JPS6035872A - Picture formation device - Google Patents

Abstract

PURPOSE:To reduce the size of the titled device and to speed up copying by dividing photodetecting elements to be driven and LEDs into N blocks respectively and turning on the LEDs in parallel. CONSTITUTION:In order to copy pictures for one row, the photodetecting elements to be driven and the LEDs 30 are equally divided into N blocks respectively. In each block, data from the photodetecting elements are applied to data lines Data 1-Data N and N shift registers 33-1-33-n, N latches 31-1-31-n and N drivers 32-1-32-n and N drivers 32-1-32-n are arranged to turn on the LEDs in parllel. Therefore, one row can be copied apparently by a clock signal corresponding to N times a clock line OCK of the shift register.

Description

[Detailed Description of the Invention] [Technical Field] This invention reads a document image as pixels (dots) using an image sensor, and writes the pixels according to the read image information using a dot line printer head such as an optical writing head. The present invention relates to an image forming apparatus.

[Prior art]

FIG. 1 shows a schematic configuration diagram of an example of a conventional digital copying machine.

A document on a document table 2 is illuminated by an illuminator 1, and an image of the document is formed on an image sensor 6 by a lens 5 via mirrors 3 and 4. The mirror 3 scans the document at a speed V in synchronization with the rotational speed of the photosensitive drum 7. At this time, since the mirror 4 moves at 1/2 the speed of the mirror 3, the optical path length from the document surface to the lens 5 is always equal.

In this way, one part of the original is sequentially displayed on the image sensor 6.
Images for each row are formed, and image data for each row is created.

On the other hand, a high-voltage charger 8, a developer 9, a transfer charger 10, a cleaner 11, etc. are arranged around the photosensitive drum 7.
An LED array head 12 serving as an image forming means is installed on the drum rotation direction (arrow) side of the high voltage charger 8 so that the LED array is perpendicular to the drum rotation direction.
As a result, the individual light emitting surfaces arranged in a row are imaged on the surface of the photosensitive drum 7.

According to one row of image data created by the image sensor 6, each LED of the T and ED array heads 12
By turning on/off the light, a spot of light is formed on the surface of the photosensitive drum 7, which is uniformly charged by the high-voltage charging a8, and an electrostatic latent image is formed, and this is transferred to the developing device 9. The image is transferred to paper by passing the paper between the transfer charger 10 and the photosensitive drum 7, and the image is fixed on the paper by the fixing device 14 to obtain a copy of the original.

In electrostatic photography, depending on the combination of toner polarity, charging voltage polarity, etc., it is possible to make the illuminated portion of the LED black or white. In addition, the image sensor 6 has light-receiving elements equal to the number of pixels in one row arranged in one row.
It consists of a light receiving section that outputs electrical signals according to the amount of received light, and a signal shift section that sequentially outputs electrical signals from the respective light receiving elements as serial data. Generally, COD image sensor or MO
There are 8-type image sensors, etc., and the former uses the shift function of the COD to sequentially shift out according to the amount of light received, and converts the shifted out charge amount into voltage and converts it into image data. The latter one sequentially selects the output of each light receiving element using a MOS switch, converts the signal into a voltage, and uses it as image data.

FIG. 2 shows the electrical connection relationship between the image sensor 6 and the optical writing LED array head 12. The image sensor 6 in this example is composed of a photodiode or the like, and has one light receiving element 21-1 to 21-m that outputs an electric signal according to the amount of light received.
A signal from the parallel hetometer is input in a column (one-dimensional) to the shift register 22 in 7 barrels, and an output corresponding to the amount of received light is sequentially obtained from the serial output SO, which is converted to a voltage level by the amplifier 23. . On the other hand, LED array head 1
2, LEDs 24-1 to 24-m are arranged in one row, their cathodes are commonly grounded, and each anode is outputted to each output of a driver 25, and each input of this driver is connected to a latch. Each input of this latch 26 is connected to each stage of the parallel output of a shift register 27, respectively. Image sensor 6
The output is input to the binarization circuit 28, which outputs binary data indicating whether to turn on or turn off the corresponding LED depending on various conditions such as the magnitude relationship of the amount of received light, the value of the data of the preceding and following pixels, and the position of the target pixel. Ru. This binary output is the LED array head 12
is input to the shift input terminal S1 of the shift register 2T. At this time, the timing of inputting data from the light receiving element array 21 to the shift register 22 in parallel, the timing of shifting out data from the shift register 22, L
At the data input timing to the shift register 27 of the ED array head 12, when the data for one column is complete, the parallel data in the shift register 27 is latched all at once by the latch 26, and each LED 24-1 to 24-m is turned on. /The timing to turn off the light, etc. is generated by the timing generator 29.

Therefore, depending on the strength of the light received by the light receiving element 21-1, turning on/off the LFI: D74-1 is determined, and similarly,
The light receiving elements 21-2 to 21-m correspond to the LEDs 24-24- to 24-m, respectively, and depending on the amount of light received, the LED
Turning on/off of D is determined. Note that icK and OCR are clocks, and lsc, o'r, and c are shift registers 2, respectively.
2.27 gate timing signal.

When the image of the original is formed on the image sensor 6 one row at a time in this way, each I and FD of the LED array head 12 are turned on/off depending on the darkness of the film, and the photosensitive drum γ
An electrostatic latent image is formed on the original, making it possible to copy the original.

If you actually create this system, LED24-i~
A minimum point having a size of 24-m is formed, and the copied image is represented as a collection of these points. Therefore, a high quality copy image cannot be expected unless the LEDs 24-1 to 24-m are made as small as possible. On the other hand, since writing is performed between each row, the LEDs 24-1 to 24-m need to be arranged by the width of the paper in the direction perpendicular to the paper feed.

Generally, in order to obtain a high-quality image, it is desired that at least 16 pixels (dots) be formed per IN. 16 = 4,752 LEs
It is necessary to arrange 16 pieces of D per 1 u. Therefore, the driver 25 and latch 26 also require an array of 4,752 independent drivers and latches, and the shift register 27 must be a 4,752-bit long shift register. When fabricated outside the head 12, the anode input terminal of each LED must be drawn out from the T and E D head 12, and the
In practical terms, it is difficult to pull around far more than 00 pieces of paper. Therefore, the solution is to configure shift registers, latches, drivers, etc. with ICs and mount them on the LED head 12.

However, even if it can be implemented by IC, 4
, 752 bits, a long shift register cannot be operated at high speed in order to operate accurately. For example, A
When trying to copy about 40 sheets per minute with 4-size horizontal feed, the paper movement speed needs to be about 270 s+a/s. In this case, 270 x 16 = 4,3 per second
It will generate 20 dot rows, at least 4,320 x 4,752 bits 2 x 107 bits (20
Mbps) data must be transferred between shift registers. For example, a process such as I'L'72', I
In the case of configuring C, the clock rate of the shift register is about IR4bps. Therefore, as long as the configuration of the conventional example is used, it is possible to copy only a few sheets per minute, and there is a drawback that the advantages of high-speed copying by electrostatic photography cannot be utilized.

In addition, as the image sensor 6, a CCD that applies CCD
When using an image sensor, it is not possible to make a very large one, so the image of the original is reduced by an optical system and then transferred to a CCD.
Since it is necessary to form an image on the light receiving element array of the image sensor and read one row of images, the optical system becomes large. If a photodetector array with the same width as the document width can be formed, the SE/L
It becomes possible to form an image of the original on the light receiving element array at the same magnification using a /7 lens array, etc., and the optical system can be downsized. However, it is not possible to cut off both sides of the light receiving element array section of a CCT (CCT) line image sensor, leaving the effective portion, and arrange them in a single row. A line image sensor has been proposed in which sensors are arranged in a staggered pattern and can read one row of images at the same magnification, although there is a difference in the time at which the same dot line on the document is read when reading the document.

In this case, since there is a difference in the position of the read document between the seven adjacent COD line image scanners by the amount of multiple dot lines, the document cannot be reproduced using a conventional dot line printer head having one row of dot generating elements. In order to do this, a memory is required to store the pixel data for the plurality of dot lines. In this case, the control circuit of the dot line printer head becomes complicated and expensive.

〔the purpose〕

This invention has been made in view of the above-mentioned conventional considerations, and it divides a column image of a document into a plurality of blocks, and stores pixel data for a plurality of 8-inch blocks. An object of the present invention is to provide an image forming apparatus that is compact and capable of forming images at high speed without using a memory.

〔Example〕

The present invention will be explained below based on the drawings. Third figure,
An example of an LED array used in the present invention is shown. 30 is
It consists of LEDs arranged in a row, and the cathodes are grounded. The anode of each LED is connected to each output of N drivers 31-1 to 31-■, and the inputs of N drivers 31-1 to 31-n are connected to N latches 32-1.
~32-n, and N latches 32-1
-32-n each input has N shift registers 33-1 to 32-n.
Each output of 33-n is connected. That is, when one column is expressed by M pixels, the number of LEDs is M, and each of the shift registers 33-1 to 33-n is an M/N bit shift register. By doing this, data for one column is transferred to the shift register 33-1 by loading data for M/N pulses onto the data lines 1) atal to Data aN in synchronization with the signal of the clock line C1ock. 1 to 33-n. At this timing, a pulse is applied to the strobe line, data for this one column is latched, and each LED of the LED 30 is turned on/off via the driver 31. Then, the LEDs are turned on and off, and data for the next column is applied to the data lines DataL to DataN for M/N pulses in the darkness forming one column of images, and the shift registers 33-1 to 33 -n, and thereafter the images are constructed in J rows one by one.

FIG. 4 shows an embodiment of the present invention, in which an image sensor 61 in which four CCD image sensors 41 are arranged in a staggered manner, and an L
It is a principle diagram of the drive of ED array head 12'.

The CCI) image sensor 41 has a light receiving element array 41a in which light receiving elements are arranged in a row, receives a shift gate signal φ8 from the clock generator 42, and transfers charges according to the degree of light reception in the light receiving element array 41a to the CCD channel. input in parallel. Thereafter, each pixel data obtained by the light receiving element array 41a is sequentially shifted and outputted to the transfer signal according to φ2 and the reset signal φi. The amplifier 43 converts the data output from the CCD image sensor 41 into a voltage level that can be determined by the binarization circuit 44.

Light receiving element array 4 of adjacent CCD image sensor 41
1a, when the effective part of the image reading is connected,
They are arranged so that they are overlapped so that pixel data for the document width can be obtained without omission, and the length is 1'R1, and the distance between the light receiving element arrays 41a of adjacent CCD image sensors 41 is tbb. It is.

On the other hand, the T, ED array head 121 has a light emitting section 45, which is a dot forming element for reproducing the image read by the CCD image sensor 41, in which a number of LEDs corresponding to the number of light receiving elements array 41a are linearly arranged. The sensor 61 is arranged in the same manner as the CCD image sensor 41. In this case as well, when the dots formed by the dot forming elements are connected in the width direction, they are arranged so that they are overlapped so that dots the width of the document can be formed without exception. 'wt, and the interval between adjacent light emitting portions 45 is 'W2.

At this time, if the image sensor 6' is of the same size,\1
R,,=,~1''='W2, and when the image sensor is of a type that forms and reads a reduced image on the image sensor 61 using an optical system, tRl/'R2-t
Set it to Wl/'W2. That is, the light receiving element array 4
1 and the light emitting element portion 45 are made similar.

The binarization circuit 44 determines whether it is a black level or a white level, and outputs 1.0 data.

The four LED driver circuits 46 are connected to the shift register 33.
-1 to 33-4, latches 32-1 to 32-4, and drivers 31-1 to 31-4 are connected to four sets of circuits,
The light emitting element portions 45 each having a width of 1/4 of one column of the document width are driven. The output of the binarization circuit 44 is connected to the terminal S1 of the LED drive circuit 46, and in synchronization with the clock signal Ock from the clock generator 42, the data is shifted into the shift register, and the 12- At the timing when one column of data is stored, the clock generator 42 outputs a latch signal OLG, one column of data corresponding to each pull at that time is latched, the light emitting element emits light, and dot formation is performed.

〔effect〕

As explained above, in this invention, the light receiving element to be driven and the LED are used to copy pixels for one column.
Means for equally dividing each into N blocks and serially outputting the data output from the light receiving element in each block, a circuit for binarizing the output data, and a shifter for inputting the binarized data and outputting it in parallel. By providing registers, latches, and drivers, and configuring the LEDs to light in parallel, it is possible to copy the upper column at a clock rate N times the clock rate of the shift register, achieving high-speed copying. The effect is that it can be realized.

Furthermore, one row of the width of the original is detected by an image sensor in which light receiving elements are arranged perpendicularly to the columns in blocks of one row.
Even if an image reading system is used that obtains pixel data for each row within a block with a time difference, by arranging dot forming elements in a similar shape to the array of light receiving elements, multiple dot lines between blocks of light receiving elements can be read. This makes it possible to eliminate the need for a memory circuit for storing image data, thereby preventing an increase in costs. In particular, when a same-size image sensor is used, the reading system can be made extremely small, which has the effect of making it possible to create a compact copying machine or the like.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an example of a conventional digital copying machine.
Figure 2 shows a conventional line image sensor and writing LED.
The electrical connection diagram of the array head, FIG.
FIG. 4, which is an electrical connection diagram of an example of an ED array head, is a principle diagram of the drive of the image sensor and write LED array head according to an embodiment of the present invention. 6-=6'! ......Line image sensor 12.12'...LED array head 15-21.41a...Light reception Element array 22.27.33...Shift register 24.3
0 ・・・・・・・・・・・・LED25.31 ・・
・・・・・・・・・Driver 29.42 ・・・・・・
......Timing generator 41...
・・・・・・・・・・・・Old・CCD image sensor 4
5・・・・・・・・・・・・・・・・・・・・Light emitting element part 46・・・・・・・・・・・・・・・・・・・
・LFD drive circuit 16-1

Claims (1)

[Claims] In an image forming apparatus that reads a document image with an image sensor and forms an image based on each pixel data read by the image sensor, a plurality of image forming apparatuses that form an image based on a plurality of image sensors and pixel data from the image sensor. An image forming apparatus comprising a means for forming an image, wherein the image sensor and the image forming means are arranged in similar shapes.