JPS6131666B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical scanning device used in high-resolution facsimiles, laser printers, etc. that perform reading and recording using laser light.

Conventionally, in this type of device, the primary light used for recording is converted from the laser light incident on the optical modulation element by outputting a signal obtained by AM modulating the carrier input to the modulation driver with a data signal to the optical modulation element. The primary light is incident on a rotating polygonal mirror, and by rotating the polygonal mirror, the laser beam is scanned and read over the document or recording medium.
I am recording. However, the output of the gas laser used in the above-mentioned device is not always constant due to gas pressure, thermal fluctuations in the resonator, etc. Furthermore, the amount of light reflected by the polygon mirror differs slightly on each mirror surface, etc. It was not possible to read and record faithfully. Furthermore, due to the structure, it is not easy to manufacture all the surfaces in the same manner so that the scanning light beams on all the surfaces are parallel, resulting in uneven pitch.

Therefore, as a means to avoid problems such as pitch unevenness and light intensity disparity caused by the use of multiple surfaces of a rotating polygon mirror, a method of using only one surface of the polygon mirror or a specific few surfaces may be considered. For example, if only one surface is used, data for one line will be recorded using that one surface, and using multiple surfaces will result in differences in light intensity and uneven pitch between each surface. I don't get it.

However, the difference in light amount caused by the non-constant output of laser light has not yet been solved. In addition, in AM modulation performed by a modulation driver, if the surface of the rotating polygon mirror used is in a position other than the recordable position, the data signal is "0", but the carrier that performs the above-mentioned AM modulation still exists. Therefore, the signal after modulation does not disappear completely,
The output of the primary light of the light modulation element does not become completely "0". Therefore, although the primary light is output slightly, the laser beam is reflected and scanned even on surfaces other than the specific use surface, and as a result, in the case of a recording device, a thin recording is made even on the white part of the recording medium. As a result, the entire recorded image becomes dark and the image quality is poor, and in the case of a reading device, extra light irradiates the document and enters the photoelectric conversion element, which adversely affects the read signal.

The present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide an optical scanning device in which the amount of light on the recording surface or document surface is always constant and the image quality is excellent.

The present invention relates to a reading or recording device that performs optical scanning using a rotating polygon mirror, in which only a specific surface of the rotating polygon mirror is used for reading or recording, and the specific surface used is in a position where it can reflect laser light. In addition, before reading or recording one line, the amount of reflected light irradiated onto the document or recording medium is detected, and the level of the signal outputted by the optical stabilization circuit is adjusted according to the amount of light described above. The above object is achieved by adjusting the amount of primary light in the light modulation element by changing it according to the level.

Hereinafter, one embodiment of the present invention will be specifically described using FIGS. 1 and 2.

FIG. 1 is a schematic configuration diagram showing an optical scanning device according to an embodiment of the present invention, and FIG. 2 is a signal waveform diagram within the device.

A laser tube 1 filled with helium neon gas or the like irradiates a light modulation element 2 with laser light. The light modulation element 2 causes a diffraction phenomenon by inputting the amplitude modulation signal output from the modulation driver 3, and outputs primary light used for recording using the incident laser light. The rotating polygon mirror 5 that is rotationally driven by the motor 4 is composed of a plurality of mirror surfaces.
By rotating, the angle with respect to the incident primary light is changed, and the reflected light is caused to main-scan on the recording medium. Although a plurality of specific surfaces may be used for recording with the rotating polygon mirror 5, only one surface is used in this embodiment. A light amount detection sensor 6 for detecting the amount of reflected light is provided at the end of the main scanning line outside the recordable area.
is provided. Moreover, the rotation detection sensor 7 is
This is to detect the rotational state of the rotating polygon mirror 5, and before the surface used for recording reaches a position where the primary light can be reflected, signals a and b are sent to the area with a slight time interval. The signal c is outputted to the designation circuit 8, and as the rotating polygon mirror 5 rotates, the signal c is outputted to the area designation circuit 8 when the reflected light from the rotary polygon mirror 5 deviates from the recording area on the recording medium. The area specifying circuit 8 outputs the carrier signal d to the optical modulation driver 3 by inputting the signal a, and stops outputting the carrier signal d by inputting the signal c. Further, by inputting the signal b output from the rotation detection sensor 7 at a constant time interval from the signal a, the area designation circuit 8 sends the optically stabilized area signal e to the selector 9.
Further, at a predetermined time interval from the signal b, a data area designation signal f for setting a recordable area is output to the selector 9 for a predetermined time.
A data signal input terminal 10 and a designated signal input terminal 11 are connected to the selector 9, and when the optically stabilized area signal e is input from the area designation circuit 8, the data signal input terminal 10 and the designated signal input terminal 11 are connected to each other. When the designation signal g is output to the optical stabilization control circuit 12 and the data area designation signal f is input from the area designation circuit 8, the data signal h input from the data signal input terminal 10 is output to the optical stabilization control circuit 12. Output to. The light amount detection selector 6 detects the amount of primary light obtained from the designation signal g output from the selector 9 based on the light stabilization area signal e, and outputs a sampling signal i to the light stabilization control circuit 12. The optical stabilization control circuit 12 inputs the specified signal g, converts it into a D/A, and outputs it to the optical modulation driver 3. The optical stabilization control circuit 12 also inputs the sampling signal i, and adjusts the maximum light intensity of the scanning light accordingly. The level of the data signal h for one line input later is changed so that the data signal h is always constant. That is, when the sampling signal i is lower than a predetermined level, a high level data signal h is output to the optical modulation driver 3, and conversely, when it is higher than the predetermined level, a low level data signal h is output to the optical modulation driver 3. The optical modulation driver 3 is
Only when the carrier signal d and the designation signal g or data signal h are input at the same time, the corresponding amplitude modulation signal j is output to the optical modulation element 2. In addition, 13 is a recording body, and 14 is a laser beam absorption part.

Next, the operation of this device will be explained.

When recording is to be performed, the motor 4 first starts rotating in response to an applied start signal.
When the surface of the rotating polygon mirror 5 used for recording reaches a predetermined position, the rotation detection sensor 7 outputs a signal a to an area designation circuit 8, and the area designation circuit 8 further sends a carrier signal d to the optical modulation driver 3. Output. When the rotating polygon mirror further rotates, the rotation sensor 7 outputs a signal b to the area designation circuit 8, and as a result, the area designation circuit 8 outputs a light stabilized area signal e.
is outputted to the selector 9, and furthermore, a data area designation signal f is outputted to the selector 9 at regular time intervals only for a fixed time period sufficient to record one line. The selector 9 receives the light stabilization area signal e and outputs a predetermined designation signal g, such as "1111", which is input from the designation data input terminal 11, to the light stabilization control circuit 12. The optical stabilization control circuit 12 does not receive the sampling signal i from the optical detection sensor 6 at this point, and optically modulates the analog signal obtained by D/A converting the specified signal g of "1111" mentioned above. Output to driver 3. An amplitude modulation signal j corresponding to the designated signal is output from the optical modulation driver 3 to which an analog signal corresponding to the carrier signal d and the designated signal g is inputted, to the optical conversion element 2, which receives the laser beam. 2 outputs primary light. The output primary light is incident on the specific use surface of the rotating polygon mirror used for recording, and the reflected light is first
Photodetection sensor 6 provided at the left end on the optical scanning line
irradiate. Note that the zero-order light traveling straight from the laser tube 1 irradiates the light absorption member 14 and disappears. The light detection sensor 6 detects the amount of the irradiated laser light and outputs a sampling signal i according to the amount of light to the light stabilization control circuit 12.

According to the output of the data area designation signal f, the data signal h is input to the data input terminal 1 at a certain timing.
0 is input to the selector 9. The selector 11, which has already received the data area designation signal f from the area designation circuit 8, outputs the data signal h to the optical stabilization control circuit 12. Here, in order to always obtain a constant recorded image, the light stabilization control circuit 12 controls the optical stabilization control circuit 12 according to the sampling signal i input in advance, that is, when the level of the sampling signal i is lower than a predetermined level, the optical stabilization control circuit 12 A data signal h' is outputted to the optical modulation driver 3 so that the maximum amount of light irradiated onto the recording medium can be fixed at a low level when the level is high. Carrier signal d and data signal
The optical modulation driver 3 inputting h′ receives the data signal
An amplitude modulation signal j corresponding to h' is output to the optical conversion element 2. Since the light modulation element 2 changes the amount of primary light used for recording in accordance with the amplitude modulation signal j, the maximum amount of light irradiating the recording medium 13 is always constant on any line.

As the angle of the rotating polygon mirror 5 changes with the rotation of the motor 4, the laser beam scans the recording medium 13, and after one line of data is recorded, the data whose output time has been determined in advance is generated. The area designation signal f turns off, and when the rotating polygon mirror 5 rotates and the surface to be used deviates from the recordable angle and position, the rotation detection sensor 7
outputs the signal c to the area specifying circuit 8, and thereby the carrier signal d is also turned off. If the carrier signal d is off, the optical modulation driver 3
The output of is “0”, and the light modulation element 2 is 1
Since the secondary light can be output, the rotating polygon mirror 5 is not irradiated with laser light.

One line is recorded by the above-described series of operations, and by repeating this, recording is performed sequentially.

Although the above description is about the recording device, the reading device is provided with a photoelectric conversion element that reads the reflected light of the laser beam that is incident on the document placed at the position of the recording medium in the above-mentioned embodiment. In addition, the present invention can be implemented in the same manner by making the selector 9 output a specific signal such as "1111" regardless of whether the optical stabilization area signal e or the data area designation signal f is input. .

As is clear from the above description, the present invention uses only a specific surface of a rotating polygon mirror for reading or recording, and generates a carrier only when the specific surface used is in a position where it can reflect laser light. In addition, before reading or recording one line, the amount of reflected light irradiating the document or recording medium is detected, and the level of the designated signal or data signal is changed according to the amount of light, and the level of the designated signal or data signal is changed to This is to adjust the light intensity of the secondary light, and if only a specific surface is used and other surfaces are in the reflective position, carrier generation is interrupted and the laser light is irradiated onto the document or recording medium. By preventing this, differences in the amount of light and uneven pitch between each surface, which occur when the entire surface of the rotating polygon mirror is used, cannot occur, and the entire recorded image becomes dark during recording. There is no occurrence of so-called fogging, and the image quality can be significantly improved by successively adjusting the amount of light for each line.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an optical scanning device according to an embodiment of the present invention, and FIG. 2 is a signal waveform diagram within the same device. 6... Light amount detection sensor, 7... Rotation detection sensor, 8... Area designation circuit, 12... Light stabilization control circuit.

Claims (1)

[Claims] 1. A laser oscillator that emits a laser beam, a light modulation element that modulates the laser beam and outputs a primary beam, and changes the reflection angle of the incident primary beam by rotating it to produce a document or a recording medium. a rotating polygon mirror that scans a straight line above; a rotation detection sensor that detects the position of a specific use surface of the rotating polygon mirror; According to the light level detected by the light level detection sensor and the light level detected by the light level detection sensor, the reading device adjusts a predetermined designated signal so that the amount of light irradiated onto the document surface is constant for all lines. a light stabilization control circuit that adjusts and outputs the level of the input data signal so that the maximum amount of light irradiated to the recording medium is constant for any line in a recording device; According to the signal, a carrier signal is generated only while the primary light is incident on a specific use surface of the rotating polygon mirror, the data signal is enabled to be input to the light amount stabilizing circuit, and the light amount detection sensor is activated. an area designation circuit that inputs the designation signal to the light amount stabilizing circuit during the operation, and an area designation circuit that inputs the designation signal or the data signal and the carrier signal simultaneously to modulate the amplitude modulation signal into the optical modulation circuit. An optical scanning device comprising: an optical modulation driver that outputs an output to an element and operates the optical modulation element.