JPH054366Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to an image reading device used in a copying machine, etc., and is particularly designed to improve the workability of installing each part necessary for reading an image. The present invention relates to an image reading device.

[Prior art] Conventionally, as this type of image reading device, for example, the 6th image reading device
There is something like the one shown in the figure. A light transmission port 2 is opened on one side of the housing 1, and a transparent platen 3 is attached to the light transmission port 2 portion, with which side A of the original comes into contact. The unit 4 includes a light source 5 that irradiates light onto the A side of the original through the light transmission aperture 2, an imaging lens 6 that forms an image of the light reflected from the A side of the original onto a predetermined area, and a lens 6 that The image sensor 7 is disposed at the image area and converts optical information from side A of the document into electrical information.
The image is read by processing the image information sensed by the sensor.

[Problems to be Solved by the Invention] Incidentally, in such an image reading device, the image reading section 4, such as the imaging lens 6 and the image sensor 7, is installed inside the housing 1 via a mounting bracket (not shown). However, considering the installation error, the positions of the imaging lens 6 and image sensor 7 and the position of the platen 3 attached to the light transmission port 2 of the housing 1, in other words, the position of the original A side This results in a situation where the distance between the two changes slightly. On the other hand, when attempting to downsize the device itself, it is usually difficult to secure a sufficiently large storage space for the image reading section 4 within the housing 1, so it is necessary to use an imaging lens 6 with a shallow focal depth. I don't get it.

Under such circumstances, the imaging lens 6
and the distance d1 between the image sensor 7 and the document A side,
Assuming that d2 changes slightly with respect to the set distance,
Optimal imaging position of imaging lens 6 and image sensor 7
This results in a relatively large deviation from the surface position, resulting in a problem in that the resolution of the original image read by the image sensor 7 is extremely reduced due to the focus deviation.
In order to solve this problem, it is possible to make fine adjustments to the mounting positions of the imaging lens 6 and image sensor 7 after assembly, but this is a new method that makes optical adjustment troublesome. A problem arises.

[Means for solving the problem] This invention was made by focusing on the above problem, and it is possible to solve the problem without making troublesome optical adjustments.
An object of the present invention is to provide an image reading device that can accurately read document image information.

In other words, this invention consists of a light source that illuminates the document surface, an imaging lens that forms an image of reflected light from the document surface on a predetermined image formation site, and a light source that is placed at the image formation site of this imaging lens and that creates an optical image of the document. The image reading device houses an image sensor that converts the image into an electrical signal in a housing, and comprises a transparent platen at the end of the housing facing the document to be read, and reads the document image through the platen. The housing includes at least a base housing having reference surfaces for positioning the image sensor, the imaging lens, and the platen, and a side housing that defines a space together with the base housing.

In such technical means, the application of this invention is not limited to fixed type devices used in copying machines, etc., but also includes manual scanning type devices. Furthermore, the light source that is a constituent member of the image reading section may be appropriately selected from LEDs, fluorescent lamps, halogen lamps, etc., and the number and arrangement position thereof may also be appropriately selected. Furthermore, the imaging lens may be selected as appropriate, including a converging light transmission body made of a large number of optical fiber groups, and the image sensor is also limited to one consisting of a large number of photoelectric element groups. However, it also includes sensitive materials. Furthermore, the design of the material, shape, etc. of the platen attached to the light transmission opening of the housing may be changed as appropriate.

Further, as long as the base housing has a positioning reference surface for an image sensor or the like, the shape and structure of the base housing may be changed as appropriate. Furthermore, each positioning reference surface may be a direct mounting surface for the target member, or it may be used solely for positioning the target member and a separate mounting surface for the target member may be provided. Good too. Furthermore, the side housing can be selected as appropriate as long as it blocks external light from the image reading section.

[Operation] According to the above-mentioned technical means, the base housing, which constitutes a part of the storage housing of the image reading unit, determines the relative positional relationship of the platen, the imaging lens, and the image sensor using each positioning reference plane. In order to set it uniquely, if each positioning reference plane is adjusted in advance according to the appropriate positional relationship, the light image from the document that comes into contact with the platen surface position will be formed on the image sensor in the optimal state via the imaging lens. be done.

Further, since the side housing and the base housing define a storage space for the image reading section, external light directed toward the image reading section is blocked.

[Example] This invention will be described in detail below based on the example shown in the attached drawings.

1 and 2 show an application of this invention to a fixed image reading device used in a copying machine.

The basic configuration of this image reading device is similar to the conventional one, in which a light transmission port 2 is provided at the end surface of the housing 1 facing the document A, and a transparent platen 3 is attached to the light transmission port 2. On the other hand, an image reading unit 4 is housed in the housing 1, and the image reading unit 4 includes a pair of light sources 5 such as LED arrays arranged with the light transmission opening 2 in between. (specifically, 5a, 5b (see Figure 5)), and a focusing optical transmission body consisting of a large number of optical fiber groups that image the structure from the document A irradiated by the light source 5 onto a predetermined region. An image forming lens 6 such as the above, an image sensor 7 arranged at the image forming position of the image forming lens 6 and converting optical information from the document A into electrical information, and driving and controlling the light source 5 and the image sensor 7 as appropriate. and a control board 8.

In this embodiment, the housing 1 includes an elongated base housing 10 extending along the main scanning direction (longitudinal direction) of the image sensor 7, and a pair of side surfaces disposed on both sides of the base housing 10 in the width direction. Housing 30 (specifically 30
a, 30b).

The base housing 10 has a horizontal flat plate portion 11 extending in the longitudinal direction, and a pair of vertical wall portions 12 (specifically, 12a, 12b) is erected, and a mounting flange 13 extending along the horizontal flat plate portion 11 is protruded from the outside of the vertical wall portion 12. The surface of the horizontal flat plate portion 11 of the base housing 10 is a sensor positioning reference surface 1 for positioning and mounting the image sensor 7.
4, and recesses 15 in the width direction corresponding to the width dimension of the imaging lens 6 are formed inside the vertical wall portions 12, and the bottom surfaces of the recesses 15 position and mount the imaging lens 6. It is formed as a lens positioning reference surface 16 for placing the lens, and further,
The top surface of the vertical wall portion 12 is formed as a platen positioning reference surface 17 for positioning the surface of the platen 3. Also, the horizontal flat plate portion 11
An image sensor 7 is installed at each corner near the vertical wall 12 of the
A positioning protrusion 18 is formed to restrict movement in the plane direction. In FIG. 1, reference numeral 19 indicates a mounting hole formed in the mounting flange 13; 20 indicates a screw hole formed on both sides of the vertical wall portion 12 in the width direction for screwing the side housing 30;
Reference numeral 1 indicates a screw hole formed on the top surface of the vertical wall portion 12 for screwing the platen holding plate 22, and reference numeral 23 indicates a screw hole provided on one side of the horizontal flat plate portion 11 for a group of photoelectric conversion elements of the image sensor 7. The drawer opening 24 of the drawer part 7b that guides the information from 7a to the control board 8 is a harness opening opened on one side of the horizontal flat plate part 11 for connecting the harness leading to the light source 5 to the control board 8. .

On the other hand, the side housing 30 has a vertical flat plate part 31 extending in a direction perpendicular to the horizontal flat plate part 11 of the base housing 10. At the same time, a hollow protrusion 32 is formed extending along the protrusion 32, and an inclined surface 33 facing diagonally upward is formed on the protrusion 32. Furthermore, when the lower side of this inclined surface 33 is used as a light source mounting surface 34, one side A step portion 35 is formed on the upper side of this inclined surface 33, and the upper surface of this step portion 35 is used as a platen support surface 36. The hollow portion of the protruding portion 32 is used as a space for arranging a harness leading to the light source 5. Further, on the inside of the lower half of the vertical flat plate portion 31, guide protrusions 37 extending along the longitudinal direction are formed in two stages, upper and lower, and the control board 8 is fitted between the guide protrusions 37. It is designed to be inserted and supported.
In FIG. 1, reference numerals 38 are screw insertion holes provided at both ends of the vertical flat plate portion 31 in the longitudinal direction corresponding to the screw holes 20, and 39 are screw holes for screwing the light source 5 to the light source mounting surface 34. This is a screw hole.

In this embodiment, the base housing 1 is provided on the lower surface side of the platen holding plate 22, as shown in FIGS. 1, 3, and 4.
A locking pin 41 is provided in a protruding manner corresponding to the recess 15 of the vertical wall portion 12 at 0. A coil spring 42 is locked to this locking pin 41, and the coil spring 42 holds the surface of the imaging lens 6. It is designed to be pressed and biased from above. Incidentally, reference numeral 43 indicates a screw insertion hole formed in the platen holding plate 22. Furthermore, in this embodiment, as shown in FIGS. 1 and 5, a sensor pressing member 45 made of an elastic material, for example, is provided at the boundary between the protrusion 32 and the vertical flat plate 31 in the side housing 30. is fixed along the longitudinal direction of the protrusion portion 32, and this sensor pressing member 45 presses down the image sensor 7 disposed on the horizontal flat plate portion 11 of the base housing 10.

Furthermore, in this embodiment, as shown in FIGS. 1 and 5, light-shielding plates 51 are fixed to both sides in the width direction of the imaging lens 6 with double-sided tape or the like. The lower end of the plate 51 is arranged to protrude downward from the lower end surface of the imaging lens 6 to block light directly directed from the light source 5 toward the image sensor 7 side.

Next, a case of assembling the image reading device according to this embodiment will be described.

First, as shown in FIG. 1, after placing the image sensor 7 on the sensor positioning reference surface 14 of the horizontal flat plate portion 11 of the base housing 10, the image sensor 7 is placed on the lens positioning reference surface 16 of the recess 15 of the vertical wall portion 12. Both ends of the imaging lens 6 are placed. on the other hand,
The light source 5 is screwed and fixed in advance to the light source mounting surface 34 of the protrusion 32 of the side housing 30, and the side housing 30 in this state is assembled to both sides of the base housing 10 in the width direction with screws 61,
The image sensor 7 is pressed down from above by a sensor pressing member 45 attached to the protrusion 32 of the side housing 30.

Thereafter, the platen 3 is placed on the platen support surface 36 of the side housing 30, and the platen holding plate 22 is attached to the platen positioning reference surface 17 of the base housing 10 with the screws 6.
By fixing 2, the platen holding plate 2
2 to press down the platen 3, while the imaging lens 6 is pressed from above by the biasing force of the coil spring 42 built into the lower side of the platen holding plate 22.

Further, a control board 8 is fitted and fixed into the guide protrusion 37 of the side housing 30 assembled to the base housing 10, and the light source 5 and image sensor 7 are electrically connected to the control board 8. For example, at this stage, the assembly process of the image reading device is completed.

The operating principle of the image reading device assembled in this way is the same as the conventional one, and as shown in FIGS. The image of the document is read by focusing the reflected light from the image sensor 7 on the image sensor 7 via the imaging lens 6, and processing the sensed information from the image sensor 7 with the control board 8.

At this time, the relative positional relationship among the platen 3, the imaging lens 6, and the image sensor 7 is uniquely set by the base housing 10. That is, the platen 3 is placed on the platen support surface 36 of the side housing 30, but by appropriately adjusting the assembly position of the side housing 30 with respect to the base housing 10 at the time of assembly, the platen holding plate 22 The surface position of the platen 3 that is pressed in substantially coincides with the platen positioning reference surface 17 of the base housing. Further, the position of the imaging lens 6 is regulated by the lens positioning reference surface 16 of the base housing 10, and furthermore, the floating of the imaging lens 6 is effectively suppressed by the biasing force of the coil spring 42. Therefore, the position of the imaging lens 6 matches the lens positioning reference plane 16. Furthermore, the position of the image sensor 7 is regulated by the sensor positioning reference surface 14 of the base housing 10, and the floating of the image sensor 7 is effectively suppressed by the holding force of the sensor holding member 45, so that the image sensor 7 is The position of the sensor 7 matches the sensor positioning reference plane 14. Therefore, if the positions of the lens positioning reference surface 16 and the sensor positioning reference surface 14 are fixedly set with respect to the platen positioning reference surface 17, the imaging lens 6 can be adjusted from the surface position of the platen 3, in other words, from the document A side. The distance d1 from the document A to the image sensor 7 and the distance d2 from the document A side to the image sensor 7 are kept constant with high precision.If the values of each dimension d1 and d2 are set to appropriate values in advance, The light image will be formed on the image sensor 7 without being out of focus.

[Effects of the invention] As explained above, according to the image reading device according to the invention, the relative positional relationship between the document surface, the imaging lens, and the image sensor can be determined by the base housing, which is a component of the housing. This allows the optical information from the document surface to be read by the image sensor without shifting its focus, making it possible to suppress the reduction in resolution of the document image and improve image quality. can be kept.

Further, since troublesome optical adjustment is not required to set the relative positional relationship between the document surface, the imaging lens, and the image sensor, the workability of assembling the image reading device can be improved accordingly.

Furthermore, since the side housing can effectively block external light directed toward the image reading section,
There is no concern that the image reading operation will be impaired.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing an embodiment of the image reading device according to the invention, FIG. 2 is a perspective view showing its assembled state, and FIG. 3 is a sectional view taken along the line in FIG.
FIG. 4 is an enlarged view of the middle part of FIG. 3, FIG. 5 is a sectional view taken along the line taken along the line in FIG. 2, and FIG. 6 is a schematic diagram showing an example of a conventional image reading device. Explanation of symbols, A...Manuscript, 1...Housing,
3...Platen, 4...Image reading section, 5...Light source, 6...Imaging lens, 7...Image sensor,
10...Base housing, 14...Sensor positioning reference surface, 16...Lens positioning reference surface, 1
7...Platen positioning reference surface, 30...Side housing.

Claims (1)

[Scope of utility model registration request] A light source that illuminates the document surface, an imaging lens that focuses reflected light from the document surface onto a predetermined image formation region, and a device that is placed at the imaging region of the imaging lens and converts the optical image of the document into an electrical signal. An image reading device in which an image sensor is housed in a housing, an end face of the housing facing a document to be read is constituted by a transparent platen, and the document image is read through the platen, the housing comprising: An image reading device comprising: a base housing having reference surfaces for positioning at least an image sensor, an imaging lens, and a platen; and a side housing defining a space together with the base housing.