JP2545790Y2 - Multiple beam scanner - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-beam scanning apparatus for scanning and exposing a photosensitive material with a plurality of light beams.

[0002]

2. Description of the Related Art FIG. 7 shows a known scanning apparatus. That is, the light beam emitted from the light source 100 is divided into a plurality of light beams required by the beam splitter 108, and each of the divided light beams is provided independently for each light beam. To adjust the light amount of each light beam, and then reduce the distance between adjacent light beams via a reduction optical system 102 such as an optical fiber, for example, to reduce the totality of the plurality of reduced light beams. Are input in parallel to an overall light amount adjusting mechanism 103 such as a neutral density filter or a polarizing filter, and then the photosensitive material 105 is scanned and exposed. Further, since the optimum exposure light amount on the photosensitive material 105 varies depending on the sensitivity characteristics of the photosensitive material 105, a part of the light beam transmitted through the entire light amount adjusting mechanism 103 is branched by the half mirror 107, and the branched light is The light amount monitor 104 is configured to be incident on the light amount monitor 104, the light amount is detected by the light amount monitor 104, and the total light amount adjustment mechanism 103, for example, a neutral density filter is driven and adjusted by the total light amount adjustment circuit 106 based on the detected value. This adjustment provides adequate attenuation. Some of the plurality of light beams are configured to be emitted from a plurality of light sources independent of each other.

[0003]

However, in the case of the above-described conventional apparatus, since the light amount adjusting mechanism 101 is a manual type, the light amounts of the respective light beams on the photosensitive material 105 at the time of mechanical adjustment are uniformly adjusted. , So-called beam balance adjustment is troublesome. Further, when the optical transmittance of the reduction optical system 102 changes due to a change in temperature or the like, the beam balance on the photosensitive material 105 fluctuates, so that the exposed photosensitive material 105 has, for example, a density different from that of the other parts. There is a defect that exposure unevenness in which stripes are repeatedly generated like a pattern occurs and quality is deteriorated. Further, as described above, since the light beam is always attenuated by the overall light amount adjusting mechanism 103, a loss occurs in the light amount, and there is a problem that a larger amount of light is required.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and provides a multi-beam scanning apparatus capable of reducing the light quantity loss without troublesome beam balance adjustment, quality deterioration due to exposure unevenness and the like. With the goal.

[0005]

SUMMARY OF THE INVENTION According to the present invention, in a multiple beam scanning apparatus for scanning and exposing a photosensitive material with a plurality of light beams, the light emission amount is adjusted for each light beam based on an electric signal. A light beam generator; first light amount detecting means provided for each light beam generator for detecting the light amount of the light beam emitted from each light beam generator; It is provided movably between a position where the light beam passing through the optical system for imaging is not blocked and a position where the light beam is blocked, and when the scanning exposure is performed, the light beam is moved to the former position and the light amount of the light beam is not detected. When detecting the light amount of the light beam, the second method is to move to the latter position and detect the light amounts of the plurality of light beams one by one at different timings.
And an electric signal based on the light amount data detected by the first light amount detecting means, which is provided for each of the light amount detecting means and the light beam generator, and adjusts the light amount of each light beam generator. Feedback control means, and second feedback control means for feeding back an electric signal based on the light quantity data detected by the second light quantity detection means to equalize the light quantity between the plurality of light beam generators. I do.

[0006]

According to the present invention, the light beam generator is provided for each light beam, and the light emission amount is adjusted based on the electric signal. The second light amount detecting means for detecting the light amount of the light beam emitted from the light beam generator moves to a position where the light beam for exposure is not blocked when scanning and exposing the photosensitive material, and detects the light amount of the light beam. When detecting, it moves to the position to block. At the latter position, if a plurality of light beam generators are configured so that light beams lit one by one from a plurality of light beam generators are incident on the second light amount detection means, the second feedback control means An electric signal based on the light amount data of each light beam detected by the detecting means is fed back to the light beam generator, and the light amounts between the light beam generators are made uniform. In each of the light beam generators, the first feedback control means feeds back an electric signal based on the light quantity data detected by the first light quantity detection means to each light beam generator, and adjusts the light quantity individually.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of a multiple beam scanning device according to the present invention. This device includes a light emitting diode 17 that emits a light beam (laser light) by an electric signal.
A plurality of, for example, five channels 1 to 5 each having
A reference density signal generating circuit 20 for providing an electric signal relating to the light beam quantity as a reference to the light emitting diodes 17 of each of the channels 1 to 5;
7, a timing determination device 30 for determining a timing of emitting a light beam, and a dot generator circuit 40 for providing an image signal to the light emitting diodes 17 of each of the channels 1 to 5.
As shown in FIG. 2, the interval between the light beams generated from the light emitting diodes 17 of the respective channels 1 to 5 is narrowed so that the photosensitive material 6
3. A reduction optical system 50 for exposing 3, a photocell 61 movably provided between a position that blocks a light beam transmitted through the reduction optical system 50, and a position that does not block the light beam, and the photocell 61. Light amount (C) is converted to voltage signal (V)
And a light amount monitor 60 including a C / V converter 62 for converting the light amount into the light amount.

The reference density signal generating circuit 20 generates reference exposure data for equalizing the light emission amount of each light beam, and is constituted by a rotary switch 21 and a D / A converter 22. I have. The rotary switch 21 generates an arbitrary reference voltage, and the D / A converter 22 converts the reference voltage into an analog voltage value. This electric signal is branched and applied to each of the channels 1 to 5.

The channels 1 to 5 have the same circuit configuration, and the configuration will be described with channel 1 as a representative.
Channel 1 includes an analog switch 11, a comparator 12, a buffer 13, an A / D converter 14, a D / A converter 15, a comparator 16, and the light emitting diode 1 described above.
7 is provided. The analog switch 11 has two switch circuits, and receives an input signal from the reference density signal generation circuit 20 through one of the switch circuits.
And the input signal from the light amount monitor 60 can be output to the comparator 12 via the other switch circuit. The opening / closing operation of the two switch circuits is performed by the timing determination device 30 described later. This is performed based on the T1a signal from the signal generation circuit 37. Specifically, while T1a is output, the two switch circuits of the analog switch 11 are both closed and T1a
Both are open when is not output.

The comparator 12 compares the reference voltage RV from the reference density signal generation circuit 20 with the voltage signal PD supplied from the C / V converter 62. When RV> PD, the direction of increasing the amount of light, RV <PD In the case of (1), the data is output to the buffer 13 so as to decrease the light amount. Buffer 13
Is converted into digital data by the A / D converter 14 and then converted to analog data by the D / A converter 15. The signal output from the A / D converter 14 to the D / A converter 15 is performed based on the T1b signal from the timing signal generation circuit 37.

The D / A converter 15 has a latch function, and holds the light emission amount data of the light beam until the next data is sent. Data from the D / A converter 15 is supplied to a comparator 16 and sampled and held.
The comparator 16 is also supplied with a detection signal PQ1 output from a light receiving diode 18 for detecting the amount of light beam generated by the light emitting diode 17. The comparator 16 outputs the output signal of the D / A converter 15 and the detection signal PQ1.
And feedback control is performed so that the light amount of the light beam generated by the light emitting diode 17 becomes the light amount corresponding to the output (light emission amount data) of the D / A converter 15. This control is performed based on the T1c signal from the timing signal generation circuit 37.

Here, the light receiving diode 18 and the comparator 16 constitute a first feedback control system. The light emission timing of the light emitting diode 17 is determined by the OR gate 19 to which the T1d signal from the timing signal generation circuit 37 and the signal D1 from the dot generator circuit 40 are input.
And a transistor 19 provided on the output side of the OR gate 19
a, and the two signals T1d, D1
Is emitted when at least one of them is input. The light beam generated by the light emitting diode 17 passes through the reduction optical system 50.

As shown in FIG. 2, the reduction optical system 50 includes an optical fiber array 51, a waveguide 52, a zoom lens 53, and a condenser lens 54. Optical fiber array 51
Are provided in a number corresponding to the number of channels. One end is guided to the light emitting diode 17 of each channel, and the other end is guided to the waveguide 52 in close proximity. Therefore, a plurality of light beams generated from the light emitting diodes 17 which are separated from each other in size are brought closer to each other by passing through the optical fiber array 51, and thereafter, pass through the waveguide 52, the zoom lens 53, and the condenser lens 54. The photosensitive material 63 is exposed in parallel.

At a position where a light beam to be exposed to the photosensitive material 63 through the condenser lens 54 is blocked, the photocell 61 is provided by a position switching mechanism described later. When scanning and exposing the photosensitive material 63, the photocell 61 is returned to a position where the light beam is not blocked. FIG. 6 shows a position switching mechanism of the photocell 61. The photocell 61 is fixed to one end of an arm 64 provided rotatably about a shaft 65, and the other end of the arm 64 is pulled by a solenoid 66, whereby the photocell 6
Switch the position of 1. When the solenoid 66 is excited,
The arm 64 rotates counterclockwise until it comes into contact with the stopper 68, and moves to a position indicated by a solid line in the drawing, that is, a position where the light beam for scanning and exposing the photosensitive material 63 is blocked. When the solenoid 66 is demagnetized, the elastic force of the spring 67 causes
The arm 64 rotates clockwise until it comes into contact with the stopper 69, and moves to a position indicated by a dotted line in the drawing, that is, a position not blocking the light beam. The solenoid 66 is provided with a timing signal T generated from the timing signal generation circuit 37.
Based on S, it is excited by the drive circuit.

The photocell 61 is provided to detect the light amount of the light beam generated from each of the light emitting diodes 17 and perform beam balancing. Light beams generated one by one from each of the light emitting diodes 17 are sequentially incident thereon. You. The light amount detected by the photocell 61 is converted into a voltage value by a C / V converter 62, and this voltage value is fed back to the comparator 16. Here, the photocell 61 and C /
Light quantity monitor 60 provided with V converter 62, comparator 1
2, buffer 13, A / D converter 14, D / A converter 1
5 and the comparator 16 constitute a second feedback control system.

The beam balance is performed based on a signal from the timing determination device 30. The timing determination device 30 includes the above-described timing signal generation circuit 37. The timing signal generation circuit 37 includes an oscillator 31 for determining a timing signal and two frequency-dividing circuits 3
2, 33, a signal is input from each of an auto beam balance start switch 34, a reference position sensor 35, and an encoder 36. The oscillator 31 is, for example, 0.2 msec.
Emit a signal every time. The frequency dividing circuit 32 to which a signal is applied from the oscillator 31 is an integral multiple of the signal from the oscillator 31, for example, 5
A signal is emitted every 10 msec, which is 0 times, and a frequency dividing circuit 33 to which a signal is added from the frequency dividing circuit 32 emits a signal every integer multiple of the signal from the frequency dividing circuit 32, for example, every 10 times 100 msec.

Further, as shown in FIG. 3, the reference position sensor 35 and the encoder 36 are arranged such that the reduction optical system 50 for scanning the photosensitive material 63 attached to the rotating drum 37 has the tip a of the photosensitive material 63.
It can be used to determine a period in which the gap c between the rear end b and the rear end b is used as a detection field, that is, a blanking period in which scanning is not substantially performed. Rotating drum 37
A slit disk 38 is attached so as to rotate integrally with the rotary drum 37 around the axis of the shaft. The slit disk 38 has a reference position slit 38a and an encoder slit 38b. Only one reference position slit 38a is formed, and many encoder slits 38b are formed at a constant pitch in the circumferential direction of the slit disk 38. The reference position sensor 35 is a slit 38
a, the reference position signal is supplied to the timing signal generation circuit 37. When the encoder 36 detects the slit 38b, the detection signal is transmitted to the timing signal generation circuit 3 each time.
7 is output.

The timing signal generating circuit 37 includes timing signals T1a to T5a, T1b to T5b, and T1c to T5.
c and T1d to T5d are output to the respective channels 1 to 5, T1a to T5a are output to the analog switch 11, T1b to T5b are output to the A / D converter 14, and T1
c to T5c are output to the comparator 16, and T1d to T5d are output to O.
Output to the light emitting diode 17 via the R gate 19 and the like.

These signals are supplied to the timing signal generation circuit 3
7 is output when a start signal START is input from the start switch 34 for auto beam balance and when the blanking period occurs at a fixed period after the start of scanning exposure, and the H level is set in the former case and the latter case. Is different. For example, in the former case,
It goes to the H level at the timing shown in FIG. At this time, T
1a to T5a and T1d to T5d are 100 msec, T1
b to T5b and T1c to T5c are 80 msec. In the latter case, T1c to T5c and T1d to T5d
Become H level at the timing shown in FIG.
5a and T1b to T5b remain at the L level. That is, the analog switch 11 and the A / D converter 14 do not operate. At this time, T1c to T5c are 1.6 msec, and T1
d to T5d are 1.8 msec. In the former case, the pattern is determined by the oscillator 31, the two frequency dividers 32,
The determination of the pattern in the latter case is performed by the reference position sensor 35, the encoder 36, and the oscillator 31.

Next, the operation of the automatic beam balance in the thus constructed device of the present invention will be described. This auto beam balance is controlled by the dot generator circuit 4
This is performed before the image signals D1 to D5 are output from 0. When the start switch 34 is turned on, the timing signal generation circuit 37 changes the timing signal TS to H as shown in FIG.
Level, the solenoid 66 is excited, the photocell 61 is moved to a position where the light beam is interrupted, and the H level signals T1a, T1b, T1c, T1d are then converted to the analog switch 11 of the channel 1, the A / D conversion. To the detector 14, the comparator 16, and the light emitting diode 17, respectively.
Accordingly, the first channel light emitting diode 17 to which T1d is input emits light regardless of the output of the image signal D1. At this time, the light emitting diodes 17 of the other channels do not emit light. The light beam passes through the reduction optical system 50 and irradiates the light receiving surface of the photocell 61 which has been previously moved to the position where the light beam is blocked as described above.

The amount of light detected by the photocell 61 is C
The voltage value is converted by the / V converter 62 and fed back to the analog switch 11. That is, the second feedback control system operates. At this time, the analog switch 11 is closed because the timing signal generation circuit 37 outputs the high-level T1a, and the comparator 12 outputs the reference voltage from the reference density signal generation circuit 20.
The voltage RV is compared with the voltage PD output from the C / V converter 62, and when RV> PD, the direction of increasing the amount of light, RV <P
In the case of D, the data is output to the buffer 13 so as to decrease the amount of light.

The data from the buffer 13 is converted into digital data by an A / D converter 14. At this time, since H1 level T1b is output from the timing signal generation circuit 37, the digital data is given to the D / A converter 15, where it is converted into analog data and held. Since T1c is also at the H level at this time, the comparator 16 operates to compare the output of the D / A converter 15 with the light quantity signal PQ1 fed back from the light receiving diode 18, and the light quantity signal PQ1 is set to D / A Control is performed so that the light amount corresponds to the output value (light emission amount data) from the converter, that is, the first feedback control system operates.

Thus, the light amount of the light beam of channel 1 is adjusted to a desired value via the first and second feedback control systems. Thereafter, the timing signal generation circuit 37 similarly applies a signal to the next channel 2. As a result, the light amount of the light beam is adjusted to a desired value in the channel 2 via the first and second feedback control systems. Hereinafter, similarly, the remaining three channels 3, 4, 5
The light amount of the light beam is sequentially adjusted to a desired value,
The light beam intensities of all the channels 1 to 5 on the light amount monitors match the reference signal, and the balance is in place.

Thereafter, the timing signal TS is set to L level, the solenoid 66 is demagnetized, and the photocell 61 is moved to a position where the light beam is not blocked. Then, when the amounts of light beams in all the channels 1 to 5 become uniform, the scanning of the photosensitive material 63 attached to the rotating drum 37 is started. Next, based on the image signal, the dot generator circuit 40 outputs the signals D1 to D5 to the OR gate 1 of each channel.
Give 9 Accordingly, the light emitting diodes 17 provided in each channel emit light when the signals D1 to D5 are input to the OR gate 19. This time is a scanning exposure period as shown in FIG.
7 to L level signals T1a, T1b, T1c, T1d
Is output, the light emitting diode 17 emits light with the light amount based on the light emission data held by the comparator 16, and exposes the photosensitive material 63.

Also, during the scanning exposure, during the above-described blanking period, the first feedback control system sets the light emission amount of the light beam from the light emitting diode 17 of each of the channels 1 to 5 as the instruction, that is, the comparator 16. It is detected whether or not the light is emitted with the light amount based on the light emission data held at the time. If not, the light amount is controlled so that the light emission amount becomes as instructed. Specifically, as shown in FIG.
8a is detected, and thereafter, when the encoder slit 38b is detected by the encoder 36 at a fixed pulse number N, the timing signal generation circuit 37 outputs H level T1c to T5c.
Are output for, for example, 1.6 msec, and T1d to T5d are output for, for example, 1.8 msec. During this time, the comparators 16 of the channels 1 to 5 operate, and the light emitting diodes 17 of the channels 1 to 5 emit light simultaneously. Then, each light receiving diode 18 detects the light amount of the light beam generated from each light emitting diode 17 and feeds back the light amount data to the operating comparator 16 to control the light amount of the light beam. As a result, the light-emitting diodes 17 of the respective channels have the light amounts almost simultaneously as instructed.

Although a light emitting diode is used as a light beam generator in the above embodiment, the present invention is not limited to this, and another light source may be used. However, it is limited to those whose light emission amount can be adjusted by an electric signal. Further, in the above embodiment, the case where the number of light beams is five is described as an example. However, the present invention is not limited to five, and the same applies to a scanning device using two or more light beams. Applicable to

[0027]

As described above in detail, according to the present invention, the second light amount detecting means is moved to a position where the light beam for exposure is not blocked when the photosensitive material is scanned and exposed, and the light amount of the light beam is reduced. Since the light beam is moved to a position where the light beam is blocked when the light beam is detected, the light beam for the light exposure is not attenuated by the second light amount detecting means during the scanning exposure, and the light amount loss does not occur. In addition, since the light beams illuminated one by one from a plurality of light beam generators are incident on the second light amount detecting means, the second feedback control means performs the detection based on the light amount detected value of each light beam. Feedback control to equalize the light amounts among the plurality of light beam generators, and in each light beam generator, based on the light amount data detected by the first light amount detection means, each light beam generator The first feedback control means provided respectively adjusts the light amount of the light beam output from the light beam generator by performing feedback control individually, and further controls the electric signal given to the light beam generator. Therefore, the beam balance adjustment can be easily performed without any trouble.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a multiple beam scanning device according to the present invention.

FIG. 2 is a schematic diagram showing a reduction optical system.

FIG. 3 is a diagram showing the periphery of a scanning rotary drum.

FIG. 4 is a time chart when performing an automatic beam balance adjustment.

FIG. 5 is a time chart of light amount control performed during a blanking period.

FIG. 6 is a diagram showing a photocell position switching mechanism.

FIG. 7 is a block diagram showing a conventional multiple beam scanning device.

[Explanation of symbols]

 1 to 5 channels 12 comparator 13 buffer 14 A / D converter 15 D / A converter 16 comparator 17 light emitting diode 18 light receiving diode 20 reference density signal generating circuit 30 timing determination device 50 reduction optical system 60 light quantity monitor 61 photocell 62C / V converter

Claims (1)

(57) [Scope of request for utility model registration] 1. A multi-beam scanning apparatus for performing scanning exposure on a photosensitive material with a plurality of light beams, a light beam generator provided for each light beam and adjusting a light emission amount based on an electric signal; A first light amount detecting means provided for the beam generator, for detecting the light amount of the light beam emitted from each light beam generator, and passing through an optical system for forming an image on the photosensitive material When the scanning exposure is performed, the light beam is moved to the former position and does not detect the light beam amount, but detects the light beam amount. A second light amount detecting means for moving to the latter position and detecting respective light amounts of the plurality of light beams one by one at different timings; and a first light amount detecting means provided for each light beam generator. Light detected by means Feeding back the electrical signal based on the data, the light quantity adjustment of the light beam generator first
Feedback control means, and second feedback control means for feeding back an electric signal based on the light quantity data detected by the second light quantity detection means to equalize the light quantity among the plurality of light beam generators. Multi-beam scanning device.