JPH0610916U - Optical scanning device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide an optical scanning device capable of reducing the size and cost of the device and reliably detecting the position of scanning light for writing. The scanning light for monitoring L13 that has passed through the slit 25 of the scale 23 is reflected by the fifth reflection mirror 27 and the fourth reflection mirror 21 to enter the condenser lens 19, and is focused by passing through this condenser lens 19. The monitor scanning light L13 is supplied to the third reflecting mirror 17 and the sixth reflecting mirror 17.
The light is reflected by the reflecting mirror 29 and is reflected toward the condenser lens 31, and this condenser mirror 33 causes the scanning light for monitoring L13.
Is focused on the light receiving surface 35 of the photodetector 33.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical scanning device used for a laser photo plotter or the like.

[0002]

[Prior art]

 2. Description of the Related Art Conventionally, for example, in an optical scanning device used for a laser photoplotter or the like, light for writing (hereinafter referred to as writing light) is scanned and deflected in the main scanning direction by an optical deflector, and the polarized writing light ( Hereinafter, the scanning light for drawing) is passed through the fθ lens and then is irradiated to a scanning object such as a photoconductor to draw the printing information on the scanning object. Further, a condenser lens is arranged between the optical deflector and the scanning target so that the scanning light for drawing is vertically irradiated to the scanning target.

In the above-described optical scanning device, in order to obtain the timing of modulating the drawing light based on the print information input from the outside, the scanning light for drawing which is passed through the fθ lens is used for the drawing scanning light. The scanning position is detected, and the drawing light is modulated based on the detected scanning position. Specifically, for example, a scale is arranged at a position equivalent to a scanning target on the optical path of the monitor scanning light that has passed through the fθ lens and the condenser lens, and a plurality of slits provided at equal intervals on the scale are monitored. The scanning pulse of the drawing scanning light is detected by counting the number of pulses of the pulse signal obtained each time the scanning light for scanning passes, and the writing light is modulated at the timing according to the detected scanning position of the scanning light for drawing. It is carried out.

In such a conventional optical scanning device, for example, a condenser lens and a condenser lens are arranged behind the scale, and the scanning light for monitoring that has passed through the slit is converted by the condenser lens and the condenser lens. The light was collected on the light-receiving surface of the detector and the pulse signal was obtained from the output of the photodetector. Also, in other conventional devices, the scanning light for monitoring that has passed through the slit is made incident on the peripheral surface of the fluorescent optical fiber disposed in parallel with the scale behind the scale, and both ends of the fluorescent optical fiber are The light was guided to and received by the photodetectors arranged at both ends.

[0005]

[Problems to be solved by the device]

 However, in the conventional method in which the scanning light for monitoring that has passed through the slit is focused on the light receiving surface of the photodetector by the condenser lens and the condenser lens, a condenser lens that matches the length of the scale must be used. There was a problem that the lens became long and the cost was high. Further, since two condenser lenses must be used together with the condenser lens for vertically irradiating the scanning object with the scanning light for drawing, it is necessary to adjust the assembling of the condenser lenses for two when the apparatus becomes large. There was a problem that there was.

On the other hand, in the conventional method in which the monitor scanning light passing through the slit is incident on the peripheral surface of the fluorescent optical fiber, when the incident position of the monitor scanning light is the central portion in the longitudinal direction of the fluorescent optical fiber. There is a difference in the amount of light attenuation when the light is guided from the incident position to both ends of the fluorescent optical fiber, and the amount of light received by the photodetector varies, and There was a problem that the scanning position of light could not be detected accurately.

The present invention has been made in view of the above-mentioned problems, and it is possible to reduce the size and cost of the device, and to reliably detect the position of the drawing scanning light. The purpose is to provide.

[0008]

[Means for Solving the Problems]

 To achieve the above object, the present invention provides a condenser lens through which the scanning light for drawing and the scanning light for monitoring that have passed through the fθ lens pass, and an optical path of the scanning light for monitoring that passes through the condenser lens. A scale provided with a plurality of slits at intervals along the scanning direction of the monitor scanning light, and scanning of the drawing scanning light based on the monitor scanning light that has passed through the slits. In the optical scanning device for detecting the position, a reflection mirror that reflects the scanning light for monitoring and makes it enter the condenser lens is provided at a position where the scanning scanning light passing through the slit passes. The scanning position of the scanning light for drawing is detected based on the scanning light for monitor which has been made incident on the condenser lens and has passed through the condenser lens. To. Further, in the present invention, the monitor scanning light reflected by the reflection mirror is made incident on the condenser lens without passing through the scale. Further, according to the present invention, a condenser lens for collecting the monitor scanning light is arranged on the optical path of the monitor scanning light which is incident on the condenser lens by the reflection mirror and passed through the condenser lens.

[0009]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration of an optical scanning device according to a first embodiment of the present invention, which is provided in, for example, a laser photoplotter or the like.

The optical scanning device of the first embodiment shown in FIG. 1 has a configuration in which the light sources for the scanning light for monitoring and the scanning light for drawing are common, and in FIG. 1, 1 is a light source, which is a semiconductor laser. It outputs a light beam such as. Reference numeral 3 denotes a beam splitter, which splits the light beam output from the light source 1 into a writing light L1 and a monitoring light L3 for detecting a writing position. Reference numeral 5 is an optical shutter that modulates the drawing light L1 separated by the beam splitter 3 based on print information from the outside and makes it enter the polygon mirror 7, and 9 and 11 are monitors separated by the beam splitter 3. The first and second reflection mirrors reflect the light L3 toward the polygon mirror 7. The monitor light L3 reflected by the first and second reflecting mirrors 9 and 11 is incident on the upper side of the reflecting surface of the polygon mirror 7 in FIG. 1 rather than the drawing light L1.

The drawing light L1 and the monitor light L3 incident on the polygon mirror 7 are scan-deflected by the polygon mirror 7 along the main scanning direction X (corresponding to the scanning direction of the monitor scanning light) to draw. Scanning light L11 and monitor scanning light L13.

Further, reference numerals 13 and 15 in FIG. 1 constitute fθ lenses for scanning the drawing scanning light L11, which has been deflected by the polygon mirror 7 on the scanning target A, at a constant speed. The drawing scanning light L11 and the monitor scanning light L13 that have passed through the fθ first and second lenses are incident on the third reflection mirror 17. The third reflection mirror 17 reflects the drawing scanning light L11 and the monitoring scanning light L13 that have passed through the fθ first and fθ second lenses 13 and 15 toward the condenser lens 19.

The condenser lens 19 is for vertically irradiating the scanning light L 1 1 for drawing, which is reflected by the third reflection mirror 17, onto the scan target A, and the scanning for drawing which has passed through the condenser lens 19 is carried out. The light L11 is irradiated onto the scan target A, and the monitor scanning light L13 that has passed through the condenser lens 19 is incident on the fourth reflection mirror 21. The fourth reflection mirror 21 reflects the monitor scanning light L13 that has passed through the condenser lens 19 toward the scale 23. The scale 23 has a plurality of slits 25 at equal intervals along the main scanning direction X. It is provided in.

Reference numeral 27 in FIG. 1 denotes a fifth reflecting mirror that reflects the monitor scanning light L 13 that has passed through the slit 25 to the fourth reflecting mirror 21, and is used for the monitor reflected by the fifth reflecting mirror 27. The scanning light L13 enters the fourth reflecting mirror 21 without passing through the scale 23, is reflected by the fourth reflecting mirror 21 and enters the condenser lens 19. In the first embodiment, the fifth reflection mirror 27 corresponds to the reflection mirror described in the claims.

Further, reference numeral 29 in FIG. 1 denotes a sixth reflection mirror, which reflects the monitor scanning light L 13 reflected by the fourth reflection mirror 21 and focused by passing through the condenser lens 19 toward the condensing lens 31. To do. The sixth reflection mirror 29 is arranged at a position that does not block the optical paths of the drawing scanning light L11 and the monitoring scanning light L13 traveling from the fθ first and second lenses 13 and 15 to the third reflection mirror 17. There is. The condenser lens 31 condenses the monitor scanning light L 13 reflected by the sixth reflection mirror 29 on the light receiving surface 35 of the photodetector 33.

Although not shown in FIG. 1, in the optical scanning device of the first embodiment, the scanning position of the drawing scanning light L11 is determined based on the output signal of the optical detector 33. Based on the position detection unit for detecting, the control unit for controlling the operation of the entire optical scanning device, and the scanning position of the scanning light for drawing L11 detected by the position detection unit, the drawing light L1 is based on the print information. A driver for driving the optical shutter 5 provided for modulation is connected.

Next, the operation of detecting the scanning position of the drawing scanning light L11 in the optical scanning device of the first embodiment having the above configuration will be described. The drawing light L1 obtained by separating the light beam from the light source 1 by the beam splitter 3 enters the polygon mirror 7 after passing through the optical shutter 5. The scanning light L 11 for drawing, which is deflected by the polygon mirror 7 along the main scanning direction X, passes through the fθ first lens 13 and the fθ second lens 15 and then is directed to the condenser lens 19 by the third reflection mirror 17. Then, the condenser lens 19 irradiates the scan target A vertically.

On the other hand, in order to detect the scanning position of the drawing scanning light L11 on the scanning target A, the monitor light L3 obtained by separating the light beam from the light source 1 by the beam splitter 3 is The drawing light L1 reflected by the two reflection mirrors 9 and 11 toward the reflection surface of the polygon mirror 7 is incident on the upper side of the reflection surface of the polygon mirror 7 in FIG. The scanning light for monitoring L13 deflected by the polygon mirror 7 along the main scanning direction X passes through the fθ first lens 13 and the fθ second lens 15 and then undergoes the third reflection, like the drawing scanning light L11. The light is reflected by the mirror 17, passes through the condenser lens 19, and after passing through the condenser lens 19, follows a path different from the drawing scanning light L11.

The monitor scanning light L 13 that has passed through the condenser lens 19 is reflected by the fourth reflecting mirror 21 and is irradiated toward the scale 23, and only the monitor scanning light L 13 that has passed through the slit 25 of the scale 23. The light is reflected by the fifth reflection mirror 27 again toward the fourth reflection mirror 21. The monitor scanning light L13 reflected by the fifth reflection mirror 27 enters the fourth reflection mirror 21 without passing through the scale 23, is reflected by the fourth reflection mirror 21 and enters the capacitor lens 19.

The scanning light for monitoring L13 incident on the condenser lens 19 from the side of the fourth reflection mirror 21 is condensed to some extent by the condenser lens 19 and is incident on the third reflection mirror 17, and the third reflection mirror 17 After being reflected toward the sixth reflecting mirror 29, it is reflected toward the condenser lens 31 by the sixth reflecting mirror 29. Further, the monitor scanning light L13 is condensed by the condenser lens 31 on the light receiving surface 35 of the photodetector 33.

By the way, the monitor scanning light L13 applied to the light receiving surface 35 is the light that has passed through the slit 25 of the scale 23, and the slits 25 are equally spaced along the main scanning direction X as described above. It is provided. The scanning speed of the monitor scanning light L 13 on the scale 23 is constantly corrected by the fθ first and second lenses 13 and 15.

Therefore, the light receiving surface 35 of the photodetector 33 is intermittently irradiated with the monitor scanning light L13 condensed by the condensing lens 31 at equal time intervals, and accordingly, the photodetector 33. The number of pulses of the pulse signal output from the counter is counted by a position detection unit (not shown), and the scanning position of the drawing scanning light L11 is detected by the position detection unit. Then, the driver is controlled by a control unit (not shown) based on the detected scanning position of the drawing scanning light L11, and thereby the optical shutter 5 is driven, and the drawing light L1 is modulated based on the print information.

As described above, according to the optical scanning device of the first embodiment, the monitor scanning light L 13 that has passed through the slit 25 of the scale 23 is directed to the condenser lens 19 by the fifth reflection mirror 27 and the fourth reflection mirror 21. The monitor scanning light L13 is focused by the condenser lens 19 and is incident on the third reflection mirror 17, and the monitor scanning light L13 is condensed by the third reflection mirror 17 and the sixth reflection mirror 29. The light is reflected toward the lens 31 and the condensing lens 31 condenses the monitor scanning light L13 on the light receiving surface 35 of the photodetector 33. Therefore, the monitor scanning light L13 that has passed through the slit 25 can be condensed to some extent by passing through the condenser lens 19. Therefore, it is not necessary to use a condenser lens in the past even after passing through the scale. In order to focus the monitor scanning light L13 on the light receiving surface 35 of the photodetector 33, a relatively small and inexpensive condenser lens 31 can be used, and the optical scanning device can be made compact. Lower costs can be achieved.

Further, since the condenser lens 19 and the condenser lens 31 are used to irradiate the light receiving surface 35 of the photodetector 33 with the scanning light L13 for monitoring, the conventional fluorescent optical fiber is used for monitoring. Compared to the case where the scanning light is guided to the light receiving surface of the photodetector, the attenuation of the light during the light transmission is suppressed to a minimum, so the scanning position of the scanning light for drawing is kept constant while keeping the amount of light received by the photodetector constant. Can be accurately detected.

Furthermore, in the first embodiment, the monitor scanning light L13 that has passed through the slit 25 is reflected by the fifth reflecting mirror 27 to the fourth reflecting mirror 21 without passing through the scale 23. The monitor scanning light L13 reflected by the five-reflection mirror 27 does not pass through the slit 25 again. Therefore, the monitor scanning light L13 that has been irradiated onto the scale 23 from the fourth reflection mirror 21 side and passed through the slit 25 does not pass through the slit 25 when the scale 23 is irradiated for the second time. It is possible to prevent the monitor scanning light L13 from being affected by the change of the pulse width and the interval of the above. When the monitor scanning light L13 is irradiated with the scale 23 before and after the reflection by the fifth reflection mirror 27 and the above-described influence does not reach the monitor scanning light L13, the slit 25 The monitor scanning light L13 that has passed through may be reflected by the fifth reflection mirror 27 via the scale 23 to the fourth reflection mirror 21.

In the first embodiment, the monitor scanning light L13 that has passed through the slit 25 of the scale 23 is condensed on the light receiving surface 35 of the photodetector 33 by the condenser lens 19 and the condenser lens 31. However, the configuration shown in the next second embodiment may be adopted.

FIG. 2 is a perspective view showing a schematic structure of an optical scanning device according to a second embodiment of the present invention. In FIG. 2, the same elements as those of FIG. 1 are designated by the same reference numerals as those of FIG. Is attached and the description is omitted. Then, in the optical scanning device of the second embodiment, the monitor light L3 separated by the beam splitter 3 is pre-polarized by the λ / 4 plate 37, passes through the slit 25, and then passes through the condenser lens 19, The monitor scanning light L13 reflected by the three-reflection mirror 17 is further made to pass through the fθ second lens 15 and the fθ first lens 13 to be incident on the polygon mirror 7.

Then, the scanning light for monitoring L13 is reflected by the polygon mirror 7 and becomes a beam of light L5 toward the light source 1. Therefore, a polarization beam splitter 39 is arranged on the optical path of the beam light L5, the optical path of the beam light L5 is bent by the polarization beam splitter 39, and a photodetector is provided on the optical path of the bent beam light L5. 41 is provided and the light receiving surface 43 of the photodetector 41 is irradiated with the light beam L5.

With this configuration, the scanning scanning light L 13 that has passed through the slit 25 is condensed on the light receiving surface 43 by the same fθ first and second lenses 13 and 15 and the condenser lens 19. Therefore, it is possible to further reduce the size and cost of the optical scanning device.

Further, in the first and second embodiments, the optical scanning device in which the light source for the drawing scanning light L11 and the light source for the monitoring scanning light L13 are common has been described. It goes without saying that the light source of the scanning light for drawing may be provided separately, and the present invention can be applied to an optical scanning device used in, for example, a laser beam printer other than the laser photo plotter.

[0031]

[Effect of device]

 As described above, according to the present invention, the monitor scanning light that has passed through the fθ lens and the condenser lens, and then passed through the slit is reflected by the reflection mirror and re-enters the condenser lens, and then passes through the condenser lens. Since the scanning position of the drawing scanning light is detected based on the monitoring scanning light, the scanning scanning light that has passed through the slit is focused by the passage of the condenser lens again. Therefore, a condenser lens for condensing the monitor scanning light that has passed through the slit is not necessary, and the number of condenser lenses can be reduced to make the apparatus compact and low cost. Further, since the scanning light for monitoring that has passed through the slit can be finally collected on the light receiving surface of the photodetector, it is not necessary to let the scanning light for monitoring be received by the photodetector via the fluorescent optical fiber or the like. . Therefore, not only a fluorescent optical fiber is unnecessary, but also the attenuation of the light until the scanning light for monitoring is finally received by the photodetector can be suppressed to a minimum, so that the scanning light for drawing can be suppressed. The scanning position can be accurately detected. Further, according to the present invention, since the monitor scanning light reflected by the reflection mirror is incident on the condenser lens without passing through the scale, the monitor scanning light passing through the slit is reflected. The light does not pass through the slit again after being reflected by the mirror, so that it is possible to prevent the influence of the error due to the second passage of the slit from affecting the monitor scanning light.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an optical scanning device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a schematic configuration of an optical scanning device according to a second embodiment of the present invention.

[Explanation of symbols]

 13 fθ First lens (fθ lens) 15 fθ Second lens (fθ lens) 19 Condenser lens 23 Scale 25 Slit 27 Fifth reflection mirror (reflection mirror) 31 Condenser lens L11 Drawing scanning light L13 Monitor scanning light X Main Scanning direction (scanning direction of monitor scanning light)

Claims (3)

[Scope of utility model registration request] 1. A condenser lens through which the scanning light for drawing and the scanning light for monitoring that have passed through the fθ lens pass through, and a scanning light for monitoring that is disposed on the optical path of the scanning light for monitoring that has passed through the condenser lens. A scale provided with a plurality of slits at intervals along the scanning direction of, in the optical scanning device for detecting the scanning position of the scanning light for drawing based on the scanning light for monitoring that has passed through the slit, A reflection mirror that reflects the monitor scanning light and makes it enter the condenser lens is provided at a position where the monitor scanning light that has passed through the slit passes, and the reflection mirror makes the condenser lens enter the condenser lens and pass through the condenser lens. An optical scanning device, wherein the scanning position of the drawing scanning light is detected based on the monitor scanning light. 2. The optical scanning device according to claim 1, wherein the monitor scanning light reflected by the reflection mirror is incident on the condenser lens without passing through the scale. 3. A condenser lens for condensing the monitor scanning light is arranged on an optical path of the monitor scanning light which is incident on the condenser lens by the reflection mirror and has passed through the condenser lens. 2. The optical scanning device according to 2.