JPH0686012A - Reader - Google Patents

Abstract

PURPOSE:To provide a high quality picture signal and to provide a reader with high reliability by forming light transmissive resin provided with prescribed film thickness on the surfaces of a circuit board and respective semiconductor chips. CONSTITUTION:The light transmissive resin 22 such as silicone resin, epoxy resin and polyether amide is formed with the film thickness T less than approximately 100mum on the surfaces of the circuit board 15 and the semiconductor chips 20 provided with a prescribed height B for deterioration prevention and environmental resistance measures. Consequently, without being affected by the gaps between the semiconductor chips 20, the surface of the light transmissive resin 22 is flatened and especially, optical defects are prevented from being generated on the light transmissive resin 22 on the semiconductor chips 20. Thus, the scatter and the attenuation of light at the light transmissive resin 22 are reduced and read sensitivity and the picture resolution of MTF or the like are improved. Also, since the uneveness of the surface is eliminated, the distortion of pictures and sensitivity dispersion can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an original contact type reading apparatus used in a facsimile apparatus or an image scanner apparatus for inputting images in a computer.

[0002]

2. Description of the Related Art FIG. 6A is a partial perspective view showing the structure of an example of a conventional reading device. This reading device
A light source 62 for illuminating 0 from an oblique direction, and a document 60.
A rod lens array 61 for forming reflected light from the image forming an original image, a plurality of semiconductor chips 70 having a light receiving surface 71 formed of a large number of photoelectric conversion elements for receiving the original image, and a semiconductor The semiconductor chip 70 is composed of a circuit board 65 to which the chip 70 is fixed, and the photoelectric conversion elements of the respective semiconductor chips 70 are sequentially scanned while the original 60 is stepwise conveyed by one scanning line. Is output to.

FIG. 6B is a partial cross-sectional view of the vicinity of the semiconductor chip 70 shown in FIG. Semiconductor chip 70
Are electrically connected to the wiring pattern 66 of the circuit board 65 by bonding wires 67 such as Au wires and Al wires, as shown in the partial cross-sectional view of FIG. On the surface of 65,
For prevention of deterioration and environmental resistance, a light transmissive resin 72 such as a silicone resin is formed so as to have a film thickness of about 0.5 mm to about 1 mm. Since the protective films 68 of SiO ₂ , SiN or the like are formed on both sides of the wiring pattern 66, deterioration with time in this portion is reduced. on the other hand,
When the light-transmissive resin 72 does not exist, the wiring pattern 6
6 may corrode and the bonding wire 67 may come off, resulting in a defective connection.

Further, in the reading apparatus shown in FIG. 6A, since the original image is formed by using the rod lens array 61, the original image becomes an erecting equal-magnification image and the original image is received without omission. Are close to each other so that the semiconductor chips 70 are almost in close contact with each other. Therefore, the semiconductor chip 70
The effect of the gap between them does not appear on the surface of the light-transmissive resin 72, and it is possible to form the light-transmissive resin 72 with few optical defects.

[0005]

In order to reduce the cost and improve the performance of the conventional reader shown in FIG. 6 (a),
A reader has been studied in which a plurality of lenses are used instead of the rod lens array 61 to divide an image of a document into a plurality of regions to form an image, and the inverted reduced image is received by a plurality of semiconductor chips. In such a reading apparatus, since the original image is formed at a reduction magnification, the dimensions of the semiconductor chip 70 are reduced as shown in the partial cross-sectional view of FIG. A0.
When forming the light transmissive resin 72 of about 5 mm to 1 mm, there is a problem that the gap between the semiconductor chips 70 becomes larger than the conventional one, and the surface of the light transmissive resin 72 becomes uneven.

Therefore, light scattering and attenuation on the surface of the light transmissive resin 72 increase, which lowers the reading sensitivity and increases the MTF.
(Modulation Transfer Function) has a problem of causing deterioration of image resolution. Further, there is a problem in that due to the unevenness of the surface of the light-transmissive resin 72, light is converged or diverged due to the lens effect, which causes image distortion and sensitivity variation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reading device which can obtain a high quality image signal and has high reliability in order to solve the above-mentioned problems.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a light source for illuminating an original document and linearly arranged at a predetermined interval for forming an image of the original image by forming reflected light from the original document. A plurality of lenses, a plurality of semiconductor chips having a large number of photoelectric conversion elements linearly arranged in one-to-one correspondence with each lens for receiving the original image, and the semiconductor chips are fixed. In a reader equipped with a circuit board
About 100 μm on the surface of each semiconductor chip and circuit board
The reading device is characterized in that a light-transmitting resin having the following film thickness is formed.

[0009]

According to the present invention, the light-transmitting resin having a film thickness of about 100 μm or less is formed on the surface of each semiconductor chip and the circuit board for receiving the original image.
The surface of the light-transmitting resin formed on each semiconductor chip becomes flat, and the number of optical defects that cause deterioration in image quality is extremely reduced.

[0010]

1 is a partial perspective view of a reading apparatus according to an embodiment of the present invention, and FIG. 2 is a partial sectional view taken along the optical axis thereof. The reading device is an LED for illuminating the document 10.
(Light emitting diode), a light source 12 such as a fluorescent lamp, and the original 1
A plurality of lenses 11 linearly arranged at a predetermined interval for forming reflected light from 0 to form a document image, and one lens for each lens 11 for receiving the document image. It is composed of a plurality of semiconductor chips 20 each having a light receiving surface 21 composed of a large number of photoelectric conversion elements, which are linearly arranged correspondingly, a circuit board 15 to which the semiconductor chips 20 are fixed, and the like.

The light emitted from the light source 12 illuminates the original 10 in an oblique direction, and the light reflected from the original 10 is reflected by each lens 11 into a plurality of blocks A to.
The read signals corresponding to the image information of the original 10 are time-sequentially formed by sequentially scanning a plurality of photoelectric conversion elements provided on the semiconductor chip 20 corresponding to the blocks A to E, which are imaged for each E. Is output. It should be noted that the housing 13 that holds the lenses 11 is provided with a light blocking plate 13 a between the lenses 11 in order to prevent stray light and ambient light.

In FIG. 3, the semiconductor chip 20 is the circuit board 15
FIG. 3 is a partial plan view showing a state in which it is fixed to. The semiconductor chip 20 includes a light receiving surface 2 including 64 photoelectric conversion elements P1 to P64 such as photodiodes and phototransistors.
1, a terminal SI to which a scanning start signal is input, a terminal CLK to which a scanning clock signal is input, a terminal VDD to which a power source is connected, a ground terminal GND, a terminal SIG for outputting a read signal, and a ground terminal AGND for an analog circuit. , And a terminal SO for outputting a scanning end signal, and these terminals are electrically connected to the wiring pattern 16 formed on the circuit board 15 by bonding wires 17.

FIG. 4 is a partial sectional view of the vicinity of the semiconductor chip 20. Semiconductor chip 2 having a height B of about 0.4 mm
0 and the surface of the circuit board 15 are formed with a light transmissive resin 22 such as a silicone resin, an epoxy resin, or a polyether amide with a film thickness T of about 100 μm or less for the purpose of preventing deterioration and environmental resistance. . As a result, the light-transmitting resin 2 is not affected by the gap between the semiconductor chips 20.
The surface of 2 becomes flat, and in particular, optical defects do not occur in the light transmissive resin 22 on the semiconductor chip 20. Therefore, light scattering and attenuation in the light transmissive resin 22 is reduced, and reading sensitivity is improved and image resolution such as MTF is improved. Further, since the surface irregularities are reduced, it is possible to suppress image distortion and sensitivity variations.

Next, using a silicone resin as an example,
A method of forming the light transmissive resin 22 on the surfaces of the semiconductor chip 20 and the circuit board 15 will be specifically described. First, when n-heptane was used as a solvent and the silicone resin was dissolved to a concentration of 7% by weight, the viscosity became 1.3 centistokes (room temperature 25 ° C.). Next, one drop of the melted silicone resin was dropped from above the semiconductor chip 20 with a dispenser or the like to apply drip, and then it was put into a heating tank and heated at a temperature of 150 ° C. for about 1 hour to be cured. According to JIS-A), the light transmissive resin 22 having a dielectric breakdown voltage of 20 kV / mm could be formed.

When the film thickness of the obtained light transmissive resin 22 was measured by an interference film thickness meter, the average film thickness value x = 13.6 μm and the standard deviation σ = 2.1 μm were obtained when the sample number n = 16. The obtained transmittance is 92.7 at the wavelength λ = 550 μm.
It became%.

Similarly, when the light-transmitting resin 22 having a film thickness of 1 μm and 5 μm was formed, the silicone resin concentration was set to 3% by weight, and drip coating was performed under the same conditions as above to cure. For films having a thickness of 50 μm and 100 μm, a silicone resin having a concentration of 7% by weight was drip-coated many times and then cured. As a comparative example, the film thickness is 0.5 m.
m, 0.8 mm, 1.0 mm
A silicone resin having a concentration of 100% by weight which was not diluted with a solvent was drip-coated and cured.

Film thicknesses of 1 μm and 5 thus obtained
μm, 10 μm, 50 μm, 100 μm, 0.5 mm,
For the semiconductor chip 20 on which the 0.8 mm and 1 mm light transmissive resin 22 is formed, the MTF (Mo
(dulation transfer function) and PRNU (Photo Response Non-Uniformity) representing the sensitivity variation were measured, and a reliability test was performed.

As shown in FIG. 5, the MTF has 4 LP / mm in which there are 4 sets of black and white rectangular waves per 1 mm.
A value obtained by dividing the amplitude V at the spatial frequency of by 100 by the amplitude W when the white background is read, that is,

[0019]

[Equation 1]

It was calculated using the definition formula In addition, M
The larger the value of TF, the better the resolution.

PRNU is one of the semiconductor chips 20.
This is a value indicating the variation in sensitivity within each unit. VMAX is the maximum output when a coated paper with an optical density OD value of 0.07 is read, and VMIN is a coated paper with an optical density OD value of 0.07. When the minimum value of the output when

[0022]

[Equation 2]

It was calculated using the definition formula Note that P
The smaller the numerical value of RNU, the smaller the variation in sensitivity.

The reliability test is conducted at a temperature of 85 ° C. and a humidity of 8
It was left to stand in a 5% atmosphere for 500 hours for accelerated deterioration and examined for abnormalities such as electrode corrosion.

The results of these tests are shown in Table 1 below.

[0026]

[Table 1]

From the above results, considering that the characteristics required for the facsimile apparatus and the image scanner apparatus are MTF 60% or more and PRNU 10% or less, the film of the light-transmissive resin 22 formed on the surface of the semiconductor chip 20. It is understood that the thickness is preferably about 100 μm or less. Also, if it is too thin, the reliability is low, so the film thickness is about 5
It is preferably at least μm.

[0028]

As described in detail above, according to the present invention,
(1) The presence of the light-transmissive resin improves the environment resistance of the semiconductor chip and can prevent Al corrosion in particular. (2) Since the film thickness of the light transmissive resin is smaller than that of the conventional one, the attenuation of light is reduced and the reading sensitivity can be improved. (3) Since a low-viscosity resin solution is used when forming a light-transmitting resin having a small film thickness, unevenness on the surface of the semiconductor chip is naturally reduced, and sensitivity variation (PR
NU) becomes good. (4) Since the film thickness of the light-transmitting resin is thinner than in the conventional case, stray light due to light scattering is less likely to occur, and the image resolution (MTF) is improved.

[Brief description of drawings]

FIG. 1 is a partial perspective view of a reading device according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view taken along the optical axis of FIG.

FIG. 3 is a partial plan view showing a state in which the semiconductor chip 20 is fixed to the circuit board 15.

FIG. 4 is a partial cross-sectional view near a semiconductor chip 20.

FIG. 5 is a graph showing the definition of MTF.

FIG. 6A is a partial perspective view showing an example of a conventional reading device, and FIG. 6B is a partial cross-sectional view near a semiconductor chip 70.

FIG. 7 is a partial cross-sectional view showing a bonding wire 67 with respect to a wiring pattern 66 of a circuit board 65.

FIG. 8 is a partial cross-sectional view showing a light-transmissive resin 72 on a semiconductor chip 70 in a conventional reading device.

[Explanation of symbols]

 Reference numeral 10 original document 11 lens 12 light source 13 housing 13a light shielding plate 15 circuit board 16 wiring pattern 17 bonding wire 20 semiconductor chip 21 light receiving surface

Claims (1)

[Claims] 1. A light source for illuminating a document, a plurality of lenses linearly arrayed at predetermined intervals for forming reflected light from the document to form a document image, the document image A plurality of semiconductor chips having a large number of photoelectric conversion elements, which are linearly arranged in a one-to-one correspondence with each lens, and a circuit board to which the semiconductor chips are fixed. In the device, about 100 μm on the surface of each semiconductor chip and circuit board
A reading device, wherein a light-transmitting resin having the following film thickness is formed.