JPH0591060U - Contact image sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] A contact image sensor that scans an original with infrared light, selectively forms an image of infrared reflected light on the sensor,
Removes noise caused by light other than infrared light. [Infrastructure] The infrared rays emitted from the infrared light emitting LED 2 are reflected by the original 8 and the reflected light corresponding to the shade of the original document is transmitted through the rod lens array 3 and the visible light cut filter 5 and the sensor 7
Image above. At this time, visible light, ultraviolet light, or the like having a shorter wavelength than infrared light is absorbed by the visible light cut filter 5, so external light noise does not reach the sensor 7. [Effect] With a structure similar to that of a conventional visible light image sensor, by changing the light source to an infrared emitting LED and inserting a visible light cut filter in the optical path, a contact image sensor that reads the design of an original with infrared light can be easily performed. Can be provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an image sensor unit that optically reads a document.

[0002]

[Prior Art]

 FIG. 3 is a sectional view showing the structure of a conventional contact image sensor. As shown in the figure, a rod lens array 3 and a document illumination LED 9 having a spectral characteristic with a peak near green of wavelength 565 nm are provided in the frame 1, and a cover glass 4 is arranged on the reading side of the document 8 to provide the document. The light from the illumination LED 9 is applied to the document 8, and the reflected light corresponding to the light and shade of the document at that time is transmitted through the rod lens array 3 to be guided to the sensor substrate 6, and an image is formed on the sensor mounted on the substrate. Then, a contact image sensor having a structure in which reflected light is converted into an electric signal there is generally known.

[0003]

[Problems to be solved by the device]

 Most of the conventional contact-type image sensors for manuscript illumination LED arrays (hereinafter referred to as LEDs) have spectral characteristics having a peak near a green wavelength of 565 nm. This LED is used as an infrared emitting LED with a peak emission wavelength of 880 nm, and characters / designs are printed on the original with a coloring material close to a black body that absorbs infrared rays, and an image sensor that recognizes the characters / designs is required for security. Was there. However, in an image sensor having a structure in which the green LED is simply replaced with the red light emitting LED, the sensor itself has sensitivity in the visible light region and the ultraviolet light region, which is a shorter wavelength region other than infrared light, and therefore, is not suitable for the image sensor. When external light enters, unnecessary wavelengths of light are reflected by the document and guided to the sensor, which causes a problem in reading the document. Therefore, it is an object of the present invention to provide a contact-type image sensor having means for guiding only the wavelength region peculiar to the infrared emitting LED to the sensor.

[0004]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention uses an infrared light emitting LED as an LED of a contact type image sensor, and glass or plastic is provided between a sensor substrate and a rod lens array, which is an optical path through which light reflected from a document passes. By providing a visible light cut filter consisting of, the infrared light is selectively transmitted, and only the light in the infrared wavelength range specific to the infrared emitting LED reaches the sensor.

[0005]

[Action]

 According to the contact-type image sensor configured as described above, the infrared light emitted from the infrared-emitting LED toward the document is reflected according to the shade of the pattern of the document adhered to the cover glass, and If light in the wavelength region shorter than about 700 nm is transmitted through the lens array, it is absorbed by the visible light cut filter, and light in the intrinsic wavelength region of the infrared emission LED, that is, 880 nm is the peak emission wavelength. Only the infrared light that reaches the sensor reaches the sensor and is converted into an electrical signal.

[0006]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 is a sectional view showing the structure of a contact image sensor of the present invention. In FIG. 1, the contact image sensor of the present invention is a sensor substrate on which a rod lens array 3 mounted on a frame 1, an infrared emitting LED 2, a cover glass 4, a visible light cut filter 5 made of glass or plastic, and a sensor 7 are mounted. It is composed of 6. A pattern is printed on the manuscript 8 with a color-developing body close to a black body that absorbs infrared rays, and the pattern is closely attached to the cover glass 4 so that the infrared light from the infrared emitting LED 2 is reflected according to the shade of the pattern. ing.

FIG. 2 is a diagram showing the spectral transmittance of the visible light cut filter used in the present invention and the spectral characteristics of the LED. The spectral transmittance A of the visible light cut filter 5 is almost 0% on the short wavelength side of 700 nm or less. The spectral characteristic B of the infrared light emitting LED 2 is monochromatic light having a peak at 880 nm and can pass through the visible light cut filter 5. The light in the normal visible light range, for example, the spectral characteristic C of a green LED often used in general contact image sensors has a peak emission wavelength at 565 nm, and this light is absorbed by the visible light cut filter. Visible light and ultraviolet light of other wavelengths will be similarly absorbed, and external light noise will not reach the sensor. Also, except for the pattern printed with a color-developing material that absorbs infrared rays, this image sensor will read it as white, which is effective in terms of security.

FIG. 3 is a view showing the structure of a conventional contact image sensor, in which a frame 1 is mounted with an LED 9 for original illumination, a rod lens array 3, a cover glass 4, and a sensor substrate 6 on which a sensor 7 is mounted. ing. The original 8 moves while being in close contact with the cover glass 4, and the reading operation is sequentially performed. The original 8 is illuminated with light from the LED 9 for illuminating the original, and the intensity of light according to the design of the original is reflected and enters the sensor 7, and the intensity of this light corresponds to the output from the sensor 7 to read. Is done.

As described above, the visible light cut filter 5 is added to the conventional contact image sensor and the infrared light emitting LED 2 is used as a light source, and only the light of a specific wavelength is read into the image sensor as read data. Is now possible.

[0010]

[Effect of the device]

 As described above, this invention has a simple structure in which a visible light cut filter is inserted in the optical path between the document surface and the sensor of the contact type image sensor which has been generally used in the past, and the light source is an red light emitting LED. It functions as a contact image sensor that reads the design of the original with infrared rays, and recognizes that the design printed with a coloring material whose absorption of infrared rays is close to a black body is black, and the design with other inks is white. It has the effect that it can be used for various purposes.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a contact image sensor of the present invention.

FIG. 2 is a diagram showing a spectral transmittance of a visible light cut filter used in the present invention and a spectral characteristic of an LED.

FIG. 3 is a cross-sectional view showing the structure of a conventional contact image sensor.

[Explanation of symbols]

 1 Frame 2 Infrared LED 3 Rod lens array 4 Cover glass 5 Visible light cut filter 6 Sensor substrate 7 Sensor 8 Original A Spectral transmittance of visible light cut filter B Spectral characteristic of infrared emitting LED C Spectral characteristic of green LED

Claims (1)

[Scope of utility model registration request] 1. A contact image sensor having a rod lens array and an LED for illuminating an original in a frame, a cover glass attached to a front original reading side of the frame, and a sensor substrate attached to a rear frame portion of the frame. A contact image sensor, wherein the LED for illuminating the original is an LED emitting infrared light, and a visible light cut filter is incorporated between the sensor substrate and the rod lens array.