JPH0134419B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a close-contact type reading device that reads image information while in close contact with a document.

A reading device using a lens system is generally used in facsimile machines and the like. Figure 1 shows a typical example. The document 1 is conveyed in the sub-scanning direction (in the direction of the arrow) by the rotation of the feed roller 2 with the side to be read facing down. A platen glass 3 whose longitudinal direction coincides with the main scanning direction is disposed in the middle of the conveyance path of the original 1, and the original 1 moves while sliding in contact with the upper surface of the platen glass 3. A fluorescent lamp 4 is arranged below the platen glass 3.
The light beam 5 emitted from this passes through the platen glass 3 and exposes the original 1 to the slit. After passing through the platen glass 3 , the reflected light 6 from the original 1 travels downward, has its course changed by a mirror 7 , passes through a lens 8 , and forms an image on an image sensor 9 . M.O.S.
The image sensor 9, which is composed of a CCD or the like, photoelectrically converts the optical image line by line, and reading is performed using a raster scan method.

However, in such a conventional reading device, since the size of the image sensor 9 is relatively small, it is necessary to set a large magnification of the optical image using a lens. Therefore, there are disadvantages in that the optical path length becomes long and the reading device itself becomes large. Also, since a lens was used, the amount of peripheral light in the optical image decreased,
Another drawback was that various aberrations occurred.

A contact type reader has been proposed to improve the drawbacks of the prior art. This reading device does not require a lens system. FIG. 2, in which the same parts as in FIG. 1 are given the same reference numerals, shows this proposed contact type reading device. Board 1
An image sensor 12 whose longitudinal direction coincides with the main scanning direction is formed on the lower surface of the image sensor 1 . A plurality of electrodes 13 are led out from the image sensor 12 for operating it and obtaining necessary image signals.

In this contact type reading device, a light beam 5 emitted from a fluorescent lamp 4 passes through an electrode 13 and an image sensor substrate 11, and exposes the lower surface of the original 1 in a slit shape. Reflected light 6 from the original 1 is reflected by the substrate 11 and enters the image sensor 12 .

However, with this proposed close-contact reader,
Since it is necessary to illuminate the original 1 from the image sensor 12 side, not only the substrate 11 on which the image sensor 12 is formed must be transparent, but also the electrode 13 must be transparent at least in the portion through which light passes. Making the electrodes transparent not only makes the device expensive, but also has the disadvantage that if the electrodes are not completely transparent, shading occurs in the read image.

On the other hand, for example, JP-A-53-140048 and JP-A-Sho
No. 53-68019 discloses a glass plate and a fiber substrate,
Alternatively, techniques have been disclosed that use prisms and optical fibers to allow light to reach the light receiving part without passing through the electrodes, but both of these techniques use at least two
This requires multiple optical elements, and position adjustment between these elements is troublesome.

The present invention has been developed in view of the above circumstances, and does not require a transparent electrode, and moreover uses a single optical system that does not require a transparent electrode, and from the incidence of the light beam to the illumination of the document and the arrival of the light beam reflected from the document to the photoelectric conversion element. It is an object of the present invention to provide a close-contact type reading device that can be read using an element.

In the present invention, a light source for illuminating a document and a light beam emitted from this light source are incident on a contact type reading device, and a first
A prism substrate is used to reflect light from a second reflective surface at a predetermined distance and then emit the light to the outside. The prism substrate is provided with a photoelectric conversion element disposed at a position where it is emitted to the outside again through the prism substrate, and by refracting the optical path, the light beam does not need to cross the electrode, thereby achieving the above-mentioned purpose.

The present invention will be explained in detail with reference to Examples below.

FIG. 3 shows a contact type reading device according to an embodiment of the present invention. This reading device includes a reading optical system 15 equipped with an image sensor 12, and a fluorescent lamp 4 for causing a light beam to enter a predetermined position of the reading optical system. Reading optical system 1
The upper surface of the device 5 is covered with a slit-shaped transparent window 16 and a light shielding layer 17 for preventing leakage of light rays in other parts. The document 1 is conveyed in the direction of the arrow by the feed roller 2 while slidingly contacting the transparent window 16 and the light shielding layer. On the other hand, transparent window 1
6 and the light shielding layer 17, a prism substrate 18 having both end surfaces inclined at a predetermined angle, and fixing members 19 and 21 for fixing these both end surfaces are arranged. A one-dimensional image sensor 12 is formed on the lower surface of the prism substrate 18 along the main scanning direction. A light shielding layer 22 is formed on the lower surface other than the surface on which the image sensor 12 is formed. The electrode 23 of the image sensor 12 is arranged on the light shielding layer 22 . Further below, a protective layer 24 is formed except for the vicinity of one end where the first fixing member 19 is present. The protective layer 24 is for protecting the image sensor 12 and the electrodes 23. The first fixing member 19 of this reading optical system 15
The first end surface 18 of the prism substrate fixed by
A has an inclination angle of 45 degrees with respect to the conveyance direction of the document 1. Further, the second end surface 18B fixed by the second fixing member 21 is approximately
It has an inclination angle of 60 degrees. A fluorescent lamp 4 for illuminating the original 1 is arranged below the first end surface 18A.

Now, when a reading operation is started with this contact type reading device, originals are fed one by one from an automatic document feeder (ADF) (not shown). The sent out document 1 is conveyed stepwise by a feed roller 2 while being synchronized with the reading of the document.
As a result, image information for one line by the raster scan method appears one after another on the transparent window 16.

On the other hand, at the start of the reading operation, the fluorescent lamp 4 is turned on, and the emitted light beam 5 enters from the bottom surface of the prism substrate 18 and is totally reflected by the first end surface 18A. The reflected light beam 5 changes its course 90 degrees clockwise and passes through the prism substrate 18. Then, it is fully reflected on the second end surface 18B, and this time about 120
The beam changes its course counterclockwise and enters the transparent window 16. As a result, the reading portion of the document 1 located directly above the transparent window is illuminated. The reflected light from the original 1 enters the prism substrate 18 again through the entrance window 16 and reaches the image sensor 12 . Since the image sensor 12 reads the image signal in synchronization with the driving of each line of the original 1, a desired image signal can be obtained. Note that when the light beam 5 is not totally reflected at each end face, these end faces may be processed into mirrors.

As explained above, according to the present invention, since the incident light beam is routed so as not to cross the electrodes of the photoelectric conversion element, it is sufficient to use only one prism substrate, and the reading device can be manufactured at low cost. be able to. In addition, since only one optical element (prism substrate) can be used for everything from the incidence of the light beam to the illumination of the document and the arrival of the light beam reflected from the document to the photoelectric conversion element, it is possible to use only one optical element (prism substrate). Compared to this, there is an advantage that there is no deterioration in the amount of light and image quality due to positional fluctuations between elements or dirt on the surfaces of opposing elements.

In addition, although a protective layer and a fixing member were used in the example,
These can be omitted as appropriate.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a conventional reading device using a lens, FIG. 2 is a schematic configuration diagram of a conventional close-contact type reader, and FIG. 3 is a close-contact type reader according to an embodiment of the present invention. FIG. 1... Original document, 4... Light source, 12... Image sensor, 16... Transparent window, 18... Prism board.

Claims (1)

[Scope of Claims] 1. A light source for illuminating a document, and a light beam emitted from the light source is incident and reflected on a first reflective surface, and then a light beam is emitted from the light source and is then reflected on a first reflective surface. A prism substrate that is further reflected by the reflective surface of No. 2 and emitted to the outside, and the reflected light from the document surface irradiated by the light beam emitted from this prism substrate enters this prism substrate again, and then passes through this prism substrate and is emitted again. 1. A close-contact reading device comprising: a photoelectric conversion element disposed at a position where the light is emitted to the outside.