JPH0354457Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an optical scanning device that records an image on a recording member by scanning a laser beam modulated by a modulator based on a video signal with a deflector. It is.

[Background technology of the invention] Generally, as shown in FIG. 2, an optical scanning device used in a laser printer or the like sends a laser beam emitted from a laser oscillator 1 to a modulator 2 such as an acousto-optic modulator (AOM). , is modulated according to a separately supplied video signal 3, and is deflected in the main scanning direction by a deflector 4 such as a polygon. The deflected laser beam passes through an imaging lens 5 such as an fθ lens and is directed to a photosensitive material, film, etc. that moves in the sub-scanning direction.
An image is recorded on a recording member 6 such as plain paper.
Note that 7 is a photodetector such as a photoelectric conversion element for synchronization detection (hereinafter simply referred to as origin detection), which is provided to determine the timing of the various scanning lines onto the recording member 6; A video signal 3 is supplied to the modulator 2 based on the origin detection signal outputted from the modulator 2.

[Problems in the Background Art] However, in order to determine whether or not the laser beam is correctly modulated by the video signal 3 supplied to the modulator 2 in a conventional optical scanning device, it is necessary to use the recording member 6, for example. If a film, photosensitive material, etc. is used, it cannot be confirmed until it is developed. Therefore, if modulator 2 fails during scanning,
Even though video signal 3 is being supplied,
Since nothing is recorded on the recording member 6 and failure cannot be confirmed until the output is seen, the problem arises that the recording member is wasted and work efficiency is reduced.

[Object of the invention] An object of the invention is to provide an optical scanning device that can detect whether or not laser light is correctly modulated according to a video signal.

[Summary of the invention] The present invention is an optical scanning device that records an image on a recording member by scanning a laser beam modulated by a modulator based on a video signal with a deflector; a printing area indicating circuit that outputs a printing area signal indicating that the printing area is being scanned; when a video signal is detected while the printing area signal is being output; a video signal detection means for outputting a video detection signal indicating that the printing area signal has been detected; when the zero-order light of the laser beam modulated based on the video signal is detected while the printing area signal is being output; zero-order light detection means for outputting a light detection signal; detecting an exclusive state between the video detection signal and the zero-order light detection signal that occurs during the output period of the printing area signal and outputting a modulation detection signal; The present invention provides an optical scanning device equipped with a modulation detection means.

[Embodiment of the invention] FIG. 1 is a block diagram showing an embodiment of the invention. In the figure, 10 is a laser oscillator, 11
12 is a modulator such as an AOM that modulates the laser beam according to a video signal supplied separately; 12 is a modulator that reflects the 0th-order light of the laser beam modulated by the modulator 11, and transmits only the 1st-order light according to the video signal; 13 is a deflector such as a polygon, 14 is fθ
15 is a photodetector for detecting the origin; 16 is a recording member such as film, sensitive material, or plain paper; 17 is a print area indicating circuit; 18 is a flip-flop video signal detection means; Photodetector 20, amplifier 21, waveform forming circuit 22,
Zero-order light detection means constituted by a flip-flop 23, 24 is an EXNOR circuit 25, an AND circuit 26,
This is a modulation detection means composed of NAND circuits 27 and 28. Note that the constituent requirements of the video signal detection means 18, the zero-order light detection means 19, and the modulation detection means 24 are not limited to those described above.

Next, the operation of the present invention will be explained with reference to the timing chart of FIG. Note that the image recording operation in the present invention is as described above with reference to FIG. 2, so a description thereof will be omitted.

The laser beam emitted from the laser oscillator 10 is diffracted by the modulator 11 into zero-order light and first-order light, and the zero-order light is reflected by the reflection plate 12 for modulation detection and enters the zero-order light detection means 19. On the other hand, the primary light passes through a pin spot provided on the reflecting plate 12 for recording, is deflected by a deflector 13, and records an image.

When the primary light scans the photodetector 15, the photodetector 15 sends an origin detection signal 30 as shown in FIG. 3 to the printing area indicating circuit 17. The print area instruction circuit 17 starts counting the scanning timing of the primary light based on the origin detection signal 30, and the primary light reaches the recording member 16.
While scanning the printing area, the printing area signal 31
The video signal detection means 18 and the zero-order light detection means 19
and sends it to the modulation detection means 24.

When the print area signal 31 is output, a video signal 32 is supplied from a video signal supply section (not shown) to the modulator 11 and the video signal detection means 18,
The modulator 11 modulates the laser light according to the video signal 32.

The video signal detection means 18 is composed of a flip-flop as shown in the figure, and the video signal 31 is connected to the clear (CLR) terminal.
2 to the clock (CK) terminal and input terminal D.
is pulled up to a high level. As shown in FIG. 3, the flip-flop 18 is activated by the print area signal 31, and when the video signal 32 is input during that time, the video detection signal 33 (High level) is output from the output terminal Q.
The signal is sent to the modulation detection means 24. When the scanning of the primary light printing area is completed, the printing area signal 31 input to the clear terminal becomes Low level, and the video detection signal 33 becomes Low level.

On the other hand, the zero-order light detection means 19 converts the zero-order light modulated by the video signal 32 into an electrical signal using the photodetector 20, and generates a waveform-formed zero-order light signal via the amplifier 21 and the waveform forming circuit 22. 34 to the clock (CK) terminal of the flip-flop 23.
The flip-flop 23 receives the print area signal 31.
(High level) activates the
During this time, when the zero-order optical signal 34 is input, a zero-order optical detection signal 35 (High level) is output from the output terminal Q and sent to the modulation detection means 24.

Then, the modulation detection means 24 outputs the video detection signal 33 and the zero-order light detection signal 35 to the EXNOR circuit 24.
By negating the exclusive OR in step 5 and then ANDing the output signal 25a of the EXNOR circuit 25 and the print area signal 31 in the AND circuit 26, a modulation detection signal 36 indicating the presence or absence of modulation is obtained. The presence or absence can be detected. For example, as shown in FIG. 3a, the video detection signal 33 (High level) is output, and the 0th order light detection signal 35 (High level)
When is output, a modulation detection signal 36 (High level) is detected from the modulation detection means 24 as shown in the figure.
It can be confirmed that the laser beam is correctly modulated by the modulator 11.

However, as shown in FIG. 3b, when the laser beam is not modulated due to a failure of the modulator 11, the 0th order light is also not modulated, so the 0th order light detection signal 35 from the 0th order light detection means 19 remains at a low level. . Therefore,
The modulation detection signal 36 from the modulation detection means 24 is also
It remains at a low level, confirming that the laser beam is not modulated correctly.

Also, at this time, the output signal 25 of the EXNOR circuit 25
a, video detection signal 33 and zero-order light detection signal 3
By detecting the output signals 37 and 38 obtained through the NAND circuits 27 and 28, respectively,
It is possible to determine whether the modulator 11 or the video signal detection means 18 is at fault.

For example, when the laser beam is correctly modulated as shown in FIG. 3a, the output signal 25a of the EXNOR circuit 25 is at a high level, so the NAND circuit
The output signals 37 and 38 of 28 both become low level, and it can be confirmed that the modulator 11 and the video signal supply means 18 are operating normally.

On the other hand, as shown in FIG. 3b, the video detection signal 33
Despite the high level, 0th order light detection signal 3
5 is at a low level, the output signal 37 of the NAND circuit 27 is at a high level, and the output signal 37 of the NAND circuit 28 is at a high level.
The output signal 38 of is at a low level. Then,
When the output signal 37 of the NAND circuit 27 is at a high level, it can be confirmed that the modulator 11 has failed. On the contrary, the video detection signal 33
Low level and 0th order light detection signal 35 is High
In the case of level, the output signal 37 of the NAND circuit 27
becomes a low level, and the output signal 38 of the NAND circuit 28 becomes a high level. Therefore, when the output signal 38 of the NAND circuit 28 is at a high level, it can be confirmed that the video detection means 18 has failed.

In this way, when the modulation detection signal 36 is not output (Low level), the printing operation is stopped and the output signals 36, 37, 38 from the modulation detection means 24 are used to operate lamps, alarms, etc.
It is possible to let the operator confirm the abnormality and at the same time inform the operator of the abnormal location.

[Effects of the invention] As described above, the present invention can confirm whether the laser light during printing is correctly modulated by detecting the presence or absence of a modulation detection signal, and can quickly detect modulator failures. can be found in
It is possible to prevent unnecessary use of recording media and improve the efficiency of printing work.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 2 is a diagram for explaining a conventional optical scanning device.
FIG. 3 is a timing chart of various signals in the present invention. 17... Print area indicating circuit, 18... Video signal detection means, 19... Zero-order light detection means, 24...
Modulation detection means.

Claims (1)

[Claims for Utility Model Registration] In an optical scanning device that records an image on a recording member by scanning a laser beam modulated by a modulator based on a video signal with a deflector, counting the scanning timing of the laser beam, a printing area designation circuit 17 that outputs a printing area signal 31 while scanning the printing area of the recording member 16; and when a video signal 32 is detected while the printing area signal 31 is being output, the video signal 32; and a video signal detection means 18 that outputs a video detection signal 33 indicating that 32 has been detected; 0-order light detection means 19 that outputs the 0-order light detection signal 35 when detected; and the video detection signal 33 and the 0-order light detection signal 3 generated during the output period of the print area signal 31.
1. An optical scanning device comprising: modulation detection means 24 for detecting an exclusive state with 5 and outputting a modulation detection signal 36.