JP2005223424A - Close contact type image sensor unit and mounting method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein mechanical distorsions or warpages occur in a sensor unit due to thermal expansion and shrinkage, when an optical guide body is bonded and fixed on a frame, with respect to a method of mounting a contact type image sensor. <P>SOLUTION: An optical guide body is not fixed by bonding in the frame of an image sensor unit, but is fixed mechanically with an elastic member. This method allows the optical guide body to be movable for changes due to the temperature, and the distorsions of the unit body is eliminated and deterioration in image quality due to the temperature changes can be prevented. Further, the manufacturing time until adhesive is cured can be reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus such as an image scanner, a facsimile, or a copying machine, and more particularly to an image sensor unit provided in an image reading unit.

In recent years, image scanners have become widespread as means for taking photographs and printed materials into computers, and there are many prior arts. (See, for example, Patent Document 1).
FIG. 6 shows a main configuration of a current image scanner which is a conventional technique, in which (a) is a perspective view and (b) is a cross-sectional view. Here, an LED with low power consumption and low heat generation is used as the light source. A light beam emitted from an LED (not shown) disposed on the end surface of the light guide 61 is converted into a linear shape by the light guide, and illuminates the document surface on the document table glass 66.

The illuminated image of the original is imaged and photoelectrically converted by the SELFOC lens array 62 as an optical lens on the light receiving surface of a line sensor 67 as a photoelectric conversion element. The line sensor, the SELFOC lens array, and the light guide are arranged in the frame 63 of the image sensor and are integrated as an image sensor unit.
The image scanner is configured to scan the document surface by moving it in a direction perpendicular to the longitudinal direction of the image sensor unit. ing.
The image photoelectrically converted by the line sensor 67 is A / D converted, corrected by an image processing circuit, and transferred to a computer. The image signal captured by the computer is synthesized and reproduced as an image by an output device such as a monitor or a printer.

Japanese Patent Laid-Open No. 11-341219

  A plan view of a conventional image sensor unit is shown in FIG.

  In this configuration, since the light guide 4 is bonded to the light guide mounting portion in the frame with an adhesive and is formed as a single unit, the light guide disposed in the light guide mounting portion is not rattled. Does not occur. As a constituent material of the image sensor unit, the frame is made of polycarbonate resin, and the light guide is generally made of acrylic resin from the viewpoint of transparency.

  However, when the image sensor unit changes in temperature according to the environmental temperature, there is a problem that mechanical distortion and warpage of the unit due to thermal expansion and contraction occur due to the difference in thermal expansion coefficient of the resin, and the image sensor unit is deformed. For this reason, the focal position of the lens changes as the distance between the original irradiation surface and the SELFOC lens array varies. In general, the depth of field of a SELFOC lens array is as narrow as 1 mm or less, and if the lens focal position shifts due to warpage or the like, a defocused image signal is given. Further, since the light guide and the like are distorted, the amount of light applied to the document fluctuates, and an image signal having a different brightness may be given.

On the other hand, the light emitted from the LEDs arranged on the end face of the light guide is irradiated through the light guide extending in the longitudinal direction, and the amount of emitted light changes according to the distance in the longitudinal direction. In this case, if the light guide and the frame are not bonded and fixed, the light guide is rattled, and the position of the light guide changes within the frame. It was difficult to obtain the amount of light reflected from the. In this case as well, there is a problem that image signals with different brightness are given in the same manner.

In order to solve the above problems, the present invention provides a light source for illuminating a read original, a light guide for guiding light from the light source in a one-dimensional direction, and reflecting light from the original to form an image at an equal magnification. An image sensor unit having an image forming unit that is incident on a three-dimensional light receiving element array, and a frame that integrally holds the light source, the image forming unit, and the one-dimensional light receiving element array;
The light guide is formed on the frame, is disposed with at least one elastic member in the light guide mounting portion, and is held in the light guide mounting portion by the elastic force of the elastic member. This is an image sensor unit.

  The present invention also provides a light source for illuminating a read original, a light guide that guides light from the light source in a one-dimensional direction, and a reflected light from the original that forms an equal magnification and is incident on a one-dimensional light receiving element array. An image sensor unit having an image means and a frame that integrally holds the light source, the image forming means, and the one-dimensional light receiving element array, wherein the light guide is one-dimensional more than the shape of the light guide mounting portion. The light guide has a shape that is curved with respect to the direction, and the light guide has an elastic force and a restoring force when the light guide is disposed in the light guide mount. The image sensor unit according to claim 1, wherein the image sensor unit is held.

  A light source for reading document illumination; a light guide that guides light from the light source in a one-dimensional direction; and imaging means that forms reflected light from the document at an equal magnification and enters the one-dimensional light receiving element array; An image sensor unit mounting method having a frame that integrally holds the light source, the imaging means, and the one-dimensional light receiving element array, wherein the light guide is formed on the frame and at least one in the light guide mounting portion. Another object of the present invention is to provide a mounting method of an image sensor unit, which is held by the elastic force of two elastic members.

  Furthermore, the present invention provides a light source for illuminating a read original, a light guide that guides light from the light source in a one-dimensional direction, and forms reflected light from the original at the same magnification so as to enter the one-dimensional light receiving element array. An image sensor unit mounting method having an image means and a frame that integrally holds the light source, the image forming means, and the one-dimensional light receiving element array, wherein the light guide is more than the shape of the light guide mounting portion. And the light guide is formed by the elastic force and the restoring force when the light guide is disposed in the light guide mounting portion. The image sensor unit mounting method according to claim 5, wherein the image sensor unit is held in a mounting unit.

Furthermore, in the present invention, it is desirable that the elastic member is an elastic member having a shape formed by curving a part of a frame material or an elastic member such as rubber is used. In the present invention, it is preferable that the elastic member is disposed at a position where the light source and the light guide are in close contact with each other.

  In this way, even if the environmental temperature changes, the position of the light guide can be expanded and contracted according to the temperature while the position of the light guide is fixed by the elastic member. It will not cause mechanical deformation such as warping. As a result, there is no change in the image quality of the output image of the white scanned original, or the focus is not blurred.

More specifically, since the original irradiation position and its focal position do not change with respect to temperature fluctuations, a predetermined amount of reflected light can be obtained, and the temperature change in the performance of the image reading apparatus is eliminated. Moreover, since it is not bonded, it is easy to attach and detach, and it is easy to rework after mounting. And since the hardening time of an adhesive agent becomes unnecessary, there exists an advantage which can shorten manufacturing time. Since the position of the light guide is fixed by the elastic member, there is no backlash of the light guide in the frame without adhesive fixing, and the position of the light guide is not changed even by vibration or the like. .

The features of the present invention will be described in detail below with reference to examples.
(Example 1)
FIG. 1 is a top view of a contact image sensor of the present invention. An illuminating light source 4 made of LED is connected to an acrylic light guide 4 and is disposed in a frame 3 formed by molding polycarbonate. The light guide 4 and the light source 5 obtain a pressing force in the longitudinal direction of the light guide by the elastic member 1 disposed in the light guide mounting portion of the frame, and are pressed in the direction opposite to the light source in FIG. .

FIG. 2 is a diagram showing an example of the shape of the pressing member 2 provided in the frame.
By devising the shape of the frame member as shown by 2 in the figure and forming it in a spring shape, a force for pressing the light guide downward in the drawing is applied. A protrusion connected to the main body of the light guide is provided at a position corresponding to the pressing member 2, and the protrusion extends in the left-right direction in FIG. 1 along with the thermal expansion and contraction in the longitudinal direction of the light guide. Since it moves a little, it is necessary to provide a slight gap on the left and right sides of the pressing portion 2.

  The light guide 4 has a tapered shape on the right side of the drawing, and is configured to compensate for a decrease in the amount of light at the front end of the light guide. The SELFOC lens array 6 condenses the light reflected by the illumination light emitted from the light guide when it strikes the original paper, and guides it to a light receiving element disposed immediately below it to convert it into an image signal.

  The contact image sensor unit formed of these materials repeats thermal expansion and contraction due to temperature changes because the main material is resin. For the A4-sized frame (effective length 23 cm) and the light guide (effective length 22 cm), the thermal expansion of the frame and the light guide in the longitudinal direction was 0.264 mm and 0.528 mm, respectively, in the range from room temperature to 50 ° C. And the difference is 0.264 mm.

  At this time, the light guide 4 is strongly pressure-bonded to the opposite side in the frame by the elastic member 1 provided in the light guide mounting portion of the frame in FIG. 1, and can move from the left end of the light guide as a base point. It has become. Since the light guide body relatively contracts when the temperature decreases, the light guide body is attracted by the left hand side of the frame in FIG.

  Further, in this case, a pressing member 2 for pressing the light guide 4 in the lateral direction is disposed at a frame portion corresponding to the upper portion of the light guide 4 and presses the light guide 4 to the lower side in FIG. Therefore, the vertical play is not generated.

  Using the image sensor unit created by this method, the image reading apparatus shown in FIG. 7 was assembled, and an A4 size original reading test was performed at different operating temperatures. In this image sensor unit, warping and distortion do not occur according to temperature changes, and the focus of the SELFOC lens array 6 can be kept constant. As a result, there was almost no change in the amount of light read in the range of 0 ° C. to 50 ° C. with respect to the entire A4 size surface, and it was possible to provide a beautiful image that was not out of focus.

  In the present invention, the elastic member is provided with the rubber material, but the frame material itself may be used as the elastic member instead. In this case, in order to give an elastic force to the frame wall on the light source side, the polycarbonate material is curved and formed, and the restoring force can be used as a force for pressing the light source and the light guide.

  Furthermore, the elastic member may be constituted by a spring, and the material is not limited as long as it has an elastic force.

(Comparative example)
In the same manner as described in the prior art, the light guide was fixed with an adhesive at three points of the frame as shown in FIG. The adhesive used was epoxy and had high hardness, and the light guide did not move within the frame. Using this image sensor unit, an A4 size original reading test was conducted in the same manner as in Example 1.

  As the temperature rises, the light guide is more stretched than the frame, so when viewed in plan, the non-bonded part sticks out to the non-bonded side starting from the bonding point in FIG. The light guide is curved in such a shape. As a result, the illumination position on the document of illumination light emitted from the light guide changes. In addition, the unit is deformed along with this deformation, and the shape of the Selfoc lens is also curved, so that the position where the reflected light is condensed also slightly changes.

  As a result, even when a white original is read, the amount of light received by the light receiving element does not substantially change at the adhesion point, but a light amount decrease of about 2% is observed at the apex portion of the curve.

  In addition, a slightly gray portion that does not exist on the original paper appears in the output original at the curved point portion at high and low temperatures. This means that the read image quality has changed due to mechanical distortion generated in the image sensor unit.

(Example 2)
Another embodiment of the present invention will be described with reference to FIGS.
FIG. 3 is an external view showing a planar shape of a light guide formed of an acrylic material used in the present invention, and is characterized by being bent and shaped like a bow. A method of fixing the light guide in the vertical direction will be specifically described.

  FIG. 4 shows a state in which this light guide is assembled to the frame. The light guide formed in the shape of a bow is assembled in the light guide mounting portion formed on the frame, thereby generating a force that is pressed against the light guide mounting portion by the restoring force of the acrylic material. The force with which this light guide is pressed is shown by arrows in FIG. The vertical position in the figure is fixed by this force, but since it is not adhesively fixed, a slight movement can be allowed according to the temperature change, so that the image sensor unit is not warped or distorted. .

  The longitudinal direction is fixed in the same manner as in the first embodiment, but the mechanical movement accompanying the temperature change is always based on the light source side portion of the light guide where the pressing force works. As a result, when the image reading apparatus is used, it is possible to eliminate the change in image quality due to the temperature change.

  An advantage of the present invention is that, when an image sensor unit is manufactured, a defect due to contamination of dust or the like may occur after assembly, and this can be easily collected and repaired.

The present invention provides a housing structure that is not easily affected by temperature changes of an image sensor unit. The present invention can be applied to a multifunction printer having a built-in scanner or a reading device because the operating temperature range of the document reading device is widened and the reading quality is improved.

The top view of the image sensor unit of this invention by which the light guide was integrated in the flame | frame which is this invention. The figure which shows the frame shape provided with the pressing member of the light guide used for this invention. The conceptual diagram which shows the planar shape of the curved light guide used for this invention. The figure which shows the planar shape of the image sensor unit in which the curved light guide of this invention was integrated. The external view which shows the image sensor unit which has a light guide fixed with the conventional adhesive agent. The figure which shows the perspective view and sectional drawing which show the conventional common image sensor unit. The perspective view which shows the flat bed type image reading apparatus using an image sensor unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Elastic member 2 Pressing member 3 Frame 4 Light guide 5 Light source 6 Selfoc lens array 7 Adhesive

Claims (8)

A light source for illuminating a read document, a light guide for guiding light from the light source in a one-dimensional direction, an imaging means for forming reflected light from the document at an equal magnification and entering the one-dimensional light receiving element array; An image sensor unit having a frame that integrally holds the light source, the imaging means, and the one-dimensional light receiving element array,
The light guide is formed on the frame, is disposed with at least one elastic member in the light guide mounting portion, and is held in the light guide mounting portion by the elastic force of the elastic member. Image sensor unit.   The image sensor unit according to claim 1, wherein the elastic member is a part of the frame or a rubber material.   The light source is disposed at at least one end of the light guide, and the elastic member is disposed between the frame and the light source, and is movable with respect to expansion and contraction of the light guide accompanying a temperature change. The image sensor unit according to claim 1, wherein the image sensor unit is provided.   The light source is disposed at at least one end of the light guide, and the elastic member forms a part of the frame, and is movable with respect to expansion and contraction of the light guide accompanying a temperature change. The image sensor unit according to claim 1 or 2, characterized in that A light source for illuminating a read document, a light guide for guiding light from the light source in a one-dimensional direction, an imaging means for forming reflected light from the document at an equal magnification and entering the one-dimensional light receiving element array; An image sensor unit having a frame that integrally holds the light source, the imaging means, and the one-dimensional light receiving element array,
The light guide has a shape that is curved with respect to the one-dimensional direction more than the shape of the light guide mounting portion, and the light guide has the elastic force and the light guide is in the light guide mounting portion. The image sensor unit according to claim 1, wherein the image sensor unit is held in the light guide body mounting portion by a restoring force when arranged in the light guide body. A light source for illuminating a read document, a light guide for guiding light from the light source in a one-dimensional direction, an imaging means for forming reflected light from the document at an equal magnification and entering the one-dimensional light receiving element array; A mounting method of an image sensor unit having a frame that integrally holds a light source, the imaging means, and the one-dimensional light receiving element array,
The image sensor unit mounting method, wherein the light guide is formed on the frame and is held in the light guide mounting portion by an elastic force of at least one elastic member. A light source for illuminating a read document, a light guide for guiding light from the light source in a one-dimensional direction, an imaging means for forming reflected light from the document at an equal magnification and entering the one-dimensional light receiving element array; A mounting method of an image sensor unit having a frame that integrally holds a light source, the imaging means, and the one-dimensional light receiving element array,
The light guide has a shape that is curved with respect to the one-dimensional direction more than the shape of the light guide mounting portion, and the light guide has the elastic force and the light guide is in the light guide mounting portion. The image sensor unit mounting method according to claim 6, wherein the image sensor unit is held in the light guide body mounting portion by a restoring force when disposed in the light guide body. An image reading apparatus using the image sensor unit according to claim 1 as an image reading unit.

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