JP2787816B2 - Optical scanning device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device that scans a light beam on a surface to be scanned, and in particular, controls the light beam to form an appropriate spot on the surface to be scanned. The present invention relates to an optical scanning device suitable for recording and reading a high-definition image.

2. Description of the Related Art Conventionally, in an optical scanning device that scans and exposes a light beam onto a recording medium surface, a part of an optical system or an optical system is used to maintain a scanning position of the light beam at a constant position on the recording medium surface. A method of driving a partially provided reflecting mirror or the like is known (for example, see JP-A-61-190311, JP-A-61-278814, and JP-A-59-15217).

At this time, the information used to control a part of the optical system and the like includes a detecting means for detecting unevenness in the feeding of the recording medium, and a storage means for preliminarily storing surface tilt information of a polygon mirror or the like as a deflector. (For example, see JP-A-59-1).
No. 5217, JP-A-61-190311).

A method of driving a light source or a part of an optical system is known as a method of keeping the image point of a light beam at a constant position from the surface of a recording medium at the time of exposure scanning (for example, see Japanese Patent Application Laid-Open Publication No.
63-78167). At this time, as information for controlling this, information obtained by a photodetector provided in a part of the optical system or information already stored in a storage means is used (for example, Japanese Patent Application Laid-Open No. 60-100113). No., JP-A-61-25367).

[Problems to be Solved by the Invention] However, in the above conventional example, for example, when the imaging position of the light beam is kept constant or the scanning position is kept constant by the information obtained from the storage means, There is a problem that the correction control becomes impossible when the position shift or the optical scanning position shift occurs due to a cause other than the information related to the information stored in the storage means.

In addition, when correction control is performed based on information obtained from a photodetector provided in a part of the optical system or a detection unit for detecting unevenness of the recording medium, the imaging position shift and the scanning position over the entire scanning line are required. It is extremely difficult to correct and control the deviation in terms of the configuration of the apparatus, and it is necessary to perform the correction from the detection of information in almost real time. This is also extremely difficult in view of the processing time of the electronic circuit.

Accordingly, an object of the present invention is to provide an optical scanning device capable of effectively correcting and controlling at least one of an imaging position shift and an optical scanning position shift that occur during scanning in order to solve the above-described problems. is there.

[Means for Solving the Problems] In the present invention for achieving the above object, a light beam from a light source is connected to a scanning means for one-dimensionally scanning the light beam, and a light beam from the light source is formed on a scanning object. In an optical scanning device that condenses and scans the object to be scanned through an imaging unit that forms an image,
The optical scanning position is scanned based on information from at least one of the first detecting means for detecting the optical scanning position on the object to be scanned and the second detecting means for detecting the image forming position of the light beam, and the information from the first detecting means. The imaging position of the light beam is set in the optical axis direction of the imaging unit based on information from the first control unit and the second detection unit that control the surface in a direction perpendicular to the surface (the surface formed with time of the scanning beam). And at least one of the second control means for controlling, and it is determined that at least one of the optical scanning position and the image forming position of the light beam has been stabilized within a predetermined fluctuation range, and then it is possible to perform an intended operation such as scanning recording. It is configured to start a scanning operation.

[Operation] In the present invention having the above-described configuration, the scanning recording or the like is performed after the imaging position or the scanning position of the light beam is once stabilized within the predetermined fluctuation range in the entire effective scanning area. The desired scanning operation can be performed while keeping the light beam in a predetermined state over all the scanning lines without excessively burdening the configuration.

Embodiment FIG. 1 shows a first embodiment of the present invention.
1 is a light source device comprising a semiconductor laser and a collimator lens, 2 is a control system for at least one of an image forming position and a light scanning position of a light beam, and 3 is a rotary polygon mirror for deflecting and scanning a light beam from the light source device 1. Reference numeral 4 denotes a driving motor of the rotary polygon mirror 3, 5 denotes a scanning lens system, 6 denotes a photosensitive drum, 15 denotes a CCD, M
A light beam detector using a two-dimensional imaging device such as an OS, 16 is a beam splitter that partially divides a scanning beam and guides it to a light beam detector 15, and 17 processes a signal obtained by the light beam detector 15. A signal processing circuit, 18 is a control circuit that issues a control signal to the control system 2 based on an output signal of the signal processing circuit 17, and 19 is a light source device that drives the light source device 1 based on image data and an output signal of the signal processing circuit 17. This is a light source drive control circuit.

In the first embodiment having the above configuration, first, the light source device 1
Therefore, in order to stabilize at least one of the image forming position and the scanning position of the light beam within a predetermined range, a light beam that is weak enough not to be exposed on the recording body 6 is emitted. This light beam is scanned by the rotating polygon mirror 3 and the scanning lens 5
Then, the light is guided to the light beam detector 15 via the light beam splitter 16. At this time, the light beam detector 15 and the signal processing circuit 17 for detecting the spot diameter and scanning position of the light beam,
If the imaging position shift or the scanning position shift is detected, the control circuit 18 drives the imaging position and / or the scanning position control system 18 based on the detected information, and corrects the image forming position shift or the scanning position shift. Is done. After such an operation, if it is determined by the signal processing circuit 17 that the spot diameter or scanning position of the light beam has been stabilized within a predetermined range in the entire effective scanning area on the light beam detector 15, the processing circuit 17 A signal is sent to the light source drive control circuit 19, and the light source drive control circuit 19 starts driving the light source device 1 based on the image data.

FIG. 2 shows a second embodiment. In the figure, reference numeral 16 'denotes a reflecting mirror which reflects all light beams to the light beam detector instead of a splitter for partially splitting the scanning light beam, and 20 denotes a reflecting mirror based on an output signal of the signal processing circuit 17. This is a control system for driving the reflection mirror 16 ', and the other members or elements having the same reference numerals as those in FIG. 1 are the same.

In the second embodiment, after the above-described correction control, it is determined that the image forming position and the optical scanning position of the light beam have been stabilized within a predetermined fluctuation range, and the light source device 1 transmits the light beam carrying the image information. Immediately before the start, the reflection mirror 16 ′ is flipped up by a signal from the signal processing circuit 17 so that the light beam is exposed on the recording body 6.

FIG. 3 shows a third embodiment in which the beam splitter 16 is removed and the light beam detector 21 is replaced.
Is disposed at a position immediately before the recording body 6. Further, a control system 22 for driving the light beam detector 21 based on the output signal of the signal processing circuit 17 is provided.

In the third embodiment, after the above-described correction control operation, it is determined that the imaging position and the scanning position of the light beam have been stabilized within a predetermined range, and the light source device 1 sends a light beam carrying image data. At this time, the light beam detector 21 is raised or lowered from the position shown in FIG. 3 by a signal from the signal processing circuit 17, and the light beam is exposed on the recording medium 6.

As the light beam detectors 15 and 21, any device can be used as long as it detects a light scanning position or an image forming position.

For example, the fact that the light beam deviates from a predetermined scanning line on the recording body 6 or is inclined with respect to this scanning line means that a pair of photoelectric conversion elements extending along the scanning line is recorded as described above. The detection is performed with a detector arranged at a position optically equivalent to the body 6. When a light beam is scanned along a predetermined scanning line, the same amount of light is detected by the pair of photoelectric conversion elements, and is processed by the signal processing circuit 17 so that the light scanning position is appropriate. Is detected. However, when the light beam deviates from a predetermined scanning line, a large amount of light is detected in one of the photoelectric conversion elements, and the light is detected by a processing circuit.
The processing at 17 detects the degree of the deviation. Also,
The inclination of the light beam with respect to the scanning line means that the magnitude of the amount of light detected from one photoelectric conversion element to the other photoelectric conversion element changes, and the degree of the change is measured by the processing circuit 17 to obtain the inclination. Is detected.

By driving the control system 2 based on such detection information of the optical scanning position, the optical scanning position is appropriately controlled. As means for moving the optical scanning position, a light source, a scanning unit, an imaging unit, In general, any method or means capable of tilting the optical axis, such as a method of driving at least a part of the object to be scanned, may be used.

As a means for detecting the image forming state of the light beam, for example, a slit-shaped photoelectric conversion element extending at right angles to the scanning line is arranged at a position optically substantially equivalent to the recording body 6.

If the imaging position of the light beam is in a predetermined relationship with respect to the recording body 6 which is the surface to be scanned, for example, a slit-shaped photoelectric conversion element detects a maximum peak value, or a spot having a light amount distribution with a minimum dispersion. Or is detected as a spot with the maximum sharpness, and is processed by the processing circuit 17 to detect that the image position of the light beam is appropriate.

Then, by driving the control system 2 based on such detection information of the image forming position, the image forming position is appropriately controlled. However, such an image forming position moving means also includes a light source,
In general, any method or means that can change the focal length or the like of the imaging system, such as a method of driving at least a part of the scanning means and the imaging means, may be used.

In the above-described correction control, the control system 2 is fixed to an appropriate position by performing laser scanning a plurality of times in advance before performing recording or the like. However, when a certain environmental change occurs, the correction control operation is performed intermittently. May be performed.

Further, the light beam detectors 15 and 21 may have a function of detecting only one of the imaging position and the optical scanning position, or may have a function of detecting both of them. With such a structure, it is possible to adopt a configuration in which the elements for detecting the imaging position and the optical scanning position are alternately arranged. Then, for example, switching is performed for each light beam scanning, and the output from the element having one function is processed by the processing circuit 17 to perform correction control. Of course, a light beam detector having each function may be separately provided and processed by the respective processing circuits to separately and simultaneously perform the correction control operation.

[Effects of the Invention] As described above, according to the present invention having the above-described configuration, scanning recording or the like is performed after the imaging position and / or the scanning position of the light beam is stabilized within a predetermined range. The position of the light beam or the light condensing state over the entire effective scanning area during image recording and the like can be determined without imposing an excessive burden on the apparatus, and without complicating or complicating the apparatus. Above can be kept properly.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention, FIG. 2 is a block diagram of a second embodiment of the present invention, and FIG. 3 is a block diagram of a third embodiment of the present invention. 1 light source device, 2 control system, 3 rotating polygon mirror, 5
... Scanning lens system, 6 photosensitive drums, 15, 21 light beam detector, 16 beam splitter, 16 'reflection mirror, 17 signal processing circuit, 18 control circuit, 19 …… Light source drive control circuit, 20, 22 …… Control system

Claims (2)

(57) [Claims] An optical scanning device for condensing and scanning a light beam from a light source on a scanned object via a scanning means and an image forming means,
First detection means for detecting an optical scanning position on the object to be scanned, and first control means for controlling the optical scanning position in a direction perpendicular to the scanning surface based on information from the first detection means. And
An optical scanning device configured to start an intended scanning operation after it is determined that an optical scanning position is stabilized within a predetermined fluctuation range. 2. An optical scanning device for condensing and scanning a light beam from a light source on a scanned object via a scanning means and an image forming means,
First detecting means for detecting the image forming position of the light beam, first control means for controlling the image forming position of the light beam in the optical axis direction of the image forming means based on information from the first detecting means, A second detecting means for detecting the upper light scanning position, and a second controlling means for controlling the light scanning position in a direction perpendicular to the scanning surface based on information from the second detecting means; An optical scanning device configured to start an intended scanning operation after it is determined that a scanning position and an image forming position of a light beam are stabilized within predetermined fluctuation ranges, respectively.