JP2001024864A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read data necessary for image formation in appropriate order without adding a memory by reading the image data while changing order of reading addresses of image data held by a data holding means in accordance with a rotation direction of a polygon motor for controlling an irradiated beam light. SOLUTION: A semiconductor laser control part for controlling laser scanning controls driving of a laser driver 402 in a laser beam printer and controls oscillation of a semiconductor laser 403. A timing controller 101 receives image data 1 to which specified processing is applied by an image processing part, is synchronized anew by a reference clock in the timing controller 101, then converts the data into a specified image data sequence (image data 2) and transmits them to the laser driver 402. The laser driver 402 converts the data into a driving signal of a semiconductor laser 403 in accordance with the image data sequence received from the timing controller 101.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a digital copying machine and a laser beam printer, and more particularly to an image forming apparatus for controlling reading of image data synchronized with laser scanning for forming image data. The present invention relates to a forming apparatus.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, if a plurality of types of polygon motors for scanning a laser can be used, it is an effective means for shortening the development period and reducing the apparatus cost. However, depending on the device, the rotation direction may be different due to the difference in the optical arrangement between the photosensitive drum and the polygon mirror.

In such a case, a process of inverting the order of image data to be output and outputting the image data is required. Further, when handling an image obtained by reading a document with a scanner, it is necessary to perform the same processing depending on the document scanning direction.

[0004]

As means for solving the above problems, means for adding a memory and inverting the image, or for inverting the image while reading the image in an image reading section are used.

[0005] However, in the case of the above solution, the cost is increased by adding a memory, and the throughput is reduced.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide an image forming apparatus for reading data necessary for image formation in an appropriate order without adding a memory.

That is, an image forming apparatus which forms a latent image on a photosensitive member by controlling the irradiation of a semiconductor laser in accordance with image data comprises a plurality of data holding means for storing image data in accordance with a write instruction signal; Image data reading means for reading the read image data from any of the plurality of data holding means in accordance with a reading instruction signal, wherein the image data reading means is provided with a rotating direction of a polygon motor for controlling a beam light to be irradiated. The image data is read by changing the order of the read addresses of the image data held in the data holding means in accordance with (1).

In the image forming apparatus, when the read signal has a high attribute, the image data reading means sets the memory address of the data holding means to an ascending address from address 0, and outputs a low attribute. In this case, the image data is read in the order of descending addresses from the memory address 4096.

The image forming apparatus further includes a timing controller for outputting the write instruction signal and the read instruction signal, and the timing controller alternately outputs respective instruction signals to output the instruction signals to the plurality of data holding units. Control for synchronizing writing and reading of image data.

[0010] In the image forming apparatus, the image data reading means may be operated in accordance with a setting of an image reading mode.
The order of addresses for reading image data from the data holding means is switched.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of a laser beam printer to which the present embodiment is applied will be described with reference to FIG.

FIG. 4 is a sectional view showing the internal structure of the laser beam printer (hereinafter abbreviated as LBP) of the embodiment. In the figure, reference numeral 440 denotes an LBP main body, which forms an image on recording paper as a recording medium based on a supplied character pattern or the like. 400 is a switch and LE for operation
An operation panel on which a D display and the like are arranged, and 401 is an LB
A printer control unit that controls the entire P440 and analyzes character pattern information and the like. The printer control unit 401 mainly converts character pattern information into a video signal and outputs the video signal to the laser driver 402.

The laser driver 402 is a semiconductor laser 40
And a laser beam 4 emitted from the semiconductor laser 403 in accordance with the input video signal.
04 is turned on / off. The laser light 404 is swung right and left by a rotating polygon mirror (polygon mirror) 405 to scan on the electrostatic drum 406. Thus, an electrostatic latent image of a character pattern is formed on the electrostatic drum 406. This latent image is developed by a developing unit 407 around the electrostatic drum 406 and then transferred to a recording sheet. This recording paper uses a cut sheet, and the cut sheet recording paper is LBP4.
The sheet is stored in a sheet cassette 408 mounted on the sheet 40, is taken into the apparatus by a sheet feeding roller 409 and conveying rollers 410 and 411, and is supplied to the electrostatic drum 406.

<Writing of Image Data> FIG. 1 is a diagram for explaining the configuration of a semiconductor laser control unit for controlling laser scanning according to this embodiment. The semiconductor laser controller controls the driving of the laser driver 402 in the LBP to control the oscillation of the semiconductor laser 403.

Reference numeral 101 denotes a timing controller which receives image data (image data 1) which has been subjected to predetermined processing by the image processing unit, resynchronizes with a reference clock in the timing controller 101, and then outputs a predetermined image data stream. The image data is converted into (image data 2) and sent to the laser driver 402. The laser driver 402 converts the drive signal into a drive signal for the semiconductor laser 403 according to the image data string received from the timing controller 101.

The operation of the timing controller 101 will be described with reference to FIG. The timing controller is 300 mm in the main scanning direction, 1200 dpi, about 16
kbit (4k × 4bit) two line memories (2
01, 202) and a parallel / serial conversion unit 203.

In inputting image data, 4-bit parallel data is input in synchronization with a write clock. The input image data is input to two line memories. The line memory includes a write clock serving as a write reference clock, a write enable permitting writing, a read enable serving as a read reference clock, a read enable permitting reading, a read mode controlling read address order, and a line memory at power-on. A reset signal that clears the data in is input.

These write, read enable, clock, and reset signals input to the line memory are supplied to the printer control unit 4 which controls the entire LBP 440.
01.

FIG. 3 is a timing chart showing input of image data and write enable and read enable signals. In this figure, it is assumed that each signal is valid at the Low level for both the write enable and the read enable.

When data is written in the line memory 1 (201) as shown in FIG.
02), writing is prohibited and reading is permitted.

When data writing to the line memory 2 is permitted, writing to the line memory 1 is prohibited and reading is permitted. For example, reading and writing are alternately performed between the two line memories. It is configured to be

The read image data is converted from 4-bit parallel data to 1-bit serial data by a parallel / serial conversion unit and output.

In the timing chart of FIG.
The read / write timing has been described based on the low level state of the read enable signal. However, in the timing chart of FIG.
Use levels.

In the read mode, the enable signal is Hig
At the h level, the read address starts from address 0 and is read out in order of the larger address value. In the case of the low level, the read address starts from address 4096 and is read out in the smaller address value.

In the case of FIG. 5, the read enable signal 1 is L
In this case, the data stored in the line memory is read from the last memory address, address 4096, in descending address order. The read enable signal 2 is at a high level. In this case, the read enable signal 2 is read from the first address 0 of the memory address in ascending address order.

If the read enable signal is switched between High and Low in accordance with the rotation direction of the polygon mirror 405, the image data can be read in an appropriate order.

<Reading of Image Data According to Image Formation> Next, reading of image data according to image formation will be described. The laser driver 402 controls the irradiation of the semiconductor laser 403 in accordance with the formation of the target image data. The laser light emitted by the polygon mirror 405 is swung in the left-right direction to form a latent image on the electrostatic drum 406. At this time, the timing controller 101
Monitors the rotation of the polygon mirror 405 and determines the address order for reading stored image data in accordance with the rotation direction.

(1) When the polygon motor is used in reverse rotation Since all the image data strings need to be inverted, the read modes 1 and 2 are fixed at the Low level, so that the power is reduced from the address 4096 of the line memory to the descending power. The data can be used in a form that matches the image to be formed by reading out the data with the smaller address value.

(2) When reading an image while moving the original using the RDF image reading mode, the input image data sequence is inverted from the normal image and becomes a mirror image. The read mode may be switched according to the color document feed start signal. Even in this case, by setting both the read modes 1 and 2 to the Low level, it is easy to invert the image data string.

[0030]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine) Machine, facsimile machine, etc.).

Another object of the present invention is to supply a storage medium (or a recording medium) on which a program code of software for realizing the functions of the above-described embodiments is recorded to a system or an apparatus, and to provide a computer (a computer) of the system or the apparatus. It is needless to say that the present invention can also be achieved by a CPU or an MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. Also,
When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also the operating system (OS) running on the computer based on the instructions of the program code.
It goes without saying that a case where the functions of the above-described embodiments are implemented by performing some or all of the actual processing, and the processing performs the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the program code is read based on the instruction of the program code. Needless to say, the CPU included in the function expansion card or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

When the present invention is applied to the storage medium, the storage medium stores program codes for executing the processing corresponding to the above-described timing chart (shown in FIG. 3).

[0034]

As described above, according to the present invention,
By controlling the read address order from the line memory according to the rotation direction of the polygon motor and the original reading mode by the scanner, it is possible to read the data necessary for image formation in an appropriate order, thereby increasing costs and
Image formation can be performed without lowering the throughput of the apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a semiconductor laser control unit that controls laser scanning according to an embodiment.

FIG. 2 is a diagram illustrating the operation of a timing controller.

FIG. 3 is a diagram illustrating input of image data and timings of a write enable signal and a read enable signal.

FIG. 4 is a diagram illustrating a configuration of a laser beam printer.

FIG. 5 is a diagram for explaining High and Low levels of a read enable signal;

[Explanation of symbols]

 101 Timing Controller 201 Line Memory 1 202 Line Memory 2 203 Parallel / Serial Converter 402 Laser Driver 403 Semiconductor Laser

Claims (4)

[Claims] 1. An image forming apparatus for forming a latent image on a photoconductor by controlling irradiation of a semiconductor laser in accordance with image data, comprising: a plurality of data holding means for storing image data in accordance with a write instruction signal; Image data reading means for reading the stored image data from any of the plurality of data holding means in accordance with a reading instruction signal, wherein the image data reading means is a polygon motor for controlling a beam light to be irradiated. An image forming apparatus for reading image data by changing the order of read addresses of the image data held in the data holding means in accordance with the rotation direction of the image data. 2. The image data reading means, wherein when the read signal has a High attribute, the image data is read in ascending order from a memory address of the data holding means.
2. The image forming apparatus according to claim 1, wherein when the attribute is Low, image data is read in order of descending addresses from address 4096 of the memory address. 3. A timing controller for outputting the write instruction signal and the read instruction signal, wherein the timing controller alternately outputs respective instruction signals to write image data to the plurality of data holding units. 2. The image forming apparatus according to claim 1, wherein control is performed so that reading is synchronized. 4. The image forming apparatus according to claim 1, wherein the image data reading unit switches an order of addresses for reading image data from the data holding unit according to a setting of an image reading mode.