JP3501576B2 - Document reading device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a support structure of a traveling body in an image scanner or a document reading apparatus used in an image forming apparatus such as a facsimile or a copying machine. About. 2. Description of the Related Art An image scanner or a facsimile,
Document reading devices used in image forming apparatuses such as copying machines
A document table on which a document is placed, a slide rail provided immediately below the document table in parallel with the document table, a document illumination light source for moving and scanning the document, and a first reflection mirror are held. A first traveling body, and a second traveling body that holds second and third reflection mirrors that scan in the same direction with a movement amount of 第一 of the first traveling body, and each traveling body is mounted on a slide rail. Move along. Each traveling body includes a slider that slides on the upper surface of the slide rail. Japanese Utility Model Laid-Open No. 5-47942 discloses that a running body reciprocating on a rail surface such as a slide rail with a slider made of a material having low friction and low wear is provided with a rail. In order to prevent the vibration from the reading device body etc. from transmitting and the mirror etc.
There is disclosed a technique of attaching a slider to a traveling body via a damping member for absorbing vibration. With this configuration, vibration of the mirror held by the traveling body can be prevented, and disturbance such as periodic bending of the image can be prevented. FIG. 3A shows a state in which the mirror resonates, and FIG. 3B shows a normal image (vertical line) obtained when the mirror does not resonate, and an abnormal image. [0003] However, in the above-mentioned conventional example, a damping member is attached between the traveling body and the slider in such a manner that the slider is damped in all directions. Therefore, when the traveling body moves in the horizontal direction on the rail, the frictional resistance of the slider acts in the horizontal direction, so that the elasticity of the damping member causes the position of the slider to be opposite to the traveling body moving direction. Deviation occurs. In addition, such a displacement in the horizontal direction has a drawback that the slider easily induces a “stick-slip” phenomenon in which the slider repeatedly moves forward and backward minutely in the moving direction, and as a result, the entire traveling body shakes to disturb the reflected light flux. Resulting in periodic stretching of the image. That is, FIGS. 4 (a), (b), and (c) show the problems caused by stick-slip and the like.
(a) When the traveling body causes a bouncing or feeding unevenness as in (b), expansion and contraction in the sub-scanning direction occurs in the image as shown in (c). In addition, the bouncing of the traveling body is likely to be caused by the rail vibrating in the vertical direction, but this problem cannot be solved by the conventional vibration damping structure. The present invention has been made in view of the above, and prevents a slider provided on a traveling body from being displaced in a direction opposite to a moving direction of the traveling body or preventing a stick-slip phenomenon from occurring. It is another object of the present invention to provide a reading device capable of preventing transmission of vibration to an optical component. [0004] In order to achieve the above object,
The invention of claim 1, said platen document Te had at the original table below for placing <br/> and provided parallel to the horizontal slide Les - moving and Le, on the slide rail in the horizontal direction Traveling body,
A slider in which a shaft is inserted and supported so as to be vertically movable in a hole provided in the bottom of the traveling body, wherein the shaft of the slider does not tilt in the hole. Yo
The cylindrical guide member having a sufficient axial height
With a small gap between it and the outer periphery of the
The shaft of the slider is perpendicular to the running body in the guide member.
And wherein the damping member exerts a damping effect to absorb are slidably inserted only in a direction, and occurs due to motion in the vertical direction of the sliding Doko vibration is located I do. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the accompanying drawings. FIG. 1 is a front sectional view of a reading apparatus to which the present invention is applied. FIG. 2 is a detailed sectional view of a portion around the slider. In FIG. 1, a document table (contact glass) 2 is placed on an upper surface of a housing 1 of the reading apparatus, and a first traveling body is placed on a slide rail 3 horizontally extended below the document table 2. 4. The second traveling body 5 is a slider 6
, And reciprocally scans horizontally. A light source 10 and a first mirror 11 are mounted on the first traveling body 4,
The second traveling body 5 has second and third mirrors 12 and 13 mounted thereon. The light emitted from the light source 10 to the original surface is reflected by the original surface, and the first mirror 11, the second and third mirrors 12, 1
3. An image is formed on a light receiving element 16 such as a CCD through a lens 15. As the vibration directions of the traveling bodies 4 and 5 which affect the image quality of the read image, two vibrations are considered: a vibration in the horizontal direction H which is the moving direction of the traveling body and a vibration in the vertical direction V which is the vibration direction of the rail. However, since the vibration in the horizontal direction H is the original sliding direction, it hardly affects the optical system.
On the other hand, the vibration in the vertical direction (bending direction of the rail) V greatly affects the obtained image quality. Therefore, in the present invention, the relative displacement in the horizontal direction between the slider 6 and the traveling bodies 4, 5 is restricted, and the occurrence of stick-slip due to the displacement in the horizontal direction is prevented. On the other hand, by providing a damping member 23 that absorbs vibration in the vertical direction, vibration in the vertical direction of the rail and vibration in the vertical direction caused by stick-slip and the like are absorbed and mitigated to prevent deterioration in image quality. It is intended. That is, the method of mounting the slider shown in FIG. 2 is based on the above concept. That is, a low friction, cylindrical guide member 2 is provided in a support hole 20 (bent in a cylindrical shape) provided on the bottom surface of each of the running bodies 4, 5.
1, the shaft portion 22 of the slider 6 is supported so as to be able to advance and retreat in the vertical direction and not to be displaced in the horizontal direction. (Elastic member) 23 was fitted to the outer periphery of the shaft 22. Also,
A retaining ring 24 was fixed to the tip of the shaft 22 to prevent the slider from coming off. The guide member 21 is fitted to the outer periphery of the shaft 22 while holding a small gap therebetween, thereby restricting the degree of freedom of movement of the slider 6 including the shaft 22 in the horizontal direction. The minute gap has such a size as to allow the shaft 22 to move in the vertical direction, while prohibiting displacement in the horizontal direction. The guide member 21 is configured to have a sufficient axial height so that the shaft portion 22 does not tilt, and is formed of a low-resistance material that does not increase sliding resistance between the shaft 22. Further, the damping member 23 is fitted and disposed on the outer periphery of the shaft 22, and absorbs and reduces vibration generated due to the vertical movement of the slider. In FIG. 2, between the damping member 23 and the shaft 22, and further between the damping member 23 and the bottom surface of the traveling body or the slider 6
Although there is a gap between the upper surface and the upper surface, the gap may not be provided, or a gap may be provided as necessary. As described above, according to the present invention, the degree of freedom of movement of the slider with respect to the traveling body in the horizontal direction is restricted, and furthermore, the damping member is provided in the vertical direction which is the vibration direction of the rail. Thus, it is possible to realize a reading device which prevents the vibration of the rail from being transmitted to the traveling body, prevents stick-slip, and can also absorb the vibration of the reading device main body or the like and which does not cause image disturbance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration explanatory view of an image reading apparatus to which the present invention is applied. FIG. 2 is a sectional view showing an example of a support structure of a slider by a traveling body. FIGS. 3 (a) and (b) are diagrams showing a resonance state of a mirror, and a diagram showing defects found in an obtained image. FIGS. 4A and 4B are diagrams showing a traveling abnormality of the traveling body,
(c) is a diagram comparing a normal image with an abnormal image. [Description of Signs] 1 housing, 2 platen (contact glass), 3 slide rail, 4 and 5 running body, 6 slider, 10 light sources, 11, 12, 13 mirror, 15 lens, 20
Support holes, 22 shafts, 23 damping members,

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/04-1/20 H04N 1/04 106 G02B 26/10 H04N 1/00

Claims (1)

(57) [Claims 1 wherein said platen and have at the platen below which a document is placed and provided parallel to the horizontal slide Les - Le and, horizontally on the slide rail move to the traveling body, in the traveling body document reading device including a slider which is movably inserted and supported the shaft portion in the vertical direction, to provided within the hole in the bottom of the said bore, sliding Enough to prevent the child's shaft from tipping
A cylindrical guide member having an axial height is provided between the outer periphery of the shaft portion and
Between the guide members
The shaft of the slider is only perpendicular to the running body.
A document reading apparatus characterized by having a damping member which is slidably inserted therein and has a damping member exhibiting a vibration damping effect of absorbing vibration generated due to vertical movement of the slider. apparatus.