JP2001255486A - Method for detecting rotational speed of rotating polygon mirror driving motor and image recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably perform the rotation control of a rotating polygon mirror driving motor irrespective of the arrangement of a sensor to detect the scanning timing of a light beam and the size of the plane tilt of the rotating polygon mirror. SOLUTION: After an SOS signal is inputted before the following SOS signal is inputted, a clock signal inputted from an oscillator is counted by a counter, and an SOS interval between adjacent reflection planes is measured by a prescribed speed of rotation of a rotating polygon mirror. By equalizing the measured SOS interval between each reflective surfaces, and obtaining an average SOS interval between each reflective surfaces (step 100), an SOS jitter component is extracted and stored in a memory (step 102). During image recording operation, the acquired SOS signal (step 106) is delayed by the corresponding average SOS interval, and the phase of the SOS signal is corrected (step 108). The rotation control of the rotating polygon mirror driving motor is performed by using the corrected SOS signal (correcting SOS signal) (step 110).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a rotation speed of a rotary polygon mirror driving motor and an image recording apparatus, and more particularly, to deflecting a light beam from a light source by rotation of a rotary polygon mirror to place it on a photosensitive member. When recording an image by scanning and exposing a light beam, the main scanning timing of the light beam is detected by detecting means to detect the rotation speed of a rotary polygon mirror drive motor that rotates the rotary polygon mirror. The present invention also relates to a method for detecting the rotation speed of a rotating polygon mirror driving motor in an image recording apparatus for controlling the rotation of a rotating polygon mirror driving motor at a constant speed, and an image recording apparatus.

[0002]

2. Description of the Related Art An image recording apparatus, such as a laser printer or an electrophotographic copying machine, for recording an image by scanning a light beam on a photoreceptor by an optical scanning device has become widespread. 2. Description of the Related Art Generally, an optical scanning device rotates a light beam modulated based on image data output from a light source such as a semiconductor laser (hereinafter, referred to as an “LD”) via a collimator lens or the like at a predetermined speed. The light is incident on the reflecting surface of the mirror. Due to the rotation of the rotary polygon mirror, the incident angle of the light beam is deflected while continuously changing, and the light beam scans the photosensitive member.

In an image recording apparatus, a motor for rotating a rotary polygon mirror (hereinafter referred to as a rotary polygon mirror driving motor) is normally rotated at a predetermined rotation speed.
The rotating polygon mirror is rotated at a predetermined rotation speed. The constant speed rotation control of the rotary polygon mirror drive motor is performed so that the phase difference between the reference oscillation frequency and the actually measured rotation frequency of the rotary polygon mirror drive motor falls within a predetermined range. (PLL control) for controlling the voltage applied to the driving IC is generally used.

There are two main techniques for detecting the rotation frequency (rotation speed) of a rotary polygon mirror drive motor. 1
One is a rotating body (rotating polygon mirror driving motor or rotating polygon mirror)
This is a technique using a multi-pole magnetized driving magnet (hereinafter, simply referred to as a “magnet”) provided on a printed circuit board and a Hall element or a comb-like electric wire (FG sensor) provided on a printed circuit board. This is because the magnet also rotates by the rotation of the rotating body, so that when the magnetic pole of the magnet crosses the pattern of the Hall element or the comb-like electric wire (FG pattern), a voltage pulse synchronized with the rotation of the rotating polygon mirror driving motor is generated. What you get.

However, in this technique, there are limitations on the accuracy of dividing the magnets, the position accuracy between the Hall elements, and the dividing accuracy of the FG pattern, and uneven magnetization of the magnets (fluctuation in the magnetic force between the magnetic poles and division between the magnetic poles). It is difficult to perform high-precision constant-speed control of the rotary polygon mirror drive motor due to fluctuations in the magnetic force of the magnet due to temperature changes, and the like.

On the other hand, another technology is a sensor (SOS) provided in an optical scanning device for detecting a scanning timing of a light beam in order to control a writing position of an image.
Sensor), and is not affected by magnetic force fluctuations caused by the magnet at all, so that the constant speed rotation control of the rotary polygon mirror drive motor can be performed with high accuracy.

More specifically, as shown in FIG. 13, when the light beam output from the light source 202 is deflected and scanned by the rotation of the rotary polygon mirror 200, the light beam on the upstream side in the scanning direction is incident on the SOS sensor 204. And SOS sensor 2
From 04, a scanning start timing signal of the light beam, that is, a pulse signal synchronized with the rotation of the rotary polygon mirror driving motor 206 rotating the rotary polygon mirror 200 is obtained. The motor drive circuit 208 compares the phase of this pulse signal (hereinafter, referred to as “SOS signal”) with the reference oscillation frequency, and controls the drive voltage based on the comparison result, thereby providing a rotary polygon mirror drive motor. 206 is controlled to rotate at a constant speed. This technique is particularly effective in an image forming apparatus including a plurality of optical scanning apparatuses (for example, an image forming apparatus that forms a color image) when a writing position determined for each optical scanning apparatus is accurately adjusted.

[0008]

SUMMARY OF THE INVENTION However, SOS
The SOS signal obtained from the sensor includes, in addition to a component based on the actual rotation of the rotary polygon mirror driving motor (hereinafter, referred to as “actual rotation performance component”), a component of the rotary polygon mirror due to a tilt of the rotary polygon mirror or the like. A fluctuation component with one cycle of rotation (hereinafter referred to as
"SOS jitter component").
When the influence of the OS jitter component becomes large, there is a problem that an accurate rotation frequency of the rotary polygon mirror driving motor cannot be detected.

Here, the SOS jitter component will be described in detail. As shown in FIG. 14, the incident (passing) position of the light beam on the SOS sensor 204 varies depending on the degree of the inclination of the reflection surface of the rotary polygon mirror on which the light beam has entered. Since the magnitude of the surface tilt differs for each reflecting surface, the position where the light beam enters the SOS sensor 204 also differs for each reflecting surface.

At this time, as shown in FIG. 15, if the SOS sensor 204 is mounted obliquely with respect to the scanning direction of the light beam due to layout reasons or variations in mounting, the SOS sensor 204 of the light beam is not used. The timing at which the light beam enters the SOS sensor varies depending on the position of incidence (passing) on the SOS. That is, the SOS of the light beam
The timing of incidence on the sensor changes for each reflection surface.

Further, even when the influence of the inclination of the SOS sensor with respect to the scanning direction of the light beam on the timing of incidence of the light beam on the SOS sensor is small, if the surface tilt difference between the respective reflection surfaces is large, the light is not incident on the SOS sensor. , The timing of incidence on the SOS sensor changes for each reflecting surface.

S in the scanning direction of such a light beam
SOS due to tilt of OS sensor or tilt of rotating polygon mirror
The change in the timing of incidence on the sensor appears as SOS jitter. If the inclination of the SOS sensor with respect to the scanning direction of the light beam or the tilt of the rotating polygon mirror is large, the influence of the SOS jitter is large. If the SOS signal at this time is used for rotation control of the rotary polygon mirror drive motor, rotation control failure (hunting failure: long-period rotation failure) is caused, and the image quality of the image is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is not limited to the arrangement of a sensor for detecting the scanning timing of a light beam or the size of the rotating polygon mirror. It is an object of the present invention to provide a method of detecting a rotation speed of a rotary polygon mirror drive motor capable of stably controlling the rotation of a drive motor, and an image recording apparatus.

[0014]

In order to achieve the above object, according to the first aspect of the present invention, a light beam from a light source is deflected by the rotation of a rotary polygon mirror, and the light beam is scanned and exposed on a photosensitive member. When an image is recorded by detecting the main scanning timing of the light beam by the detecting means, the rotation speed of the rotary polygon mirror driving motor for rotating the rotary polygon mirror is detected, and the rotation polygon mirror is detected. A method for detecting a rotation speed of a rotary polygon mirror drive motor in an image recording apparatus for controlling a drive motor to rotate at a constant speed, comprising: The present invention is characterized in that a rotational component of the rotary polygon mirror driving motor is detected by removing a fluctuation component having a periodicity as a cycle.

According to the first aspect of the present invention, when the rotation polygon mirror driving motor is controlled to rotate at a constant speed using the detection signal of the scanning timing of the light beam, one rotation of the rotation polygon mirror is regarded as one cycle. The fluctuation component having the periodicity is removed from the detection signal, and the rotation speed of the rotary polygon mirror drive motor is detected. That is, when the detecting means is disposed at an angle with respect to the scanning direction of the light beam, or when the rotating polygon mirror is tilted, fluctuation of a detection signal having one cycle of one rotation of the rotating polygon mirror (hereinafter referred to as "jitter"). Component) is removed,
Regardless of the magnitude of the jitter component, the rotation speed of the rotary polygon mirror drive motor can be accurately detected. In addition, it is possible to reliably prevent the rotation fluctuation of the long-period rotary polygon mirror driving motor (rotary polygon mirror) due to the occurrence of jitter, and to prevent deterioration in image quality.

Specifically, focusing on the periodicity of the fluctuation component, for example, based on a detection signal before acquiring a detection signal used for detecting the rotation speed, as described in claim 2, It is preferable to obtain the fluctuation component and remove the fluctuation component from a detection signal used for detecting the rotation speed.

In this case, as described in claim 3, the rotation polygon mirror is rotated a predetermined number of times, and the detection signal is obtained by the detection means and the time until the next detection signal is obtained. Each signal acquisition interval is measured, and for each reflection surface of the rotary polygon mirror, the measured signal acquisition interval is averaged to extract a fluctuation component having periodicity of the detection signal, and an image recording operation is performed. Sometimes, the phase of the acquired detection signal is changed based on the extracted fluctuation component having periodicity, and the fluctuation component having periodicity may be removed from the detection signal.

In addition, because of the periodicity of the fluctuation component, the magnitude of the fluctuation component is substantially constant for each reflecting surface regardless of the number of rotations of the rotating polygon mirror. In one rotation of the rotating polygon mirror, a detection signal of a scanning start timing of a light beam by a specific first reflecting surface of the rotating polygon mirror, and a light by a specific second reflecting surface different from the first reflecting surface. Only the detection signal of the beam scanning start timing may be used for detecting the rotation speed, and the fluctuation component may be removed.

According to a fifth aspect of the present invention, there is provided an image recording apparatus for recording an image by deflecting a light beam by rotating a rotary polygon mirror and scanning and exposing the light beam on a photosensitive member. A rotating polygon mirror driving motor for rotating the mirror, a detecting means for detecting the scanning timing by the light beam, and the rotating polygon mirror being rotated a predetermined number of times, and a detection signal of the scanning timing by the light beam is obtained by the detecting means. Measuring means for measuring each signal acquisition interval until the next detection signal is acquired, and for each reflection surface of the rotary polygon mirror, averaging the measured signal acquisition intervals to obtain the detection signal. Extracting means for extracting a fluctuation component having a periodicity with one rotation of the rotary polygon mirror as one cycle; and extracting the image based on the fluctuation component extracted by the extraction means. By changing the phase of the detection signal detected by said detecting means during recording operation, a phase changing means for removing fluctuation component having a periodicity from the detection signal,
Detecting means for detecting the rotation speed of the rotary polygon mirror drive motor based on the detection signal whose phase has been changed by the phase change means; and rotating based on the rotation speed of the rotary polygon mirror drive motor detected by the detection means. Motor control means for controlling the polygon mirror drive motor to rotate at a constant speed.

According to the fifth aspect of the present invention, the rotating polygon mirror is rotated a predetermined number of times by the measuring means, and the detection signal indicating the main scanning timing of the light beam is acquired by the detecting means. Each signal acquisition interval until a signal is acquired is measured. The extraction means averages the measured signal acquisition intervals for each reflection surface of the rotating polygon mirror. As a result, of the fluctuations in the signal acquisition interval, a randomly generated fluctuation component such as a rotation speed fluctuation of the rotary polygon mirror driving motor is canceled, and a fluctuation component having periodicity with one rotation of the rotary polygon mirror as one cycle is canceled. Is extracted. That is, it is possible to extract a jitter component generated when the detection unit is disposed at an angle with respect to the scanning direction of the light beam or when the rotary polygon mirror is tilted.

At the time of the image recording operation, the phase changing means changes the phase of the detection signal obtained by the detection means by advancing or delaying it based on the extracted fluctuation component (jitter component), and changes the detection signal. The variable component having the periodicity is removed from. The detecting means detects the rotation speed of the rotary polygon mirror drive motor using the detection signal after the phase change, and based on the detection result, the motor control means controls the rotation of the rotary polygon mirror drive motor at a constant speed. .

That is, the detection signal is used for detecting the rotation speed after the jitter component generated by the tilting of the detection means with respect to the scanning direction of the light beam or the tilting of the rotary polygon mirror is removed. Therefore, it is possible to accurately detect the rotation speed of the rotary polygon mirror driving motor regardless of the magnitude of the jitter component. In addition, it is possible to reliably prevent the rotation fluctuation of the long-period rotary polygon mirror driving motor (rotary polygon mirror) due to the occurrence of jitter, and to prevent deterioration in image quality.

As described in claim 6,
The motor control means delays the detection result of the rotation speed of the rotary polygon mirror drive motor by the detection means by a predetermined number of reflection surfaces of the rotary polygon mirror, and uses the result to control the rotation speed of the rotary polygon mirror drive motor at a constant speed. Good to do.

According to a seventh aspect of the present invention, there is provided an image recording apparatus for recording an image by deflecting a light beam by rotating a rotary polygon mirror and scanning and exposing the light beam on a photosensitive member. A rotating polygon mirror driving motor for rotating the polygon mirror, a detecting means for detecting a scanning timing by the light beam, and a rotation of the rotating polygon mirror during one rotation of the light polygon by a specific first reflection surface of the rotating polygon mirror. Detecting the rotation speed of the rotary polygon mirror drive motor using only the detection signal of the scanning start timing and the detection signal of the scanning start timing of the light beam by the specific second reflection surface different from the first reflection surface. Means, and motor control means for controlling the rotation of the rotary polygon mirror drive motor at a constant speed based on the rotation speed of the rotary polygon mirror drive motor detected by the detection means. It is a symptom.

According to the seventh aspect of the present invention, in the detecting means, in one rotation of the rotating polygon mirror, the main beam of the light beam by the two specific reflecting surfaces (the first reflecting surface and the second reflecting surface) is provided. The rotational speed of the rotary polygon mirror drive motor is detected using only the detection signal indicating the scan timing. On the basis of this detection result, the rotating polygon mirror driving motor is controlled to rotate at a constant speed by the motor control means.

As described above, by fixing the reflecting surface used for detecting the rotational speed of the rotating polygon mirror driving motor to a specific reflecting surface, a fluctuation (jitter) component having one rotation of the rotating polygon mirror as one cycle. Can be ignored.

In other words, even if the detection means is disposed at an angle with respect to the scanning direction of the light beam, or the detection signal is jittered due to the tilt of the rotary polygon mirror, the influence of the jitter component is removed. , Can detect rotation speed,
Regardless of the magnitude of the jitter component, the rotation speed of the rotary polygon mirror drive motor can be accurately detected. In addition, it is possible to reliably prevent the rotation fluctuation of the long-period rotary polygon mirror driving motor (rotary polygon mirror) due to the occurrence of jitter, and to prevent deterioration in image quality.

As described in claim 8,
It is preferable that the first reflection surface and the second reflection surface are adjacent reflection surfaces.

At this time, as described in claim 9, the interval between the reflection surfaces of which the fluctuation component of the detection signal having a periodicity with one rotation of the rotary polygon mirror as one cycle is minimized. It is preferable to further include setting means for setting one of the two reflecting surfaces as a first reflecting surface and the other as a second reflecting surface.

In this case, as described in claim 10, the number of reflection surfaces of the rotary polygon mirror is an even number, and the setting means rotates the rotary polygon mirror a predetermined number of times, and After the detection signal is obtained, measuring means for measuring each signal acquisition interval until the next detection signal is obtained, and between the reflection surfaces where the signal acquisition interval closest to the average value of the signal acquisition interval is measured. , Between the reflecting surfaces and 180
And selecting means for selecting between the reflection surfaces having different degrees between the reflection surfaces having the minimum variation component.

[0031]

Next, an example of an embodiment according to the present invention will be described in detail with reference to the drawings.

<First Embodiment> (Overall Configuration) FIG. 1 shows a schematic configuration of an image recording apparatus 10. As shown in FIG. 1, the image recording apparatus 1
0 is covered by a casing 12.

An image recording section 14 is provided in the casing 12. The image recording unit 14 includes a cylindrical photosensitive drum 16 that rotates at a constant speed in the direction of arrow A shown in FIG.
A light beam is directed to the photosensitive drum 16 (see arrow B in FIG. 1) based on desired image data (the image recording apparatus 10 in the present embodiment is intended for a black-and-white image, and therefore gray-scale image data). And an optical scanning device 18 for irradiating while performing main scanning.

In the vicinity of the peripheral surface of the photosensitive drum 16, a charger 2 is provided.
0 is provided. The charger 20 is provided for the photosensitive drum 16
Is uniformly charged. The photosensitive drum 16 uniformly charged by the charger 20 is irradiated with a light beam from the optical scanning device 18 by rotating in the direction of arrow A. As a result, a latent image is formed on the peripheral surface of the photosensitive drum 16.

Further, on the downstream side in the rotation direction of the photosensitive drum 16 from the irradiation position of the light beam by the optical scanning device 18,
The photosensitive drum 16 faces the peripheral surface of the photosensitive drum 16.
Is provided with a developing unit 22 for supplying the toner to the printer. The toner supplied from the developing unit 22 adheres to the portion irradiated with the light beam by the optical scanning device 18. As a result, a toner image is formed on the peripheral surface of the photosensitive drum 16.

On the downstream side in the rotation direction of the photosensitive drum 16 from the position where the developing device 22 is provided (the position where the axis of the photosensitive drum 16 is suspended), the charging surface for the transfer is opposed to the peripheral surface of the photosensitive drum 16. A body 24 is provided. The transfer charger 24 is transferred from the paper tray 26 or the manual feed tray 28 to a sheet 30 guided between the photosensitive drum 16 and the transfer charger 24.
The toner image formed on the peripheral surface of the photosensitive drum 16 is transferred.

A cleaner 32 is disposed on the downstream side in the rotation direction of the photosensitive drum 16 from the position where the transfer charger 24 is disposed, facing the photosensitive drum 16. The toner remaining on the peripheral surface of the photosensitive drum 16 after the transfer is removed by the cleaner 32.

The sheet 30 on which the toner image has been transferred is indicated by an arrow C
Conveyed in the direction. A pressure roller 34 and a heating roller 36 are located downstream of the photosensitive drum 16 in the transport direction of the sheet 30.
Is provided. The fixing device 38 heats and pressurizes the sheet 30 on which the transferred toner image has been transferred, and melts and fixes the toner. That is, in the fixing device 38, a so-called fixing process is performed, and the paper 30
A predetermined image is recorded thereon. The sheet 30 on which the fixing process has been performed and on which the image has been recorded is discharged to a discharge tray 40.

The image recording device 10 is also provided with an image processing section 42. The image processing unit 42 transmits desired image data to the optical scanning device 18 and controls a writing position of an image on the photosensitive drum 16 by a light beam. (Configuration of Optical Scanning Device) Next, the schematic configuration of the optical scanning device 18 will be described with reference to FIG.

The optical scanning device 18 has an LD 50 as a light source.
And a rotary polygon mirror 52 that reflects the light beam emitted from the LD 50 and irradiates the photosensitive drum 16 with the light beam.

The LD 50 is connected to an LD driving section 54 to which the image data from the image processing section 42 is input. The LD drive unit 54 controls the lighting of the LD 50 based on the image data, and causes the LD 50 to emit a light beam based on the image data.

A collimator lens 56 is arranged on the downstream side in the traveling direction of the light beam emitted from the LD 50. The collimator lens 56 converts the light beam emitted from the LD 50 from a diffuse light beam to a parallel light beam. The light beam converted into a parallel light beam by the collimator lens 56 is incident on the rotary polygon mirror 52 via the cylinder lens 58.

The rotating polygon mirror 52 has a plurality of reflecting surfaces 5 on its side.
It is formed in a regular polygonal shape (a regular dodecagon in the present embodiment) provided with 2A, and the incident light beam converges on this reflection surface 52A.

The rotary polygon mirror 52 is mounted on a rotary polygon mirror drive motor 60 (see FIG. 1). The rotary polygon mirror drive motor 60 is connected to a motor drive unit 62 (see FIG. 3, described later in detail).
It is controlled to rotate at a predetermined rotation speed (predetermined speed). The rotation of the rotary polygon mirror drive motor 60 causes the rotary polygon mirror 52 to rotate about the rotation axis 64 in the direction of arrow D. That is, the angle of incidence of the light beam on each reflection surface 52A changes continuously and is deflected. As a result, the photosensitive drum 16 scans in the axial direction of the photosensitive drum 16 and is irradiated with a light beam.

In the traveling direction of the light beam reflected by the rotary polygon mirror 52, the first lens 66A and the second lens 66B
Fθ lens 66 is disposed.
With the fθ lens 66, the scanning speed when irradiating the photosensitive drum 16 with a light beam becomes uniform,
An image point is formed on the peripheral surface of the photosensitive drum 16.

The light beam transmitted through the fθ lens 66 is bent by the reflection mirror 68 and irradiated on the photosensitive drum 16. A mirror 70 is arranged in the traveling direction of the light beam and in the leftmost direction of the photosensitive drum 16 shown in FIG. The mirror 70 reflects a light beam traveling in the leftmost direction of the photosensitive drum 16.

An SOS sensor 72 composed of a photodetector or the like is arranged in the direction in which the mirror 70 reflects the light beam. The SOS sensor 72 includes the photosensitive drum 1
6 is scanned in the axial direction, the photosensitive drum 16
A light beam that travels in the leftmost end direction is incident.

That is, the SOS sensor 72 detects the scanning start timing (SOS) for each line on the photosensitive drum 16 by the optical scanning device 18 and outputs the result to the SOS.
Output as a signal. This SOS sensor 72 corresponds to the detecting means of the present invention.

The image processing unit 42 controls the driving of the LD driving unit 54 based on the SOS signal, controls the output timing of the light beam based on the image data for each main scan, and controls the photosensitive drum. The writing position of the image by the light beam on 16 is controlled (see FIG. 3).

The motor drive section 62 generates a corrected SOS signal from which the SOS jitter component has been removed from the SOS signal, and uses the corrected SOS signal to rotate the motor so as to rotate at a predetermined rotational speed (predetermined speed). The drive of the polygon mirror drive motor 60 is controlled. (Configuration Example of Motor Driving Unit) FIG.
Is shown. As shown in FIG.
The motor drive unit 62 includes an oscillator 80 and a drive operation unit 82
, A delay circuit 84, and a motor drive circuit 86.

The oscillator 80 generates a clock signal having a predetermined frequency.

The clock signal generated by the oscillator 80 and the SOS signal from the SOS sensor 72 are input to the drive operation unit 82. The drive operation unit 82 includes a counter 88 as a measuring unit of the present invention, an average value calculating unit 90 as an extracting unit of the present invention, and a memory 92.

The counter 88 operates the oscillator 8 between the input of the SOS signal and the input of the next SOS signal.
The clock signal input from 0 is counted. That is, in the counter 88, the SOS between the adjacent reflecting surfaces 52A is
A signal generation time interval (hereinafter, referred to as “SOS interval”) is measured.

The average value calculating section 90 averages the count value of the counter 88 obtained by rotating the rotating polygon mirror 52 a predetermined number of times between the reflecting surfaces 52A of the rotating polygon mirror 52, and calculates the SOS between the respective reflecting surfaces 52A. The average value of the intervals (hereinafter, “average SO
S interval). The average SOS interval obtained by the average value calculation unit 90 is stored in the memory 92.

The SOS signal from the SOS sensor 72 is input to the delay circuit 84, and the delay circuit 84 corresponds to the SOS signal corresponding to the input SOS signal from the average SOS interval between the reflection surfaces 52A stored in the memory 92. The average SOS interval is read and input. In addition, the input SOS
The average SOS interval corresponding to the signal is used to acquire the next SOS signal, adjacent to the reflecting surface 52A where the light beam is deflected when acquiring the input SOS signal, and adjacent to the reflecting surface 52A. Average S between reflective surface 52A
The OS interval is read. That is,
The average SOS interval between the reflection surfaces 52A is associated with the reflection surface 52A on the side that first acquires the SOS signal.

The delay circuit 84 delays the input SOS signal by the average SOS interval, thereby
The phase of the OS signal is corrected (changed) (hereinafter, the phase-corrected SOS signal is referred to as a “corrected SOS signal”) and output to the motor drive circuit 86. That is, the delay circuit 84 corresponds to the phase changing means of the present invention.

In the motor drive circuit 86, the correction SOS
The rotation of the rotary polygon mirror drive motor 60 is controlled using the signal. Specifically, the input correction SOS signal is used as the rotation frequency of the rotary polygon mirror driving motor 60 or the correction SOS
The rotational frequency of the rotary polygon mirror drive motor 60 is obtained from the OS signal, compared with the reference oscillation frequency phase, and the drive voltage of the rotary polygon mirror drive motor 60 is controlled based on the phase difference. The motor 60 is rotated at a predetermined speed. That is, the motor control circuit 86 corresponds to the detection means and the motor control means of the present invention. (Operation) Next, as an operation of the present embodiment, a rotation control process of the rotary polygon mirror driving motor will be described. FIG. 4 shows a flowchart of a rotation control process of the rotary polygon mirror drive motor executed when a command (JOB) for instructing image recording is input.

As shown in FIG. 4, in the rotation control processing of the rotary polygon mirror driving motor, first, before the image recording operation in the image recording section 14 is started, the average SOS between the adjacent reflecting surfaces 52A is previously determined. Measure each interval (Step 10
0), and the obtained average SOS interval between the respective reflection surfaces 52A is stored in the memory 92 (step 102).

In this embodiment, in order to measure the average SOS interval, the rotating polygon mirror driving motor 60 (the rotating polygon mirror 5) is used.
2) The rotation is controlled at a predetermined speed, and the LD 50 is turned on to acquire the SOS signal. The rotation control of the rotary polygon mirror drive motor at this time is the same as the conventional control, and a hall element or an FG sensor is provided in the rotary polygon mirror drive motor 60, and a detection signal from the hall element or the FG sensor is used. Alternatively, an SOS signal may be used.

With the rotary polygon mirror driving motor 60 controlled to rotate at a predetermined speed in this way, the counter 88 outputs the oscillator between the input of each SOS signal and the input of the next SOS signal. The clock signal input from the counter 80 is counted, and the count is performed between the adjacent reflection surfaces 52A (hereinafter, referred to as the reflection surface 52A).
The SOS interval between the “reflecting surfaces 52A” is sequentially measured. When the rotating polygon mirror 52 has been rotated a predetermined number of times and the SOS interval between the reflecting surfaces 52A has been measured for the predetermined number of rotations, the average value calculating unit 90 calculates the SOS interval for each reflecting surface 52A. By averaging, an average SOS interval between the respective reflection surfaces 52A is obtained.

FIG. 5 shows the average SOS intervals between the respective reflection surfaces 52A when the number of the reflection surfaces is 12, thus obtained.

In FIG. 5, the vertical axis represents the average SOS interval (the average value of the count value of the clock signal by the counter 88), and the horizontal axis represents each reflecting surface. FIG. 5 shows a case where the normal value of the designed average SOS interval is 1000 (count value).
The rotation of the rotary polygon mirror drive motor 60 is controlled by the motor drive circuit 86 so that SOS signals are obtained at 1000 (count value) intervals.

As can be seen from FIG. 5, the average SOS interval fluctuates with a periodicity with one rotation of the rotating polygon mirror 52 as one cycle. Here, the average SOS interval will be described.

As described above, the SOS interval includes the component based on the actual rotation of the rotary polygon mirror driving motor 60 and the SOS
And components due to jitter. That is, SOS
The variation in the interval includes a variation in the actual rotation performance and a variation due to the SOS jitter.

Since the actual fluctuations in the rotational performance occur randomly, they are canceled out by taking the average of the SOS intervals. On the other hand, the SOS jitter component is generated according to the inclination of each reflecting surface of the rotary polygon mirror 52 and is substantially the same for each reflecting surface.
When the average of the SOS intervals is calculated for each interval, the average remains.
That is, only the influence of the SOS jitter component remains in the average SOS interval, and the variation in the average SOS interval shown in FIG. 5 indicates the variation component due to the SOS jitter.

After the average SOS interval is measured and stored in the memory 92, the image recording operation is started. When the image recording operation is started (Yes at Step 104), the LD 50 is turned on in order to make the SOS sensor 72 emit a light beam for each scan with the light beam, and the SO 50 is turned on.
An S signal is obtained (Step 106).

After a lapse of a predetermined time from the acquisition of the SOS signal, the LD 50 is turned on based on the image data of one line from the image processing section 42, and the photosensitive drum 16 is turned on.
, An image for one line is written.

Next, the delay circuit 84 causes the memory 9
2 corresponding to the SOS signal stored in FIG.
By delaying the acquired SOS signal by the S interval,
The phase of the OS signal is corrected (Step 108). Thereby, the SOS from the SOS signal to the next SOS signal is obtained.
The interval will be subtracted by the average SOS interval. The corrected SOS signal (corrected SOS signal) is input to the motor drive circuit 86, and the motor drive circuit 86 controls the rotation of the rotary polygon mirror drive motor 60 using the corrected SOS signal (step 110).

FIG. 6 shows the S acquired during the image recording operation.
An example of an OS signal interval (SOS interval) is shown.
As can be seen from FIG. 6, there is a variation in the SOS interval, and as described above, this variation includes a variation in the actual rotational performance and a variation in the SOS jitter.

When the SOS signal is acquired at the interval shown in FIG. 6, the delay circuit 84 delays the acquired SOS signal by the previously measured average SOS interval shown in FIG. The correction SOS signal is output from the delay circuit 84 to the motor drive circuit 86 at intervals shown in FIG.

Assuming that the actual rotational performance component is Trot and the SOS jitter component is Tjitter, the corrected SOS signal is “corrected SOS signal” = “measured SOS signal” − “average SOS interval” = (Trot + Tjitter) − ( Tjitter) = Trot.

That is, the SOS jitter component is removed, and only the actual rotation performance component can be extracted. The fluctuation of the output interval of the corrected SOS signal shown in FIG. 7 indicates the fluctuation of the rotation performance.

During the image recording operation, the rotational rotation control of the rotary polygon mirror driving motor 60 is continued by using the corrected SOS signal, and when the image recording operation is completed (YES at step 112), the process is terminated.

As described above, in the present embodiment, attention is paid to the property that the SOS jitter has a periodicity with one rotation of the rotating polygon mirror 52 as one cycle, and the mounting error of the SOS sensor 72 is reduced.
SOS generated by the influence of the tilting of the rotary polygon mirror 52, etc.
Just before the control, the jitter component is removed from the SOS signal, and the rotation of the rotary polygon mirror driving motor 60 is controlled. That is, since the rotation control is performed using only the pure rotation fluctuation component, even if a very large SOS jitter is generated, it is possible to reliably prevent a long-period rotation fluctuation caused by the generation of the SOS jitter. The image quality can be prevented from deteriorating.

As can be seen from FIG. 5, the SOS
Since the SOS signal is generated earlier due to the jitter (the SOS interval is shorter than the normal value), the acquired SOS signal is immediately delayed to generate a corrected SOS signal, which is immediately converted to a rotating polygon mirror. It is difficult to use for controlling the rotation of the drive motor 60. Therefore, in actual control, the rotation control may be performed using the signal after delaying by a predetermined number of surfaces. For example, when the corrected SOS signal shown in FIG. 7 is obtained, as shown in FIG. 8, the signal may be always delayed by one plane and the phase may be controlled using the signal.

In the above description, the case where the average SOS interval is measured and stored in advance after the job is input and before the image recording operation is started has been described, but the present invention is limited to this. Not something.

Every time a job is input, the average SO
It is not necessary to measure and store the S interval. For example, after the power of the image recording apparatus 10 is turned on, it may be performed only at the time of the first JOB input, or may be performed at every predetermined number of JOB inputs. Good.

During the image recording operation, the rotating polygon mirror 52
Alternatively, an average SOS interval may be measured using data for several rotations immediately before the above, a corrected SOS signal may be generated, and real-time control may be performed. In this case, the measurement of the average SOS signal for generating the corrected SOS signal for several rotations of the rotating polygon mirror 52 immediately after the start of the image recording operation is performed before the image recording operation is started in the same manner as described above. Alternatively, the average SOS interval in the previous image recording operation may be used.

In the above description, the average SOS interval is measured for each of the reflection surfaces 52A, and the SOS signal acquired during the image recording operation is delayed by the average SOS interval. Has been described as an example, but the present invention is not limited to this. By utilizing the periodicity of the SOS jitter component, SO
It is essential to remove the S jitter component. Hereinafter, other examples will be described as a second embodiment.
<Second Embodiment> In the second embodiment, by using only the SOS interval between the specific reflecting surfaces 52A, the S
An example in which the rotation control is performed by removing the OS jitter component will be described.

FIG. 9 shows the SOS interval between the reflecting surfaces 52A for three rotations of the rotating polygon mirror 52 (between adjacent reflecting surfaces 52A) (the normal value of the designed SOS interval is 1).
000).

FIG. 10 shows a state in which a part between predetermined adjacent reflecting surfaces 52A (hereinafter simply referred to as a “particularly between specific reflecting surfaces 52A”) is selected.
The SOS interval (refer to the arrow in FIG. 9) is shown, and the rotation of the rotary polygon mirror driving motor 60 is controlled based on the measured SOS interval. That is, the speed of the rotary polygon mirror drive motor 60 is increased or decreased based on the fluctuation of the SOS interval between the specific reflection surfaces 52A.

As described above, the measured SOS interval includes the component based on the actual rotation and the SOS jitter component, but the SOS jitter component is
Since it has a periodicity with one rotation of 2 as one cycle, its size is determined for each reflection surface (each time, almost the same for each reflection surface). Therefore, when comparing the SOS interval between the same reflection surfaces 52A, the SOS jitter component can be ignored. That is, only the fluctuation component of the actual rotation performance can be extracted.

As described above, the same reflection surface 52 is used without using any data (SOS interval) between different reflection surfaces 52A.
By using only the data between A, the rotation speed of the rotary polygon mirror driving motor 60 (rotary polygon mirror 52) can be increased or decreased based on the fluctuation of the actual rotary performance. As a result, even when a very large SOS jitter is generated, a long-period rotation fluctuation due to the generation of the SOS jitter can be reliably prevented, and a deterioration in image quality can be prevented. Further, since it is not necessary to measure the average SOS interval, the average value calculating unit 9 required in the first embodiment is required.
0, the memory 92, and the delay circuit 84 can be omitted.

In the above description, the specific adjacent reflecting surface 52A
Although the case of using the SOS interval between them has been described as an example, they need not be adjacent to each other. However, for more accurate rotation control, adjacent reflecting surfaces are preferable.

When the rotation of the rotary polygon mirror driving motor 60 is controlled using only the data between the specific adjacent reflection surfaces 52A, the reflection surface 52 having a large influence of the SOS jitter component is controlled.
If the data between A is used, the rotating polygon mirror driving motor 60 (the rotating polygon mirror 52) may rotate at a constant speed at a speed different from the desired rotation speed. For this reason,
It is preferable to use data between the reflection surfaces 52A, which are less affected by the SOS jitter component. For an example of this case,
Hereinafter, a third embodiment will be described. <Third Embodiment> In the third embodiment, the most SO
SOS between two reflecting surfaces 52A that is less affected by S jitter
An example in which the SOS jitter component is removed by using the interval to control the rotation speed will be described.

FIG. 11 shows the measurement result of the SOS interval between the reflecting surfaces 52A for three rotations of the rotating polygon mirror 52 (the normal value of the designed SOS interval is 1000).

As described above, among the SOS intervals measured in advance, the distance between the reflection surfaces at which the SOS interval closest to the average value of all the measured values (here, the measured values for three rotations) is obtained, and the average value Is selected between the reflecting surfaces closest to the mirror surface and the reflecting surfaces that are half a rotation ahead (in this case, six surfaces ahead) of the rotary polygon mirror 52 (see the arrow in FIG. 11).

Here, when the measured values of the SOS intervals for all the predetermined rotations of the rotating polygon mirror 52 are averaged, the SOS jitter component is canceled together with the actual rotation performance fluctuation component that changes randomly, and the obtained average value is obtained. Is the design S
This is almost the same as the normal value of the OS interval. That is, among the measured SOS intervals, the closest to this average value,
The influence of S jitter is small.

Therefore, the distance between the reflecting surfaces at which the SOS interval closest to the average value is obtained and the distance between the reflecting surfaces which are half a rotation (here, 6 surfaces ahead) of the rotary polygon mirror 52 with respect to the reflecting surfaces are set. By selecting this, it is possible to select between two reflecting surfaces where the influence of SOS jitter is the least.

FIG. 12 shows the measurement result of the SOS interval between the reflecting surfaces selected in this way. In the third embodiment, the rotating polygon mirror driving motor is determined based on the SOS interval. 60 rotation control is performed. As a result, 12
The rotation control of the rotary polygon mirror drive motor can be performed by using data only between the two reflection surfaces 52A having the least influence of the SOS jitter among the reflection surfaces 52A.
The rotating polygon mirror driving motor 60 (the rotating polygon mirror 52) can be stably rotated at a substantially desired rotation speed.

In this way, the first, second,
In any of the third embodiments, the rotation of the rotary polygon mirror driving motor 60 can be stably controlled even when the SOS jitter occurs. Accordingly, stable control is possible regardless of the mounting position of the SOS sensor 72, and the degree of freedom of layout restrictions is expanded. Also,
Even the rotary polygon mirror driving motor 60 having a large surface inclination can be used for the image recording apparatus.

Further, in the present invention, the image recording device 10 and the optical scanning device 18 are not limited to the configurations described above (see FIGS. 1 and 2). An optical scanning device that scans a light beam using the rotary polygon mirror 52 and an image recording device that records an image by irradiating the photosensitive drum 16 with the light beam while scanning using the optical scanning device. I just need.

Further, the present invention is limited to the case where the scanning start timing of the light beam is detected by the SOS sensor 72 and the rotation of the rotary polygon mirror driving motor is controlled using the detection signal (SOS signal). is not. The scanning timing of the light beam may be detected, and the rotation of the rotary polygon mirror driving motor 60 may be controlled using the detection signal. For example, a sensor (so-called EOS sensor) for detecting the end of scan (EOS) timing of the light beam is provided,
Instead of the SOS signal, the rotation of the rotary polygon mirror drive motor can be controlled using a detection signal (a so-called EOS signal) from an EOS sensor.

[0094]

As described above, according to the present invention, the rotating polygon mirror driving motor can be stabilized regardless of the arrangement of the sensor for detecting the scanning timing of the light beam and the size of the tilt of the rotating polygon mirror. And has an excellent effect that the rotation can be controlled.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image recording apparatus according to first to third embodiments.

FIG. 2 is a detailed configuration diagram of an optical scanning device provided in the image recording device of FIG.

FIG. 3 is a block diagram illustrating a configuration of a motor drive unit according to the first embodiment.

FIG. 4 is a flowchart showing a control process of the rotary polygon mirror drive motor according to the first embodiment.

FIG. 5 is a graph showing an example of a measurement result (SOS jitter waveform) of an average SOS interval according to the first embodiment.

FIG. 6 is a graph illustrating an example of an interval (SOS interval) between SOS signals acquired during an image recording operation according to the first embodiment.

FIG. 7 shows the SOS signal after correcting the SOS signal shown in FIG. 6;
5 is a graph showing an interval between S signals (corrected SOS signals).

8 is an SOS signal after correction shown in FIG.
SOS) after correction by one reflection surface
5 is a graph showing an interval between signals (corrected SOS signals).

FIG. 9 is a graph illustrating an example of an interval (SOS interval) between SOS signals acquired during an image recording operation according to the second embodiment.

FIG. 10 is a graph showing an SOS signal interval between specific reflection surfaces used for rotation control of a rotary polygon mirror driving motor when SOS signals are acquired at the intervals shown in FIG. 9;

FIG. 11 is a graph illustrating an example of an interval (SOS interval) between SOS signals acquired during an image recording operation according to the third embodiment.

FIG. 12 shows a case where the SOS signal is acquired at the intervals shown in FIG. 11, which is used for the rotation control of the rotary polygon mirror driving motor, and determines the interval of the SOS signal between the two reflection surfaces which is least affected by the SOS jitter. It is a graph shown.

FIG. 13 is a block diagram showing a rotation control mechanism of a conventional rotary polygon mirror drive motor.

FIG. 14 is a diagram for explaining the cause of the occurrence of SOS jitter.

FIG. 15 is a diagram for explaining the cause of the occurrence of SOS jitter.

[Explanation of symbols]

 Reference Signs List 10 image recording device 16 photoreceptor drum 18 optical scanning device 50 LD 52 rotating polygon mirror 52A reflecting surface 54 LD driving unit 60 rotating polygon mirror driving motor 62 motor driving unit 72 SOS sensor 80 oscillator 82 driving operation unit 84 delay circuit 86 motor driving Circuit 88 Counter 90 Average calculation unit 92 Memory

Claims (10)

[Claims] When a light beam from a light source is deflected by the rotation of a rotary polygon mirror and an image is recorded by scanning and exposing the light beam on a photoreceptor, a main scanning timing of the light beam is detected by a detecting means. Detecting the rotation speed of the rotary polygon mirror drive motor for rotating the rotary polygon mirror, and detecting the rotation speed of the rotary polygon mirror drive motor in an image recording apparatus that controls the rotation of the rotary polygon mirror drive motor at a constant speed A method for removing a fluctuation component having a periodicity with one rotation of the rotating polygon mirror as one cycle from a detection signal of the scanning timing of the light beam by the detection means, A method for detecting a rotation speed of a rotary polygon mirror drive motor, comprising detecting a rotation speed. 2. The method according to claim 1, further comprising: obtaining the fluctuation component based on a detection signal before acquiring the detection signal used for detecting the rotation speed, and removing the fluctuation component from the detection signal used for detecting the rotation speed. 2. The method for detecting the rotational speed of a rotary polygon mirror drive motor according to claim 1, wherein: 3. The rotating polygon mirror is rotated a predetermined number of times.
After the detection signal is obtained by the detection means, each signal acquisition interval until the next detection signal is obtained is measured, and for each reflection surface of the rotary polygon mirror, the measured signal acquisition interval is averaged. In the image recording operation, during the image recording operation, based on the extracted fluctuation component having the periodicity, change the phase of the acquired detection signal, The method according to claim 2, wherein a fluctuation component having periodicity is removed from the detection signal. 4. In one rotation of the rotary polygon mirror, a detection signal of a timing of starting scanning of a light beam by a specific first reflection surface of the rotary polygon mirror, and a specific second signal different from the first reflection surface. Only the detection signal of the scanning start timing of the light beam by the reflection surface is used for detecting the rotation speed,
The method according to claim 1, wherein the variation component is removed. 5. An image recording apparatus for deflecting a light beam by rotation of a rotary polygon mirror and scanning and exposing the light beam on a photoreceptor to record an image, wherein a rotary polygon mirror drive for rotating the rotary polygon mirror is provided. A motor, detecting means for detecting a scanning timing by the light beam, and rotating the rotary polygon mirror a predetermined number of times, and a detection signal of the scanning timing by the light beam is acquired by the detecting means, and then a next detection signal Measuring means for measuring each signal acquisition interval until is acquired, for each reflection surface of the rotating polygon mirror, averaged the measured signal acquisition interval, included in the detection signal, the rotating polygon Extracting means for extracting a fluctuation component having a periodicity with one rotation of the mirror as one cycle, based on the fluctuation component extracted by the extraction means,
A phase change unit that changes a phase of a detection signal detected by the detection unit during the image recording operation to remove a fluctuation component having periodicity from the detection signal; and a detection signal whose phase is changed by the phase change unit. Detecting means for detecting the rotational speed of the rotary polygon mirror drive motor based on the rotational speed of the rotary polygon mirror drive motor based on the rotational speed of the rotary polygon mirror drive motor detected by the detection means. An image recording apparatus, comprising: control means. 6. The motor control means delays the detection result of the rotation speed of the rotary polygon mirror drive motor by the detection means by a predetermined number of reflection surfaces of the rotary polygon mirror, and sets the rotation polygon mirror drive motor constant. The image recording apparatus according to claim 5, wherein the image recording apparatus is used for high-speed rotation control. 7. An image recording apparatus for deflecting a light beam by rotation of a rotary polygon mirror and scanning and exposing the light beam on a photosensitive member to record an image, wherein a rotary polygon mirror drive for rotating the rotary polygon mirror is provided. A detecting means for detecting a scanning timing by the light beam; a detection signal of a scanning start timing of the light beam by a specific first reflection surface of the rotating polygon mirror during one rotation of the rotating polygon mirror; Detecting means for detecting the rotation speed of the rotary polygon mirror drive motor using only the detection signal of the scanning start timing of the light beam by the specific second reflecting surface different from the first reflecting surface; And a motor control means for controlling the rotation of the rotary polygon mirror drive motor at a constant speed based on the rotation speed of the rotary polygon mirror drive motor. 8. The image recording apparatus according to claim 7, wherein the first reflection surface and the second reflection surface are adjacent reflection surfaces. 9. A method according to claim 1, wherein one of the two reflection surfaces constituting a reflection surface having a minimum periodic fluctuation component having a periodicity of one rotation of the rotary polygon mirror of the detection signal is defined as a first reflection surface;
The image recording apparatus according to claim 8, further comprising setting means for setting the other as the second reflecting surface. 10. The number of reflection surfaces of the rotary polygon mirror is an even number, and the setting unit rotates the rotary polygon mirror a predetermined number of times, and after the detection signal is obtained by the detection unit, the next detection signal Measuring means for measuring each signal acquisition interval until is acquired, between the reflection surfaces where the signal acquisition interval closest to the average value of the signal acquisition intervals was measured, and between the reflection surfaces 180 degrees different from the reflection surfaces The image recording apparatus according to claim 9, further comprising: selecting means for selecting between the reflection surfaces where the fluctuation component is minimized.