JPH09277588A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To limit a loss in a transmission path by arranging a drive circuit and a light source in a video controller and thereby shortening a transmission path for the video signal of a high frequency signal to a maximum allowable extent. SOLUTION: This image forming device is equipped with a semiconductor laser 3 for image exposure, a video controller 2 for developing print information to be recorded into bit map data, a video signal creating circuit which creates a video signal based on the bit map data, and a laser driver 4 which drives the semiconductor laser 3 in accordance with the video signal. Thus a latent image is formed on a photosensor by irradiating the photosensor with a photosignal sent from the semiconductor laser 3. In addition, the laser driver 4 and the semiconductor laser 3 are arranged in the video controller 2 to transmit the photosignal sent from the semiconductor laser 3, through an optical fiber 7.

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 using an image exposure light source such as a semiconductor laser, and more particularly to an image forming apparatus suitable for high speed and high resolution image formation.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional image forming apparatus using a laser printer as an example. In the figure, 201 is a host computer which is a higher-level control device, and the laser printer is connected to this host computer 201. Print information such as character code data and graphic images transmitted from the host computer 201 is expanded into bit map data by the video controller 202 and sent to the engine controller 203. Engine controller 2
Reference numeral 03 is connected to the video controller 202 by a video I / F circuit (interface) 204.

When the bitmap data is transmitted, the engine controller 203 generates a video signal from the data and transmits it to the laser driver 205. The video signal of the engine controller 203 is the electric cable 2
It is supplied to the laser driver 205 through 08, and the laser driver 205 drives the semiconductor laser 206, which is a light source for image exposure, on / off according to the video signal. The optical signal emitted from the semiconductor laser 206 is incident on the polygon mirror 207 rotating at a constant speed, and the polygon mirror 207 is rotated to scan in the horizontal direction, so that the charged photosensitive member (not shown) is moved to 1 A latent image of the line is formed. By repeating this operation, a desired image is formed on the photoconductor and recording is performed by the electrophotographic process.

FIG. 4 is a diagram showing the configuration of a general image forming apparatus as another conventional example. In FIG. 4, 303
Is a laser scanner unit, which rotates at a constant speed with the semiconductor laser 301 which is a light source for image exposure,
Polygon mirror 30 for scanning 01 optical signal in the horizontal direction
Includes 2. The laser scanner unit 303 is arranged at an upper position inside the machine. On the other hand, a video controller 305 that expands the print information into video map data and an engine controller 304 that generates a video signal from the video map data are arranged at a lower position in the machine. Normal,
Laser scanner unit 303 and engine controller 30
4. The video controller 305 is arranged so as to be separated with the photoconductor 308 interposed therebetween, and the paper 306 passes between them. The engine controller 304 and the laser scanner unit 303 are connected by a long electric cable 307,
The video signal is supplied to the laser scanner unit 303 through the electric cable 307.

[0005]

However, in the prior art, as shown in FIGS. 3 and 4, since the video signal is transmitted by a long electric cable, there is a limit in performing high speed printing or high resolution printing. there were. That is, in order to perform high-speed printing or high-resolution printing, it is necessary to drive the semiconductor laser with a high frequency video signal, but if the high frequency video signal is transmitted by an electric cable, the loss will inevitably increase. Therefore, in the method of transmitting a video signal with an electric cable, there is a limit to high-speed printing and high-resolution printing, and it has been difficult to achieve higher speed and higher resolution.

Further, when a high frequency video signal is transmitted through a long electric cable, the cable serves as an antenna, so that strong noise is radiated to adversely affect other devices, or the cable is susceptible to noise from the outside. Therefore, there is a problem that the device malfunctions due to external noise.
In order to solve the noise, measures such as shielding may be considered, but since it will increase the device cost,
It was not a valid solution.

In view of the above-mentioned conventional problems, the present invention can easily suppress the loss of optical signals and noise,
It is an object of the present invention to provide an image forming apparatus adapted for high speed printing and high resolution printing.

[0008]

An object of the present invention is to provide a light source for image exposure, a video controller for expanding print information to be recorded into bitmap data, and a video signal for creating a video signal from the bitmap data. An image forming apparatus that includes a creating circuit and a drive circuit that drives the light source according to the video signal, and forms a latent image on the photoreceptor by irradiating the photoreceptor with an optical signal emitted from the light source. In the image forming apparatus, the driving circuit and the light source are arranged in the video controller, and an optical signal emitted from the light source is transmitted by an optical fiber.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the image forming apparatus of the present invention. In FIG. 1, 1
Is a host computer which is a host controller. The image forming apparatus of this embodiment is connected to the host computer 1. Print information such as character code data and graphic images from the host computer 1 is transmitted to the video controller 2 in the image forming apparatus. The video controller 2 expands the transmitted print information into bitmap data.

Further, in the video controller 2, a semiconductor laser 3 which is a light source for image exposure and a laser driver 4 which drives the semiconductor laser 3 are provided. That is,
A semiconductor laser 3 and a laser driver 4 are arranged on a substrate (video controller unit) on which a circuit configuring the video controller 2 is mounted, and a laser driver is provided in the video controller 2 for creating very high-frequency bitmap data. By providing 4 and the semiconductor laser 3, the transmission path of the high frequency signal is configured to be as short as possible. The engine controller 5 transmits a control signal such as a timing signal for writing the image signal for each line to the laser driver 4 in the video controller 2 via the video I / F (interface) circuit 6.

Within the laser driver 4, there is provided a video signal generating circuit (not shown) which synthesizes the bit map data generated by the video controller 2 and the control signal from the engine controller 5 to generate a video signal. Then, the laser driver 4 drives the semiconductor laser 3 according to the obtained video signal. The semiconductor laser 3 is turned on and off according to the video signal, and is transmitted to the polygon mirror 8 as a signal by laser light. In the present embodiment, the optical signal of the semiconductor laser 3 is transmitted by the optical fiber 7 and applied to the polygon mirror 8. The polygon mirror 8 rotates at a constant speed, and the rotation causes the optical signal from the semiconductor laser 3 to scan in the horizontal direction to form a latent image on the charged photoconductor (not shown).

In this embodiment, since the laser driver 4 and the semiconductor laser 3 are provided in the video controller 2, the length of the transmission path for transmitting the high frequency video signal can be made extremely short. Therefore, the loss of the video signal is small, and even a high-frequency signal can be transmitted without trouble, and high-speed printing and high-resolution printing can be supported. In addition, since the optical signal of the semiconductor laser 3 is transmitted using the optical fiber 7, the signal of the laser light that is turned on and off at high speed can be transmitted without loss. That is, since the loss of the optical fiber 7 during high-frequency signal transmission is much smaller than that of the electric cable, the video controller 2 and the polygon mirror 8
Even if the scanning unit provided with is arranged at a distant position, a high-frequency optical signal can be transmitted without any trouble.
Further, when the optical fiber 7 is used, noise is not radiated or external noise is not received, so that no noise countermeasure is required.

FIG. 2 is a block diagram showing another embodiment of the present invention. In FIG. 2, the same parts as those of the embodiment of FIG. In the present embodiment, the optical sensor 9 is provided on the optical signal emitting side of the optical fiber 7. The optical sensor 9 is a sensor that monitors the optical signal 10 after transmission through the optical fiber 7, and the light reception signal of the optical sensor 9 is sent to the video controller 2. In the laser driver 4 of the video controller 2, a light quantity stabilization control circuit (APC) for controlling the light quantity of the semiconductor laser 3 to be kept constant is provided, and detects an optical signal at the exit side of the optical fiber 7, By performing the light quantity stabilization control based on this, the light output of the semiconductor laser 3 is constantly controlled to be constant irrespective of temperature changes, changes over time, and the like.

Usually, a method is used in which an optical sensor is provided in the vicinity of the semiconductor laser 3 to control the amount of light to a constant level. However, this method involves loss in the transmission line, etc., so that the amount of light stabilization control is performed accurately. Is difficult. In this embodiment, since the light amount is detected at the exit side of the optical fiber 7, there is a loss in the optical fiber 7, or the optical fiber 7 has a loss.
Even if the ratio of the laser light incident on is varied, the light quantity stabilization control can be accurately performed. The optical sensor 9 may also be used as a BD (beam detect) sensor that is usually used as an optical sensor for horizontal synchronization detection. By doing so, it is not necessary to newly provide an optical sensor, and the configuration can be simplified accordingly.

[0015]

As described above, according to the present invention, since the driving circuit and the light source are arranged in the video controller, the transmission path of the video signal of the high frequency signal can be shortened as much as possible, and Loss can be suppressed. Further, by transmitting the optical signal of the light source through the optical fiber, not only the high frequency signal can be transmitted with a small loss, but also noise is not emitted and the influence of external noise can be eliminated. Therefore, high-speed printing and high-resolution printing can be supported.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a block diagram showing another embodiment of the present invention.

FIG. 3 is a block diagram showing a conventional image forming apparatus using a printer as an example.

FIG. 4 is a configuration diagram showing another example of a conventional image forming apparatus.

[Explanation of symbols]

 1 Host Computer 2 Video Controller 3 Semiconductor Laser 4 Laser Driver 5 Engine Controller 6 Video I / F Circuit 7 Optical Fiber 8 Polygon Mirror 9 Optical Sensor

Claims (3)

[Claims] 1. A light source for image exposure, a video controller for expanding print information to be recorded into bitmap data, a video signal creation circuit for creating a video signal from the bitmap data, and a video signal creation circuit in accordance with the video signal. A driving circuit for driving the light source, the image forming apparatus forming a latent image on the photoconductor by irradiating the photoconductor with the optical signal emitted from the light source, in the video controller, the drive An image forming apparatus characterized in that a circuit and a light source are arranged, and an optical signal emitted from the light source is transmitted by an optical fiber. 2. The image forming apparatus according to claim 1, further comprising an optical sensor that detects an optical signal transmitted through the optical fiber, and performing light quantity stabilization control of the light source based on an output signal of the optical sensor. An image forming apparatus characterized by performing. 3. The image forming apparatus according to claim 2, wherein the optical sensor is an optical sensor for detecting a horizontal synchronizing signal.