JPH0511637U - Contact image sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a small-sized, inexpensive, and contact-type image sensor capable of highly accurate reading. A contact type image sensor including a light source for illuminating a document, a lens for collecting reflected light from the document, a photoelectric conversion element for converting the collected light information into an electric signal, and a frame holding these, By arranging the light source directly below the original, the loss of light quantity is reduced, which contributes to the downsizing of the device.By providing a slit directly below the reading position by the light source, reflection from the peripheral original surface that is unnecessary for reading The light is blocked.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an image input device such as a facsimile.

[0002]

[Prior Art]

 FIG. 2 is a cross-sectional view showing a conventional contact image sensor. In the figure, 1 is a document to be read, 2 is a transparent plate that determines the position of 1, 3 is a light source, and 4 is 1 illuminated by a light source. A lens for collecting reflected light, 5 is a photoelectric conversion element for converting the light information collected by 4 into an electric signal, and 6 is a frame for holding 1 to 5.

Reflected light from the original 1 irradiated by the light source 3 is condensed on the photoelectric conversion element 5 by the lens 4, and optical information from the original 1 is taken out as an electric signal to the outside. In this optical system, the light source 3 is irradiated obliquely downward about 45 ° with respect to the original reading position, and the irradiation light passing through the transparent plate 2 is reflected by the original 1 and again passes through the transparent plate 2 to be collected. The light is focused on the light receiving element 5 by the optical lens 4.

[0004]

[Problems to be solved by the device]

 Since the conventional contact-type image sensor is configured as described above, there is a light amount loss due to the optical path length (about 10 mm) between the light source and the original (and the transparent plate). Since it is installed laterally, it causes the size and cost of the unit outline (frame and transparent plate) to increase. In this optical system, the unread part of the document is also illuminated by the light source, and the unnecessary reflected light from this part is affected by the surrounding part of the document position to be read, and accurate reading is possible. There are drawbacks such as not being.

The present invention has been made to solve the above problems, and an object thereof is to obtain a small-sized and inexpensive contact-type image sensor. Further, the loss of light quantity is minimized and the position to be read is to be minimized. The purpose is to improve the reading accuracy by eliminating the influence from other parts.

[0006]

[Means for Solving the Problems]

 The contact image sensor according to the present invention is one in which a light source and a transparent plate are integrated and the light source is arranged so as to form a slit having a width necessary and sufficient for reading.

[0007]

[Action]

 The light source in this invention has a very short optical path because it is placed directly below the original to be read, and the loss of light amount is small, which contributes to downsizing of the device, and the slit formed by the light source is on the reading line. Since it is provided in the, it is possible to escape from influences other than the portion to be read.

[0008]

【Example】

 Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a contact-type image sensor according to the present invention, in which 1 is a document to be read, 2 is the position of 1 is a transparent glass plate, 3 is an LED array (light source) embedded in 2, 4 Is a lens for collecting the reflected light of 1 irradiated by 3, 5 is a photoelectric conversion element for converting the optical information collected by 4 into an electric signal, and 6 is a frame for holding 1-5.

The reflected light from the original 1 irradiated by the light source 3 is condensed on the photoelectric conversion element 5 by the lens 4 and is taken out as an electric signal to the outside. At this time, since the light source 3 is embedded inside the glass plate 2, the position of the light source for illuminating the original is set to an ideal position where the light amount is the largest and the unit can be downsized. . In this case, the same light source 3 (LED array) is used in two rows, and a necessary and sufficient slit (-1 mm) is formed just below the document reading position by these two light sources. Therefore, the reflected light from the peripheral document surface, which is unnecessary for reading, is blocked.

Example 2. In the above embodiments, an LED array is used as the light source and this is embedded in a glass plate, but a fluorescent lamp or a cold cathode tube may be used as the light source. Further, as a substitute for the glass plate in which the light source is embedded in the above-mentioned embodiment, a flat emission type light source (for example, EL (electro luminescence)) having a slit directly below the reading position may be substituted.

[0011]

[Effect of the device]

 As described above, according to the present invention, since the light source is arranged immediately below the original, there is an effect that there is no light quantity loss, the apparatus can be made compact, and the apparatus has high accuracy.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a conventional contact image sensor.

[Explanation of symbols]

1 original 2 transparent plate 3 light source (LED array etc.) 4 lens (rod lens array etc.) 5 photoelectric conversion element (photodiode, phototransistor, CCD etc.) 6 frame (case)

Claims (1)

[Claims for utility model registration] 1. A transparent plate for determining the position of a document to be read, a light source, a lens for collecting the reflected light from the document to be read illuminated by the light source, and a lens for collecting the light. In a two-dimensional image reading device including a photoelectric conversion element for converting the converted optical information into an electric signal and a frame for holding the photoelectric conversion element,
A contact type image sensor, characterized in that the transparent plate and the light source are integrated.