JPH03251812A - Optical recorder - Google Patents

Abstract

PURPOSE:To easily control the supporting structure and the rotation angle of a parallel plane plate by rotating the parallel plane plate according to the output of a speed detecting means which detects the rotational speed of a photosensitive body and correcting the positional deviation on the photosensitive body in a subscanning direction. CONSTITUTION:The rays which are emitted by a light source 1 and collimated by a collimator lens 3 into parallel 1 rays are deflected by a polygon mirror 4 and further imaged by an image forming lens 6 on the surface of the photosensitive body 2. At this time, the frequency signal from the speed detecting means 8 which detects the rotational speed of the photosensitive body 2 is converted by a frequency-voltage conversion part 9 into a voltage, which is inputted to an arithmetic processing part 10, and the rotation direction and rotation angle of the parallel plane plate 6 are calculated from the rotational speed of the photosensitive body 2 and supplied to a parallel plane plate driving control part 11. Thus, a parallel plane plate driving part 12 rotates the parallel plane plate 6 in a specific direction by a specific angle with the output of the control part 11 and increase the rotation angle of the plane plate for the correction of the recording position in the subscanning direction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical recording device used in printers, copiers, facsimile machines, laser engraving machines, etc. that form images based on electrophotography.

2. Description of the Related Art Conventionally, in an optical recording device, an electrostatic latent image is formed on the surface of a rotatable photoreceptor by scanning a beam of light irradiated from a light source onto a rotatable photoreceptor using deflection means such as a polygon mirror. If the beam light is shifted in the sub-scanning direction with respect to the body, it will appear as unevenness in image density, causing a problem in that image quality will be impaired. It is known that deviations in the recording position on the photoreceptor in the sub-scanning direction occur mainly due to the following causes.

The first problem is the inclination of each reflective surface of the polygon mirror with respect to the rotation axis. The second problem is variation in the rotational speed of the photoreceptor. This is due to uneven rotation of the motor, vibrations in the transmission system such as gears,
This is caused by eccentricity of the photoreceptor, etc.

For the first cause, a method is adopted in which optical correction is performed to bring the reflective surface of the polygon mirror and the photoreceptor into a conjugate relationship. To solve the second cause, methods have been adopted, such as a direct drive method in which the transmission mechanism is omitted and the photoreceptor is directly driven by a motor, or a method in which the inertia of the rotating body is increased, but the motor becomes larger and costs increase. become. For this reason, as described in Japanese Patent Application Laid-Open No. 63-192008, a mirror that rotates with a rotation axis along the main scanning direction is provided in the laser optical path to detect the rotational speed of the photoreceptor, and the detection signal is There is an invention in which the deviation of the light beam relative to the photoreceptor in the sub-scanning direction is corrected by rotating a mirror in accordance with the rotation of the mirror.

Problems to be solved by the invention The invention described in Japanese Patent Application Laid-Open No. 63-192008 is as follows:
The fluctuation of the recording position on the photoreceptor in the sub-scanning direction increases with respect to the change in the rotation angle of the mirror. For example, assuming that the distance Q from the mirror to the photoreceptor is 100 mm, the correction amount δ of the recording position on the photoreceptor in the sub-scanning direction is 10 μm<0. OI m
m), the rotation angle θ of the mirror is determined by the following equation.

θ=δ/2°C=0.01/200 = 5 x 10-” (rad) = 10 seconds However, rotating the mirror by a small angle of 10 seconds
This is extremely difficult due to factors such as uneven rotation of the motor and backlash of the gears in the transmission mechanism that transmits the rotation of the motor to the mirror.Furthermore, mirror movement of this degree can also be caused by vibration, etc. The structure in which the supporting method is difficult In the invention of claim 1, an imaging lens is disposed between a photoreceptor and a deflecting means for deflecting a beam of light irradiated from a light source, and the imaging lens and the photoreceptor are connected to each other. A transparent parallel plate, which is rotatably held with an axis parallel to the main scanning direction, is connected to a parallel plate drive unit between the photoreceptors, and the rotational speed of the photoreceptor is detected according to the output of the speed detection means. A parallel plate drive control unit is provided which outputs the output to the parallel plate drive unit.

The invention according to claim 2 further comprises disposing an anamorphic imaging lens for correcting a surface inclination of the reflecting surface of the deflecting means between a deflecting means for deflecting a beam of light irradiated from a light source and a photoreceptor; A condensing lens having a curvature in the sub-scanning direction is disposed between the light source and the deflecting means, and is rotatably held between the condensing lens and the deflecting means with an axis parallel to the main scanning direction. A parallel plate drive control unit is provided, in which a transparent parallel plate is connected to a parallel plate drive unit, and a parallel plate drive control unit outputs an output to the parallel plate drive unit in accordance with an output of a speed detection means for detecting the rotational speed of the photoreceptor.

The invention according to claim 1 is characterized in that the parallel plate drive control unit drives the parallel plate drive unit to rotate the parallel plate according to the output of the speed detection means for detecting the rotational speed of the photoreceptor.
The deviation of the recording position on the photoconductor in the sub-scanning direction is corrected according to the change in the rotation speed of the photoconductor, but the amount of correction for this deviation is
Since it is proportional to the product of the difference between the refractive index of the parallel plate and 1 divided by the same refractive index and the rotation angle of the parallel plate, by setting the refractive index of the parallel plate small, the sub-scanning on the photoreceptor can be The rotation angle of the parallel plate can be increased relative to the amount of correction of the recording position in the direction, and thereby the support structure of the parallel plate and the rotation angle of the parallel plate can be easily controlled.

The invention of claim 2 corrects the deviation of the beam light in the sub-scanning direction by using a parallel plate through which the beam light emitted from the light source and condensed by the condensing lens passes, and also sets the refractive index of the parallel plate to be small. This makes it possible to increase the rotation angle of the parallel plate relative to the correction amount of the recording position in the sub-scanning direction on the photoconductor, and furthermore, the anamorphic imaging lens allows the reflection surface of the deflection means to be connected to the photoconductor. Optical correction can be performed to make the image conjugate in the sub-scanning direction.

Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 to 4. l is a light source such as a semiconductor laser, and this light source 1
In the optical path from the to the photoreceptor 2, a collimating lens 3,
A polygon mirror 4, which is a deflecting means, and an imaging lens (fθ
A lens) 5 and a transparent parallel plate 6 are sequentially arranged. Further, a polygon mirror 4 is provided near the end of the photoreceptor 2.
A light receiving element 7 is provided for receiving the beam light deflected from the photoreceptor 2 and determining the recording start position on the photoreceptor 2.

Further, a speed detecting means 8 such as an encoder is connected to one end of the shaft of the photoreceptor 2, and the other end is connected to a motor (not shown).

As shown in FIG. 4, the speed detection means 8 is connected to the input side of the arithmetic processing section 10 via the frequency-voltage conversion section 9,
A parallel plate drive control unit 11 and a parallel plate drive unit 12 are sequentially connected to the output side of the arithmetic processing unit 10. The parallel plate drive unit 12 rotates the parallel plate 6 about an axis along the main scanning direction.

In such a configuration, a beam of light emitted from the light source 1 and made into parallel light by the collimating lens 3 is deflected by the polygon mirror 4, and further focused on the surface of the photoreceptor 2 by the imaging lens 6.

At this time, speed detection means 8 for detecting the rotational speed of the photoreceptor 2
The frequency signal is converted into a voltage by the frequency-voltage conversion section 9 and inputted to the arithmetic processing section 10 , and the arithmetic processing section 10 determines the rotational force direction and rotational angle of the parallel plate 6 according to the rotational speed of the photoreceptor 2 . is calculated, and the result is output to the parallel plate drive control section 11. A parallel plate drive unit 12 driven by the output of the parallel plate drive control unit 11 rotates the parallel plate 6 in a predetermined direction by a predetermined angle.

Here, as shown in FIG. 3, the amount of correction of the position of the beam light in the sub-scanning direction on the surface of the photoreceptor 2 is δ, the thickness of the parallel plate 6 is d, the refractive index is n, and the rotation angle is When θ is assumed, the correction amount δ of the beam light is determined by the following equation.

−1 δ−1 d sxnθ・・・・・・■Here, δ−1
0μm (0.01mm), n=1゜5mm, d=3mm
Then, θ is 0. It will be 6 degrees. This 0.
The angle of 6 degrees is a large angle compared to the angle of the conventional example (10 seconds). In other words, since the correction amount δ of the deviation of the recording position on the photoreceptor 2 in the sub-scanning direction is proportional to the product of (n-1)/n and the rotation angle θ of the parallel plate 6, the refraction of the parallel plate 6 By setting the ratio n small, it is possible to make θ larger than δ, thereby making it easier to control the support structure of the parallel plates and the rotation angle of the parallel plates 6.

Next, a second embodiment of the present invention will be explained based on FIGS. 5 to 8. The same parts as in the previous embodiment are designated by the same reference numerals, and the description thereof will be omitted. In this example, the collimating lens 3
The beam light passing through the polygon mirror 4 is focused on a polygon mirror 4 by a condensing lens (cylinder lens) 13 having a curvature in the sub-scanning direction, and the beam light deflected by the polygon mirror 4 is directed to a reflective surface 4a of this polygon mirror 4. An image is formed on the photoreceptor 2 by an anamorphic imaging lens 14 having a surface tilt correction function.
A parallel plate 6 provided between the photoreceptor 2 and the photoreceptor 2 is rotated in accordance with the rotational speed of the photoreceptor 2 to correct the deviation of the recording position on the photoreceptor 2 in the sub-scanning direction.

The deviation correction amount δ in this embodiment is determined by the following equation. Here, a is the distance from the reflective surface 4a of the polygon mirror 4 to the center of the imaging lens 14, and b is the distance from the center of the imaging lens 14 to the surface of the photoreceptor 2.

n-1,b δ# ds1nθ-・・・・・・■n
a Here, 8 = 10 μm (0.01 mm), n-1
When ゜5mm and d=3mm, θ is 0.
It will be 15 degrees. This angle of 0.15 degrees is also a large angle compared to the angle of the conventional example (10 seconds). In formula (2), the correction amount δ of the recording position deviation in the sub-scanning direction on the photoreceptor 2 is proportional to the product of (n-1)/n and the rotation angle θ of the parallel plate 6. By setting the refractive index n of 6 to a small value, θ can be made larger than δ.

Further, in this embodiment, by arranging the parallel plate 6 in front of the polygon mirror 4, the size can be reduced.

The driving means for this parallel plate 6 is the same as in the previous embodiment.

Furthermore, as shown in FIG. 8, the influence of the surface tilt of the reflective surface 4a of the polygon mirror 4 can be corrected by the imaging lens 14.

Effects of the Invention As described above, the invention of claim 1 includes an imaging lens disposed between a photoreceptor and a deflecting means for deflecting a beam of light irradiated from a light source, and an imaging lens and a photoreceptor. A transparent parallel plate, which is rotatably held with an axis parallel to the main scanning direction, is connected to a parallel plate drive unit between the photoreceptors, and the rotational speed of the photoreceptor is detected according to the output of the speed detection means. By providing a parallel plate drive control unit that outputs an output to the parallel plate drive unit, the parallel plate drive control unit drives the parallel plate drive unit in accordance with the output of the speed detection means that detects the rotational speed of the photoreceptor. By rotating the flat plate, the deviation of the recording position on the photoconductor in the sub-scanning direction is corrected according to the change in the rotational speed of the photoconductor, but the amount of correction for this deviation is determined by the refractive index of the parallel plate and 1. is proportional to the product of the value obtained by dividing the difference by the refractive index and the rotation angle of the parallel plate, so by setting the refractive index of the parallel plate to a small value, the amount of correction of the recording position on the photoconductor in the sub-scanning direction can be reduced. On the other hand, the rotation angle of the parallel plate can be increased, thereby making it easier to control the support structure of the parallel plate and the rotation angle of the parallel plate.

As described above, an anamorphic imaging lens is disposed between a deflection means for deflecting a light beam irradiated from a light source and a photoconductor, and an anamorphic imaging lens for correcting a surface inclination of the reflective surface of the deflection means. A condenser lens having a curvature in the sub-scanning direction is disposed between the light source and the deflection means, and the condenser lens and the deflection means are carefully rotated parallel to the main scanning direction. A parallel plate drive control unit that connects a freely held transparent parallel plate to a parallel plate drive unit and outputs an output to the parallel plate drive unit in accordance with an output of a speed detection means that detects the rotational speed of the photoreceptor. By providing a parallel plate that passes the beam light emitted from the light source and condensed by the condenser lens, it is possible to correct the deviation of the recording position on the photoreceptor in the sub-scanning direction, and to reduce the refractive index of the parallel plate. By determining this, the rotation angle of the parallel plate can be increased relative to the correction amount of the recording position in the sub-scanning direction on the photoreceptor,
Furthermore, the anamorphic imaging lens has the advantage that optical correction can be performed so that the reflecting surface of the deflecting means and the photoreceptor are conjugate in the sub-scanning direction.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present invention, in which FIG. 1 is a perspective view, FIG. 2 is a plan view of a parallel plate, and FIG.
The figure is a side view showing the direction of rotation of the parallel plates, FIG. 4 is a block diagram showing an electronic circuit for driving the parallel plates, and FIGS. 5 to 8 show a second embodiment of the present invention. Fig. 5 is a perspective view, Fig. 6 is a side view of the optical path system from the condenser lens to the photoreceptor, Fig. 7 is a plan view showing the imaging lens together with its imaging function, and Fig. 8 is the imaging lens. FIG. 3 is a side view showing its imaging effect. DESCRIPTION OF SYMBOLS 1... Light source, 2... Photoreceptor, 4... Deflection means, 5
. . . Imaging lens, 6 . . . Parallel plate, 8 . ...Anamorphic imaging lens

Claims (1)

[Claims] 1. Deflection means for deflecting a beam of light irradiated from a light source, an imaging lens disposed between the deflection means and the photoreceptor, and a combination of the imaging lens and the photoreceptor. a transparent parallel plate that is rotatably held with an axis parallel to the main scanning direction between the parallel plate drives, a parallel plate driving section to which the parallel plate is connected, and a speed detection means for detecting the rotational speed of the photoreceptor. and a parallel plate drive control section that outputs an output to the parallel plate drive section according to the output of the speed detection means. 2. a deflection means for deflecting a beam emitted from a light source; an anamorphic imaging lens disposed between the deflection means and a photoreceptor to correct a surface inclination of the reflective surface of the deflection means; a condenser lens having a curvature in the sub-scanning direction and arranged between the light source and the deflection means, and rotating about an axis parallel to the main scanning direction between the condenser lens and the deflection means; a transparent parallel plate held freely; a parallel plate drive unit to which the parallel plate is connected; a speed detection means for detecting the rotational speed of the photoreceptor; An optical recording device comprising: a parallel plate drive control unit that outputs output to a drive unit.