JPH0437974B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION -Field of Industrial Application- The present invention relates to an exposure optical apparatus such as an electrophotographic copying machine, and particularly relates to an improvement of a drive control section of the exposure optical apparatus.

- Prior Art - As is well known, there are two types of exposure optical devices used in electrophotographic copying machines: a movable document table type and a movable mirror carriage type. The drive of the carriage is generally controlled by a wire pulley device.

Regarding exposure optical devices controlled by such wire pulley devices, a structure in which the carriage is controlled by two sets of wire pulley devices placed on both sides in the direction of movement of the carriage has recently been developed from the viewpoint of making the device more compact and lightweight. There is a tendency for it to be recommended. That is, FIG. 1 shows a conventional mirror-carriage movable exposure optical apparatus using two sets of wire pulley devices, including a mirror-carriage 3 on which a first mirror 1 and an exposure lamp 2 are mounted, and second and third mirrors 4. ,5
The half-speed carriage 6 carrying the is mounted on rails 8A and 8B laid on both sides of the machine frame 7. The mirror carriage 3 and the half-speed carriage 6 are driven and controlled by two sets of wire pulley devices 9A and 9B arranged on both sides in the direction of movement X thereof. Each wire pulley device 9A, 9B
is equipped with wires A and B whose both ends are tied to the stay of the device fixing part, and these wires A and B are connected to the moving pulleys 10 and 11 of the half-speed carriage 6, the movable end pulleys 12 and 13, and the drive drum 14. It is connected to both sides of the mirror carriage 3, and reciprocates the mirror carriage 3 and the half-speed carriage 6 according to the rotational direction of the drive drum 14.

Therefore, such a wire pulley device 9
In the arrangement configuration of A and 9B, in order to always keep the parallelism between the mirrors 1, 4, and 5 constant, and to maintain the correct angle of each mirror with respect to the moving direction X at any moving position, It is important that not only the tension direction of each wire A, B is equal, but also that the initial tension of both wires A, B related to the expansion and contraction of each wire A, B is equal. To explain in detail the problem of the initial tension of both wires A and B, it is assumed that each wire A and B are stretched in parallel, and the mirror carriage 3 is pulled by both drive drums 14 and 14 with a force F. If we find the positions on both sides of the mirror carriage 3 when
The influence of _{the initial tensions ta and t b of} both wires A and B can be understood. That is, if the initial lengths of the wires A and B from the drive drums 14 and 14 to the mirror carriage 3 are la _{and lb} , _and the spring constants of both wires A and B are R, then both wires A , the length of the relevant part of B after deformation
L _a and L _b are given as L _a = _la + (F-t _a )/R L _b = l _b + (F-t _b )/R. Here, in the assembly and adjustment state of the exposure optical device, since l _a = l _b is set,
The condition for the mirror carriage 3 to move while maintaining its initial parallelism with respect to the moving direction is that La ₌ L _b , that is, (F- _ta )/R = ( F-t _b )/R... It is necessary that the first formula is satisfied.

As can be understood from the first equation, in order to always keep the parallelism of the mirror carriage 3 constant, which has a large effect on focus and magnification, the initial tensions t _a and t _b of both wires A and B must be set equal. It is necessary to do so.

For this reason, in the past, when bonding wires A and B, a spring scale was used to set the initial tension of the left and right wires A and B.
Tension roller 1 with equal setting t _a , t _b or with controlled springs 15 as shown
6 is installed in the middle of the path of the wires A and B, and the initial tensions ta _and t _b of the wires A and B are set to be equal. However, such adjustment means has its limitations not only due to individual differences between the wires A and B, but also due to the measurement accuracy of the spring scale and individual differences between the tension rollers 16, and the adjustment work is complicated and takes a long time. It takes time.

-Object and Structure of the Present Invention- In view of the problems of conventional exposure optical devices as described above, the present invention aims at a structure that can easily equalize the initial wire tension of two sets of wire pulley devices on both sides of a carriage. , an exposure optical device in which a document table carriage on which a document is placed is driven and controlled by two sets of wire pulley devices placed on both sides in the direction of movement. The present invention proposes that a movable pulley and a movable end pulley be provided on both sides of the base carriage, and that the wires be stretched across these pulleys in a symmetrical state with the center of the movement direction of the document base carriage as an axis of symmetry. .

-Embodiments of the present invention- Hereinafter, details of embodiments of the present invention will be explained with reference to FIGS. 2 and 3.

The illustrated embodiment is an example in which the present invention is applied to a movable document table type exposure optical device, and in FIG.
Components that are the same as those in FIG. 1 are designated by the same reference numerals.

The feature of this embodiment is that wire pulley devices 9 are disposed on both sides of the document table carriage 17 on which the document is placed.
The wires A and 9B are made up of one common wire C. That is, left and right wire pulley devices 9A, 9 are provided on the left and right front ends of the document table carriage 17.
B movable end pulleys 12A, 12B, 13A, 13
Two sets of movable pulleys 18 that have a common arrangement of wires C that are wrapped around B and drive drums 14A and 14B.
A, 18B and 19A, 19B are fixed pulleys 1
6 and 16A. And the movable end pulley 13A of each wire pulley device 9A, 9B,
The center part of the wire C hung on 13B is the movable pulley 1
8A and 18B as a common part c ₁ , while both ends c ₂ and c ₃ of the wire C led from the movable end pulleys 12 and 12 are connected to the movable pulleys 19A and 19B.
Multiply by

Also, as shown in FIG. 3, grooves 8 are formed in the rails 8A and 8B.
C and 8D may be provided, and the projections 17A provided on the lower surface of the carriage 17 may be fitted through sliding members 17B to stabilize movement.

Next, the reciprocating movement of the carriage 17 will be explained.

First, as the drive drum 14 rotates in the direction of the arrow as shown in _FIG .
Since it is pulled like F ₂ , the wires C ₂ and C ₃ are pulled. The wire C is then passed through the other movable end pulley 12B, the drive drum 14B, the movable end pulley 13B, the movable pulleys 18B and 18A, and then from the movable end pulley 13A to the fixed pulley 16A to the drive drum 1.
Return to 4A. That is, when the drive drums 14A, 14B rotate in the direction of the arrow, the movable pulleys 18A, 18
Since B, 19A, and 19B are rotatable, the driving force from the wires from both sides is equal,
It moves by the same amount as the movement of wire C while being guaranteed. After the carriage 17 has moved a predetermined distance, the drive drum 14 is moved by a clutch (not shown).
When A and 14B are reversed, the carriage 17 is reversely fed by the movable pulleys 18A and 18B by the wire _C1 and returns to its original position.

-Other Embodiments- As shown in FIGS. 4 and 5, near the center of the wires C ₂ and C ₃ , the front wall 17a of the document table carriage 17
If you fix it with the mounting plate 20 on the original platen carriage 1
7 is regulated by the tension of the wires C ₂ and C ₃ on both sides, and a stable state can be obtained. Furthermore, the fourth
In addition to the configuration shown in FIGS. 5 and 5, a protrusion 17A as shown in FIG.
If the sliding member 17B is engaged with one of the rail grooves 8C and 8D, even more stable movement of the document table carriage 17 can be obtained.

Since the apparatus of the embodiment has the above-described structure, the tension of the wires of the wire pulley devices 9A and 9B on both sides of the document table carriage 17 is always adjusted equally at the common part, so that the entire wire tension is adjusted in the common part. By simply keeping the tension approximately constant, optical scanning with excellent magnification and focus can be obtained.

- Effects of the present invention - According to the present invention, since the endless wire of the wire pulley device is wound around the movable pulleys and the movable end pulley provided on both sides of the document table carriage, the initial tension of the wire can be easily set to be equal. Moreover, this tension state is uniform on both sides and is always automatically maintained, so the carriage always moves in a stable state and the carriage does not tilt, completely preventing the occurrence of image distortion etc. In addition, it is possible to obtain an exposure optical device in a normal position with constant magnification.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a conventional exposure optical device, FIG. 2 is a perspective view of an exposure optical device according to the present invention, and FIG. 3 is an enlarged sectional view of a part for guiding a carriage.
FIGS. 4 and 5 are perspective views showing other embodiments. 9A, 9B...Wire pulley device, 17...Document stand carriage, 18A, 18B, 19A, 19
B...Movable pulley, C...Wire.

Claims (1)

[Claims] 1. In an exposure optical device in which a document table carriage on which a document is placed is driven and controlled by two sets of wire pulley devices arranged on both sides of the document table in the direction of movement, the wires of both wire pulley devices are composed of a single endless wire. An exposure optical system characterized in that a movable pulley and a movable end pulley are provided on both sides of a base carriage, and the wire is stretched across these pulleys in a symmetrical state with the center of the moving direction of the document base carriage as an axis of symmetry. Device.