JP3642692B2 - Image reading device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is an image reading apparatus used for reading an original such as a scanner for a facsimile or a personal computer or a digital PPC.
[0002]
[Prior art]
A light amount detection member using an exposed CCD (bare chip CCD) and an image reading apparatus including the light amount detection member have been proposed (see Japanese Patent Application Laid-Open Nos. 9-61239 and 9-8336).
[0003]
11 and 12 are schematic sectional views of a conventional image reading apparatus.
In the light amount detection member 2 shown in the image reading apparatus 1 of FIG. 11, a lens fixing housing 4 is mounted on a circuit board 3, and three sets of optical lenses 5 (L1, L2) which are optical lens groups are provided therein. , L3) is fixed. The optical lens L1 is a chromatic aberration correction lens, the optical lens L2 is an imaging lens, and the optical lens L3 is a distortion correction lens. Then, a sealed space 6 is formed by the optical lens L3, the housing 4, and the circuit board 3, and a bare chip CCD 7 is fixed on the circuit board 3, and each electrode is connected to the circuit board 3 by a bonding wire or the like. Yes.
[0004]
When the light quantity detection member 2 having the above-described configuration is mounted on the image reading apparatus 1, the light source irradiates the document 8 and alignment is performed so that the reflected light is accurately imaged on the CCD 7 via the optical lens 5. .
[0005]
In such an image reading apparatus 1, the optical lens 5 is fixed to the housing 4. Instead, in the light amount detection member 10 shown in the image reading apparatus 9 of FIG. 12, a similar optical lens 5 a is used. Is configured to be movable along the optical axis direction, and the reflected light from the document 8 is accurately imaged on the CCD 7 via the optical lens 5 by adjusting the position thereof.
[0006]
[Problems to be solved by the invention]
In each of the image reading devices 1 and 9, each operation of fixing the housing 4 to a predetermined part of the image reading device 1 and fixing the circuit board 3 on which the CCD 7 is mounted and the optical lens 5 to the housing 4, respectively. However, optically accurate alignment is necessary simultaneously with these operations. In the figure, the X-axis direction is the main scanning direction (one-dimensional direction of the CCD 7), and the Y-axis direction is the sub-scanning direction. By adjusting both axial directions, the two-dimensional area is flat without distortion. An imaging plane is formed, and the Z-axis is in the optical axis direction. By adjusting the position of the optical lens 5, the optical resolution (MTF) and the magnification of the optical system are brought close to the design values. Further, the MTF of the optical lens 5 is maximized by adjusting the Z-axis rotation.
[0007]
However, there is a problem that very fine dust or the like is enclosed in the sealed space 6 by performing such fine adjustment.
That is, when the circuit board 3 is fixed to the housing 4, when two screws are tightened and fixed (hereinafter, such a screwing portion is referred to as a screwed portion p <b> 1), the X-axis direction and the Y-axis direction are adjusted. At the same time, the optical positions of the optical lens 5 and the CCD 7 are determined. However, if the adjustment cannot be performed as required, the screw at the screwing portion p1 must be loosened and readjusted. There is a problem that the image quality is deteriorated, for example, fine dust or dirt generated by friction caused by the friction enters the sealed space 6 and adheres to the light receiving surface of the CCD 7 to generate white stripes or black stripes in the read image. .
[0008]
FIG. 13 is a time chart of image signals by the image reading devices 1 and 9, and the occurrence of noise is indicated by an arrow N. This is because dust or the like is attached to a part of the light receiving surface, thereby blocking the optical path. This is what happened.
[0009]
Therefore, the present invention has been completed in view of the above circumstances, and its purpose is to reduce the degree of dust or dirt adhering to the light receiving surface of the bare chip CCD, or to eliminate it, and thereby to improve the image quality of the read image. An object of the present invention is to provide an image reading apparatus having an improved image quality.
[0010]
Another object of the present invention is to provide an image reading apparatus that can be easily manufactured by a simple operation, thereby reducing the time required for accuracy adjustment, thereby increasing the manufacturing yield and reducing the production cost. .
[0011]
[Means for Solving the Problems]
The image reading apparatus of the present invention includes a light amount detecting member that is hermetically sealed by providing a bare chip CCD inside a housing in which a light transmission portion is disposed, the optical lens, and a lens mounting housing in which the optical lens is provided. The image reading main body composed of a body is fixed by optical positioning, and the reflected light from the manuscript by the light emitted from the light source is sequentially passed through the optical lens and the light transmitting portion to form an image on the bare chip CCD. In the image reading apparatus configured as described above,
The housing of the light amount detection member and the lens mounting housing of the image reading body are in surface contact, and a groove is formed on the contact surface of the lens mounting housing. It is.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail with reference to FIGS. 1 to 10 with an image reading apparatus (bare chip CCD having a reading width of 310 mm) having a resolution of 600 DPI.
FIG. 1 is a schematic cross-sectional view of the light quantity detection member 11, and FIG. 2 is a schematic cross-sectional view of an image reading apparatus 12 equipped with the light quantity detection member 11. 3 is a schematic cross-sectional view of the image reading apparatus 12 shown in FIG. 4 is a schematic cross-sectional view of another light quantity detection member 13, FIG. 5 is a schematic cross-sectional view of an image reading apparatus 14 equipped with the light quantity detection member 13, and FIG. 6 is an image showing a specific structure of the image reading apparatus 14. FIG. 7 is an exploded perspective view of the main part of the image reading device 14a. FIG. 8 is a schematic sectional view of an image reading device 14b on which another light quantity detection member 15 is mounted, and FIG. 9 is an exploded perspective view of the light quantity detection member 15. FIG. 10 is a schematic view showing an adjustment method in the XY axis direction.
[0013]
In the light quantity detection member 11 of FIG. 1, a printed circuit board 17 made of glass epoxy is provided inside a polycarbonate casing 16, a bare chip CCD 18 is mounted on the circuit board 17, and each electrode is bonded with a bonding wire or the like. The circuit board 17 is connected. Various electronic component chips such as an IC, an operational amplifier, a resistor, and a capacitor are provided on the outer surface of the circuit board 17. Further, a transparent substrate 19 made of synthetic resin, glass, or the like, which is the light transmission portion, is provided on the housing 16 so as to face the bare chip CCD 18. And the housing | casing 16 is airtightly sealed and the sealed space 20 is formed.
[0014]
2 and 3 show a mounting structure when the light quantity detection member 11 is mounted on the image reading device 12, 21 is an optical lens, 22 is a lens mounting housing provided with the optical lens 21, for example, polycarbonate To make. As the optical lens 21, for example, three sets of optical lenses 5 (optical lens L1: chromatic aberration correction lens, optical lens L2: imaging lens, optical lens L3: distortion correction lens) used for the light amount detection member 2 are used. Reference numeral 23 denotes a base plate which is a part of the image reading main body of the image reading device 12, and the lens mounting housing 22 is fixed to the base plate 23. Reference numeral 24 denotes a document to be read by the image reading device 12. Further, the image reading body is provided with a light source such as an LED, a xenon tube, or a cold cathode tube.
[0015]
In order to manufacture the image reading device 12 having the above-described configuration, the following mounting steps (1) to (3) are sequentially performed. In addition, you may change the order of a process (1) and a process (2).
[0016]
Step (1) . . . A bare chip CCD 18 is mounted on the circuit board 17, and the circuit board 17 is fixed inside the housing 16. Further, the transparent substrate 19 is also fixed to the housing 16. And the sealed space 20 is formed by this process.
[0017]
In order to mount the bare chip CCD 18 on the circuit board 17, a die mounter is used. Then, it is fixed with an insulating adhesive (die attach paste). Then, the terminals of the bare chip CCD 18 and the wiring on the circuit board 17 are electrically connected by wire bonding, face down, and bumps.
[0018]
In order to fix the transparent substrate 19 to the housing 16, a resin-based or silicon-based adhesive is applied between the two and solidified. When the transparent substrate 19 is made of synthetic resin, it may be bonded by an ultrasonic welding method.
[0019]
Step (2) . . . The optical lens 21 is installed in the lens mounting housing 22. Then, the lens mounting housing 22 is fixed to the base plate 23.
[0020]
In order to fix the optical lens 21 to the lens mounting housing 22, a resin-based or silicon-based adhesive is used. When the optical lens 21 is made of synthetic resin, it may be bonded by an ultrasonic welding method.
[0021]
The lens mounting housing 22 is fixed to the base plate 23 which is, for example, a press sheet metal with about two screws. Further, the base plate 23 and the lens mounting housing 22 may be integrated. Alternatively, the lens mounting housing 22 and the base plate 23 may be fixed using an adhesive.
[0022]
Step (3) . . . The casing 16 obtained in the step (1) is fixed to the lens mounting casing 22. At that time, the two screws are fastened and fixed (screwed portion p2). At the same time, optical adjustment is performed.
[0023]
This optical adjustment will be described with reference to FIG.
A special adjustment adjustment test chart 32 is prepared for the image reading device 12, the test chart 32 is emitted by external illumination (light source), and is imaged on the bare chip CCD 18 through the reduction optical system lens 36. Convert it. The analog signal data captured from the bare chip CCD 18 is processed by the personal computer 35 connected to the image processing controller 34 while being monitored by the oscilloscope 33. Specifically, the image reading device 12 is fixed so as to read a thin black line in the main scanning direction on a white background chart, and the signal output of the bare chip CCD 18 is uniformly corresponding to the line while focusing. In such a manner, two-dimensional adjustment is performed in the X-axis direction and the Y-axis direction. At the same time, in order to focus on the line on the chart, the position of the lens group is adjusted so that the image magnification and the image resolution (MTF) are optimized, and θ is adjusted along with the z-axis direction. Patterns for magnification and MTF are formed on the chart, and the stage for the image reading device 12 moves and the positional relationship between the chart and the image reading device 12 is determined for each adjustment.
[0024]
With such a fixing method, two-dimensional adjustment can be performed in the X-axis direction and the Y-axis direction, and further, distortion due to a gap or the like does not occur in the Z-axis direction. In this example, the number of screwed portions p2 is two, but it can be reliably fixed by further increasing the number to three or four.
[0025]
As described above, with respect to the image reading device 12, the lens mounting housing 22 is fixed to the base plate 23 (image reading main body) in the step (2), so that the optical lens 21 is aligned and the Z-axis direction is adjusted. Then, in fixing the housing 16 to the lens mounting housing 22 in the step (3), the optical position is adjusted by adjusting the X-axis direction and the Y-axis direction with the threaded portion p2. Matching is done.
[0026]
After that, a performance inspection is performed. In this performance inspection, electrical inspection is performed for each item of a) presence / absence of signal degradation due to dust, b) optical characteristics, and c) output adjustment.
[0027]
Thus, in the image reading device 12 having the above-described configuration, the hermetically sealed casing 16 is fixed to the lens mounting casing 22 and at the same time the alignment is performed at the screwed portion p2. If the adjustment cannot be made, Even when the screw at the screwing portion p <b> 2 is loosened and readjusted, minute dust and dust generated thereby do not enter the housing 16.
[0028]
Next, another light quantity detection member 13 (image reading devices 14 and 14a) shown in FIGS. 4 to 7 will be described.
In the light quantity detection member 11, the circuit board 17 provided with the electronic component chip is used. Instead, the light quantity detection member 13 uses the ceramic circuit board 25 and the bare chip CCD 18 is mounted thereon. Instead of the transparent substrate 19, an acrylic curvature aberration correction lens 26 is provided. In addition, the same code | symbol is attached | subjected to the same location as the light quantity detection member 11. FIG.
[0029]
In mounting the light quantity detection member 13 on the image reading devices 14 and 14a, various electronic component chips (interface circuits) such as an IC, an operational amplifier, a resistor, and a capacitor are provided on the outer surface of the housing 16 of the light quantity detection member 13. A printed circuit board 27 made of glass epoxy is installed. FIG. 6 shows a case where the connector 28 is provided as an example.
[0030]
Also in the image reading apparatuses 14 and 14a having the above-described configuration, the dust-tight dust 16 and the dust are collected by fixing the hermetically sealed casing 16 to the lens mounting casing 22 and performing the alignment at the screwing portion p2. I can no longer enter the casing 16.
[0031]
Specifically, as shown in FIG. 7, a tap screw 37 is inserted into a large through-hole 39 provided in the housing 16 in a loose state and screwed into a hole 40 provided in the lens mounting housing 22 so that the X axis It can be freely moved and adjusted with respect to the direction and the Y-axis direction, and the position is fixed, thereby further tightening. Further, the housing 16 and the lens mounting housing 22 are configured to come into contact with each other by surface contact. However, since the groove 41 is formed on the contact surface of the lens mounting housing 22, dust or the like is surfaced. Even if it exists above, it enters the inside of the groove 41, so that adjustment with high accuracy can be performed.
[0032]
Further, in the other light quantity detection member 15 (image reading device 14 b) shown in FIGS. 8 to 9, in the light quantity detection member 11, the sealed space 20 of the housing 16 is large. The space is small. In addition, the same code | symbol is attached | subjected to the same location as the light quantity detection member 11. FIG.
[0033]
Reference numeral 29 denotes a transparent substrate, and reference numeral 30 denotes a plate-like body. A through portion 31 corresponding to the rectangular shape of the transparent substrate 29 is provided, and the transparent substrate 29 is provided in the through portion 31. Then, a resin-based or silicon-based adhesive is applied around the transparent substrate 29 and fixed. When the transparent substrate 29 is made of a synthetic resin, it may be bonded by an ultrasonic welding method.
[0034]
Then, by mounting the plate-shaped body 30 on the circuit board 17, a narrow sealed space 31 is formed by the circuit board 17, the plate-shaped body 30 and the transparent substrate 29, and the bare chip CCD 18 is accommodated in the sealed space. .
[0035]
Thus, also in the image reading device 14b having the above-described configuration, the dust-tightness of the light quantity detection member 15 that is hermetically sealed is fixed to the lens mounting case 22, and at the same time, the position is adjusted by the screwing portion p2, so that minute dust and dirt are collected. I can no longer enter the sealed space 31.
[0036]
In addition, in such a small sealed space 31, the degree of dust being enclosed becomes extremely small when manufactured in a clean room, and the light receiving surface of the bare chip CCD 18 is not contaminated. Black lines are not generated and the image quality is improved. Incidentally, even when compared with the light quantity detecting member 11, the volume of the sealed space is reduced to about 1/30.
[0037]
It should be noted that the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the scope of the present invention.
[0038]
【The invention's effect】
As described above, according to the present invention, in an image reading apparatus that forms an image of reflected light from an original by light emitted from a light source on a bare chip CCD through an optical lens, the bare chip is provided inside the casing in which the light transmission portion is disposed. The light quantity detecting member that is hermetically sealed with the CCD is fixed to the image reading body provided with the optical lens by optical positioning, and the reflected light that has passed through the optical lens is imaged on the bare chip CCD through the light transmitting portion. With this configuration, the light quantity detection member can be fixed to the image reading body at the same time while performing two-dimensional adjustment in the X-axis direction and Y-axis direction and further adjustment in the Z-axis direction. Therefore, it is possible to reduce the time required for accuracy adjustment by manufacturing easily, thereby increasing the manufacturing yield. I was able to today.
[0039]
Further, in the present invention, by using a hermetically sealed light amount detection member, the degree of dust or dirt adhering to the light receiving surface of the bare chip CCD is reduced or eliminated, and thus, the read image can be reduced. An image reading apparatus with improved image quality could be provided.
[0040]
Furthermore, in the present invention, the sealed space of the hermetically sealed light quantity detection member can be made smaller, and thereby the degree of dust and dirt enclosed in the space is significantly reduced, and the light receiving surface of the bare chip CCD is contaminated. As a result, white and black streaks are not generated in the read image, and the image quality is remarkably improved.
[0041]
In addition, in the present invention, since the bare chip CCD is mounted on the circuit board, the analog processing circuit is provided on the circuit board, thereby shortening the distance between the two, thereby improving the S / N ratio. There is also.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a light amount detection member used in an image reading apparatus of the present invention.
FIG. 2 is a schematic cross-sectional view of the image reading apparatus of the present invention.
FIG. 3 is a schematic cross-sectional view of the image reading apparatus of the present invention.
FIG. 4 is a schematic cross-sectional view of a light amount detection member used in another image reading apparatus of the present invention.
FIG. 5 is a schematic cross-sectional view of another image reading apparatus of the present invention.
FIG. 6 is a perspective view illustrating a specific configuration of a main part of the image reading apparatus according to the present invention.
FIG. 7 is an exploded perspective view of a main part of the image reading apparatus of the present invention.
FIG. 8 is a schematic cross-sectional view of still another image reading apparatus of the present invention.
FIG. 9 is an exploded perspective view of a light amount detection member according to the present invention.
FIG. 10 is an explanatory diagram showing an adjustment method in the X-axis / Y-axis direction.
FIG. 11 is a schematic cross-sectional view of another conventional image reading apparatus.
FIG. 12 is a schematic cross-sectional view of another conventional image reading apparatus.
FIG. 13 is a time chart of an image signal by a conventional image reading apparatus.
[Explanation of symbols]
1, 9, 12, 14, 14a, 14b
Image reader 2, 10, 11, 15 Light quantity detection member 3, 17, 27 Circuit board 4, 16 Case 5, 5a Optical lens 6, 20, 31 Sealed space 7 CCD
8, 24 Document 18 Bare chip CCD
19, 29 Transparent substrate 21 Optical lens 22 Lens mounting housing 23 Base plate 25 Ceramic circuit boards p1, p2 Screwed portions

Claims (1)

An image composed of the optical lens and a lens mounting housing provided with the optical lens, the light quantity detecting member hermetically sealed by providing a bare chip CCD inside the housing provided with the light transmitting portion. In an image reading apparatus configured to be fixed with respect to a reading main body by optical positioning, and reflected light from a manuscript by light emitted from a light source sequentially passes through the optical lens and the light transmitting portion and forms an image on a bare chip CCD . ,
An image characterized in that a housing of the light amount detecting member and a lens mounting housing of the image reading body are in surface contact, and a groove is formed on a contact surface of the lens mounting housing. Reader.

Images