JP2695322B2 - Optical system drive - 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 device used in a scanner of an image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art As is well known, in a fixed platen type copying machine, a light source unit having a lamp as a light source and a first mirror is reciprocally moved to scan an original document placed on the original platen. The second and third mirrors mounted on the movable mirror unit, the fourth and fifth mirrors mounted on the mirror holder, and the sixth fixedly arranged light reflected from the document.
Expose the photosensitive drum through the mirror, and then perform a developing process to supply toner to the exposed surface of the photosensitive drum,
After that, a transfer process of transferring the toner image on the photoconductor drum onto a sheet is performed to form an image.

[0003] Here, the mirror unit is driven synchronously at half the moving speed of the light source unit in order to keep the optical path length from the document table to the lens constant. As a driving device for the light source unit and the mirror unit, one using a wire has been widely used.

[0004]

However, a drive device using a wire has a drawback in that a large number of pulleys are required due to the complicated winding of the wire, and the structure is first of all complicated. Secondly, there is a drawback that the manufacturing cost becomes high because it takes time to wind the wire. Further, there is a drawback that reliability is deteriorated with time due to elongation of the wire.

The present invention solves the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide an optical system driving device which has a simple device structure, can improve reliability, and can significantly reduce the cost. And

[0006]

In the optical system driving device of the present invention, the light source unit is reciprocally moved, and the mirror unit provided in the optical path between the light source unit and the photosensitive member is moved in the moving direction of the light source unit. An optical system driving device for moving at a predetermined speed ratio to a fixed rack gear arranged along the moving path of the light source unit, and a longitudinal unit provided along the fixed rack gear for moving the mirror unit. A movable rack gear that is movable in any direction, a first pinion and a second pinion that mesh with the fixed rack gear and the movable rack gear, respectively, and the first pinion and the second pinion are integrally attached to a rotating shaft. The light source unit is moved along the fixed rack gear by the rotation of the rotating shaft to move the light source unit, and the first pinion and the second pinion are moved. The diameter ratio of the pitch circle on, becomes and a traveling body that is set in association with the speed ratio between the light source unit and said mirror unit, the object can be achieved.

[0007]

According to the above construction, the first pinion and the second pinion rotate as the rotary shaft of the traveling body rotates. Then, due to the rotation of the first pinion that meshes with the fixed rack gear, the traveling body moves by itself along the fixed rack gear to move the light source unit. At this time, the movable rack gear with which the second pinion meshes moves forward as the traveling body moves, but on the other hand, the movable rack gear is moved backward by the rotation of the second pinion. Here, since the diameter ratio of the pitch circles of both gears is set corresponding to the speed ratio of the light source unit and the mirror unit, the traveling body and the movable rack gear move in the same direction at a predetermined speed ratio. Therefore, the mirror unit is driven in the moving direction of the light source unit at a predetermined speed ratio.

[0008]

The present invention will be described below with reference to examples.

The optical system driving device of the present invention is used, for example, in a scanner of a fixed platen type copying machine.

The scanner, as shown in FIG.
A light source unit 20 which is located below 0 and scans a document on the document table 10 is provided. The light source unit 20 has a movable base 21 that is movable over the entire length in the scanning direction. The movable base 21 includes a lamp 22 and a reflector 23.
And the first mirror 24 and the like are mounted.

The light emitted from the lamp 22 is emitted from the document table 1
The originals above 0 are illuminated. The reflected light from the document is guided to the movable mirror unit 31 via the first mirror 24. The mirror unit 31 includes a second mirror 32 and a third mirror 32.
A mirror 33 is mounted, and the reflected light guided to the mirror unit 31 is converted in the reverse optical path by the second mirror 32 and the third mirror 33, and is guided to the position of the mirror holder 40 through the lens 34. .

A fourth mirror 41 and a fifth mirror 42 are mounted on the mirror holder 40. The fourth mirror 41 and the fifth mirror 42 reverse the optical path of the guided reflected light and guide the reflected light to the sixth mirror 43 fixedly arranged in the copying machine. The sixth mirror 43 converts the optical path of this reflected light downward, and exposes it on a photosensitive drum (not shown). A known image forming process is performed below.

The mirror unit 31 is a light source unit 20.
Is located at one end of the moving path and is located at the center of the moving path, and the moving range is from the center to the other end of the moving path. The mirror unit 31 is synchronously driven at a speed of 1/2 in the moving direction of the light source unit 20 by an optical system driving device described below.

The optical system driving device is provided below the moving path of the light source unit 20 over the entire length of the moving path, and above the fixed rack gear 50 in parallel with the fixed rack gear 50. It is provided with a movable rack gear 60 that is movable in the longitudinal direction, and a traveling body 70 that is self-propelled along the fixed rack gear 50 and that drives the light source unit 20 and the movable rack gear 60.

As shown in FIG. 2, the fixed rack gear 50 has elongated holes 51 at both ends thereof, and a screw 52 is passed through the elongated holes 51 and screwed into the screw holes of the frame of the copying machine main body to form a frame. It is installed with the tooth side facing up. Then, by using the long hole 51, the mounting position of the fixed rack gear 50 in the longitudinal direction with respect to the frame can be finely adjusted.

The movable rack gear 60 is the fixed rack gear 5
It is supported near 0 with the tooth side facing up. The length of the movable rack gear 60 is approximately half the length of the fixed rack gear 50, and the movable rack gear 60 is reciprocated along the fixed rack gear 50. One end of the movable rack gear 60 has the mirror unit 3
Connected to 1.

The traveling body 70 is attached to the lower surface of the movable base 21 of the light source unit 20. The traveling body 70
Is a first pinion 71 and a second pinion 7 that mesh with the fixed rack gear 50 and the movable rack gear 60, respectively.
2 As shown in FIG. 2, the first pinion 71 and the second pinion 72 are coaxially supported by the same rotary shaft 73. The first pinion 71 has a diameter larger than that of the second pinion 72, and the diameter ratio of the pitch circles thereof corresponds to the speed ratio between the light source unit 20 and the mirror unit 2:
It is set to 1. This diameter ratio is realized by setting the number of teeth of both gears to 2: 1 in this embodiment.

The rotating shaft 73 of the traveling body 70 is
A motor (not shown) mounted on the first pinion 71 and the second pinion 72 rotates the motor in both forward and reverse directions.
Is rotated in directions a and b shown in FIG. When the first pinion 71 rotates in the direction of the arrow a, the rack formed by the first pinion 71 and the fixed rack gear 50.
The traveling body 70 is fixed to the fixed rack gear 50 by the pinion mechanism.
The light source unit 20 supported by the movable base 21 is moved in the scanning direction indicated by the arrow A.

When the light source unit 20 is located at the scanning start position, the mirror unit 31 of the movable rack gear 60 is provided.
The other end on the side opposite to the connecting position meshes with the second pinion 72.

According to the optical system driving device of the present invention having such a mechanism, the light source unit 20 and the mirror unit 31 are synchronously driven as follows.

When the light source unit 20 is located at the scan start position, the mirror unit 31 is located at the center of its moving path. When the first pinion 71 and the second pinion 72 are rotated in the direction of arrow a from this state and scanning is started, the first pinion 71 meshes with the fixed rack gear 50, and the fixed rack gear 50 is fixed. When the pinion 71 makes one rotation in the a direction, the traveling body 70 moves in the arrow A direction by the pitch circumference of the first pinion 71. The movable rack gear 60 is the second pinion 72.
Since it is connected to the traveling body 70 via the
Along with this, it moves by an amount corresponding to the direction of arrow A, but at this time, since the second pinion 72 is also rotated in the direction of arrow a, the rack and pinion constituted by the second pinion 72 and the movable rack gear 60. The mechanism moves the movable rack gear 60 also in the direction of arrow B, which is the opposite direction to the scanning direction.

The amount of movement of the movable rack gear 60 in the direction of arrow B is the amount of movement in the direction of arrow A because the diameter of the pitch circle of the second pinion 72 is 1/2 the diameter of the pitch circle of the first pinion 71. It becomes 1/2 of. Therefore, arrows A and B
After all, due to the difference in the amount of movement in the direction, the movable rack gear 60
Is to be moved in the scanning direction by a movement amount of 1/2 of the traveling body 70. Since the mirror unit 31 is connected to the other end of the movable rack gear 60, according to the above configuration, the mirror unit 31 is moved in the moving direction of the light source unit 20 at a speed ratio of 1/2 of the moving speed of the light source unit 20. You can move in sync with. Therefore, the optical path length can be kept constant regardless of the movement position of the light source unit 20 during scanning.

When the light source unit 20 reaches the other end of its moving path, that is, the scan end position, the mirror unit 3
1 is also located at the other end of the moving path, and the first pinion 71 and the second pinion 72 are rotated in the arrow b direction. As a result, the light source unit 20 moves in the direction of the arrow B, and the mirror unit 31 moves at a speed of 1/2 in the moving direction. Therefore, when the light source unit 20 returns to the scan start position, the mirror unit 31 returns to the center of the moving path shown in FIG.

[0024]

As described above, the optical system driving device of the present invention drives the light source unit and the mirror unit synchronously at a predetermined speed ratio by the combination of two rack gears and two pinions. The number of parts can be reduced compared to a wire type drive device that requires a pulley,
The device configuration can be simplified.

Moreover, it is only necessary to coaxially support the two pinions on the same rotary shaft, and the idle gear that is often used in this type of gear device becomes unnecessary. Therefore, also in this respect, it is convenient for simplifying the device configuration.

Further, since complicated wire winding work is not required at the time of assembling, the manufacturing efficiency can be improved and a large cost reduction can be expected. Furthermore, since there is no decrease in accuracy due to the elongation of the wire, it is possible to maintain an accurate driving state for a long period of time. Therefore, the reliability can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the overall structure of an optical system driving device of the present invention.

FIG. 2 is a perspective view showing a rack and pinion mechanism which constitutes the optical system driving device of the present invention.

[Explanation of symbols]

 10 Document Plate 20 Light Source Unit 21 Movable Base 22 Lamp 31 Mirror Unit 40 Mirror Holder 50 Fixed Rack Gear 60 Movable Rack Gear 70 Traveling Body 71 First Pinion 72 Second Pinion 73 Rotation Shaft

Claims (1)

(57) [Claims] 1. An optical system driving device for reciprocating a light source unit and moving a mirror unit provided in an optical path between the light source unit and a photoconductor at a predetermined speed ratio in a moving direction of the light source unit. A fixed rack gear arranged along the moving path of the light source unit, a movable rack gear provided along the fixed rack gear and movable in the longitudinal direction to move the mirror unit, and the fixed rack gear. A rack gear and a first pinion and a second pinion that mesh with the movable rack gear, respectively.
The pinion and the second pinion are integrally attached to a rotary shaft, and the rotation of the rotary shaft causes the light source unit to move by self-propelled along the fixed rack gear.
The diameter ratio of the pitch circles of the pinion and the second pinion is
An optical system driving device comprising a traveling body set in association with a speed ratio between the light source unit and the mirror unit.