JP2002311359A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scanner capable of constituting a precise and fast output machine therewith which can handle a large-size plate material and has a small spot diameter. SOLUTION: By combining a plurality of scanning units which can be controlled independently and having a scanning unit main body and an image forming lens part exchangeable to each other, the scanner for the output machine for outputting a press plate for printing can be constituted. A unit 1210 to a unit 4 240 being the scanning unit is installed horizontally so that adjacent scanning lines can be overlapped. Sensors 422, 424 and 426 capable of detecting a scanning line are installed on the image forming surfaces of the overlapping parts of the adjacent scanning lines (overlapped printing areas).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer to plate (hereinafter abbreviated as "CTP") output machine for outputting a printing plate used for printing and a CAD output for a printed circuit board on a film. The present invention relates to an optical scanning device used for a plotter for outputting, a photo typesetting machine for outputting a printing plate, and the like.

[0002]

[Technical background] In the printing industry, currently called CTP, the data from a typesetting editor is printed directly on a printing plate (offset plate, etc.), eliminating the need for a film or other underprinting material. The system to do it is beginning to spread. Exposure in these CTP output machines is based on the relative movement between the plate material and the scanning light source. 1) Internal drum method The plate material is fixed on the inner surface of the drum, and is rotated at high speed while moving in the center axis direction inside the drum. 2) External drum method A plate material is fixed on the outer surface of the drum, and the rotation of the drum and the movement of the drum itself in the direction of the rotation axis are performed. Alternatively, a method of scanning with a laser beam moving parallel to the rotation axis 3) Planar scanning method While scanning the laser beam with one scanning mirror,
The method is classified into a method of moving the laser beam for scanning while fixing the plate material in parallel to a plane, and a method of moving the plate material planarly while fixing the scanning laser beam. In many cases, one laser light scanning module is used in these systems.

A scanning apparatus 100 using a plurality of scanning modules having a configuration as shown in FIG. 1 also exists. In the scanning device 100 shown in FIG.
7, 127, 137. These scanning lines are assigned to the respective scanning modules 110, 120 and 130. Scanning modules 110, 120, 13
Numeral 0 is composed of scanning mirrors (polygon mirrors) 113, 123, 133 for scanning and lens units 114, 124, 134, respectively. This scanning module comprises deflection units 111, 121, 13
1 modulates the incident laser light according to the print data, and then the mirrors 112, 122, 132
3, 123, 133 and the lens unit 11
4, 124, 134 on the scanning surface, the scanning lines 117,
127 and 137. Scan lines 117, 127, 137
Are scanned in this order to form a scan path. There are sensors 118, 128, 138 and 148 for detecting the intersection between the start point and the end point on the printing surface of the scanning line. The intersection between the end point of one scanning line and the start point of the next scanning line is monitored, and deflection is performed. The units 111, 121, and 131 are controlled so as to form one line. As shown in FIG. 1, sensors 118, 128, 138, and 148 for detecting the intersection are provided between the respective scanning modules before the printing surface.

[0004]

In a system in which a plate material is moved on a flat surface and scanned by a laser beam in a direction perpendicular to the moving direction with one polygon mirror or the like, printing is performed, and the optical system becomes huge. Due to the above reasons, it is not possible to take a very large scanning width, and because the optical system is enlarged, the optical path length is increased and the spot of the laser beam is increased, so that a large-sized output device such as A1 or A0 can be used. Was unsuitable. That is, if the distance between the polygon mirror and the plate material is reduced and the scanning angle is increased, the spot diameter of the laser beam is different between the center and the end of the scanning, so that the optical system for correcting this becomes large. Conversely, if the scanning angle is reduced by increasing the distance between the polygon mirror and the plate material, the optical path length increases and the device becomes larger,
As described above, it becomes difficult to reduce the spot diameter of the laser beam. Further, in order to increase the scanning speed, it is necessary to rotate the polygon mirror at high speed, but it is difficult with a large polygon mirror. Also, in order to reduce the scanning angle, a scanning device using a plurality of scanning modules has conventionally been a method of sequentially scanning with a scanning module, and the scanning time per scan was not short.
As described above, in the conventional output device, when the output product becomes large, the device becomes large, the mechanism becomes complicated, and further, high accuracy is required, so that the output device is expensive. Further, even if the scanning is performed in a plurality of scans, the scanning time is not reduced. Therefore, an object of the present invention is to provide a scanning device capable of configuring a high-precision, high-speed output device or the like having a small spot diameter, capable of handling a large-sized plate material, and providing a highly versatile optical scanning unit. That is.

[0005]

In order to achieve the above object, the present invention relates to an optical scanning device having a plurality of scanning units, wherein the scanning unit comprises a scanning unit main body and an imaging lens unit. The scanning unit body is configured to be interchangeable, the laser light source modulated by an image signal, a lens for collimating light from the laser light source, a scanning mirror for scanning a light beam emitted from the lens, A motor for rotating the scanning mirror, a rotation sensor for detecting the rotation speed of the motor, a mirror surface detection sensor for detecting the phase of the scanning mirror,
An origin sensor for detecting a scanning start point and an end point,
The image forming lens unit has a lens for forming an image of a light beam from the rotating mirror, and includes an image processing unit that divides and transmits an image signal corresponding to each scanning unit to the plurality of scanning units. A control unit for controlling scanning by a signal from each of the sensors, wherein the plurality of scanning units perform scanning simultaneously under the control of the control unit. Thus, since the scanning unit main body is provided with the origin sensor and the scanning unit main body and the imaging lens are configured to be interchangeable with each other,
It is possible to use an appropriate imaging lens unit according to the object to be scanned, and to simplify the mounting of the scanning unit. For this reason, by using this optical scanning device, it is possible to configure a high-precision, high-speed output device that can handle a large-sized print medium, has a small spot diameter, and has a small diameter. There are a plurality of laser light sources modulated by an image signal of the scanning unit main body, the image processing unit divides an image signal according to the plurality of laser light sources, and the plurality of scanning units are provided to the control unit. It is also possible to adopt a configuration in which scanning is performed simultaneously by a plurality of scanning lines while being controlled. With this configuration, scanning can be performed quickly. Further, since the scanning unit main body can further include a laser light source for the origin sensor, it is not necessary to use a laser whose output changes according to the scan target for origin detection,
A stable origin output signal can be obtained. The control unit includes, for each of the plurality of scanning units, a video clock generation circuit that variably generates a video clock frequency based on a signal from an origin sensor that detects the scanning start point and the end point. The length can be adjusted. Further, for each of the plurality of scanning units, an attitude control mechanism having a tilt mechanism for adjusting the inclination of the laser scanning line and an optical axis height adjusting mechanism for adjusting the vertical position of the laser scanning line. Is provided, it is possible to adjust the inclination and height of the scanning line for each scanning unit. The plurality of scanning units are arranged so that the areas that can be scanned overlap each other, and a sensor that detects scanning is arranged in an area where scanning between the scanning units overlaps or an equivalent position, and the control unit is configured to detect the scanning from the sensors. By controlling the connection position of the scanning of each scanning unit by the connection point detection signal, the connection of the scanning lines of the adjacent scanning units can be matched. The control unit has, for each of the scanning units, a memory that stores an image signal to be printed by the unit, and the capacity of the memory is a capacity that can also store an image signal of a portion where scanning overlaps. The image processing means can add a non-printing signal when dividing and sending the image signal to each unit, and controls the scanning connection position of each scanning unit by the added non-printing signal. You can also. Furthermore, a sensor for measuring the unevenness of the medium on the laser scanning surface in an area where the scanning between the scanning units overlaps, the control unit controls the length and the connection position of the scanning line according to the measured unevenness of the medium And the connection of the scanning lines of the adjacent scanning units can be surely matched.
The control unit may control the connection position of the scanning lines to be changed so as to make the connection position of the laser scanning lines inconspicuous.

[0006]

Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 is an embodiment of the present invention.
FIG. 3 is a diagram illustrating a configuration of one scanning unit. FIG. 2 (a)
Is a plan view, and FIG. 2B is a front view. 2, a scanning unit 200 includes a scanning unit main body 300 including a light source and a scanning system, an imaging lens unit 390 including an fθ lens system for imaging the scanned laser light on an imaging scanning surface, and The posture control mechanism 360 is configured. The imaging lens unit 390 includes an fθ lens 394 and a cylindrical lens or a toric lens 396.
Contains. The laser beam passes through these two parts and reaches the imaging plane 400. The scanning unit main body 300 and the imaging lens unit 390 are detachably connected to each other. The attitude control mechanism section 360 has a tilt mechanism for adjusting the inclination of the scanning line by the laser light, and an optical axis height adjustment mechanism for adjusting the vertical position of the scanning line by the laser light.

<Scanning Unit Body> The scanning unit body 300 has a laser beam for generating a laser beam for printing.
Diode 320, LD collimator lens 321,
Beam splitter 322, cylindrical lens 3
23, a reflection mirror 324, a polygon mirror 330, and a motor 332 for rotating the polygon mirror. These form an optical scanning system for printing. In this embodiment, three printing lasers 320 are prepared and are slightly shifted up and down.
As shown in (b), scanning is performed simultaneously with three laser beams. Thus, printing can be performed three times faster than when one laser beam is used. The number of printing lasers 320 to be installed can be arbitrarily selected according to the printing speed. The three laser beams from the three printing lasers 320 change their course at right angles by the beam splitter 322, pass through the cylindrical lens 323, and enter the polygon mirror 330 by the reflection mirror. The polygon mirror 330 is rotated by a motor 332. Thereby, the incident laser light is reflected by one of the surfaces forming the polygon and is swung in the horizontal direction, so that the scanning operation can be performed. In order to detect the origin of scanning, mirrors 316 and 317 for directing light from the origin laser diode 310 and polygon mirror 330 to the origin detecting element, reflection mirrors 313 and 315, and origin detecting element are provided in the scanning unit main body 300. 352 and 354 are installed. At the start of scanning (when the laser beam comes to the lower side in FIG. 2A), the reflecting mirror 316
Since the laser light of the origin laser diode 310 is incident on the polygon mirror 330 from the polygon mirror 330, the laser light is reflected by the reflection mirror 316, reaches the TOP origin detection element 354 from the reflection mirror 317, and the scanning start point is detected. Is done. At the end of the scanning (when the laser beam comes to the upper side in FIG. 2A), the laser beam of the origin laser diode 310 returns to the reflecting mirror 324, and the laser beam is reflected by the reflecting mirror 313 and the origin lens. 314,
END origin detection element 352 via reflection mirror 315
And the end point of the scanning is detected. In order to synchronize the surfaces of the polygon mirror and the like, the surface detection optical sensor 356 integrating the light emitting element and the light receiving element is used.
The reference mark described above is detected once per rotation. Thereby, the phase (position) of the polygon mirror can be detected. In the scanning unit of the embodiment, a DC brushless motor having a rotation speed detection sensor using a Hall element is used as a motor for driving the polygon mirror. When the scanning unit is configured in this manner, the distance from the polygon mirror 330 to the imaging plane 400 can be reduced, and the spot diameter of the laser beam at the center and the end of the scanning becomes almost the same. The diameter can also be easily reduced. Since the scanning angle is small, the optical system can of course be small and can be configured at low cost. Further, since everything related to scanning, such as the origin mechanism, is included in the scanning unit main body 300, the imaging lens unit 390 can be completely separated, and it can be easily changed to various types of devices having different specifications. That can be dealt with.

<Scanning Device> By combining a plurality of the scanning units described above, a scanning device for a computer toe plate (hereinafter abbreviated as CTP) output machine for outputting a printing plate, for example, can be constituted. . FIG. 3 shows FIG.
3 shows an example of a scanning device configured by combining four scanning units shown in FIG. 3, a unit 1 210 to a unit 42 which are the scanning units shown in FIG.
40 is set horizontally so that adjacent scanning lines can overlap each other. Sensors 4 capable of detecting the scanning lines are provided on the imaging scanning surfaces of the portions where the adjacent scanning lines overlap (overlap printing area) 412, 414, and 416.
22, 424, 426 are detachably installed.
Sensors 421 and 42 are also provided on the imaging scan planes at both ends of the scan.
8 may be removably installed. Further, the relationship between the mounting position of the rotating magnet of the DC motor and the polygon mirror and the reference mark position is the same in all the scanning units. With the scanning device having such a configuration, the respective scanning units operate simultaneously to perform desired printing at high speed on a medium relatively moving in a direction perpendicular to the light scanning on the imaging scanning surface. It can be carried out.

<Output System> FIG. 4 shows an example of the configuration of an output system incorporating the above-described scanning device. In FIG. 4, an output device 500 in which a print medium 510 moves on a plane
Has a scanning device configured by combining a plurality of scanning units 200 installed on a mount 520. In such a configuration, data from the design CAD system 560 is edited by an RIP (Raster Image Proc).
esor) via the multi-line interface 600 from the system 570 to each scanning unit for output.

<Control System of Scanning Device> The control system of the scanning device (the multi-line interface 600 in FIG. 4) will be described in detail with reference to FIGS. This control system can be configured using a microprocessor or the like. (Signal from Sensor) First, a signal from a sensor used in the control system of the scanning device will be described with reference to FIGS. FIG. 5 is a diagram related to signals related to scanning, and FIG. 6 is a diagram for describing detection of a change in a print medium. As described in FIG. 3, the scanning units are arranged so that the scanning ranges overlap. FIG.
2A shows a signal for detecting the timing of the scanning. In the present embodiment, the scanning is performed by rotating the polygon mirror 330 of the scanning unit shown in FIG. The timing corresponding to one surface of 330 is shown. Signal 1 is a scanning start point signal, which is a signal from the TOP origin detection element 354 in FIG. Signals 2 and 3 are signals (connection start point signal and connection end point signal) for starting or ending printing by a certain scanning unit in an area where the scanning ranges overlap (overlap printing area). Sensor 4 in
21, 422, 424, 426, and 428. This sensor arrangement is also shown in FIG. As shown in FIG. 5B, the detection of the connection start point for the scanning unit n is also the detection of the connection end point for the scanning unit n-1. Therefore, by adding a sensor for starting the detection of the connection point of (n + 1) to the unit n, it is possible to obtain a connection start point signal and a connection end point signal apparently for n unit units. In addition, it is not always necessary to arrange these sensors on the printing surface, and when the sensors cannot be arranged on the printing surface, by using a mirror or the like, a connection start point and a connection end point from the overlapping area of the printing surface are determined. It may be arranged at an equivalent position where an equivalent signal can be detected. The signal 4 is a scanning end point signal, which is a signal from the END origin detection element 352 in FIG. It should be noted that a sensor that generates a splice start signal and a splice end signal cannot receive laser light when a print medium is mounted, and is used without a print medium mounted. In the following description, the time between the scan start point signal and the scan end point signal is t, and the time between the connection start point signal and the connection end point signal is T. The fact that the actual correction value of each scanning unit can be set by obtaining signals from sensors having such a relationship will be described below.

In FIG. 4, the print medium 510 moving in a direction perpendicular to the scanning direction (sub-scanning direction) may be deformed at a position where printing is performed. This deformation may be a case where the print medium swells and becomes convex, and a case where it becomes concave and concave. If such a deformation occurs at the connection point of the scanning of the unit light unit described above, the scanning length is changed, and the scanning is interrupted or the line width is changed due to double scanning. Become. FIG. 6A shows units 1 and 2
Indicates that a dent is formed on the print medium in the overlap area of, and the print areas of the unit 1 and the unit 2 overlap, and the scanning is performed twice. To detect this, the depth of the dent (or the height of the bulge) Δ
L needs to be detected. FIG. 6B shows a sensor for detecting the deformation of the print medium. FIG. 6 (b)
In order to measure the distance L when the object 812 at the position A is at the position B, the laser light source 81
The light reflected from the object to be measured 812 from light 0 is received by a light receiving unit such as the objective lens 814 and the CCD 816 to detect the change L2. Thereby, the depth ΔL of the dent portion (or the height of the bulge portion) can be measured. Such a sensor may be arranged, for example, on an overlap area before the scanning device of the mounting base 520 in FIG. 4 is attached so as to detect deformation of the print medium in the overlap area before scanning. To When the printing medium is a photosensitive material, it is necessary to use a laser beam having a wavelength other than the photosensitive wavelength when the printing medium is a photosensitive material.

(Control Operation) FIG. 7 is a functional block diagram showing the relationship between control for each scanning unit and overall control. The parts that perform overall control include a polygon motor control unit 610, an image processing unit 620, and a print medium control unit 63.
0, print medium fluctuation detecting section 640, connecting point detecting section 650
There is. The print medium fluctuation detection unit 640 detects the deformation of the print medium described with reference to FIG. The connection point detection unit 650 outputs the start signal and the end signal of the connection point described with reference to FIG. As shown in FIG. 8, the configuration of these detection units 650 is such that a laser diode is detected by a photodiode
After that, the pulse converter 744 outputs a pulse signal having a constant width. The scanning unit control unit 700 that controls each scanning unit includes a print image signal control unit 710, a video clock delay unit 720, a video clock generation unit 730, a scan start point detection unit 740, a scan end point detection unit 760, and a mirror. There is a phase plane detector 780.
The scanning start point detection unit 740 and the scanning end point 760 are a scanning start point signal and a scanning end point signal which are detection signals from the TOP origin detection element 354 and the END origin detection element 352 in FIG. 2 (see FIG. 5A). Is output. These detectors also have the configuration shown in FIG. Further, the mirror phase plane detection unit 780 outputs a signal from the plane detection optical sensor in FIG. 2, and detects the position of the polygon mirror reflection surface of each scanning unit.

The control operation for the scanning unit and the like will be described with reference to the functional block diagram of FIG. 7 and the diagrams showing the configurations of FIGS. In FIG. 7, a polygon motor control unit 610 controls a motor that rotates a polygon mirror of each scanning unit, so that the rotation speed of the polygon mirror and the position (phase) of the reflection surface of the polygon mirror are controlled.
Is controlling. When the polygon motor control unit 610 detects that the rotation of the polygon mirror of each scanning unit has become the same based on a signal from a rotation speed sensor installed in the motor, the polygon motor control unit 610 outputs the polygon and mirror signals from the mirror phase detection unit 780. Based on the phase detection signal of the reflection surface of the mirror, it is detected whether or not the reflection surfaces of the polygon mirrors of all the scanning units are substantially the same. If the phases are shifted, the motor is controlled to adjust the phases. In this way, when synchronization between the scanning units can be achieved, the image processing unit 6
20 develops print data in the order of printing, divides scanning lines corresponding to the number of laser diodes into signals corresponding to each scanning unit, and simultaneously transmits those signals to the print image signal control unit 710 of each scanning unit. I do. For example, when three laser diodes are used as shown in FIG. 2, image signals for three scanning lines are sent to each scanning unit. This signal is sent to the respective laser diode 320 of each scanning unit, which modulates the laser light generated therefrom. The laser beam that has now exited from the laser diode 320 is converted into a parallel beam by the collimator lens 321, and becomes a beam splitter 322.
At a right angle, passes through the cylindrical lens 323, and goes to the reflecting surface of the polygon mirror 330 by the reflecting mirror 324. Then, the polygon mirror 330 oscillates the laser light, passes through the fθ lens 394, converges on the cylindrical lens or the toric lens 396, forms an image on an image forming surface, and prints an image on a print medium.

(Video clock frequency) The time T during which one printing unit performs printing on a printing medium is determined by the video clock generation unit 730 of each scanning unit control unit 700.
T = (1 / f) × DOTS, where f is the video clock frequency generated in. DOTS represents the number of dots on a scanning line. Assuming that the video clock frequency is constant, the times t and T between the scanning start point and the scanning end point have the following relationship. If the mirror surface has jitter or the like and t becomes longer, that is, if the scanning speed of the mirror becomes slower, the time T does not change. Therefore, the length of the scanning line printed on the printing medium becomes shorter, and the scanning line between the scanning units becomes smaller. It loses connection. Conversely, when t becomes short, that is, when the scanning speed of the mirror increases, the length of the scanning line to be printed increases, and the scanning lines between the scanning units overlap. Therefore, in order to keep the length of the scanning line printed on the print medium constant even if there is surface jitter, etc., the frequency of the video clock is changed according to the variation of t, and the scanning time is changed. What should be done is.

(Correction of surface jitter) In order to keep the length of the scanning line printed by each scanning unit on the printing medium constant,
As described above, it is necessary to change the frequency of the video clock in response to the change in t to change the time for scanning the scanning line. However, the video clock frequency is corrected by the video clock generator 730.
This is performed using a scan start point signal, a scan end point signal, and the like. The operation of the video clock generator 730 will be described in detail with reference to FIG. FIG. 9 is a functional block diagram showing the configuration of the video clock generator in detail. In FIG. 9, the scanning start detection signal generated for each mirror surface in the i-th scanning unit is counted by a counter 739, and the counter 739 resets the count value by the mirror phase surface detection signal. Thus, the count value of the counter 739 can specify the mirror surface with reference to the phase surface detection signal. The correction of the inter-plane jitter will be described. The counter 735 counts the scanning time t from the scanning start point detection signal to the scanning end point detection signal using the reference clock from the clock generator 734. Now, _assuming that the video clock frequency of the i-th scanning unit is f _ik , the time between the start point and the end point corresponding to this f _ik is t _ik . Note that k is a polygon
Represents the mirror surface (1 to n) of the mirror 330, f _i1 , t
_i1 corresponds to the value of the mirror surface 1 of the i-th scanning unit. In FIG. 9, a numerical value for generating the f _{ik of a} certain plane k is set in each register 738 as an initial value f _i0 . In such a relationship, the correction described below is performed on the fluctuation of t _ik . (1) First, the counter 735 measures the time t _ik between the start point and the end point. (2) The arithmetic unit 736 _checks the difference between t _i0 and t _ik stored in the register k corresponding to a certain surface of the register 738. (3) Do nothing if they are the same. (4) If there is a difference, a new numerical value is set in the register 738 to change _{fik so} that the length of the scanning line is always kept constant. For example, when it becomes larger than t _ik f
so as to reduce the _ik, it is corrected so as to increase the _{f ik} when it becomes smaller than _{t ik.} (5) The above-described correction is performed for each surface. Note that _fi0 is set in advance as an initial value for each surface according to the distance between the start point and the end point, the number of motor revolutions, the focal length of the lens, the length of the scanning line on the print medium, the number of print dots (resolution), and the like. Sought and related. In this manner, the oscillation frequency value set in the register 738 by the arithmetic unit 736 is selected by the data selector 731 according to the mirror surface selection signal from the counter 739, and is converted into an analog value by the digital / analog converter 732. Then, the VCO 733 generates a video clock corresponding to the print mirror surface. The initial value for each surface can be obtained using the scanning start point signal and the scanning end point signal detected by the mirror surface of the polygon mirror. That is, the initial value in the video clock frequency correction is as shown in FIG.
Can be obtained in the register 738 using the time when the counter 737 measures the time from the connection start point to the connection end point in. Since this time is obtained by directly measuring the scanning line on the medium, the video frequency corresponding to the required number of dots on the medium can be accurately obtained. The correction in this case can be performed by closed-loop control, and it is possible to converge to an optimum value by measuring the time while changing the clock frequency. Note that the actual print medium may slightly deviate from the measurement position of the detection sensor. In this case, by multiplying the calculated value by a coefficient equivalent to the amount of deviation, it is possible to reduce errors in the print medium surface.

(Video clock generation circuit) Data selector 731, D / A converter 732, VCO 733 of FIG. 9
The clock generation configuration shown in FIG.
It can be replaced with a frequency synthesizer using an LL (phase lock loop) circuit. In FIG.
The signal from the oscillator 792 and the value from the register 738 are selected by the data selector 731 and set in the variable frequency divider 795, and the signal from the VCO 796 is frequency-divided by the value and compared by the phase comparator 793. And its output to a low-pass
The signal is returned to the VCO 796 via the filter 794. Thereby, the register 7 selected by the data selector 731
The value from 38 controls the oscillation frequency (video clock) of the VCO 796.

(Connection Correction) The connection of the scanning lines for printing between the scanning units is corrected by changing the delay amount of the video clock. This correction is performed at the position of the print medium by a signal from a sensor for detecting a connection point shown in FIG. The connection point detection sensor is attached to the start position of the scanning line of each scanning unit. The delay amount is corrected by the video clock delay unit 720 in FIG. First, the connection of scanning between the scanning units will be described with reference to FIG. FIG. 11A illustrates a case where the scanning time T between the scanning units is the same. FIG. 11A shows a case where the same number of dots are scanned by each scanning unit, which is a normal scanning. In this case, for example, as shown in FIGS. 11A and 11A, when it is detected that the scanning unit is entirely scanned on the left side, as shown in FIGS. It is necessary to control the scanning in the same way as shifting the entire scanning unit to the right. Further, as shown in FIGS. 11A and 11B, when it is detected that each scanning unit is entirely scanned to the right, the scanning is similarly performed by shifting the entire scanning unit to the left. Need to be controlled.
Although this is described in the case where the scanning lines are entirely displaced, it is necessary to similarly shift the scanning between the scanning units even when there are portions where the scanning lines overlap between the scanning units. This scanning is controlled by the delay of the video clock. Further, as shown in FIG. 11B, it is possible to control so that each scanning unit has a different scanning time T. This means that each scanning unit scans a different number of dots (different length). The control is performed in such a manner that the connection points of the scanning lines of each scanning unit are controlled so as not to be a straight line in the sub-scanning direction, for example, to be random for each scanning. If the point where scanning is connected is a straight line, it is conspicuous when there is an error in a slightly connected portion. This can be prevented by randomly shifting the connected portion by several dots for each scanning line. In order to control the connection of the scanning in this way, it is necessary to divide the image signal into the scanning units according to the length of the scanning line in accordance with the control of the connection. It should be noted that such a connection point can be controlled so as not to be a straight line in the sub-scanning direction, even if the scanning time T between the scanning units is the same. This is because, in FIG. 11A, the position of the connection start point (connection end point) in the overlap area is, for example, as shown in (1), (2), and (3), for example, every time scanning is performed. It is changed to. This can be done by delaying the video clock. FIG. 12 shows a detailed configuration of the video clock delay unit 720 that controls this connection.
Hereinafter, a control operation of connection correction by the circuit shown in FIG. 12 will be described. (1) The counter 722 measures the time from the scanning start point signal from the TOP origin detection element 354 attached to the polygon mirror side to the connection start point signal that starts the scanning line. (2) The calculating unit 723 calculates a delay amount in units of the number of dot clocks and a delay amount selection value of the delay line 728 for performing a smaller delay from the value from the counter 722, and stores the calculated value in the register 725. And 726 (3) Counter 724 for counting the number of video clocks
Becomes the value set in the register 725, the gate 727 is opened, and the video clock is supplied to the delay line 728.
, And the delay line 728 outputs the video clock with a delay of the amount set in the register 726. As a result, a video clock signal delayed according to the delay amounts set in the registers 725 and 726 is output. As shown in FIG. 11A, in order to correct the connection of scanning between the scanning units, the register 7 is used.
The determination of the delay amount of the video clock by setting to 25 or 726 may be performed at an arbitrary timing when there is no medium, such as immediately before printing. In order to control the connection at random, an initial value is set as in the case of the delay control, and then, for example, the register 725 and the register
It is necessary to change the value set to 26. this is,
12, a connection correction signal corresponding to a change in the connection of scanning lines from the image processing unit 620 is input to the calculation unit 723 to change the value set in the register.

In the above description, the connection position of the scanning lines is controlled by delaying the video clock using the delay circuit. However, it is provided in the print image signal control unit 710 for each scanning unit. The image processing unit 620 stores the image signal of each scanning unit in a memory for storing the image signal.
It can also be performed by controlling the image signal sent from the. This will be described with reference to FIG. FIG. 13 is a diagram showing the relationship between the print range of each scanning unit and the memory provided in the print image signal control unit 710 of each unit. In FIG. 13, it is assumed that the units 1 to 4 are printing the respective print ranges. The memory provided in each unit can store an image signal for printing the printing range corresponding to the number of scanning lines according to the number of laser diodes, and can also store an image signal of an overlap portion. Has capacity. The print image signal control unit 710 reads the image signal from the memory,
The output of the laser diode 320 is modulated by this signal to print on the print medium. The image signal stored in each memory is sent from the image processing unit 620 to the print image signal control unit 710 of each unit. The image signal sent from the image processing unit 620 to each unit has a configuration of non-printing data + image signal of printing range + non-printing data. "Non-printed data"
Is data for turning off the output of the laser diode and preventing printing, and is added by the image processing unit 620. By controlling the length of the “non-print data” before and after the “image signal in the print range”, it is possible to control the connection position of the scanning lines between the units. This control is performed by inputting a signal input to the video clock delay unit 720 to the image processing unit 620 and determining the length of “non-print data” to be added based on the signal.

(Correction of Medium Fluctuation) Fluctuation of the medium is shown in FIG.
An error is calculated based on the signal from the medium fluctuation detecting unit shown in FIG. 2B, and the error is corrected by changing the clock delay amount and the video clock frequency. Error a
Is a = tan, where ΔL is the depth of the dent (the height of the bulge) and θ is the angle of the laser to be scanned.
θ. It is necessary to correct this error a. First, as shown in FIG. 12, in order to correct with the delay amount of the video clock, the register 72 is changed according to the value of the print medium fluctuation signal input to the arithmetic unit 723.
The value set to 5,726 is corrected. If the amount of variation ΔL is large enough not to be controlled by the delay amount, for example, if the amount of variation is larger than the overlap region, then the correction is performed by changing the video clock frequency. As shown in FIG. 9, each of the registers 738 corresponds to the value of the print medium fluctuation signal input to the arithmetic unit 736.
This is done by correcting the set value to.

<Summary> In the above-described embodiment of the present invention, for example, a plurality of small scanning units having a scanning width of about 80 mm are arranged side by side from the end of the print medium to constitute an optical scanning apparatus. So that they can be scanned simultaneously. In this case, the number of dots scanned by one scanning unit is, for example, about 8000 dots. Each scanning unit has a small scanning width, so that the spot diameter of the laser beam can be reduced, and since the optical system is compact, it can be realized at low cost, and the focal length of the scanning lens of the scanning optical system is shortened. And high accuracy can be realized. Since the focal length of the scanning lens is reduced, the jitter performance of the mirror rotation motor, which is inversely proportional to the focal length, can be greatly improved, and high accuracy can be achieved at low cost. Since the size of the scanning mirror can be reduced, the rotation speed of the motor can be increased, and high-accuracy and high-speed printing can be performed. In addition, any size can be dealt with by increasing the number of scanning units. When a plurality of scanning units are used in this way, the scanning polygon mirrors need to rotate in synchronization with each other, and the scanning start of each scanning unit needs to be synchronized. In other words, the printing data is sent by the control circuit after the scanning line segments corresponding to the number of laser diodes are divided for each scanning unit, and the scanning position of each polygon mirror and the rotation of the polygon mirror are changed. If the numbers are different, the scanning lines cannot be accurately reproduced.
Therefore, in the embodiment of the present invention, for example, a sensor for detecting that the polygon mirror reflection surface of each scanning unit is oriented in a fixed direction is installed, and the polygon mirror reflection surfaces of all the scanning units have substantially the same reflection surface. And the start of scanning of each polygon mirror is synchronized. Since each scanning unit includes the entire scanning mechanism in the main body, the scanning unit also functions as a single unit. Therefore, it is possible to reduce the cost by mass-producing the same small unit. In addition, even if one of the scanning units fails, all the scanning units are almost the same. Therefore, by replacing the scanning units, good maintenance can be maintained. In addition, since the main unit of the scanning unit includes everything related to scanning, such as an origin detection sensor, it is possible to completely separate the imaging lens unit, and easily change to different types of devices with different specifications. That can be dealt with. In addition, since the laser for print scanning and the laser for origin detection, whose output varies depending on the print medium, are separated, the output signal of the origin detection sensor is stabilized by the laser for origin, which has a constant light intensity, so that it is always accurate. The origin can be detected.
At the time of connection in the sub-scanning direction, an attitude control mechanism is provided for each scanning unit so that adjustment can be performed for each scanning unit. Using this, it is possible to adjust the inclination of the scanning line and the vertical position of the scanning line for each scanning unit.

<Other Embodiments> In the above description, a case where a polygon mirror and a laser diode are used as an example has been described. However, a plane mirror is used instead of the polygon mirror, and a gas laser is used instead of the laser diode. The same configuration can be obtained by modulating the light with an AOM (ultrasonic light modulation element) or the like using the above method. FIG. 3 and FIG. 4
FIG. 14 shows an example in which the scanning units are arranged in a horizontal line. For example, as shown in FIG.
2, 222, 232, 242, and 252 can also be shifted in the sub-scanning direction. FIG. 14A is a view seen from above, and FIG. 14B is a perspective view. FIG.
As shown in (a), the respective scanning units are arranged so as to be shifted in the sub-scanning direction, and are arranged such that the respective units overlap. In the case of such a configuration, the light beam emitted from the imaging lens can have a telecentric imaging configuration in which the light flux is imaged vertically on the print medium. In the case of such a configuration for forming an image, the deviation (concavity and convexity) before and after does not matter, and it is not necessary to detect the irregularity of the print medium. In this case, the sensor for detecting the connection point cannot function as the start and end of the connection point as shown in FIG. In the above description, the case where the print medium is an output device that moves on a plane has been described as an example. However, it is apparent that the present invention can be applied to another method, for example, an external drum method. That is, as shown in FIG.
If a plurality of scanning units 210, 220, 230, and 240 are arranged so that the scanning direction is the same as the center axis of the drum, output can be performed with one rotation of the drum, and the scanning portion can be configured at low cost. The optical scanning device described above can be applied not only to printing on a medium, but also to, for example, processing of a material by strong laser light.

[0022]

By combining a plurality of scanning units according to the present invention described above, it is possible to configure a high-precision, high-speed output device capable of handling a large-sized print medium, having a small spot diameter. Further, the scanning unit is a highly versatile optical scanning unit because the scanning unit body and the imaging lens are configured to be interchangeable.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a scanning device having a plurality of scanning modules.

FIG. 2 is a plan view illustrating an optical system of a scanning unit according to an embodiment of the invention.

FIG. 3 is a diagram in which a scanning device is configured by combining a plurality of scanning units.

FIG. 4 is a diagram showing an overall system configuration of an output device incorporating a scanning device.

FIG. 5 is a diagram showing the timing of a signal from a sensor.

FIG. 6 is a diagram illustrating detection of unevenness of a medium.

FIG. 7 is a functional block diagram of a control system of the scanning device.

FIG. 8 is a block diagram for obtaining a signal from a sensor.

FIG. 9 is a block diagram of a video clock generator.

FIG. 10 is a diagram showing another configuration for generating a clock.

FIG. 11 is a diagram illustrating a relationship between usage of an overlap area and scanning time.

FIG. 12 is a block diagram illustrating a configuration of a video clock delay unit.

FIG. 13 is a diagram showing a relationship between a printing range of each scanning unit and a memory provided in each unit.

FIG. 14 is a diagram showing another arrangement configuration of the scanning unit.

FIG. 15 is a diagram showing another configuration of the output device.

[Explanation of symbols]

Reference Signs List 100 scanning device 110, 120, 130 scanning module 111, 121, 131 deflection unit 112, 122, 132 mirror 113, 123, 133 scanning mirror 114, 124, 134 lens unit 117, 127, 137 scanning line 200 scanning unit 300 scanning Unit main body 310 Laser diode for origin 313, 315, 316, 317 Reflection mirror 314 Lens for origin 320 Printing laser diode 321 Collimator lens 322 Beam splitter 323 Cylindrical lens 324 Reflection mirror 330 Polygon mirror 332 Polygon Mirror motor 352 END origin detecting element 354 TOP origin detecting element 356 Surface detection optical sensor 360 Attitude control mechanism 390 Imaging lens unit 394 fθ lens 396 toric lens or cylindrical lens 400 imaging plane 412, 414, 416 overlap printing area 421, 422, 424, 426, 428 sensor 500 output device 510 printing medium 520 mounting base 560 design CAD system 570 editing RIP system 600 Multi-line interface 610 Polygon motor control unit 620 Image processing unit 630 Print medium control unit 640 Print medium fluctuation detection unit 650 Joint point detection unit 700 Scanning unit control unit 710 Print image signal control unit 720 Video clock delay unit 730 Video clock Generator 740 Scan start point detector 760 Scan end point detector 780 Mirror phase plane detector 810 Laser light source 812 Measurement object 814 Objective lens 900 Print drum

 ──────────────────────────────────────────────────の Continuation of the front page (71) Applicant 501094018 Isamu Nitta 1130-9, Terachi, Niigata, Niigata (72) Inventor Kimio Omata 1-1-21, Ootabo, Urawa-shi, Saitama 17-55 Nakao-Shio, Chino-shi, Japan (72) Inventor Isamu Nitta 1130-9, Teriji, Niigata-shi, Niigata F-term (reference) 2C362 AA43 AA45 AA48 BA32 BA33 BA49 BA68 BA69 BA70 BA90 BB29 BB30 BB35 BB37 BB38 BB39 CB55 CB75 CB78 DA04 2H045 AA53 BA22 BA36 CA88 CA98 DA11 5C051 AA02 CA07 DA02 DB02 DB22 DB24 DB30 DC04 DC05 DC07 DE07 DE29 FA05 5C072 AA03 BA03 BA04 BA16 HA02 HA06 HA09 HA13 HB08 WA06 XA03

Claims (10)

[Claims] 1. An optical scanning device in which a plurality of scanning units are arranged, wherein the scanning unit is configured to be interchangeable between a scanning unit body and an imaging lens unit, and the scanning unit body is configured to transmit an image signal. A laser light source to be modulated, a lens for collimating light from the laser light source, a scanning mirror for scanning a light beam emitted from the lens, a motor for rotating the scanning mirror, and detecting a rotation speed of the motor. A rotation sensor, a mirror surface detection sensor that detects the scanning mirror phase, and an origin sensor that detects a scanning start point and an end point. The imaging lens unit forms an image of a light beam from the rotation mirror. Image processing means for splitting and transmitting an image signal corresponding to each scanning unit to the plurality of scanning units. No, the a control unit for controlling the scan by a signal from each sensor, said plurality of scanning units, the optical scanning device characterized by simultaneously scanning is controlled in the control unit. A plurality of laser light sources that are modulated by image signals of the scanning unit main body, wherein the image processing unit divides the image signal according to the plurality of laser light sources; , Controlled by the control unit,
2. The optical scanning device according to claim 1, wherein scanning is performed by a plurality of scanning lines at the same time. 3. The optical scanning device according to claim 1, wherein the scanning unit body further includes a laser light source for the origin sensor. 4. The control unit further comprises a video clock generation circuit for variably generating a video clock frequency based on a signal from an origin sensor for detecting the scanning start point and the ending point for each of the plurality of scanning units. The optical scanning device according to claim 1, wherein a length of the scanning line is adjusted. 5. A tilting mechanism for adjusting a tilt of the laser scanning line and an optical axis height adjusting mechanism for adjusting a vertical position of the laser scanning line for each of the plurality of scanning units. The optical scanning device according to claim 1, further comprising an attitude control mechanism. 6. The plurality of scanning units are arranged so that regions that can be scanned with each other are overlapped with each other.
The sensor which detects scanning is arrange | positioned, The said control part controls the connection position of the scanning of each scanning unit by the connection point detection signal from the said sensor, The Claims any one of Claims 1-5 characterized by the above-mentioned. Optical scanning device. 7. The control unit according to claim 1, wherein:
A video clock delay circuit for adjusting a position of the laser scanning line in the left-right direction, wherein a scanning connection position of each scanning unit is performed by controlling a delay amount of the video clock delay circuit. Item 7. The optical scanning device according to Item 6. 8. The control unit, for each of the scanning units,
A memory for storing an image signal to be printed by the unit; a capacity of the memory is a capacity capable of storing an image signal of a portion where scanning is overlapped; 7. The method according to claim 6, further comprising: adding a non-printing signal when dividing and transmitting the image signal; and controlling a scanning connection position of each scanning unit by the added non-printing signal. Optical scanning device. 9. A sensor for measuring unevenness of a medium on a laser scanning surface in a region where scanning between the scanning units overlaps, wherein the control unit controls a length of a scanning line according to the measured unevenness of the medium. The optical scanning device according to claim 6, wherein the optical scanning device controls the connection position. 10. The control section according to claim 6, wherein the control section controls the connection position of the scanning lines so as to make the connection position of the laser scanning lines inconspicuous. Optical scanning device.