paper will be completely shifted. That is, if a value smaller than the specific delay time is transferred to the CPU, the paper is fed too quickly and the image transfer position will be delayed, whereas a value larger than the specific delay time is transferred to the CPU. In this case, there is a disadvantage that the paper feed is too slow and the image transfer position is advanced. Conventional copying machines cannot cope with such data abnormalities, and once a data abnormality occurs, no further copying work can be performed.

<Object of the Invention> In view of the above-mentioned drawbacks, it is an object of the present invention to provide a paper feed timing control device for a copying machine that can copy at a substantially accurate position even if an incorrect inherent delay time is transferred to the CPU.

<Structure and Effects of the Invention> The present invention sets the paper feeding timing for aligning the leading edge of the original image formed on the photoreceptor with the leading edge of the copy paper in the transfer unit from the time when scanning of the original is started to the time when the copying paper is transferred. A copying machine that is controlled by a delay time until it starts feeding paper to a copying machine,
has a battery-backed RAM that stores a unique delay time that is the optimal delay time unique to the copier;
In a copying machine that reads the inherent delay time at the start of operation and sets it as a control delay time, means for determining whether or not the read inherent delay time is accurate based on whether or not it is within a predetermined range; The present invention is characterized by comprising means for setting a pre-stored fixed time as the control delay time when it is determined that the inherent delay time is inaccurate.

By configuring as described above, according to the present invention, even when the inherent delay time has caused memory corruption or data transfer has not been performed correctly, the delay can be delayed by a preset value (a certain amount of time). Time is controlled. A suitable value that does not cause abnormality in operation for this certain period of time,
For example, by setting an average delay time in a copying machine of the same model as the copying machine, the copying position will not be extremely shifted even when the data is good, and copies will be made in approximately the correct position. In this way, even in the event of data abnormality, the next best response is taken, resulting in the advantage of improving the reliability of the copying machine.

<Embodiment> FIG. 1 is a flowchart showing the operation of a control section of a copying machine to which a paper feed timing control device according to an embodiment of the present invention is applied. The configuration of each part of the copying machine is similar to that shown in FIGS. 3 and 4. Step n when turning on the copier
l (hereinafter, step ni is simply referred to as ni).
22, input the inherent delay time into register A. Even if you judge whether this value is “00H” or not using n2, it will be “OOH”.
If so, data transfer was not performed (it was defective)
Judging by this, proceed to n3 for a preset period of time (
50H) is input to register A, this value is converted to a hexadecimal value (n8), and the process returns to the main routine. In this embodiment, (50H) is a value corresponding to the average delay time in copying machines of the same type.

If the value of register A is not “OOH” at n2, n
Proceed to step 4, enter only the first digit number (lower 4 bits 1-) into register B, and check whether this number is a number from 0 to 9.05
Judge by. As mentioned above, the specific delay time is stored in decimal numbers, so the number of each digit must be between 0 and 9. However, if the transfer is not successful or if the memory is garbled, (A, B, C, D, E, or F in hexadecimal number of 4 bits). When n5 determines that the value is like this, it is determined that the data is abnormal and the process goes to n3. At n6, just the 10th digit (higher 4 bits) is input to register B, similar to the operation at n4 above, and at n7 it is input. It is determined whether the value is a numerical value between 0 and 9. If this digit is also normal, direct n
Proceed to 8. Value transferred from RAM 22 (inherent delay time)
is converted to hexadecimal and used as a value for delay time control.

If the value in the 10th digit is a number other than the decimal system, it is determined that the data is abnormal and the process proceeds to n3, where a certain time is input, and the process proceeds to n8.

Note that among the above operations, n2. n5. In the present invention, n7 corresponds to means for determining whether or not the inherent delay time is accurate, and n3 corresponds to means for setting a constant time as a control delay time.

As a result of the above operations, according to this embodiment, if the transfer of the unique delay time is not performed correctly when the copying machine is powered on, or the unique delay time data stored in the RAM 22 becomes inaccurate. Even if the copying machine of that model has an average delay time, the paper is fed and the copying process is performed based on that value, so there is no chance of copying due to a copying machine error. This can contribute to improving the reliability of the copying machine.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the operation of a control section when the power is turned on in a copying machine using a paper feed timing control device according to an embodiment of the present invention. FIG. 2 is a diagram showing an interrupt routine for paper feed timing control during the copying process in a general copying machine, and FIGS. 3 and 4 are a schematic structural diagram and a schematic block diagram of the general copying machine.

Claims (2)

[Claims] (1) The paper feed timing is such that the leading edge of the original image formed on the photoreceptor and the leading edge of the copy paper match in the transfer unit, and the paper feeding to the transfer unit starts after scanning of the original starts. The copying machine is controlled by a delay time until the copying machine starts, and has a battery-backed RAM that stores a unique delay time that is an optimal delay time unique to the copying machine, and reads the unique delay time at the start of operation. In a copying machine that sets a delay time for control in a copying machine, there is a means for determining whether the read inherent delay time is accurate based on whether or not it is within a predetermined range, and a means for determining whether the read inherent delay time is inaccurate or not. A paper feed timing control device for a copying machine, comprising: means for setting a pre-stored fixed time as the control delay time when it is determined that there is a delay time. (2) The paper feed timing control device for a copying machine according to claim 1, wherein the certain time is an average delay time for copying machines of the same type.