JP2003307689A - Optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a pitch interval control method in synthesizing the beams of a plurality of semiconductor lasers. <P>SOLUTION: The optical scanner is constituted of a plurality of semiconductor lasers, a plurality of collimating lenses, a laser synthesizing unit consisting of a prism and a laser driving device, a cylindrical lens, a polygon motor, an f-θ lens, a reflection mirror for a light receiving sensor, the light receiving sensor, and a beam pitch interval control circuit (including a beam position detection circuit and a laser rotating and driving circuit). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device for forming a latent image by scanning a plurality of laser beams modulated by image signals on a photoconductor, and performing sub-scanning pitch interval control of a plurality of semiconductor lasers. And an image forming apparatus therefor.

[0002]

2. Description of the Related Art An optical scanning device for forming a latent image by modulating a laser beam emitted by a laser beam driving circuit of a plurality of semiconductor lasers with an image signal and raster-scanning the laser beam onto a photosensitive drum by a scanner motor. A sensor that detects the pitch intervals of the plurality of laser beams is arranged near the photosensitive drum.

On the other hand, as a method for detecting the pitch interval, there are a method of measuring the time length of the output signal detected by the light receiving sensor, a method of detecting the peak of the voltage level, and the like.

[0004]

However, in the above-described conventional example, since the light receiving sensor and the optical scanning device are separately constructed, when the optical device is replaced, the place where the image forming mounting is installed. Will be forced to adjust in. Further, in the inter-pitch detection method, the measurement clock frequency in the time length measurement or the scale of the voltage level detection circuit increases in order to improve accuracy.

The present invention has been made to solve the above problems, and a first object of the present invention is to dispose a light receiving sensor in an optical scanning device so that the scanning pitch between the optical scanning device is increased. It is an object of the present invention to provide an optical scanning device which has been adjusted, does not require adjustment when exchanging the optical scanning device, and can realize an inter-pitch detection circuit with labor saving.

A second object of the present invention is to provide an optical scanning device capable of accurately detecting pitch intervals by measuring the pitch intervals of a plurality of semiconductor lasers.

[0007]

The first invention has been made in view of the above problems, and realizes the scanning beam interval detection with a labor-saving structure. In order to solve this problem, the optical scanning device of the present invention is provided with the lateral structure shown below.

That is, an optical scanning device having a plurality of semiconductor lasers and using the plurality of semiconductor lasers as a light source to generate a latent image on an image carrier, the optical scanning device rotating parallel to the optical axes of the plurality of semiconductor lasers. A laser rotation driving means for rotationally driving an axis, a beam scanning position detecting means for detecting scanning positions of the plurality of semiconductor lasers, and a scanning position for controlling the laser rotation driving means according to the result of the beam position detecting means. And a beam position detecting means at a position corresponding to a non-image area, which is the same as the distance from the light emitting points of the plurality of semiconductor lasers to the image bearing rest in the optical scanning device. The beam scanning position detecting means is composed of a photoelectric conversion element, and at least two or more are provided for each beam of the plurality of semiconductor lasers, and the intervals between the light conversion elements are substantially perpendicular to the main scanning direction. The semiconductor laser is arranged so as to be wider than the beam spot diameter of the semiconductor laser, and the center axis of the interval between the photoelectric conversion elements for an arbitrary laser beam among the plurality of semiconductor lasers and the center of the interval between the photoelectric conversion elements for the other laser beam. The axes are arranged at a pitch interval in the sub-scanning direction, the plurality of semiconductor lasers are all turned on or sequentially turned on, and the beam position detection means determines all beams of the plurality of semiconductor lasers or scanning positions for each beam. It is characterized in that the beam pitch is adjusted by the laser rotation driving means so that the output of the photoelectric conversion element is detected.

A second aspect of the present invention has been made in view of the above problems, and it is an object of the present invention to improve the accuracy of scanning beam interval detection. In order to solve this problem, the laser driving device of the present invention has the following structure.

That is, the plurality of semiconductor lasers are all turned on or sequentially turned on, and the beam position detecting means detects the scanning positions of all the beams or each beam of the plurality of semiconductor lasers, and outputs the photoelectric conversion elements. Laser rotation angle measuring means for measuring the angle of the laser rotation driving means when the rotation is not performed, rotation angle storing means for storing the result of the laser rotation angle measuring means, and preset from among the results of the rotation angle storing means It is characterized in that it has a beam interval setting means for selecting any of the above angles, and adjusts the beam pitches with the value selected by the beam interval setting means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the optical scanning device according to the embodiment.

The optical scanning unit 1 of this embodiment has a semiconductor laser a3 and a semiconductor laser b5.

Reference numeral 2 denotes a laser synthesizing unit, which comprises a semiconductor laser a3 and a semiconductor laser b5, a collimating lens a7 and a collimating lens b8, a prism 9, and a unit rotation driving section (not shown). The rotation axis of the rotation drive unit is parallel to the optical axes of the semiconductor laser a3 and the semiconductor laser b5 and is at the center.

In the non-image area, the laser beam a4 emitted from the semiconductor laser a3 has a collimating lens a7,
The light enters the prism 9 and the cylindrical lens 10 and reaches the polygon mirror 11. The polygon mirror 11 is rotated at a constant angular velocity by a scanner motor (not shown). The laser beam a4 reaching the polygon mirror 11 is polarized by the polygon mirror 11, and the f-θ lens 1
The light is converted by 2 to be scanned at a constant speed in the direction perpendicular to the rotation direction of the photosensitive drum 17, reflected by the reflection mirror a13, and received by the light receiving sensor 14. In the image area, the laser beam c15 is similar to the laser beam a4 in the f-θ lens 1.
After 2 is emitted, the photosensitive drum 17 is irradiated with light via the reflection mirror b16.

On the other hand, the laser beam b6 emitted from the semiconductor laser b5 enters the collimator lens b8 and the prism 9. Laser beam b polarized in prism 9
6 is combined with the laser beam a4 at a preset beam interval. In the non-image area, the light enters the cylindrical lens 10 and is polarized by the polygon mirror 11, f
The light enters the −θ lens 12, and the reflection mirror a13 causes the light receiving sensor 14 to receive the light. The image region is similar to that of the semiconductor laser a3 and will not be described.

The light receiving sensor 14 is located in the optical scanning unit 1 and is arranged at a position where the scanning lengths of the laser beam a4 and the laser beam c15 are the same with respect to the semiconductor laser a3.

FIG. 2 is a block diagram showing the sensor configuration of a light receiving sensor in the optical scanning device, and FIG. 3 is a flow chart for explaining the operation of the beam pitch control circuit.

In FIG. 2, reference numeral 21 denotes a beam position reference sensor, which determines an image writing position. Reference numeral 22a denotes a semiconductor laser a (hereinafter abbreviated as LD1) pitch sensor a, 22b.
Is an LDl pitch sensor b, which are arranged at right angles to the scanning direction of the laser beam and at intervals wider than the length in the direction perpendicular to the spot diameter of LDl. Also 23a
Is a semiconductor laser b (hereinafter abbreviated as LD2) pitch sensor a, and 23b is an LD2 pitch sensor b, which are arranged at intervals perpendicular to the scanning direction of the laser beam and wider than the length in the direction perpendicular to the spot diameter of LD2. ing. L
The distance between the Dl pitch sensor and the LD2 pitch sensor does not matter.

Next, the operation of the beam pitch control circuit 18 will be described. First, the LDl is turned on and the light receiving sensor 14 is scanned. The beam is detected by the LDl pitch sensor a22a. If detected, the laser rotation drive circuit 20 rotates the laser synthesizing unit, for example, in the clockwise direction (+ direction). LDl pitch sensor a22 again
When the beam is detected at a and the output signal is no longer detected, the LDb pitch sensor b22b performs the same detection. When the LD1 pitch sensor a22a and the LD1 pitch sensor b22b stop detecting signals, LD
The l spot 24a is located at the LDl pitch sensor a22a and the LDl pitch sensor b22b.

Then, LD1 is turned off, LD2 is turned on, and the light receiving sensor 14 is scanned. LD2 pitch sensor a2
The beam is detected at 3a. When detected, the laser rotation drive circuit 20 rotates the laser synthesizing unit counterclockwise (one direction). LD2 pitch sensor a again
When the beam is detected by 23a and the output signal is no longer detected, the same detection is performed by the LD2 pitch sensor b23b. When no signal is detected by the LD2 pitch sensor a23a and the LD2 pitch sensor b23b,
The LD2 spot 24b is the LD2 pitch sensor a23a.
And LD2 pitch sensor b23b.

(Second Embodiment) FIG. 4 is a block diagram showing the arrangement of a beam pitch control circuit according to the second embodiment of the present invention.

Reference numeral 25a denotes an output signal of the LDl pitch sensor a, which is waveform-shaped by the waveform shaping circuit a28 and inputted as a reset signal to the step counter a29. 25b is LD
The output signal of the sensor b between l pitches is waveform-shaped by the waveform shaping circuit b30 and is used as a hold signal, and the
Input to 9. The step counter a29 continues to output the reset signal while the LDl pitch sensor a output signal 25a is output, and simultaneously outputs the hold signal while the LDl pitch sensor b output signal 25b is output. Holds the count value of. The output signal of the step counter a29 is the count UP
The signal is input to the pitch counter 34.

Similarly, 26a is an output signal of the LD2 pitch sensor a, which is waveform-shaped by the waveform shaping circuit c31 and is inputted to the step counter b32 as a reset signal. 26b
Is the output signal of the LD2 pitch sensor b, and the waveform shaping circuit d
The waveform is shaped at 33 and is input to the step counter b32 as a hold signal. The step counter b32 is an LD
While the 2-pitch sensor a output signal 26a is being output, the reset signal is continuously output, and at the same time the LD 2-pitch sensor b output signal 26b is output, a hold signal is output and the count value of the step counter b32 is held. To do. The output signal of the step counter b32 is input to the pitch counter 34 as a count DOWN signal.

The pitch counter 34 is a semiconductor laser a.
(Hereinafter abbreviated as LD1) 3 and a semiconductor laser b (hereinafter referred to as LD2
A counter for measuring the pitch interval of 5 measures the difference value between the adjustment angle of LD1 and the adjustment angle of LD2. The output signal of the pitch counter 34 is a motor control signal generation circuit 35.
For controlling the rotation direction of the laser synthesizing unit 2
A signal and a STEP signal for controlling the rotation speed are generated. The laser rotation drive circuit 20 generates a K-bit motor drive signal based on the DIR signal and the STEP signal.

FIG. 5 is a block diagram for explaining the operation of the light receiving sensor 14 and a flow chart for explaining the operation of the beam pitch control circuit 18.

The LDl is turned on and the light receiving sensor 14 is scanned. The beam is detected by the LDl pitch sensor a22a. If detected, the laser rotation drive circuit 20 causes the laser synthesizing unit 2 to rotate clockwise (+ direction), for example.
To rotate. The beam is detected again by the LDl pitch sensor a22a, and when the beam is no longer detected, the step counter a29 is counted up, and the laser rotation drive circuit 20 further rotates the laser synthesizing unit 2 clockwise (+ direction). . When it is no longer detected by the LDl pitch sensor a22a, then the LDl pitch sensor b22 is detected.
The detection is started at step b, the step counter a29 is counted up until it is detected, and the laser rotation drive circuit 2
At 0, the laser synthesizing unit is rotated clockwise (+ direction). When the detection signal is detected by the LDl pitch sensor b22b, the LDl is turned off, and then the step counter a29 is held and the count UP value is generated.

Next, the LD 2 is turned on, and the light receiving sensor 14
Scan the top. The beam is detected by the LD2 pitch sensor a23a. When detected, the laser rotation drive circuit 20 rotates the laser synthesizing unit 2 counterclockwise (one direction). The beam is detected again by the LD2 pitch sensor a23a, and when the beam is no longer detected, the step counter b32 is counted up, and the laser rotation driving circuit 20 further rotates the laser synthesizing unit 2 counterclockwise (one direction). Let LD2 pitch sensor a23a
If it is no longer detected by, the LD2 pitch sensor b
The detection is started at 23b, the step counter b32 is counted up until it is detected, and the laser rotation driving circuit 20 rotates the laser synthesizing unit 2 counterclockwise (one direction). When the detection signal is detected by the LD2 pitch sensor b23b, the LD2 is turned off, the step counter b32 is held, and the count DOWN value is generated.

The count UP value and the count DOWN value are compared, the rotation direction of the laser is determined by the result, and the rotation STEP number is determined by the difference value.

[0029]

As described above, according to the first embodiment, by arranging the light receiving sensor in the optical scanning device, the adjustment between the scanning pitches is completed in the optical scanning device, and when the optical scanning device is replaced. The effect that no adjustment is necessary and the inter-pitch detection circuit can be realized with labor saving is achieved.

According to the second embodiment, there is an effect that the pitch intervals of a plurality of semiconductor lasers are measured to accurately detect the pitch intervals.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical scanning device according to a first embodiment.

FIG. 2 is a configuration diagram showing a sensor configuration of a light receiving sensor according to the first embodiment.

FIG. 3 is a flowchart showing an operation of a beam pitch control circuit according to the first embodiment.

FIG. 4 is a block diagram showing a configuration of a beam pitch control circuit according to a second embodiment.

FIG. 5 is a configuration diagram illustrating an operation of a light receiving sensor according to the second embodiment and a flowchart illustrating an operation of a beam pitch control circuit.

[Explanation of symbols]

1 Optical scanning unit 2 Laser synthesis unit 3 Semiconductor laser a 4 Laser beam a 5 Semiconductor laser b 6 laser beam b 7 Collimating lens a 8 Collimating lens b 9 prism 10 Cylindrical lens 11 polygon mirror 12 f-θ lens 13 Reflecting mirror a 14 Light receiving sensor 15 laser beam c 16 reflection mirror b 17 Photosensitive drum 18 Beam pitch control circuit 19 Beam position detection circuit 20 Laser rotation drive circuit 21 Beam position reference sensor 22a LDl pitch sensor a 22b LDl pitch sensor b 23a LD2 pitch sensor a 23b LD2 pitch sensor b 24a LDl spot 24b LD2 spot 25a LDl pitch sensor output signal 25b LDl Pitch sensor output signal 26a LD2 pitch sensor output signal 26b LD2 pitch sensor b output signal 27 step clock signal 28 Waveform shaping circuit a 29 step counter a 30 Waveform shaping circuit b 31 Waveform shaping circuit c 32 step counter b 33 Waveform shaping circuit d 34 Pitch counter 35 Motor control signal generation circuit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/113 H04N 1/04 104A F term (reference) 2C362 AA10 AA48 BA61 BA69 BA71 BB30 BB32 BB33 BB46 2H045 BA22 BA33 CA23 CA88 CA95 2H076 AB06 AB12 AB18 AB22 AB33 5C051 AA02 CA07 DB22 DB24 DB30 DB35 DC04 DE02 5C072 AA03 DA02 DA04 DA21 HA02 HA06 HA09 HA13 HB08 XA05

Claims (4)

[Claims] 1. An optical scanning device having a plurality of semiconductor lasers, wherein the plurality of semiconductor lasers are used as a light source to generate a latent image on an image carrier. The optical scanning device comprises rotations parallel to the optical axes of the plurality of semiconductor lasers. Laser rotation driving means for rotationally driving about a shaft Beam scanning position detecting means for detecting scanning positions of the plurality of semiconductor lasers, and scanning position control for controlling the laser rotation driving means according to the result of the beam position detecting means. And a means for arranging the beam position detecting means at a position corresponding to a non-image area, which is the same as the distance from the light emitting points of the plurality of semiconductor lasers to the image carrying rest. Characteristic optical scanning device. 2. The optical scanning device according to claim 1, wherein the beam scanning position detecting means comprises a photoelectric conversion element, and at least two or more are provided for each beam of the plurality of semiconductor lasers. The conversion elements are arranged such that the distance between them is wider than the beam spot diameter of the semiconductor laser substantially at right angles to the main scanning direction, and the center axis of the distance between the photoelectric conversion elements for any laser beam of the plurality of semiconductor lasers is set. An optical scanning device, characterized in that the center axis of the interval between the photoelectric conversion elements for the other laser beam is arranged at a pitch interval in the sub-scanning direction. 3. The optical scanning device according to claim 2, wherein the plurality of semiconductor lasers are all turned on or sequentially turned on, and all the beams or each beam of the plurality of semiconductor lasers are turned on by the beam position detecting means. An optical scanning device, wherein the scanning position is detected, and the beam pitch is adjusted by the laser rotation driving means so that the output of the photoelectric conversion element disappears. 4. The optical scanning device according to claim 1, wherein the plurality of semiconductor lasers are all turned on or sequentially turned on, and the beam position detection means outputs all the beams or one of the plurality of semiconductor lasers. Laser rotation angle measuring means for detecting the scanning position for each beam and measuring the angle of the laser rotation driving means when the photoelectric conversion element is not output, and a rotation angle for storing the result of the laser rotation angle measuring means. And a beam interval setting unit for selecting an arbitrary angle preset from the results of the storage unit and the rotation angle storage unit, and adjusting the beam pitch between the beam pitches with the value selected by the beam interval setting unit. An optical scanning device characterized by the above.