JPH09114162A - Light beam recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the limit to the improvement in image quality by providing a support frame for supporting a polygon motor on the support surface, a damper supported on the support surface and a driving means for driving the damper. SOLUTION: A polygon motor 61 and an electric motor 62 operated as a damper 62 are provided on a support frame 70. It is desirable that the electric motor 62 is the same as the polygon mirror 61 in respects of starting characteristic, rating and the like. The polygon motor 61 and the electric motor 62 are fixed at the positions of the maximum amplitude parts A1, A2 in the antiplane bending secondary mode to the support frame 70. Accordingy, the vibration produced by the polygon motor 61 is cancelled by the vibration produced by the electric motor 62, so that the light beams of the respective colors radiated on a photoreceptor 4 are applied to designated positions of the photoreceptor 4 to be exposed without any influence of vibration of the polygon motor 61. Accordingly, an image of high image quality can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam recording apparatus, and more particularly to a light beam recording apparatus which suppresses vibration generated by a polygon motor of a light beam scanner to improve image quality.

[0002]

2. Description of the Related Art A light beam recording apparatus emits a light beam modulated in accordance with an image signal, deflects the light beam by a polygon mirror rotated by a polygon motor, and performs sub-scanning by the deflected light beam. The photoreceptor rotated in the main scanning direction is scanned in the main scanning direction to form an electrostatic latent image on the photoreceptor in accordance with an image signal. The electrostatic latent image on the photoreceptor is converted into a toner image by development, the toner image is transferred onto a transfer medium, and after the transfer is fixed and recorded as an image.

In order to improve the quality of an image to be recorded, it is necessary to suppress the fluctuation of the exposure position of the light beam by suppressing the vibration of the polygon motor, and the light beam by suppressing the displacement of the photosensitive member. It is necessary to suppress the fluctuation of the relative position with respect to the position.

As a conventional light beam recording apparatus for realizing these things, for example, Japanese Patent Laid-Open No. 4-29127.
No. 3 and Japanese Patent Laid-Open No. 5-103064.

In the light beam recording apparatus described in Japanese Patent Laid-Open No. 4-291273, a light beam scanner is fixed to an optical system fixing base which integrally has a positioning portion for positioning the image carrier, and this optical system fixing base. Is fixed to the housing of the apparatus at the center of the image carrier. With this configuration, the positional accuracy of the light beam scanner and the image carrier is guaranteed, and thereby the image quality is improved easily and at low cost.

In the light beam recording apparatus described in Japanese Patent Application Laid-Open No. 5-103164, the light beam scanner is fixed to a support member having a natural frequency separated by a predetermined value from the frequency generated by the light beam scanner. It has a configuration as described below. With this configuration, the resonance phenomenon of the support member that fixes the light beam scanner is suppressed and the image quality is improved.

[0007]

However, according to the conventional light beam recording apparatus, the one disclosed in Japanese Patent Laid-Open No. 4-291273 guarantees the positioning accuracy of the light beam scanner and the image carrier. However, since the vibration of the polygon motor changes the exposure position of the light beam and the relative position with respect to the photoconductor, there is a limit in improving the image quality.

Further, in the one disclosed in Japanese Patent Laid-Open No. 5-103064, the vibration of the polygon motor suppresses the resonance of the support member for fixing the light beam scanner, but the vibration of the polygon motor causes the exposure position of the light beam and the photosensitive member. Since the relative position of is changed, there is a limit to the improvement of image quality.

Accordingly, it is an object of the present invention to provide a light beam recording apparatus which suppresses the vibration of a polygon motor and eliminates the limit of improving the image quality.

[0010]

In order to achieve the above-mentioned object, the present invention deflects a light beam modulated by an image signal by a polygon mirror which is rotationally driven by a polygon motor, and exposes the light beam thus deflected. In a light beam recording apparatus for forming an electrostatic latent image on the photoconductor by scanning a body and performing image recording based on the electrostatic latent image, a support frame for supporting the polygon motor on a support surface. And a vibration absorber supported on the support surface of the support frame, and a drive means for driving the vibration absorber.

[0011]

FIG. 1 shows a light beam recording apparatus according to a first embodiment of the present invention, wherein 1 is a scanner section for reading an original, 2 is an image forming apparatus main body, and 3 is a paper feeder. A cassette 4, a plurality of photoconductors provided for each color, an optical system 5 for forming an electrostatic latent image on each photoconductor 4, and a plurality of photoconductors 6 for developing the electrostatic latent image with toner of each color A developing unit 7 is a transport belt that is driven to rotate in the direction of arrow A to transport the sheet, and 8 is a fixing device having fixing rolls 8a and 8b. In the optical system 5, a light beam scanner 80 provided for each color is supported by the support frame 70, and includes a semiconductor laser oscillator, a polygon mirror, a reflection mirror, and the like, which will be described later. Reference numeral 9 denotes a paper discharge tray, and reference numeral 10 denotes a manual feed tray.

FIG. 2 shows a light beam scanner 80 arranged on a support frame 70. The semiconductor laser 51 emits a light beam (laser beam) whose intensity is modulated by an image signal, and the light beam is corrected into collimated light. A collimator lens 52, a cylindrical lens 53 that condenses the light beam at a predetermined position in the sub-scanning direction, and a plane mirror 5 that reflects the light beam that has passed through the cylindrical lens 53.
4, a polygon mirror 55 having a mirror surface for deflecting the light beam rotated by the polygon motor 61, and fθ lenses 56 and 57 for correcting the light beam so that the scanning speed becomes constant on a predetermined main scanning line. , A cylindrical mirror 58 that reflects the light beam onto the above-described predetermined main running line and corrects the surface tilt of the mirror surface of the polygon mirror 55 together with the cylindrical lens 53, and a plane mirror 59 that extracts the light beam that does not contribute to image formation. And a photodetector 60 for detecting the light beam extracted by the plane mirror 59, and the photoconductor drum 4 in which the irradiation region of the light beam is located on the predetermined main scanning line described above. Further, on the support frame 70, an electric motor 62 arranged in a positional relationship described later with the polygon motor 61 is provided. The electric motor 62 preferably has the same starting characteristics and rating as the polygon motor 61.

FIG. 3 shows a light beam scanner 80, which shows the structure shown in FIG. 2 in a simplified manner, a support frame 70 for supporting the same, and a photosensitive member 4. Beam scanner 80
As shown in FIG. 4, the polygon motor 61 and the electric motor 62 of FIG.
It is fixed to the support frame 70 at the position 2. This is because, considering the mass and rigidity of the light beam scanner 80, the combined system of the light beam scanner 80 and the support frame 70 needs to be regarded as bending vibration of the beam. Generally, in bending vibration of a beam, the amplitude of the vibration becomes larger in the lower order mode. Therefore, in this embodiment, the polygon motor 61 and the electric motor 62 are out of plane bending 2.
It is arranged considering the next mode.

The operation of the above configuration will be described.

As shown in FIG. 5, when the start signal is output, the polygon motor 61 reaches the constant speed region after the lapse of time t, and thereafter rotates at a predetermined cycle T. Then T
The electric motor 62 is started with a delay time of / 2, and in the constant speed region, the polygon motor 61 and the polygon motor 61 are rotated in a phase difference of π, that is, in a reverse phase.

On the other hand, an image signal is generated by the scanner section 1 based on the reading of the original, and after image processing, it is stored in a memory (not shown) for each color. When the scanning start signal (SOS) is output from the photodetector 60, a light beam modulated according to the image signal read from the memory for each color is emitted from the semiconductor laser 51, and the collimator lens 52,
It is deflected by a polygon mirror 55 which is rotated by a polygon motor 61 through a cylindrical lens 53 and a plane mirror 54, and is irradiated onto a photoreceptor 4 charged by a charger (not shown) through fθ lenses 56 and 57 and a cylindrical mirror 58. . A toner image for each color is formed on the photoconductor 4 for each color by the development of the electrostatic latent image by the developing unit 6, and the toner image is fed from the paper feed tray 3 and conveyed by the conveyor belt 7.
The recording paper, which is sequentially transferred to the recording paper conveyed above, is subjected to fixing treatment by the fixing device 8, and the recording paper having the fixed image is ejected to the paper ejection tray 9.

Since the vibration generated by the polygon motor 61 is canceled by the vibration generated by the electric motor 62, the light beam for each color irradiated on the photoconductor 4 is not affected by the vibration of the polygon motor 61. Four
The predetermined position of is exposed. Therefore, a high quality image can be obtained.

FIGS. 6A and 6B show the vibration amount of the polygon mirror 55, FIG. 6A shows the vibration amount of the conventional light beam scanner without the electric motor 62, and FIG. The vibration amount in the first embodiment in which the electric motor 62 is provided in the positional relationship shown in FIG. 4 with respect to the polygon motor 61 is shown. As is clear from the comparison between (a) and (b),
In the embodiment, the vibration amount is reduced to 1/2. Therefore, in the first embodiment, the electric motor 62 operates as a vibration absorber.

FIG. 7 shows a polygon motor 61 in a light beam recording apparatus according to a second embodiment of the present invention, which is supported by a support frame 70 and rotates a polygon mirror 55. An electric motor 62 connected by a connecting member 90 is provided above the polygon motor 61.

In the above structure, when the electric motor 62 is rotated in a phase opposite to that of the polygon motor 61, the same effect as that of the first embodiment can be obtained. The electric motor 62 may be provided below the polygon motor 61.

FIG. 8 shows a control system in a light beam recording apparatus according to a third embodiment of the present invention. The acceleration sensor 91 is attached to a polygon motor 61 and detects an acceleration of vibration of the polygon motor 61, and an acceleration sensor. 91
Amplifier 92 for amplifying the sensor signal of the electric motor 62 by shifting the phase of the amplified signal of the amplifier 92 by 180 °.
It has a phase converter (including a drive circuit) 93 for driving the.

In the above configuration, when the acceleration of vibration of the polygon motor 61 is detected by the acceleration sensor 91,
The acceleration signal is amplified by the amplifier 92. The phase of the amplified acceleration signal is a half cycle (π = 18
0 °), and the electric motor 62 is driven in the shifted phase. As a result, the electric motor 62 can function as a vibration absorber with higher accuracy than in the first embodiment. In the third embodiment, the acceleration sensor 91 may be replaced with a displacement sensor.

FIG. 9 shows a polygon motor 61 in the light beam recording apparatus according to the fourth embodiment of the present invention. The polygon motor 61 includes an acceleration sensor 91 and an exciter 105.
Is attached.

In the above structure, when the acceleration sensor 91 detects the acceleration of the polygon motor 61, the detected acceleration is integrated by the integrating amplifier 101, converted into a speed, and simultaneously amplified. The amplified speed signal is the phase inverter 1
In 02, the phase is inverted by 180 °, and the phase of the excitation signal output from the signal generator 103 is matched with the phase inverted by 180 °. The excitation signal whose phase is controlled in this way is
After being amplified by the power amplifier 104, the vibration exciter 105 is driven to apply a vibration having an inverted phase of 180 ° to the polygon motor 61. This controls the vibration of the polygon motor 61. Here, as the vibrator 105, for example, a vibrator utilizing the piezoelectric effect of a piezoelectric element such as barium titanate crystal is preferable.

FIG. 10 shows an electrodynamic exciter that can be used as the exciter 105. The magnetic pole 111, the field coil 112, the support spring 113, the drive coil 114, and the exciter table 11 are shown.
5 and the linear bearing 116, when the drive coil 114 is energized with the field coil 112 energized to generate the magnetic flux 117, the vibration table 115 vibrates. This vibration may be applied to the polygon motor 61.

FIG. 11 shows another exciter that can be used as the exciter 105, and is constructed by using two rotating bodies 161 and 162. Here, 161A and 162A are rotating bodies 1
The reference positions 61 and 162 are shown, and both are in opposite phases and rotate in the opposite directions at the same rotation speed. Reference position 161A,
162A is the imbalance point of the rotating bodies 161, 162,
In (a) and (c), it cancels out, but in (b) and (d), they are added, so that an exciting force in the direction of the arrow is generated. This exciting force can be applied to the polygon motor 61.

FIG. 12 shows a polygon motor 61 of a light beam recording apparatus according to a fifth embodiment of the present invention, which is supported on a support frame 70 and has a window 1 through which a light beam L passes.
The whole is covered with a vibration absorbing material 121 having 22. The polygon motor 61 rotates the polygon mirror 55 as in the first to fourth embodiments.

[0028]

As described above, according to the light beam recording apparatus of the present invention, the vibration of the polygon motor is absorbed, so that the limit of the improvement of the image quality can be eliminated.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a light beam recording apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a light beam scanner according to the first embodiment.

FIG. 3 is an explanatory diagram showing a vibration absorber according to the first embodiment.

FIG. 4 is an explanatory view showing a mounting position of the vibration absorber according to the first embodiment.

FIG. 5 is a timing chart showing the operation timing of the vibration absorber according to the first embodiment.

FIG. 6 (a) shows the vibration amount of a conventional light beam scanner,
(b) is a graph showing the vibration amount in the first embodiment.

FIG. 7 is an explanatory diagram showing a vibration absorber in a light beam recording device according to a second embodiment of the invention.

FIG. 8 is a block diagram showing a vibration absorber system in a light beam recording apparatus according to a third embodiment of the invention.

FIG. 9 is a block diagram showing a system of a vibration absorber in a beam recording device according to a fourth embodiment of the present invention.

FIG. 10 is an explanatory view showing a vibration exciter acting as a vibration absorber in the fourth embodiment.

FIG. 11 is an explanatory diagram showing a vibration exciter acting as a vibration absorber in the fourth embodiment.

FIG. 12 is an explanatory diagram showing a vibration absorber in a light beam recording device according to a fifth embodiment of the present invention.

[Explanation of symbols]

 1 Scanner Part 2 Image Forming Device Main Body 3 Paper Feed Cassette 4 Photosensitive Member 5 Optical System 6 Developing Device 7 Paper Conveying Belt 8 Fixing Device 8a, 8b Fixing Roll 9 Paper Ejection Tray 10 Manual Feed Tray 51 Semiconductor Laser 52 Collimator Lens 53 Cylindrical Lens 54 Plane mirror 55 Polygon mirror 56, 57 fθ lens 58 Cylindrical mirror 59 Planar mirror 60 Photodetector 61 Polygon motor 62 Electric motor 70 Support frame 80 Optical beam scanner 90 Connecting member 111 Magnetic pole 112 Field coil 113 Support spring 114 Drive coil 115 Add Vibration table 116 Linear bearing 117 Magnetic flux 121 Vibration absorber 161 and 162 Rotating body

Claims (4)

[Claims] 1. An electrostatic latent image on the photoconductor by deflecting a light beam modulated by an image signal by a polygon mirror driven to rotate by a polygon motor and scanning the photoconductor with the deflected light beam. In the light beam recording apparatus for forming an image and performing image recording based on the electrostatic latent image, a support frame for supporting the polygon motor on a support surface, and a vibration absorbing member supported on the support surface of the support frame. An optical beam recording apparatus comprising: a device and a driving unit that drives the vibration absorber. 2. The light beam recording apparatus according to claim 1, wherein the support frame supports the polygon motor and the vibration absorber at a position where a maximum value of different polarities of vibration amplitude is reached. 3. The vibration absorber is an electric motor or a vibration exciter, and the driving means drives the electric motor or the vibration exciter at a rotation phase opposite to the rotation phase of the polygon motor. The optical beam recording device according to claim 1. 4. The driving means includes a detecting means for detecting the rotation phase of the polygon motor.
The light beam recording apparatus described.