JP2999831B2 - Optical system drive for copier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system driving apparatus for a copying machine for moving an optical system of the copying machine along a document surface.

[0002]

2. Description of the Related Art Conventionally, as a method of exposing a photoreceptor in a copying machine, an original platen moving exposure system often used for a small personal model and a platen fixed full surface exposure system often used for a large high-end model. Although there is a method called an optical system moving exposure method, a method called an optical system moving exposure method is most widely used. The optical system moving exposure method is a method in which an optical system is moved along an original to optically scan the surface of the original, and the reflected light at this time is incident on a photosensitive member through the optical system to perform exposure. is there. Therefore, in a copying machine employing such an optical system moving exposure system, an optical system driving device for driving the optical system is an essential component.

[0003] Here, as an optical system driving device, a timing belt which is held between a pair of pulleys driven by a motor by holding the optical system so as to be slidable in parallel along a document table. In general, the motor is configured to be driven by being connected to a wire or a wire. In recent years, a stepping motor is often used as a motor because it has advantages such as high accuracy positioning by open loop control and low cost.

[0004]

However, a driving stepping motor vibrates greatly depending on its driving frequency. For this reason, when a stepping motor is used as a drive source for driving the optical system, the vibration is transmitted to the optical system, and the image quality is degraded.
FIG. 4 is a graph illustrating the relationship between the speed and the time of the optical system that moves by being driven by the stepping motor. That is, the optical system is accelerated at the time of the rise of the stepping motor, after a predetermined time t ₁ has elapsed to stabilize the travel of the constant speed.
However, even after running at a constant speed is stabilized, the speed of the optical system slightly changes because vibration of the stepping motor is transmitted. Although a low-vibration stepping motor has been developed in recent years, the effect of the vibration of the stepping motor on the image quality of the copying machine has not been eliminated.

[0005]

According to the first aspect of the present invention,
An optical system that irradiates the original on the platen and irradiates the reflected light onto the photoconductor is slidably held in parallel along the platen, and the tangential direction matches the sliding direction of this optical system and it can be rotated. A pair of pulleys are arranged, a stepping motor for driving at least one of these pulleys is provided, and a timing belt made of a flexible member is stretched between the pulleys and connected to the optical system.

According to a second aspect of the present invention, the stepping motor according to the first aspect is mounted on a frame via a vibration isolating member.

[0007]

According to the first aspect of the present invention, when the pulley is rotated by being driven by the stepping motor, the timing belt wrapped around the pair of pulleys is rotated to follow. Move along the platform. Therefore, during the movement of the optical system, the optical system irradiates the original on the document table with light, and the reflected light is incident on the photoconductor through the optical system to be exposed to the photoconductor. Thus, the timing belt is formed of a flexible member. Therefore, the vibration generated by the stepping motor is absorbed by the timing belt, and is hardly transmitted to the optical system. This prevents the image quality from deteriorating due to the vibration of the optical system.

According to the second aspect of the invention, the vibration generated in the stepping motor is absorbed by the vibration isolating member, and the transmission of the vibration to the optical system is further reduced. Therefore, it is possible to provide higher quality image formation.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. An optical system 1 is slidably mounted in a copying machine body (not shown) in parallel along a document table (not shown). That is, the optical system 1 is slidably held by a pair of rails (not shown) arranged in parallel along the document table, and is a first scanner 2 and a reflection mirror both having a light source and a reflection mirror (not shown). It is formed by the second scanner 3.

Next, a rectangular frame 4 for an optical system driving device is provided in the main body of the copying machine, and a drive shaft 5 is supported by bearings 6 in the frame 4 so as to be rotatable. The first shaft 7 and the second shaft 8 provided in pairs are also attached. The drive shaft 5, the first shaft 7, and the second shaft 8 are all mounted so that their axial directions coincide with each other, and the drive shaft 5 and the first shaft 7 are attached to one side of the frame 4. The second shaft 8 is disposed at an intermediate position of the frame 4. The pair of first shafts 7 are coaxially arranged, and the pair of second shafts 8 are coaxially arranged. Further, the first shaft 7 and the second shaft 8 are slidably attached to the drive shaft 5 within a small range in a direction of coming into contact with and separating from the drive shaft 5. Urged in a direction away from the drive shaft 5.

A stepping motor 10 is mounted on the frame 4 between the drive shaft 5 and the second shaft 8. The stepping motor 10 has its rotating shaft 11 extending into the frame of the frame 4 and the rotating shaft 11
It is installed at an angle that is parallel to. Here, an anti-vibration member 12 is interposed between the stepping motor 10 and the frame 4. The structure is shown in FIG.
The anti-vibration member 12 has a compression spring constant of 600 to 70, for example.
0 kg / cm, or shear spring constant 100-150 kg / c
m or a rubber rubber having a rubber hardness of 50 to 60 JIS-A.

A motor pulley 13 is fixedly attached to the rotating shaft 11 of the stepping motor 10, and a drive pulley 14 is fixedly attached to the drive shaft 5 on the same tangent line as the motor pulley 13. I have. A timing belt 15 is stretched between the motor pulley 13 and the driving pulley 14 without slack. Here, this timing belt 15
Is formed of a member having little expansion and contraction. For example,
A member in which chloroprene rubber is coated on a core such as glass fiber or Kepler.

A first driving pulley 16 as a pulley and a second driving pulley 1 are provided at both ends of the driving shaft 5.
7 is fixedly mounted, and a first driven pulley 18 as a pulley is rotatably mounted on the first shaft 7 and a second driven pulley 19 as a pulley is mounted on the second shaft 8. . Here, the first driving pulley 16 and the first driven pulley 18, both having the same diameter,
The second driving pulley 17 and the second driven pulley 19, both having the same diameter, have twice the circumference. The first driving pulley 16 and the first driven pulley 18 are located on the same tangent, and the second driving pulley 17 and the second driven pulley 19 are located on the same tangent. Is positioned. A first timing belt 20 connected to the first scanner 2 is stretched between the first driving pulley 16 and the first driven pulley 18 without slack. A second timing belt 21 connected to the second scanner 3 is stretched around the second driven pulley 19 without slack.
Here, the first timing belt 20 and the second timing belt 21 are formed of a flexible member having relatively high elasticity. For example, a member in which a core such as nylon is coated with urethane.

In such a configuration, when a driving pulse is applied to the stepping motor 10, its rotating shaft 11 rotates, and the driving shaft 5 rotates through the timing belt 13.
Is driven to rotate. Then, the first timing belt 20 stretched between the first driving pulley 16 and the first driven pulley 18, the second driving pulley 17, and the second driven pulley 1
9 rotates together with the second timing belt 21 and drives the first scanner 2 and the second scanner 3. Thereby, the first scanner 2 and the second scanner 3 move along the document table and scan the document surface. That is, the slit light emitted from the first scanner 2 is sequentially applied to the document surface, and the reflected light is reflected from the first scanner 2 to the second scanner 3 and is not shown via various lenses and mirrors not shown. The light is incident on the photoreceptor and is used for exposing the photoreceptor.

At this time, the first driving pulley 16 rotates at twice the peripheral speed of the second driving pulley 17, so that the first timing belt 20 rotates at twice the speed of the second timing belt 21. Therefore, the first scanner 2 moves twice as long as the second scanner 3, and the optical path length from the reflection of the document surface to the incidence on the photosensitive member is kept constant. Thus, the magnification is kept constant during one copy.

However, the stepping motor 10 generates a large vibration depending on the driving frequency. On the other hand, in the present embodiment, since the vibration isolating member 12 is interposed in the mounting portion of the stepping motor 10 with respect to the frame 1, the vibration of the stepping motor 10 is reduced.
2 and the vibration is hardly transmitted to the first scanner 2 and the second scanner 3. In addition, the first timing belt 20 and the second timing belt 21 both formed of members having flexibility absorb vibrations that the vibration isolator 12 of the stepping motor 10 cannot absorb.
Vibration is less likely to be transmitted to the first scanner 2 and the second scanner 3. Therefore, a slight change does not occur in the speed of the traveling optical system 1, and the quality of an image formed on the photosensitive member by the optical system 1 is improved. In addition, the graph of FIG.
Optical system 1 that is driven and moved by stepping motor 10
The relationship between the speed and the time is illustrated. That is, t
_{After one} hour, the optical system 1 shifts to traveling at a constant speed. At this time, the speed of the optical system 1 does not slightly change and is maintained in an extremely stable state.

Further, when the vibration of the stepping motor 10 is transmitted to the frame 4 and the main body of the copying machine, each part resonates and noise is generated. Generation of noise due to such resonance is prevented.

[0018]

According to the present invention, since the optical system is connected and at least one of the timing belts is wound around a pair of pulleys driven by the stepping motor, the timing belt is formed by a flexible member. The transmission of vibrations to the optical system can be reduced by absorbing the vibrations caused by the timing belt, so that the image quality can be prevented from deteriorating due to the vibrations of the optical system, thereby contributing to high quality image formation. Further, when the stepping motor is attached to the frame via the vibration isolating member, the vibration generated in the stepping motor can be absorbed by the vibration isolating member, and the transmission of the vibration to the optical system can be further reduced. It has effects such as being able to provide higher quality image formation.

[Brief description of the drawings]

FIG. 1 is an overall plan view showing an embodiment of the present invention.

FIG. 2 is a longitudinal side view showing a mounting structure of a stepping motor.

FIG. 3 is a graph illustrating the relationship between the speed of an optical system and time.

FIG. 4 is a graph illustrating a relationship between speed and time of an optical system showing an example of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical system 10 Stepping motor 12 Vibration-proof member 16, 17, 18, 19 Pulley 20, 21 Timing belt

Claims (2)

(57) [Claims] 1. An optical system which is slidably held in parallel along a platen to irradiate light on a document on the platen and causes reflected light to be incident on a photoreceptor, in the same sliding direction as the optical system. A pair of rotatable pulleys having a tangential direction in a direction, a stepping motor for driving at least one of these pulleys, and a flexible member that is bridged between the pulleys and connected to the optical system. An optical system driving device for a copying machine, comprising a belt. 2. The apparatus according to claim 1, wherein the stepping motor is mounted on the frame via a vibration isolating member.