JPH01194753A - Image formation device - Google Patents

Abstract

PURPOSE:To obtain an image effective signal in a direction of accurate sub scan at a various kinds of variable magnification by generating the image effective signal in a direction of sub scan based on the number of driving pulses applied on a stepping motor which drives a read optical system. CONSTITUTION:A first microcomputer 1 performs the general control of the whole of a device, and also, performs process sequence control. To the first microcomputer 1, a second microcomputer 2 which controls the read optical system of an image is coupled. The second microcomputer 2 drives the stepping motor 4 at speed corresponding to the variable magnification, and performs the sub scan. At this time, the second microcomputer 2 counts the number of driving pulses applied on the stepping motor 4, and generates the image effective signal inverted at a timing when the number of driving pulses arrives at a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an image forming apparatus such as a copying machine or a printer. and,
a second microcomputer coupled to the first microcomputer to control an image reading optical system; the second microcomputer drives the reading optical system using a stepping motor; The present invention relates to an image forming apparatus that performs magnification change in the sub-scanning direction by changing the magnification through the .

(Prior Art) For example, an electrophotographic copying machine includes an image reading means for scanning an image on a document, a writing means for writing an image signal from the image reading means onto a photoreceptor drum, and a writing means for writing an image signal from the image reading means onto a photoreceptor drum. image forming means for forming an image from a static N latent image;
It is composed of many elements, such as a paper feeding means that supplies paper. Generally, each of these elements is controlled by a microcomputer.

By the way, a conventional electrophotographic copying machine of this type includes a first microcomputer that controls the entire device including a series of process sequence controls for forming an image from an electrostatic latent image, and a microcomputer that scans the document and reads the image. At least two microcomputers are provided, a second microcomputer controlling the reading optical system. In order to determine the effective image area in the sub-scanning direction, in other words, to eliminate the image signal obtained by reading the non-original area, the image signal for writing is supplied to the writing means through the gate. At the same time, this gate is opened and closed by the first microcomputer.

(Problems to be Solved by the Invention) In the conventional image forming apparatus configured as described above, when changing the magnification, the magnification in the sub-scanning direction is changed by changing the scanning speed of the reading optical system.

However, when the scanning speed of the reading optical system is changed, the distance from the home position of the reading section of the reading optical system to the leading edge of the document is constant, so the reading section of the reading optical system moves from the home position to the leading edge of the document. The time varies depending on the magnification. Therefore, the scanning start time of the image effective area in the sub-scanning direction is calculated, and then the elapsed time after the start of movement of the reading section of the reading optical system is counted by a timer, and the image effective f
It is necessary to turn on the image valid signal in the sub-scanning direction when the time period 9f- between scans in the f1I area is reached. However, in order to carry out such counting, the resolution of the timer included in the first microcomputer is coarse, so it is difficult to accurately determine the scanning start time of the effective image area in the sub-scanning direction. On the other hand, if a high-resolution timer is separately prepared, it becomes possible to accurately count the elapsed time and accurately determine the scanning start time of the image effective area, but the circuit configuration becomes complicated.

Another method is to calculate the scanning start time of the effective image area for all magnifications in advance and have this table in the program, but since there are many types of magnification, in this case the program capacity becomes large.

The present invention was made in view of these problems, and therefore,
The purpose is to realize an image forming apparatus with a simple configuration that can obtain accurate image effective signals in the sub-scanning direction even at various magnifications.

(Means for Solving the Problems) The present invention to solve the above problems includes a first microcomputer that performs overall control of the entire apparatus and process sequence control; and a second microcomputer that controls a reading optical system, the reading optical system is driven using a stepping motor, and the driving speed is changed via the second microcomputer to change magnification in the sub-scanning direction. The image forming apparatus is characterized in that the second microcomputer is configured to generate an image valid signal in the sub-scanning direction based on the number of drive pulses applied to the stepping motor.

(Function) The first microcomputer centrally controls the entire device. On the other hand, the second microcomputer drives the stepping motor at a speed corresponding to the magnification ratio to perform sub-scanning. At this time, the second microcomputer counts the number of drive pulses applied to the stepping motor, and generates an image valid signal that is inverted at the timing when the number of drive pulses reaches a predetermined value.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the main parts of the electrical configuration of an embodiment of the present invention. In the figure, 1 is a first microcomputer that performs overall control of the entire device as well as process sequence control, and 2 is a first microcomputer 1.
3 is an optical system drive circuit controlled by the second microcomputer 2; 4 is an optical system drive circuit 3;
This is a stepping motor for the reading optical system that is rotationally driven by. A home position sensor 5 that outputs a signal indicating that the reading section of the reading optical system is at the home position is connected to the second microcomputer.

Reference numeral 6 denotes an image processing circuit that performs color separation, scaling in the main scanning direction, etc., and is composed of a microcomputer. Here 2
Cyan data and red data (6 bits), which are image data read by two image sensors (COD line sensors), are input, separated into red, blue, and black, and the colors specified by the second microcomputer 2 are input. image data (3
An example of outputting bits) is shown. 7 is a video interface that receives the output image data of the image processing circuit 6 via the first gate G1;
The signal is output to the writing means via the gate G2. Furthermore, the first
The gate G1 is controlled by the image valid signal V-VALrD2 in the sub-scanning direction output from the second microcomputer 2, and the second gate G2 is controlled by the image valid signal V-VALrD2 in the sub-scanning direction output from the first microcomputer 1. Signal V-
Controlled by VALTD1. Image valid signal V-VALI output from the second microcomputer 2
D2 is for inverting when the number of drive pulses (number of steps) to the stepping motor 4 reaches a predetermined value and validating only the image signal obtained by reading the document area.
The image valid signal V-VALID1 output from the first microcomputer 1 is for gating the image signal so that the writing area fits within the size of the transfer paper.

FIG. 2 is a block diagram of the serial interface portion within the first and second microcomputers 1.2 and the image processing circuit 6. As shown in FIG. The serial data sent from the other party's microcomputer is sent to the receiving terminal RxD and receiver RE.
is applied to the serial register SR1 via the serial register SR1. The serial data stored here is converted into parallel data and transferred to the internal bus BS via the receive buffer 7 register RXB. The data to be transferred to the other party's microcomputer is stored in the serial register SR2 via the transmission buffer 7 register TxB, where the parallel data is converted to serial data and output to the transmission terminal T' x D by the driver DR. . RCTL is a reception control circuit, and TCTL is a transmission control circuit, both of which input a clock and control the serial registers SR1 and SR2. SMR is connected to internal bus BS by a serial mode register.

Here, the data required to be transferred from the first microcomputer 1 that centrally controls the entire device to the second microcomputer 2 includes the scan code (color code), threshold level, main scanning and sub-scanning directions. variable magnification data,
There is scan stop data, etc.

Transfer of these data from the first microcomputer 1 to the second microcomputer 2 is performed by an asynchronous mode serial communication method via serial communication dedicated terminals TXD and RXD. Data transfer from the second microcomputer 2 to the first microcomputer 1 and data transfer between the second microcomputer 2 and the image processing circuit 6 are also performed using a similar serial communication method. The second microcomputer 2 outputs a signal indicating that the reading section of the reading optical system is at the home position to the first microcomputer 1 based on the output of the home position sensor 5, and The computer 1 receives this signal and transfers the data necessary for scanning to the second microcomputer 2. This data transfer is performed during a period when the stepping motor 4 is stopped, when the operating rate of the second microcomputer 2 is low.

FIG. 3 is a structural sectional view showing the main parts of the mechanical structure of an embodiment of the invention, in which a color image forming apparatus is shown. It should be noted that parts corresponding to those in FIG. In the figure, reference numeral 10 denotes a reading optical system unit, and a movable mirror unit 12 that moves on a slide rail 11.
13. A lens reading unit 15 that forms a light image of the original g$14 through these movable mirror units 12 and 13.
, the original 14 introduced through the lens reading unit 15
The image sensor 16 reads the optical image of the image sensor 12, and the above-mentioned stepping motor 4 moves the movable mirror unit 12, 13 at a predetermined speed via the wire 17.

20 is a writing unit that writes an image onto the photosensitive drum. In the filling unit 20, 21 is a motor, 22
is a polygon mirror rotated by a motor 21, which rotates and scans the laser beam from the semiconductor laser 22a;
On the surface of the photosensitive drum 23, data obtained by subjecting the image data read by the image sensor 16 to predetermined signal processing in the image@processing circuit 6 is written. On the surface of the photoreceptor drum 23, a latent image corresponding to the first color (for example, red) is first formed by main scanning by the laser beam and sub-scanning by the rotation of the photoreceptor drum 23.

This latent image is developed by the first color developer 24, and a first color toner image is formed on the drum surface. While holding the toner image thus obtained on the drum surface, the photosensitive drum 23 passes under the cleaning device 27 that has been separated from the surface thereof, and enters the next copy cycle. That is, the photosensitive drum 23 is charged again by the charger 28, and a latent image corresponding to the second color (for example, blue) is formed in the same way, and is developed by the second color developer 25, and the drum surface is Toner m of the second color is formed. Similarly,
A toner image corresponding to a third color (for example, black) is formed by the third color developer 26. The superimposed image of the three color toner images thus formed is transferred to the transfer device 29.
The image is transferred onto a transfer sheet sent from the paper feed cassette 30, conveyed to the fixing device 31, and fixed there to obtain a color hard copy. The cleaning lf & 27 comes into contact with the photosensitive drum 23 after the transfer, and
Cleaning is done.

Next, the overall operation will be explained.

After the first microcomputer 1 is powered on,
Perform initialization processing and warm-up processing.

Thereafter, when the copy switch is turned on, the scanned data is transferred to the second microcomputer 2. In the case of three-color copying, the color image forming apparatus shown in Fig. 3 performs three optical scans to overlap the images of each color. It is necessary to transfer the data from the first microcomputer 1 to the second microcomputer 2. Also, in the case of continuous monochrome copying, the equivalent level etc. may change, so before starting optical scanning, the first microcomputer 1 to the second microcomputer 1
It is necessary to transfer data to the microcomputer 2.

For example, in the case of three-color copying, this data transfer is performed at the timing shown in FIG. That is, the first microcomputer 1 reads the scanning data from the memory, and
The data of the second optical scan is transferred to the second microcomputer 2 (serial communication 1). Then, when the timing to start optical scanning arrives, the first microcomputer 1 receives a signal (READYR) from the second microcomputer 2 indicating that the exposure, light amount monitor, etc. are normal.
To confirm this, serial communication 2) causes an optical scanning start (scan start) signal (S-8TART) to be input to the second microcomputer 2 by interruption. Second
The microcomputer 2 receives this interruption and starts optical scanning. When the first optical scan is completed and the reading optical system unit 10 returns to the home position and the stepping motor 4 stops, the second microcomputer 2
A signal (1) indicating that the reading section (movable mirror unit 12) of the reading optical system is at the home position.

MER) is output to the first microcomputer 1.

When the first microcomputer receives this home position signal, it reads the next optical scanning data from the memory and transfers the next data to the second microcomputer 2. Then, when the timing to start optical scanning arrives, the first microcomputer 1 checks the signal from the second microcomputer 2 indicating that the exposure, light amount monitor, etc. are normal, and transmits the signal to start optical scanning. The input is made to the second microcomputer 2 by interruption. The second microcomputer 2 receives this interruption and starts optical scanning again. Thereafter, a third optical scan is also performed in the same manner.

The second microcomputer 2 drives the reading optical system unit 10 in each optical scan by driving the stepping motor 4 after lighting the halogen lamp 12a in the movable mirror unit 12. Image valid signal V-VAL[D2 in the sub-scanning direction output from the second microcomputer 2 during driving
．． The image valid signal V-VALIDI in the sub-scanning direction output from the first microcomputer 1 is, for example, as shown in FIG. 5 when the image is enlarged to the same size and when it is reduced, and as shown in FIG. 6 when it is enlarged.

The number of drive pulses sent to the stepping motor 4 until the reading section (movable mirror unit 12) of the reading optical system reaches the leading edge of the document from the home position (this value is constant regardless of the magnification of the variable magnification or the length of the transfer paper) ) is 81, and the number of driving pulses corresponding to the margin (width) at the leading edge of the image on the document is ΔS.
1. The number of drive pulses sent to the stepping motor 4 until the reading section of the reading optical system reaches the rear edge of the document from the home position is 82, the number of drive pulses corresponding to the margin (width) of the rear edge of the image on the document. is ΔS2, and the magnification during enlargement is M, the image effective signal in the sub-scanning direction output from the second microcomputer 2 - ALID2 is not shown in FIG. As shown, the number of driving pulses is 8.
It turns on when the number of driving pulses reaches 1+ΔS1, and turns off when the number of drive pulses reaches 82−ΔS2. On the other hand, when enlarging, the number of driving pulses is 81+Δ, as shown in Figure 6.
When S1 is reached, it turns on and the number of drive pulses is 82.
It turns off when /M+81-ΔS2 is reached. or,
The image valid signal V-VALID1 in the sub-scanning direction output from the first microcomputer 1 is created using a timer in the first microcomputer 1, and is
During both reduction and enlargement, as shown in Figures 5 and 6, the switch turns on when it is time to record on the leading edge of the transfer paper, and turns off when it comes time to record on the trailing edge of the transfer paper. . Therefore, the image signal ultimately passes through the gates G1 and G2 only during the high level period shown in FIGS. 5 and 6. Note that FIGS. 5 and 6 above show the case where the size of the original and the transfer paper are the same.

Since the rotation angle of the stepping motor 4 is determined in one pulse, the amount of movement of the reading section of the reading optical system can be determined from the number of drive pulses regardless of the scanning speed. In the above configuration, by utilizing this fact, the second microcomputer 2 outputs an accurate image valid signal V-VALI in the sub-scanning direction.
It is generating D2.

(Effects of the Invention) As described in detail above, in the present invention, the second microcomputer generates an image valid signal in the sub-scanning direction based on the number of driving pulses to the stepping motor. According to the invention, an image forming apparatus that can obtain accurate image effective signals in the sub-scanning direction even at various magnification ratios can be realized with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main part of the electrical configuration of an embodiment of the present invention, and FIG. 2 is a block diagram of the serial interface part in the second microcomputer and image processing circuit in FIG. 1. FIG. 3 is a configuration cross-sectional view showing the main parts of the mechanical configuration of the embodiment of the invention, FIG. 4 is a timing chart showing an example of communication timing, and FIGS. 5 and 6 are the first and second microcomputers. FIG. 3 is a diagram showing an example of an image effective signal in the sub-scanning direction output from the sub-scanning direction. 1... First microcomputer 2... Second microcomputer 3... Optical system drive circuit 4... Stepping motor 6... Image & processing circuit G1. G2...Gate patent applicant Konica Co., Ltd. Patent attorney Ii
Shimafuji Jigai 1 person

Claims (1)

[Claims] A first microcomputer that performs overall control of the entire apparatus and process sequence control; and a second microcomputer that is coupled to the first microcomputer and controls an image reading optical system; In an image forming apparatus that drives a system using a stepping motor and changes the magnification in the sub-scanning direction by changing the driving speed via the second microcomputer, the image forming apparatus may be configured to perform zooming in the sub-scanning direction based on the number of driving pulses to the stepping motor. An image forming apparatus characterized in that the second microcomputer is configured to generate both image effective signals in the sub-scanning direction.