JP3527646B2 - Optical scanning device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device used in a laser beam printer or the like, and more particularly to a laser scanning device (L
SU: laser scan unit), and more particularly to an optical scanning device including a circuit for generating an SOS (start of scan) signal used as a synchronization signal for timing the scanning of laser light.

[0002]

2. Description of the Related Art In an LSU, a laser beam to be scanned is received by a photodiode (hereinafter, referred to as PD) in order to obtain an SOS signal used as a timing signal when scanning the laser beam on an image plane. The SOS signal is generated based on the obtained light reception signal. For example, FIG. 1 is a configuration diagram of an LSU schematically showing an example thereof, which is a laser diode (hereinafter referred to as LD).
The laser beam light LB emitted from the laser beam No. 1 is deflected and scanned by the polygon mirror 2 rotated at a high speed within a predetermined angle range, and the laser beam light LB deflected and scanned is passed through the f.theta. Main scanning is performed on the surface. A photodiode (hereinafter referred to as PD) 5 is arranged on the scanning optical path of the laser beam light LB to receive the laser beam light LB that is deflected and scanned and output a photoelectrically received signal. The SOS signal is obtained by performing signal processing on this in the SOS signal processing circuit 6. Therefore, the control circuit 7 controls the LD drive circuit 8, the polygon mirror drive circuit 9, and the photosensitive drum drive circuit 10 based on the SOS signal, and the generated SOS is generated.
If the drawing by the laser beam light is started after a certain period of time from the signal, the drawing can be executed in the specific area 4a of the photosensitive drum 4, and the drawing synchronized with the scanning can be realized.

[0003]

By the way, the above-mentioned S
In the PD for obtaining the OS signal, it is inevitable that the received light amount of the PD varies due to fluctuations in the power of the laser beam light, surface deflection of the polygon mirror, and the like. In addition, the level of the received light signal may vary due to noise mixed in from the PD to the signal processing circuit or variation in the DC component of the circuit due to dark current or the like. Therefore, a signal component typified by such a level variation of the received light signal is mixed as noise in the received light signal. Therefore, if the received light signal including such noise is used as it is, the SOS signal is generated. The noise causes jitter in the SOS signal on the time axis, the timing of the SOS signal is changed, and it becomes impossible to obtain a highly accurate SOS signal. Particularly, in the conventional SOS signal generation circuit, since the SOS signal is obtained by comparing the light receiving signal of the PD with a predetermined threshold value, the level fluctuation of the light receiving signal appears as the timing fluctuation of the SOS signal.

An object of the present invention is to provide an optical scanning device including an SOS signal generation circuit capable of suppressing noise in a light receiving signal at a PD and stabilizing the timing of an SOS signal.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a light source, an optical scanning means for deflecting a beam of light emitted from the light source to scan the photosensitive surface, and a light receiving signal for receiving the scanned beam of light are provided. In an optical scanning device comprising a light receiving unit for outputting and a synchronization signal generation circuit for generating a synchronization signal for synchronizing scanning in the optical scanning unit based on a light reception signal from the light receiving unit, the light receiving unit is The synchronization signal generation circuit is composed of a plurality of light receiving elements arranged in the scanning direction of the light beam, and the synchronization signal generation circuit detects a time signal from a resonance amplification signal obtained by resonantly amplifying the light reception signals of the plurality of light receiving elements. Section, a timing detection section for detecting a timing signal for obtaining a synchronization signal from the light reception signal of the light receiving element, a time signal from the time signal detection section, and a timing signal from the timing detection section. Characterized in that it comprises a logic circuit for generating a synchronization signal based on the timing signal. Here, it is preferable that the light receiving unit is formed such that a width of the light receiving element, which is first scanned by the light beam, in the scanning direction is larger than a width dimension of another light receiving element in the scanning direction. In addition, the light receiving means may be configured to select every other one or a plurality of light receiving elements arranged and output a light reception signal thereof.

The time signal detecting section, the timing detecting section and the logic circuit section in the present invention are configured as follows. That is, the time signal detection unit adds the light receiving signals of the plurality of light receiving elements, a resonance amplifier that resonantly amplifies the light receiving signals added by the adding unit, and a resonance amplification signal of the resonance amplifier. First comparison means for comparing the level with a reference level to detect a cross point of the resonance amplified signal and outputting the detected cross point as a time signal. The timing detection unit includes second comparison means for comparing a sum signal of light reception signals of the plurality of light receiving elements with a reference level, and the second comparison means.
And a first timer means for outputting a timing signal which is triggered by the comparison output of the comparison means and is continued for a predetermined time. Further, the logic circuit section outputs a first gate signal upon completion of continuous output of the timing signal from the timing detection section, the first gate signal and the time signal from the time signal detection section. A second timer means for outputting a second gate signal that continues for a predetermined time based on the above, and a logic gate means for outputting a synchronization signal when the time signal and the second gate signal are input. The configuration is provided.

In the optical scanning device of the present invention, the light receiving signals output from the plurality of light receiving elements are amplified by the resonance amplifier to limit the band, and the amplitude amplification output and the time-axis output of the resonance amplification signal are amplified. Is output.
Therefore, it becomes possible to generate the SOS signal using the resonance amplification signal having a sufficiently high amplitude level, and suppress the level fluctuation of the received light signal and the influence of noise in the circuit,
It is possible to stabilize the timing of signals. Further, by making the width dimension of the light receiving element to be scanned first in the scanning direction larger than the width dimensions of the other light receiving elements, it is possible to stably obtain the timing signal used when generating the SOS signal. It is possible to generate an SOS signal with high precision timing.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. In this embodiment, L shown in FIG.
The present invention is applied to SU, and in the LSU, PD5
The SOS signal is generated by the SOS signal generation circuit 6 based on the received light signal received by and is input to the control circuit 7. The control circuit 7 controls the LD drive circuit 8 based on the input SOS signal.
To control the light emission of the LD, and also to control the polygon mirror drive circuit 9 and the photosensitive drum drive circuit 10, respectively. As a result, the predetermined area 4a of the photosensitive drum 4 is
, The laser beam light is scanned in synchronization with the SOS signal,
Draw the required pattern.

2A and 2B show the PD 5 and the SOS.
3 is a block diagram showing each configuration of a generation circuit 6. FIG. PD
Reference numeral 5 denotes N (N is an integer of 2 or more) PD elements PD-1 to PD-1 arranged in the scanning direction of the laser beam light LB.
It is composed of PD-N. Here, 5 PD5s (N =
5) PD element, for example, one conductivity type semiconductor substrate is provided with opposite conductivity type impurity diffusion regions in a row at a predetermined interval, and electrodes are respectively provided on the semiconductor substrate and each impurity diffusion region. So that each of the PD elements PD-1 to PD-N outputs a single pulsed light receiving signal by the photoelectric conversion action when the laser beam light LB is projected. Has become. In this embodiment, among the N PD elements, the PD element PD-1 that is first scanned with the laser beam light LB has a width dimension in the optical scanning direction that is larger than the width dimensions of other PD elements. The width is made larger, and here, the width is doubled. The pitch interval between the PD elements PD-1 to PD-N is set to about 31 μm from the diameter (width) of the beam to be scanned in the scanning direction. On the other hand, the SOS signal generation circuit 6 includes a time signal detection unit 11 for detecting a time signal serving as a reference when generating the SOS signal based on the light reception signal output from the PD 5, and the time signal detection unit 11 based on the time signal. The timing detection unit 12 detects a timing signal used when generating the SOS signal, and a logic circuit unit 13 that logically operates the time signal and the towing signal to output the SOS signal.

FIG. 3A shows a connection circuit between the PD 5 and the SOS signal generation circuit 6, and particularly the time signal detection section 11
3 is a diagram showing a circuit configuration of FIG. The anode of each of the five PD elements PD-1 to PD-N forming the PD5 is an adder 21.
And the received light signals of all PD elements are added.
Further, a narrow band amplifier 22 is connected to the output terminal of the adder 21, and the added light receiving signal is narrow band amplified. Although not described in detail, the narrowband amplifier 22 is configured as, for example, a resonance amplifier including an LC resonance circuit, and the resonance frequency of the LC resonance circuit is set when the laser beam light scans the PD 5. Each PD element P
The single pulse-like signals output from D-1 to PD-N are set so as to match or almost match the frequency determined by the cycle when arranged on the time axis. The output terminal of the narrow band amplifier 22 is connected to the positive input terminal of the first level comparator 23, and is compared with the ground potential input to the negative input terminal,
A cross point signal (hereinafter, SOS1 signal) is output when the output of the narrow band amplifier 22 becomes higher than the ground potential.

Further, the timing detection unit 12 is shown in FIG.
As shown in (b), the PD elements PD-1 to PD-N
Are commonly connected to each other, and the outputs of these PD elements are summed and connected to the positive input terminal of the second level comparator 31. The reference voltage Vref is connected to the negative input terminal of the second level comparator 31, the sum signal of the PD element is compared with the reference voltage Vref, and the comparison result is output. The output of the second level comparator 31 is connected to one input terminal of the first AND gate 32, and the output terminal of the first AND gate 32 is connected to the first timer circuit 33. The output terminal of the first timer circuit 33 is connected to the other input terminal of the first AND gate 32 via an inverter 34. Therefore, the first timer circuit 33 is triggered by the H level output from the first AND gate 32, and is configured to output a detection delay signal (hereinafter, a DLY signal) for the set timer time. .

On the other hand, as shown in FIG. 4, a D-type flip-flop (hereinafter referred to as DF) in which the DLY signal is input to a clock terminal via an inverter 41 is input to the logic circuit section.
F) 42 is provided, and the negative output of the F) 42 is fed back to the data input, so that the D-FF 42 operates as the DLY.
A positive output signal (hereinafter referred to as WIN1 signal) is inverted and output every time a signal is input. Further, the reset terminal has an SOS described later.
The signal is input through the inverter 43, and the SOS
Reset by signal. On the other hand, the latch 44 to which the crosspoint signal (hereinafter, SOS1 signal) is input
And a second timer circuit 46 to which the SOS1 signal is inputted via an inverter 45. Further, outputs of the latch 44 and the second timer circuit 46 are inputted to respective input terminals of a first AND gate 47. Then, the SOS signal is output from the first AND gate 47 by taking the logical product of these outputs. The WIN1 signal from the D-FF 42 is input to the enable terminal of the second timer circuit 46, and the second timer circuit 46 is triggered when the WIN1 signal is input to execute the timer operation. Also,
The SOS signal is input to the control terminal Cont of the latch 44, and the input signal is output as it is according to the level of the control terminal Cont (the control terminal is at L level), or the output at that time is held ( The control terminal is at the H level).

Next, the operation of the SOS generating circuit 6 having the above configuration will be described with reference to the timing charts of FIGS.
First, in FIG. 5, when the laser beam LB scans the PD 5, a single pulse light reception signal is obtained from each of the PD elements PD-1 to PD-N. Then, in the time signal detecting section 11, the light receiving signals of the PD elements are added in the adder 21 so that the respective light receiving signals become signals arranged on the time axis as shown in FIG. Become. On the other hand, in the timing detection unit 12, each P
By obtaining the sum signal of the light receiving signals of the D element, the sum PD signal of FIG. Then, the total PD sum signal is compared with the reference voltage Vref in the second comparator 31, and when the total PD sum signal is equal to or higher than the reference voltage, the H level is output. Then, by first inputting the H level output that is output based on the light receiving signal of the PD element PD-1 and the output that has passed through the inverter 34 from the first timer circuit 33 to the first AND gate 32,
A pulse signal as shown in FIG. 3D is output from the first AND gate 32, and the first timer circuit 33 operates with the pulse signal as a trigger for a preset time to measure the time. H for the period set as in (e)
A DLY signal whose level is maintained is output.

Here, in the timing detection section 12,
Since the width dimension of the PD element PD-1 to be scanned first in the scanning direction is set to be larger than the width dimensions of the other PD elements, as shown by the solid lines in FIGS. The output energy of the received light signal of the element PD-1 can be increased, and the signal waveform of the received light signal can be stabilized accordingly.
It is possible to stabilize the rising edge of the received light signal.
Therefore, the timing of the output from the second comparator 31 when the received light signal becomes higher than the reference level Vref can be stabilized, and the pulse signal and the DLY signal accompanying it can be generated at stable timing. It will be possible.
In particular, it is effective when the scanning speed of the laser beam light is high or when the output of the laser beam light is lowered and the level of the light receiving signal of the PD element is lowered. Incidentally, the broken line in FIG. 5 shows the case where the width dimension of the PD element PD-1 in the scanning direction is the same as that of the other PD elements. In this case, when the output energy of the received light signal is shown by the solid line, It is undeniable that the stability of the timing of the generated DLY becomes low because it is small in comparison.

Further, in the timing chart shown in FIG.
In the time signal detection section 11, when the output of the adder 21 shown in FIG. 7A is amplified by the narrow band amplifier 22, the output waveform is shown by the amplitude characteristic and the phase characteristic of the narrow band amplifier in FIG. ) Is output as a resonance amplification signal. At this time, due to the resonance amplification effect in the narrow band amplifier 22, the resonance amplification signal has a signal waveform in which the respective light reception signals are sequentially integrated over time, and the resonance amplification signal is output even after the input of the light reception signal is completed. It becomes a waveform. Then, by comparing this resonance amplified signal with the ground potential in the first level comparator 23, the time signal at the zero cross point where the resonance amplified signal intersects the ground potential, that is, the SOS1 signal, is obtained, as shown in FIG. Will be output.

Next, in the timing chart of FIG. 7, the D-FF 42 in the logic circuit section 13 is shown in FIGS.
Thus, the WIN1 signal is inverted at the falling edge of the DLY signal. When the WIN1 signal becomes H level, the second timer circuit 46 enters the input detectable state. In this state, when the falling input of the SOS1 signal in FIG.
The second timer circuit 46 starts its operation, and the output WIN2 signal becomes H level as shown in FIG. Further, the SOS1 signal is input to the latch 44, but at this time point, the SOS signal input to the control terminal Cont is at the L level, so that the output SOS-R signal is as shown in FIG. The SOS1 signal appears at the output as it is and is input to the AND gate 47. Then, as described above, when the WIN2 signal becomes the H level, the SOS1 signal is directly output as the SOS signal through the AND gate 47. Then, when the SOS signal becomes H level, the D-FF 42 is reset, so that the second timer circuit 46 is in the input prohibited state, and the SOS1 that was previously input is input.
After the signal falls, the second timer circuit 46 is no longer triggered. Therefore, as shown in FIG. 6F, after the DLY signal falls, the SOS signal rises (time β) immediately after the first SOS1 falls (time α) that triggers the second timer circuit 46. Begins and the second
The SOS signal continues to be at the H level for the predetermined time set in the timer circuit 46. The SOS-R signal is held at the H level by the rising of the SOS signal. By repeating the above operation, it is possible to generate an SOS signal corresponding to the scanning cycle of the laser beam light, as shown in FIG.

Here, the reason for using the DLY signal will be described. As shown in FIG. 6B, since the resonance amplification signal amplified by the narrow band amplifier 22 has a small amplitude value in the initial part and the final part, a slight waveform fluctuation S
There is a large possibility that the timing fluctuation of the OS signal is affected, and a constant time point is set in a region with a large intermediate amplitude value excluding the initial part and the final part.
It is preferably used as the S signal. To that end, FIG.
The DLY signal shown in (d) is generated, and this DLY signal is H
The time to reach the level is appropriately set in the first timer circuit 33, and immediately after the fall of the DLY signal, the same figure (c)
Of the SOS1 signal is first set at a certain timing, and at this timing, the SOS shown in FIG.
Generating a signal is preferred. Therefore, in the above-described embodiment, the H level of the DLY signal is set at the time when the received light signal is integrated by resonance amplification and has the maximum amplitude, that is, the time corresponding to the time when the received light signal in FIG. 6A continues. Therefore, the time when the DLY signal falls can be obtained as the time when the amplitude of the resonance amplification signal is maximum, in other words, the time when the amplitude of the resonance amplification signal becomes stable. In addition, this DL
It is desirable that the H level period of the Y signal be reduced to the L level within a time period that is 1/2 of the maximum amplitude of the output signals of the narrow band amplifiers 23 and 24. In particular, each narrow band amplifier 23,
It is preferable that the DLY signal drop to the L level at a time about one wavelength later than the time when the output of 24 becomes maximum, and in this embodiment, the DLY signal drops to the L level at a time about one wavelength before. As described above, the first timer circuit 32
Has set the time. Around this time, the signal is generally stable and considered to be the best. This makes it possible to generate an SOS signal with stable timing. The timing of the SOS signal is DL
Since the SOS1 signal falls at the time immediately after the Y signal falls, the timing error of the timer in the second timer circuit that generates the DLY signal does not affect the timing itself of the SOS signal.

As described above, according to the present invention, the received light signal from the PD 5 is amplified by the narrow band amplifier 22 for resonance amplification,
Since the SOS signal is generated based on this resonance amplification signal, the output waveform of the adder 21 does not become a similar output waveform due to the amplitude characteristic and the phase characteristic of the narrow band amplifier 22, but the laser beam Since the timing at which light scans each PD element of the PD 5 and the waveform timing of the resonance amplification signal are always kept constant, an arbitrary fixed time point of the output waveform of the resonance amplification signal is detected as the SOS timing. SOS with stable timing
It becomes possible to generate a signal. Further, in the present invention,
In the time signal detection unit, the SOS signals are added only by adding the received light signals of the plurality of PD elements, resonantly amplifying them, and comparing them with the ground potential.
One signal can be generated, and the SOS signal can be generated only by processing the SOS1 signal together with the DLY signal in the logic circuit section. Therefore, each section has a simple circuit configuration.
It is possible to configure the OS signal generation circuit.

Here, in the above embodiment, the time signal detecting section 11 is connected to the cathode side of the PD element and the timing detecting section 12 is connected to the anode side, and the light receiving signals of the PD elements are added and used. However, since the light reception signals are the same, it is possible to configure the circuit by using the output of the adder 21 of the time signal detection unit as the input of the timing detection unit 12, for example. The PD 5 uses all of the plurality of PD elements arranged, but as shown in FIG.
A large number of PD elements PD-1 to PD arranged in PD5A
With respect to −N, a plurality of PD elements may be selected, for example, every other odd-numbered PD element as shown in the figure, and the SOS signal may be generated using the light reception signal of the selected PD element. . In this case, the PD elements not used may have their cathodes grounded so that no output is produced and the adjacent PD elements are not affected. If you do this,
Depending on the difference in the accuracy of the SOS signal required for the LSU, the difference in the scanning speed or the output of the laser beam light, the PD element is appropriately selected to obtain the light receiving signal of the suitable output corresponding to each LSU, and the SOS is obtained. It becomes possible to generate a signal. However, when the PD element is selected in this way, the electrodes provided in each PD element cannot be shared by all PD elements as in the above-described embodiment, and therefore the PD elements cannot be shared.
It is undeniable that the mask pattern used in the manufacturing of the device will be complicated.

Further, in the above-mentioned embodiment, an example in which the SOS signal is generated using the PD composed of five PD elements is shown, but the number is not limited to this. If the number of PD elements is large, a high level can be obtained depending on the amplitude level of the resonance amplification signal, but in the present invention, if the amplitude of the resonance amplification signal is stable, the object can be achieved. It is not necessary to increase the number of PD elements. It is important to set an appropriate number of PDs according to the timing accuracy of the SOS signal required for the LSU. A state in which the amplitude level of the resonance amplification signal from the narrow band amplifier is saturated is shown in FIG. The figure shows signals corresponding to the respective signals of the timing chart of the embodiment shown in FIG. Further, here, a case is shown where the PD elements have the same width in the scanning direction. As described above, when the amplitude level reaches a certain level, it is possible to generate a highly accurate SOS signal without particularly affecting the timing accuracy. Also, the present invention compares the resonance amplified signal with the ground potential as in the above-described embodiment, and
Instead of generating one signal, a time signal or SOS signal may be generated by performing comparison using a potential different from the ground potential close to the ground potential as a reference voltage. In particular, when there is a direct current component in the circuit, comparison may be performed with a potential for correcting the offset due to this direct current component.

[0021]

As described above, according to the present invention, the light receiving means for receiving the light beam to be scanned and outputting the light receiving signal is constituted by a plurality of light receiving elements arranged in the scanning direction of the light beam. A sync signal generating circuit for generating a sync signal for synchronizing scanning in the optical scanning means based on a light receiving signal from the light receiving means, and a time signal obtained from a resonance amplification signal of the plurality of light receiving elements. Since the SOS signal is generated with the timing signal obtained from the light receiving signal of the light receiving element, the resonance amplification signal is band-limited and the amplitude amplification output and the time-axis output are amplified as the resonance amplification signal. As a result, it becomes possible to generate the SOS signal by using the resonance amplified signal having a sufficiently high amplitude level, and the level fluctuation of the received light signal and the noise in the circuit can be prevented. Suppressing sound, it is possible to stabilize the timing of the SOS signal. In this case, as compared with the existing optical scanning device, the existing optical scanning device can be designed by replacing the light receiving means with a structure having a plurality of light receiving elements and additionally attaching a resonance amplifier to the SOS signal generating circuit. The present invention can be realized without drastically changing.
Further, by making the width dimension of the light receiving element to be scanned first in the scanning direction larger than the width dimension of other light receiving elements,
A timing signal used when generating a signal can be stably obtained, and an SOS signal with more accurate timing can be generated.

[Brief description of drawings]

FIG. 1 is a diagram showing a conceptual configuration of an LSU to which the present invention is applied.

FIG. 2 is a conceptual diagram showing a configuration of a PD according to the first embodiment of the present invention and a block diagram showing a configuration of an SOS signal generation circuit.

FIG. 3 is a circuit diagram showing the configurations of a time signal detector and a timing detector.

FIG. 4 is a circuit diagram of a logic circuit unit.

FIG. 5 is a timing diagram of an operation for obtaining a DLY signal.

FIG. 6 is a timing diagram for obtaining a time signal.

FIG. 7 is a timing diagram for obtaining an SOS signal.

FIG. 8 is a PD and SO in the second embodiment of the present invention.
It is a circuit diagram which shows the structure of an S signal generation circuit.

FIG. 9 is a timing diagram showing an operation in a state where the gain of the narrow band amplifier is saturated.

[Explanation of symbols]

1 laser diode 2 polygon mirror 3 fθ lens 4 photosensitive drum 5 photodiodes 6 SOS signal generation circuit 7 control circuit 8, 9, 10 drive circuit 11 hours signal detector 12 Timing detector 13 Logic circuit section 14 Timing detector 21 adder 22 Narrow band amplifier (resonance amplifier) 23 First Level Comparator 31 Second Level Comparator 32 AND GATE 33 First Timer Circuit 42 D flip-flop 46 Second timer circuit

Claims (10)

(57) [Claims] 1. A light source, an optical scanning unit for deflecting a beam of light emitted from the light source to scan the photosensitive surface, a light receiving unit for receiving the scanned beam of light and outputting a light receiving signal, An optical scanning device comprising a synchronization signal generation circuit for generating a synchronization signal for synchronizing scanning in the light scanning means based on a light reception signal from the light reception means, wherein the light reception means are arranged in a scanning direction of the light beam. A plurality of light receiving elements, wherein the synchronization signal generating circuit detects a time signal from a resonance amplified signal obtained by resonantly amplifying the light receiving signals of the plurality of light receiving elements; Based on a timing detection unit that detects a timing signal for obtaining a synchronization signal from the received light signal, and a time signal from the time signal detection unit and a timing signal from the timing detection unit And a logic circuit section for generating a synchronization signal. 2. The light according to claim 1, wherein in the light receiving means, the width of the light receiving element in which the light beam is first scanned is larger than the width of the other light receiving element in the scanning direction. Scanning device. 3. The optical scanning device according to claim 1, wherein the light receiving means is selected every other one or a plurality of light receiving elements arranged and outputs the light receiving signal. 4. The time signal detector includes an adder that adds received light signals from the plurality of light receiving elements, a resonance amplifier that resonates and amplifies the received light signals added by the adder, and a resonance of the resonant amplifier. The first comparison means for detecting the cross point of the resonance amplified signal by comparing the level of the amplified signal with a reference level, and outputting the detected cross point as a time signal. Optical scanning device. 5. The optical scanning device according to claim 4, wherein the resonance amplifier is set to a resonance frequency that coincides with or substantially coincides with a period of a light reception signal output from the plurality of light receiving elements. 6. The timing detecting section is triggered by a second comparing means for comparing a sum signal of light receiving signals of the plurality of light receiving elements with a reference level, and a predetermined comparison output of the second comparing means. 6. The optical scanning device according to claim 1, further comprising a first timer unit that outputs a timing signal that continues for a time. 7. The optical scanning device according to claim 6, wherein the timing signal output from the timing detection unit is continuously output at least during the time when the light receiving signal from the light receiving unit is output. 8. The optical scanning according to claim 7, wherein the output of the timing signal output from the timing detection unit is stopped within a time period that is 1/2 of the maximum amplitude of the output signal from the resonant amplifier. apparatus. 9. The output of the timing signal output from the timing detection unit is stopped at least at a time about one wavelength later than a time at which the output of the resonant amplifier is maximized. Optical scanning device. 10. The logic circuit section is set to the first state by the end of continuous output of the timing signal from the timing detection section.
Means for outputting a gate signal, and second timer means for outputting a second gate signal that continues for a predetermined time based on the first gate signal and the time signal from the time signal detector, 10. The optical scanning device according to claim 1, further comprising a logic gate unit that outputs a synchronization signal when a time signal and the second gate signal are input.