JPS6142642A - Original scanner - Google Patents

Abstract

PURPOSE:To obtain a device free from image blurring, improved in durability, and can scan stably an original by providing a revolving shaft of a driven pulley by inclining it against a revolving shaft of a driving pulley, so that a straight line for connecting a wire and a contact start point of the driving pulley, and a straight line for connecting the wire and the driven pulley become roughly parallel. CONSTITUTION:A reflected light from an original 18 by a lamp 19 is slit-exposed to an element 27 through a rod lens array 25, and a sensor unit 27 moves and scans the original, and reads it. Also, a wire 32 is wound to a driving pulley 27 several times, and wound to a driven pulley about a half rotation, and the driven pulley 26 is inclined against the revolving shaft of the driving pulley and places so that a straight line for connecting the wire 32 and two contact start points of the driving pulley 28, and a straight line for connecting the wire 32 and two contact start points of the driven pulley 29 become parallel. In such a way, a torsion and a deformation of the surface consisting of each connecting point become the minimum, and an original can be scanned stably.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a document scanning device used in a copying machine, a facsimile machine, etc., and particularly relates to an improvement of a scanning optical system gjARh mechanism.

(Prior art) Conventionally, for example, a first single-mirror unit and a second single-mirror unit are synchronized in the same direction and moved at a speed ratio of 2:1 to scan a document, and the image is electronically transmitted in the form of a slit. In a document scanning device that exposes a photographic photoreceptor or a solid-state image sensor, a double-side drive type document scanning device that transmits motor power to both ends of the first and second mirror unit is as follows. It was configured.

FIG. 7 is a schematic perspective view of the document scanning device, and FIG. 8 is a schematic top view. 1 is the machine box, 2 is the motor, 3 is the motor pulley fixed to the motor output shaft, 4 is the drive shaft, 5
is a drive shaft pulley fixed to the drive shaft 4, 6 is a timing belt that transmits the rotational force of the motor pulley to the drive shaft pulley, 7 is a W drive shaft nut attached to the machine box 1, and 8
a and b are the first. The second NA dynamic pulleys 9a and 9b are the same as the third NA dynamic pulleys 9a and 9b. 4th NA dynamic pulley, lo
a and b are the first and second drive pulleys that are paired with the first and second drive pulleys;
Driven pulleys, lla and b are third and fourth drive pulleys 9
The 3rd. which is paired with a and b. 12 is a support unit for the first mirror facing the document placed on the machine case; 13 is a support unit for the second mirror facing the first mirror; 14a and 14b are the first mirror support units; Mirror support stand unit 12
gSf, the first and second wires that transmit the rotation of the second drive pulleys 8a, b; 15a, b transmit the rotation of the third and fourth drive pulleys 9a, b to the second mirror support 22) 13; The third and fourth wires, 16"a and 16"b, are guide rails on which the first and second mirror support stands are placed.As shown in Figure 8, the first to fourth drive pulleys are , a right-handed groove is made with a pitch slightly larger than the wire diameter, and each of the four wires is wound along this groove two and a half turns around the driving pulley and about a half turn around the driven pulley, and the ends of each It is attached to the first or second mirror support unit. Also, the above wire is stretched with a tension of 3 to 4 kg, and the rotational force of the drive pulley is applied to the first and second mirror support units by this wire. A part of the drive shaft 4 is provided with a threaded part with the same pitch and winding direction as the groove of the drive pulley, and the drive shaft nut engages with this threaded part and roughly connects to the machine case l. When the drive shaft 4 rotates in the direction of arrow A, the drive pulley 8
a, b.

The portions 9a and 9b that are in contact with the wire move in the direction of arrow B at speed V. However, since the drive shaft 4 also moves in the direction of arrow C at a speed V, the portions where the wires are in contact with the drive pulleys 8a, b, 9a, b do not move relative to each other. h12.13 moves parallel to the rails 16a,b.

In the above-described drive device, a surface (this surface is defined as a Z Because of the severe changes and twists in the wires (called "planes"), the friction between adjacent parts of the wire on the flange of the driven pulley and the driving pulley is large.
This reduced the durability of pulleys and wires.

Further, since the drive shaft 4 must be moved in the direction of its rotation axis, a drive shaft displacement device is required, and the drive shaft and its surroundings are complicated. Furthermore, due to deformation or twisting of the two surfaces, movement of the drive shaft, etc., stable movement of the mirror support unit cannot be obtained, resulting in image blurring, etc., and the load applied to the motor and timing belt is also increased.

Furthermore, in the conventional example described above, drive mechanisms are connected to both ends of the mirror support unit serving as the scanning optical system, but even if the driving mechanism is connected to one end side,
Problems similar to those described above occur in devices in which the wire is wound one or more times around the drive pulley.

(Purpose and Structure Summary) The object of the present invention is to provide a driving pulley, a driven pulley, and a wire stretched between both pulleys, the wire being wound around the driving pulley at least once,
Solving the above-mentioned problems in a document scanning device including a scanning optical system support connected to the wire between the two pulleys and a guide means for guiding the support, and improving durability; It is an object of the present invention to provide a device with a simple configuration that enables stable document scanning. In the document scanning device of the present invention, a straight line connecting the two contact starting points of the wire and the driving pulley and a straight line connecting the two contact starting points of the wire and the driven pulley are substantially parallel. The driving pulley is characterized in that the rotation axis of the driven pulley is inclined with respect to the rotation axis of the drive pulley.

(Example) An example will be described below. Figure 1 is a configuration diagram of an optical system according to an embodiment of the present invention, Figure 2 is a perspective view of the same embodiment, Figures 3 and 4.
The figure is an explanatory diagram of the scanning optical system drive mechanism of the same embodiment. In each figure, parts having the same functions as those in FIGS. 7-8 are given the same reference numerals, and explanations will be omitted unless particularly necessary. In each figure, l-16a and b are the same as in Figs. 7 and 8, 17 is the original table glass, 18 is the original, 19.19
” is the lamp that illuminates the original, and 20, 21, and 22 are the 1st lamps.
Second. A third scanning mirror, 23 is a lens, and 24 is a solid-state image pickup device such as a COD. Reference numerals 25 and 25' designate a first mirror side plate that supports the first mirror, 26 a lamp cover, and 27 a second mirror side plate that supports the second and third mirrors. 1st
The mirror support unit 12 includes a lamp 19.19'', a lamp cover 26, a first mirror 20, a first mirror side plate 25.
25', and the second mirror support stand 2 has the second and third mirrors 21, 22, and the second mirror side plate 2''7゜2.
-7', the second 1. The sum of the diameters of the second drive pulleys 8a and 8b and the diameter of the wire, and the third. Fourth
Since the ratio of the sum of the diameters of the drive pulleys 9a and 9b and the diameter of the wire is 2:l, when the drive shaft 4 rotates, the ratio of the first mirror support unit and the second mirror support unit is 2:l.
scan the document by moving at a speed of The reflected image light from the first . Second. After passing through the third mirror and lens 22, the light is irradiated onto the light receiving surface of the solid-state image sensor 23.

FIG. fJJ3 is a schematic top view of the optical system drive mechanism according to the present invention before the document scanning starts, and FIG. 4 is a schematic top view after the document scanning is finished. 1st. 3rd wA dynamic pulley 8a, 9a
left-handed, second. The fourth driving pulleys 8b and 9b are provided with right-handed grooves, and the wire is wound about two and a half times each along these grooves.

In the state before the D1 document scan starts, the drive pulley 8
The upper point of the two contact starting points between a and the wire 14a, D' is also the lower point, E is the same upper contact starting point in the state after scanning the document, and E' is also the lower contact starting point. , F is the driven pulley 10a and the wire 14a
The upper point of the two contact starting points with F' is also the lower point. Also, Gl, G2 are points where the wire 14a is attached to the first mirror support unit 12, points E, Gl, G2 . F and 1 point ', F' are each rail 14
It is located on a straight line parallel to the longitudinal direction of a. When the drive shaft 4 rotates in the inward direction, the first mirror support unit 12
moves synchronously in the direction of arrow H. Then, the part where the wire is wrapped around the drive pulley also moves in the B direction and the C direction at the same time, but since the wires wound around the pair of drive pulleys are wound in opposite directions, the moving direction is also opposite.
The forces that try to displace the mirror support unit cancel each other out, making it possible to stably move the mirror support unit parallel to the longitudinal direction of the rails 14a, b. The force that attempts to displace the single mirror unit above is applied to the two contact starting points between the wire and the driving pulley, the two contact starting points between the wire and the driven pulley, and the point at which the wire is attached to the mirror support unit. This occurs because the composed planes (these planes are called two planes) are distorted. Therefore, in the present invention, the rotation axis of the driven pulley is rotated so that the straight line connecting the two contact starting points of the drive pulley and the wire is parallel to the straight line connecting the two contact starting points of the driven pulley and the wire. It was placed at an angle to the shaft (drive shaft). Since the two contact starting points between the drive pulley and the wire move in the direction of the rotation axis of the drive shaft in synchronization with the movement of the mirror support unit, the above Z plane cannot always be kept in one plane, but the magnitude of the distortion is Considering the plane DD''F'FC, the distance DF is several hundred mm, while the distance DE which is the distortion is very small, several mm.In the embodiment, the driven pulley 8a is connected to the straight line ED' and the straight line F.
It was arranged so that F' was parallel. The same applies to other pulleys. Also, by minimizing the distortion on the two sides, it is possible to move the mirror support unit stably, and the frictional resistance between the wire and the flanges of the drive pulley and driven pulley, as well as the wires in contact with each other, is reduced. As a result, it has become possible to significantly reduce pulley wear and wire breakage, and improve durability.

Next, another embodiment according to the present invention will be described using FIGS. 5 and 6. 25 is a rod lens array, and 26 is a long solid-state image sensor. Lamp 19, low, drain 7 ray 2
5. The element 26 moves as a unit and is called a sensor unit 27. 28 is a driving pulley, 29 is a driven pulley, 30 is a guide rail of the sensor unit 27,
Similarly, 31' is a rail, and 32 is a wire. The reflected light from the original 18 from the lamp 19 passes through the rod lens array 25 and is exposed to a slit on the element 27, and the sensor unit 27 moves and scans the original to perform one reading. In this embodiment, the wire 32 is wound around the drive pulley 27 several times and around the driven pulley about half a turn.
The driven pulley 26 is rotated so that the α rotation axis is relative to the rotation axis of the drive pulley so that the straight line connecting the two contact start points of the pulley 28 and the straight line connecting the two contact start points of the wire 32 and the driven pulley 29 are parallel. It is arranged at an angle. Furthermore, when the sensor unit 27 is near the driven pulley 29, the connection point between the sensor unit 26 and the wire 32 and the upper contact start point between the driven pulley 29 and the wire 32 are
Further, when it is near the drive pulley 28 , the connection point between the sensor unit 26 and the wire 32 and the upper contact start point between the drive pulley 28 and the wire 32 are arranged so as to be parallel to the guide rail 30 . Therefore, there are four contact points between the wire 32 and the drive pulley 28 and the driven pulley 29, and between the wire 32 and the sensor unit/toe 2.
7,! Twisting and deformation of the surface formed by the - connection points are minimal.

Further, even in a reading device having a fixed optical system and a movable document table, the same effect can be obtained if the driving device is configured as described above.

Incidentally, the present invention can also be applied to an original scanning device for a copying machine that exposes an original image to an electrophotographic photoreceptor by slit exposure.

(Effects) According to the present invention, the deformation of the surface consisting of the four contact starting points between the wire and the driving pulley and the driven boob 9- and the connection point between the wire and the scanning optical system support is minimized. As a result, wear of the driving pulley and driven pulley and breakage of wire strands can be reduced, the durability of the driving device can be greatly improved, and stable document scanning without image blurring can be achieved.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an optical system of an embodiment of the present invention, Fig. 2 is a perspective view of the embodiment, Figs. 3 and 4 are explanatory diagrams of main parts of the embodiment, and Figs. 5 and 6. The figure is a front view of another embodiment of the present invention, and Figures 7A and 8 are explanatory diagrams of conventional examples. 8a, 8b, 9a, 9b are drive pulleys, jOa, jo
b, lla, and llb are driven pulleys, 12.13 is a mirror support unit, and 14a, 14b, 15a, and 15b are wires. D, -D', E, E', F, F
' is the starting point of contact between the wire and the pulley. Canon Co., Ltd. Fig. 1 Fig. 2 Fig. 5 Fig. 5

Claims (3)

[Claims] (1) A driving pulley, a driven pulley, a wire that is stretched between both pulleys, the wire being wound around the driving pulley at least once, and a wire that is connected to the wire between the two pulleys. In an original scanning device comprising a scanning optical system support body and a guide means for guiding the support body, a straight line connecting two contact start points of the wire and the drive pulley, and a straight line connecting the wire and the driven pulley. A document scanning device characterized in that the rotation axis of the driven pulley is inclined with respect to the rotation axis of the drive pulley so that a straight line connecting two contact start points of the pulley is substantially parallel. . (2) When the support body is located near the drive pulley,
A straight line connects the connection point between the wire and the support and the contact start point between the driving pulley and the wire, and when the support is located near the driven pulley, the connection point and the contact start point between the driven pulley and the wire. 2. The document scanning device according to claim 1, wherein the drive pulley and the driven pulley are arranged so that a straight line connecting the two is substantially parallel to the moving direction of the support. (3) First and second drive pulleys, first and second driven pulleys, first drive pulley, first wire stretched across the first driven pulley, second drive pulley, second driven pulley a second wire stretched around a pulley, the first wire is connected to one end of the support, the second wire is connected to the other end, and the first wire is wound around the first driving pulley. 3. The document scanning device according to claim 1, wherein the rotating direction and the winding direction of the second wire around the second drive pulley are opposite to each other.