JPH01195412A - Picture recorder - Google Patents

Abstract

PURPOSE:To block vibrations produced in an image forming section so that excellent pictures can be obtained stably by providing a vibration proofing material made of a low-hardness low-visco-elasticity elastomer between a beam scanning system and the image forming section. CONSTITUTION:In a picture recorder provided with a beam scanning optical system 3 using a deflector with a deflector 310 which is formed by uniting a frame 315, reflecting mirror 312, driving coil 311, and ligament 313 to one body, a vibration proofing member 1 made of a low-hardness low-visco-elasticity elastomer is provided, at least, between the optical system 3 containing the deflector and an image forming section 2. Therefore, a picture recorder which can block vibrations produced in the image forming section 2 and can stably produce excellent pictures can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image recording device using a laser beam, which is suitable for application to an electrophotographic color copying machine or a laser printer.

[Background of the invention]

The present applicant has proposed a laser recording device using a deflector in Japanese Patent Application No. 158559/1983. FIG. 6 is a plan view showing the configuration of the beam scanning optical system of the laser recording apparatus.

The laser beam emitted from the semiconductor laser 31 has its beam shape corrected by the collimator lens 32, passes through the cylindrical lens 33, and is made incident on the deflector 300 by the reflection mirror 41. Deflector 300 deflects the laser beam in a predetermined direction at a predetermined speed.

The deflected laser beam is focused on the image carrier 11 by the scanning lens 42 and the cylindrical drill lens 36 to form an electrostatic latent image.

The cylindrical lenses 33 and 36 are used to correct vertical tilting of the reflecting mirror provided in the deflector 300, and 38 is a reflecting mirror that directs the laser beam to the top end in the figure. When the laser beam is reflected by the sensor 39, the laser beam is reflected to the sensor 39 to obtain a signal to start scanning.

Here, one cylindrical lens 36 can be a plastic lens, and when such a plastic lens is used, it is relatively easy to match the surface shape of the lens to an optimal shape. This has advantages such as improving the performance of the entire optical system.

However, if the tilt of the reflecting mirror is very small, the above-mentioned cylindrical lenses 33 and 31 can be omitted.

The scanning lens 42 is used to properly form an image of the laser beam on the surface of the image carrier 11, and to ensure that the laser beam is properly focused on the surface of the image carrier 11.
It is used to enable constant speed scanning over the top.

Here, when the deflector 300 is vibrated at its natural frequency, the deflection angle θ of the reflecting mirror is θ−Asina+t where A: maximum deflection angle ω of the reflecting mirror: angular velocity t: as expressed in time. It becomes a sine wave operation.

For this reason, the spot position of the laser beam is set as a function of θ (
θ), as the scanning lens 42, X(θ)-A
-f-arcsin(θ/A) However, by giving f a characteristic that is the focal length of the scanning lens 42, the position of the laser beam spot on the image carrier 11 can be expressed as a function X(t) of time t. If expressed as X(t
)=A −f fist ω t. Therefore,
By using the scanning lens 42 as described above, it is possible to convert the motion to uniform motion. When an electrostatic latent image is formed by uniform motion, image quality without distortion can be obtained.

Deflector 300 used in such an optical scanning system
For example, a deflector 300 using a deflector 301 as shown in FIG. 7 can be used.

To explain with reference to FIG. 7, the deflector 300 has a vertically elongated frame 315 in the shape of a rectangle, and a drive coil 311 is provided approximately in the center of the frame 315, and a reflection mirror 312 is formed above the frame. , this reflective mirror 312
between the upper part of the frame 315 and the drive coil 31
A ligament 313 that functions as a rotation support member is formed between the lower part of the rotation support member 1 and the frame 315.

In this way, the deflector 310 has a driving coil 311, a reflecting mirror 312, and a rotationally supporting ligament 313 integrally constructed.

As the frame 315, it is possible to use crystals such as crystal, quartz, glass, etc., which are easily etched and have a large elastic modulus. If crystal is used, its thickness is 0
．． The thickness is preferably about 1 mm to 0.5 mm.

When forming the deflector 310 on the frame 315, photolithography and etching techniques are usually applied as processing means, which enables fine processing. The etched surface of the deflector 310 is usually silver plated after chrome plating to reduce electrical resistance.

Especially when a semiconductor laser is used as a light source, the reflecting mirror 312 is plated with gold, silver, aluminum, or the like to increase its reflectance. Furthermore, in order to prevent scratches and oxidation on the surface of the reflective mirror 312, the surface after plating can be coated with a protective film such as SiO or Sin.

The reflecting mirror 312 is selected to have the following shape.

That is, the shape of the laser beam is determined by the collimator lens 32.
After passing through the cylindrical lens 33, it becomes a horizontally elongated ellipse, so the shape of the reflection mirror 312 may be long in the main scanning direction.

Furthermore, when the reflection mirror 312 is vibrated at high speed, air resistance becomes a particular problem, so it is convenient to form it into a horizontally elongated ellipse as shown in FIG.

The length of the reflecting mirror 312 in the lateral direction varies depending on the focal length of the scanning lens 42, the diameter of the beam spot imaged on the image carrier 11, the scanning width on the image carrier 11, etc. According to this, a desirable value is about 4 to 10 mm.

The drive frequency f for vibrating the deflector 310 is set so that the input current of the drive coil 311 is not increased.
0 has a natural frequency f0, or f ''' f
It is desirable to select a range of o±f O/Q. Here, Q indicates the sharpness of the resonance characteristic.

[Problem that the invention seeks to solve]

According to this invention, by using a deflector that uses a deflector, it is possible to realize a laser recording device that is far more reliable and has higher image quality than conventional devices, and compared to conventional devices, it is possible to realize a laser recording device that is far more reliable and has higher image quality. become that way.

First, since the deflector is very small, it can be made smaller than when using a rotating polygon mirror, and since it does not use a motor as a rotational drive source, there is no noise. , it is possible to always achieve stable deflection vibration even during high-speed scanning.

Second, compared to a vibrating mechanical vibrating mirror, not only high-speed scanning is possible, but also a small base deflector with a large deflection angle can be realized.

Thirdly, since the polarizer is formed by etching or the like, it has high precision and there is no variation in the product.

Furthermore, since the ligament part is also made of a material with a large elastic modulus, there is less metal fatigue like that of a metal rod vibrated by a mechanical vibrating mirror, and stable operation can be expected over a long period of time.

For this reason, the laser recording device according to the present invention has very high reliability, and accordingly, a highly reliable recording device can be provided.

Fourth, since the deflector is integrally molded, it has a large deflection angle,
Since a high natural frequency can be obtained, it is suitable for devices that use large recording paper and perform high-speed recording.

Fifth, since the reflecting mirror surface of the deflector is not so large compared to the beam spot, the influence of light scattering on the reflecting surface is small. Furthermore, since the deflector is integrally molded, stable vibration of the mirror can be obtained even if the ambient temperature or environmental conditions change. Therefore, regular beam scanning can be performed. Therefore, even during high-speed recording, a good final image can always be obtained.

Although this proposal has the above-mentioned excellent features, on the other hand, it is weak against vibrations and shocks applied externally to the beam scanning optical system, and the image obtained by scanning is affected by this. There is a problem that image quality deteriorates.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image recording apparatus that can block vibrations generated in an image forming section and can stably obtain good images.

[Means for solving problems]

The above object is to provide an image recording apparatus having a beam scanning optical system using a deflector including a frame, a reflecting mirror, a driving coil, and a deflector integrally formed with a ligament. This is achieved by an image recording device characterized in that a vibration isolating material made of a low hardness viscoelastic elastomer is disposed between the two.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a main part showing an embodiment of an image recording apparatus of the present invention.

In FIG. 1, 3 indicates the laser beam and the deflector 300.
3a is a beam scanning optical system which is a writing means, 3a is an optical system board which is a substrate of the beam scanning optical system, 36.42 is the cylindrical lens and scanning lens explained in FIG. A reflecting mirror 213 that reflects the laser beam toward the image forming section 2 is a dustproof glass provided at the entrance window of the laser beam L of the image forming section 2. If the reflected light reflected from the front and back sides is returned to the laser oscillator (semiconductor laser), the laser oscillation becomes unstable, so to prevent the reflected light from returning, it is attached diagonally to the laser beam beam.

(2) is a vibration isolating material provided at the four corners between the optical system substrate 3a and the image forming section 2; 201 is a photoreceptor which is a drum-shaped image carrier that rotates in the direction of the arrow; 202 is a photoreceptor 201; 203 is a developing device, 203A, 20
3B and 203C are a plurality of developing units each loaded with, for example, red and blue color toners and black toner in order to perform multicolor recording; 204 is a pre-transfer exposure device that exposes the photoreceptor 201 to remove static electricity before transfer; Both are disposed at the peripheral edge of the photoreceptor 201.

On the other hand, 205 is a paper feed cassette, and paper feed cassettes 205A and 205B are provided for each type or size of transfer paper. 206A and 206B are the paper feed cassettes 205
A205B separates and feeds each transfer paper P one by one, and 207 is a feeder that separates and feeds out the transfer paper P.
208 is a transfer unit which is a transfer unit, and 209 is a transfer paper P on which the toner image has been transferred. A separator 20 that separates the photoreceptor 201 from the drum.
9a is a separating claw, 210 is a conveying means for conveying the separated transfer paper P to the fixing device 211, 212 is a cleaning device, 212a is a cleaning blade, and 212b is a cleaning roller.

Next, the operation of the embodiment of the present invention shown in FIG. 1 will be described.

First, the photoreceptor 201 of the image recording device starts rotating in the direction of the arrow, the surface of the photoreceptor 201 is uniformly charged by the charger 202, and the beam scanning optical system 3 performs image exposure on the photoreceptor. A first (red) electrostatic latent image is formed. This latent image is the developing device 203A loaded with red toner.
Reversal development is performed by , and a red toner image is formed. At this time, the developing device 203B.

203C, pre-transfer exposure device 204, second paper feed roller 207
, the transfer device 208 and the separator 209 do not operate, and the separation claw 20
9a.

Cleaning blade 212 of cleaning device 212
The cleaning rollers 212a and 212b are retracted so as not to damage the toner image formed on the photoreceptor 201. Thereafter, the photoreceptor 201 is charged and exposed (blue) again in the same manner as before, and reversal development is performed by the developing device 203B, so that a blue toner image is formed superimposed on the red toner image. Further, charging is performed again, third exposure (black), and reversal development by the developing device 203C are performed to form black toner images in an overlapping manner. The photoreceptor 201 having this toner image is
The pre-transfer exposure unit 204 performs exposure with a static eliminating effect. At this time, the type or size of transfer paper P selected by the operation panel (not shown) is transferred to the paper feed cassette 205.
First paper feed roller 206A from either A or 205B
Or, the toner images of the three colors are fed out one by one by the second paper feeding roller 207 and sent to the transfer unit in synchronization with the rotation of the photoreceptor 2.
Transcribed by 08. The transfer paper P on which the toner image has been transferred is transferred to the photoreceptor 2 by the separator 209 and the separation claw 209a.
01, and is transferred to the fixing device 2 by the conveying means 210.
11, and after being fixed, it is discharged outside the apparatus. On the other hand, the photoreceptor 201 from which the transfer paper P has been separated continues to rotate, and its surface is cleaned by the cleaning device 212 in preparation for the next image formation.

The above description has been about an image recording device consisting of a three-color multicolor image forming section and a beam scanning optical system. It is necessary to prevent such vibrations from being transmitted to the beam scanning optical system 3. Various materials and shapes can be used for the vibration isolating material l for this purpose. However, since extremely high vibration-proofing performance is required, the conventionally used natural rubber and butyl rubber have large impact resilience and small loss coefficient, and have low vibration-proofing performance, so they are used as vibration-proofing materials for the image recording devices mentioned above. It is not possible.

Recently, elastomers such as polyurethane and silicone gel that have low hardness and viscoelasticity have been developed as impact cushioning materials and vibration damping materials, and have been found to be suitable for the above purposes.

The following equations are generally known for the natural frequency fn (Hz) and vibration transmissibility i of a system using a vibration isolator.

fn-1/2r 61 words 4 layers where k dyn ; dynamic spring constant (Kgf/cm)
g: Gravitational acceleration (cm/sea”) W: Vibration isolating material 1
Shared load type per piece (Kg) i = (1/λ”-1) x 100% However, λ = f / fn (frequency ratio) f: Excitation frequency (Hz) If the value of λ exceeds the force I, vibration isolation It is said to be effective.

Regarding the vibration isolating material l of the image recording device shown in Figure 1, experiments were conducted to measure the above-mentioned natural frequency, vibration transmissibility, and image quality obtained when the vibration isolating material was mounted on various materials, and the results were as follows. I got good results.

First, when examining the vibrations that occur during operation of the image forming unit 2, the amplitude of vibrations centered around a frequency of 100 Hz is large, and there are only 1 vibrations with a frequency of 100 Hz or less, so the excitation frequency for the experiment was set to 100 Hz. The acceleration was set to 0.2G based on the maximum amplitude of the vibration.

As shown in FIG. 2, the experimental equipment includes a vibration table 5 of a vibration device 5.
On top of the optical system board 3a, vibration isolating materials l are installed at the same four corner positions as the actual image recording device, and a dummy load 53 is added thereon so as to have the same weight as the beam scanning optical system 3. A vibration sensor and attachment part 61 are attached to this optical system board 3a, and this is connected to the vibration analysis bag wt6 and the accelerometer 7. The vibration isolating material shown in Table 1 was attached to the above experimental apparatus, and the vibration vibration device 5 was used to generate vibrations of 100Hz,
The vibration transmitted to the optical system substrate 3a when a vibration of 0.2G was applied was measured.

In Table 1, a-GEL is made of silicone gel manufactured by Cubic Engineering Co., Ltd. (JIs K25).
30-1976) 50-200 vibration isolation material.

Sorbothane is the trade name of a polyurethane vibration damping material manufactured by B, T and R in the UK.

Shape refers to the shape and dimensions of each vibration isolating material as shown in Figure 3 (a) ~
Shown in (C).

When vibration experiments and mounting tests were conducted using the above-mentioned vibration isolating material, the results shown in Table 2 were obtained.

In Table 2, fn is the resonant frequency (natural frequency) of the beam scanning optical system 3 to which each vibration isolating material is attached, and the transmissibility is the vibration transmission rate. .

The image (actual) shows the result of visual judgment of the stability of the image obtained when the above-mentioned vibration isolating material is actually attached to the image recording device. be.

In this case, the total load of the beam scanning optical system 3 is 4.53Kg, and the load per vibration isolator l is W = 1.09Kg.
Met.

Regarding the above calculated values (theoretical values) and actual measured values, when we examine the relationship between λ and the measured vibration transmissibility when using each vibration isolating material, it becomes as shown in Figure 4, and the larger λ is, the more Vibration transmission rate is small.

Furthermore, when we examine the relationship between the jitter (variation rate of scanning time between two scanning points) that occurs in the optical system board 3a during vibration and the measured value of the vibration transmissibility, we find that the measured value of the vibration transmissibility is as shown in Figure 5. The smaller the jitter, the smaller the jitter, but there were some that were significantly out of alignment, as shown by the vibration isolating material f.

The effect of jitter on the image is that the jitter value is 0.0.
If it is 4% or less, a fairly stable and good image will be obtained, and if it is 0.
If it is less than 0.02%, a good stable image can be obtained.

Comparing Figure 4 and Figure 5, λ= f / f n
It can be seen that if is 6 or more, the jitter is 0.04% or less.

Further, from Table 2, when λ is 6 or more, the theoretical value i of the vibration transmissibility is 2.8% or less, and the results of the mounting test also show that good and stable images can be obtained.

Based on the above, it is possible to select a vibration isolating material having a vibration damping effect by examining the spring constant of the vibration isolating material-1, calculating the theoretical value i of λ and vibration transmissibility from this.

Further, from the above experiments, it was found that the use of sorbothane, a polyurethane-based viscoelastic elastomer, or α-GEL, a gel-like substance based on silicone resin, provides a good vibration damping effect.

〔Effect of the invention〕

According to the present invention, as described above, by disposing a vibration isolating material made of a low-hardness viscoelastic elastomer between the beam scanning optical system and the image forming section, vibrations generated in the image forming section are blocked and the image forming section is stabilized. Accordingly, it is possible to provide an image recording device that can obtain good images.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a main part showing an embodiment of the image recording device of the present invention, Fig. 2 is a configuration diagram showing an experimental device used for measuring and experimenting vibration of vibration isolating material, and Figs. 3(a) to 3). (c) is a diagram showing the shape of the above-mentioned vibration isolating material, FIG. Figure 5 is a diagram showing the relationship between the measured value of the vibration transmissibility of the vibration isolating material and the jitter generated in the optical system board, Figure 6 is a plan view showing the beam scanning optical system, and Figure 7 is a plane view showing the deflector. It is a diagram. l... Vibration isolating material 2... Image forming section 3...
- Beam scanning optical system 3a... Optical system substrate 5... Vibration device 6... Vibration analyzer 7... Accelerometer 31... Semiconductor laser 36... Cylindrical lens 42... Scanning lens 43...Reflector 53...
...Dummy load 61...Vibration sensor 11.2
01... Photoreceptor 202... Charger 203.
...Developer 205...Paper cassette 208
...Transfer device 209...Separator 211...
-Fixing device 212...Cleaning device 300...Deflector 30
1... Deflector 311... Drive coil 31
2... Reflection mirror 313... Ligament 3
15...Frame

Claims (4)

[Claims] (1) In an image recording apparatus having a beam scanning optical system using a deflector including a frame, a reflecting mirror, a driving coil, and a ligament integrally molded, at least an optical system including the deflector and an image forming section are provided. An image recording device characterized in that a vibration isolating material made of a low hardness viscoelastic elastomer is disposed between the parts. (2) The natural frequency of the optical system including the vibration isolating material is fn(H
z), when the excitation frequency of the image forming unit is f (Hz), f/fn>6 or the theoretical value i of vibration transmissibility is i<2.8%. The image recording device according to item 1. (3) The image recording apparatus according to claim 2, wherein the vibration isolating material is a viscoelastic polyurethane elastomer. (4) The vibration isolating material is a gel material based on silicone resin, and has a penetration rate (JIS K2530-1976-5).
3. The image recording apparatus according to claim 2, wherein the image recording apparatus is an α-GEL having a load of 50 to 200 (0 g load).