JP2000270155A - Close contact image sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the effect of an electromagnetic wave incident into a front face of an image sensor onto the image sensor. SOLUTION: A transparent conductive oxide tin film 108 is coated to a surface of a glass cover 107 placed in front of an image sensor chip 103 in this image sensor and is connected to a substrate 104 with the image sensor chip 103 mounted thereon via a conductor such as a conductive spring so as to realize an electromagnetic shield in front of the image sensor. Thus, the image sensor can provide excellent image quality by reducing the effect of an electromagnetic wave from a commercial power supply or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a contact type image sensor used for a facsimile or an image scanner.

[0002]

2. Description of the Related Art In recent years, there has been an increase in the number of devices that take in an image, such as a facsimile, and the use of a contact type image sensor has been increasing especially from the viewpoint of cost and ease of manufacturing. More recently, there has been a high need to capture images such as books, and the number of scanners that capture images by scanning them over originals called self-propelled or handy scanners has increased. It has begun to be used.

FIG. 2 is a configuration diagram showing a conventional contact image sensor.

As shown in FIG. 2, a conventional contact type image sensor includes an image sensor chip 203, an LED 202 serving as a light source, a substrate 204 on which these are mounted, and
A light guide plate 205 that guides light from a light source to a document 208;
A lens 206 for condensing the reflected light from the photodetector 08 on a light receiving element on the image sensor chip 203, a casing 201 for housing the above components, and a glass cover 207 attached to the casing 201 and supporting the light guide plate 205 and the lens 206. ing. In order to prevent the influence of electromagnetic waves and the like from the front of the sensor, a conductive sheet 209 such as an aluminum foil and a conductor 210 such as a cable for connecting GND between the conductive sheet 209 and the substrate 204 are provided. .

Hereinafter, the operation of the above-mentioned conventional contact type image sensor will be described.

First, an LED 202 serving as a light source is turned on. The light of the LED 202 is efficiently guided by the light guide plate 205, passes through the glass cover 207, and reaches the surface of the document 208. The light reflected on the surface of the original document 208 passes through the glass cover 207 again, reaches the lens 206, and is transmitted to the image sensor chip 2 by the lens 206.
Light is condensed on the light receiving element 03. Electric charges corresponding to the reflection intensity are accumulated in the light receiving elements of the image sensor chip 203 and output as image information for one line. At this time, since there is no electromagnetic shield on the front surface of the image sensor chip 203, a conductive sheet 209 such as an aluminum foil is spread under the document 208, and the conductive sheet 209 is covered by a conductor 210 such as a cable.
(Reference potential) to form an electromagnetic shield to prevent the influence of electromagnetic waves from a commercial power supply or the like.

[0007]

However, in the above-mentioned conventional contact type image sensor, since a document is placed on the front surface of the image sensor chip, it is difficult to provide an electromagnetic shield on the front surface of the sensor. Under the influence of the received electromagnetic waves, there is a problem that a dark and light portion such as a stripe pattern is generated in the read image, and the image quality is deteriorated.

Further, when a scanner of a form called a flat bed type or a sheet feed type is configured, since a component such as a document press exists below the document, an electromagnetic shield is provided below the document. Although the same effect can be obtained, especially in self-propelled and handy type scanners, a conductive sheet such as aluminum foil is laid under the original and the conductive sheet is connected to GND where the contact type image sensor is connected. It had to be connected, which was inconvenient.

[0009]

In order to solve the above-mentioned problems, a contact type image sensor according to the present invention comprises an oxide transparent conductive thin film such as an indium oxide thin film on the surface of a glass cover, and the oxide transparent conductive thin film. And a conductor such as a conductive spring that connects the GND of the substrate on which the image sensor chip is mounted.

With this configuration, it is possible to prevent the influence of electromagnetic waves from the front of the image sensor chip, and to obtain good image quality.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention provides an image sensor chip, an LED serving as a light source,
A board on which they are mounted, a light guide plate for guiding the light from the light source to the document, a lens for condensing the reflected light from the document on the light receiving element on the image sensor chip, a casing for accommodating the above components, and a light guide attached to the casing. A glass cover for supporting a light plate or a lens, a transparent conductive oxide thin film such as an indium oxide thin film on the surface of the glass cover, and a conductive connection between the transparent conductive oxide thin film and the GND of a substrate on which an image sensor chip is mounted. And a conductor such as an elastic spring, so that the influence of electromagnetic waves from the front of the image sensor chip can be prevented.

Hereinafter, an embodiment of the present invention will be described in detail using the contact type image sensor shown in FIG. 1 as an example.

(Embodiment 1) FIG. 1 is a diagram showing a configuration of a contact type image sensor according to an embodiment of the present invention.

As shown in FIG. 1, the contact type image sensor includes an image sensor chip 103, an LED 102 serving as a light source, a substrate 104 on which they are mounted, a light guide plate 105 for guiding light from the light source to a document 110, and Manuscript 11
A lens 106 for condensing the reflected light from 0 on a light receiving element on the image sensor chip 103, a casing 101 for housing the above components, and a glass cover 107 attached to the casing 101 and supporting the light guide plate 105 and the lens 106
And a transparent conductive oxide thin film 108 such as an indium oxide thin film formed on the surface of the glass cover 107 and the GND of the substrate 104 on which the transparent oxide conductive thin film 108 and the image sensor chip 103 are mounted. And a conductor 109 such as a conductive spring.

The operation of the contact type image sensor having the above configuration will be described below.

First, the LED 102 serving as a light source is turned on. The light from the LED 102 is efficiently guided by the light guide plate 105, passes through the oxide transparent conductive thin film 108 and the glass cover 107, and reaches the surface of the document 110. The light reflected on the surface of the original 110 is again transmitted to the glass cover 107.
Pass through the oxide transparent conductive thin film 108 to form the lens 1
06, and is condensed on the light receiving element of the image sensor chip 103 by the lens 106. Electric charges corresponding to the reflection intensity are accumulated in the light receiving elements of the image sensor chip 103 and output as image information for one line. At this time, the oxide transparent conductive thin film 108 serves as an electromagnetic shield by being connected to GND of the substrate 104 on which the image sensor chip 103 is mounted by a conductor 109 such as a conductive spring. Of the image sensor chip 103 and the substrate 104 are prevented from being affected by electrical noise such as electromagnetic waves coming from the front surface of the image sensor chip 103.

According to this configuration, it is possible to prevent the influence of electromagnetic waves from the front of the image sensor chip, and to obtain a good image quality.

In the above description, whether the image sensor chip for one line is composed of one chip,
Although it is not particularly specified whether the configuration is made by arranging a plurality of chips shorter than one line, the same effect can be obtained in either case.

In the above description, an example in which an image sensor for one line is provided has been described. However, for the basic colors (for example, three lines of red (R), green (G), and blue (B)). The same applies to the case where an image sensor is provided.

In the above description, an example has been described in which an LED is used as a light source and the LED is mounted on the same substrate as the image sensor chip. However, the present invention can be similarly applied to other light sources such as a fluorescent tube.

In the above description, an example in which the oxide transparent conductive thin film is formed on the image sensor chip side of the glass cover (inside the contact type image sensor) has been described. Can be similarly implemented. In this case, the conductor for connecting the oxide transparent conductive thin film described in the form of being sandwiched between the glass cover and the substrate and the GND of the substrate also includes the oxide transparent conductive thin film formed on the original side of the glass cover and the GND of the substrate. In this case, the connection from the glass cover to the substrate is sandwiched between conductors such as conductive springs.

In the above description, the casing itself is described as being non-conductive, but the casing itself is made of a conductive material such as magnesium, and the transparent conductive oxide thin film is connected to the GND of the substrate. The present invention can be similarly implemented in a case where a casing is connected instead of a conductive spring.

[0023]

As described in detail above, according to the present invention,
The effect of electromagnetic waves from the front of the image sensor chip can be prevented, and good image quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a contact image sensor according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a conventional contact image sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Casing 102 LED 103 Image sensor chip 104 Substrate 105 Light guide plate 106 Lens 107 Glass cover 108 Oxide transparent conductive thin film 109 Conductor 110 Original 201 Casing 202 LED 203 Image sensor chip 204 Substrate 205 Light guide plate 206 Lens 207 Glass cover 208 Original 209 Conductive sheet 210 Conductor

Claims (1)

[Claims] 1. An image sensor chip, a light source, a substrate on which they are mounted, a light guide plate for guiding light from the light source to a document, and light reflected from the document focused on a light receiving element on the image sensor chip. A lens, a casing for housing the components, a glass cover attached to the casing and supporting the light guide plate and the lens, an oxide transparent conductive thin film such as an indium oxide thin film on the surface of the glass cover, and the oxide transparent A contact-type image, comprising: a conductive thin film and a conductive material such as a conductive spring for connecting the GND of the substrate on which the image sensor chip is mounted; and capable of preventing the influence of electromagnetic waves from the front surface of the image sensor chip. sensor.