JPS62145960A - Picture reader - Google Patents

Abstract

PURPOSE:To attain thin profile for an original read unit to be contained and then to miniaturize the entire picture reader by providing a convergent rod lens array arranged in parallel with an original platen sequentially and leading a reflected light whose direction is turned by 90 deg.. CONSTITUTION:A light irradiated from linear light sources 3a, 3b is irradiated in an original and its reflected light is made incident in the 1st rectangular prism 11. Then the light direction is turned by 90 deg. and the light is led to the convergent rod lens array 4. The light from the array 4 is made incident in the 2nd rectangular prism 12, where the travelling direction is turned by 180 deg. and the light is formed on an image sensor 5. The optical image formed on the image sensor 5 is converted into an electric signal and outputted as a picture signal. Since the rod lens array is arranged in parallel with the original platen in this way, the thin profile is attained for the entire read unit.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image reading device, and in particular to an image reading device that guides reflected light from a document to an image sensor via a focusing rod lens array. It is related to the device.

(Prior Art) An example of a conventional image reading device will be described using the device disclosed in Japanese Patent Application Laid-Open No. 59-86362.

FIG. 5 is a schematic diagram of the structure, and numeral 1 indicates a document placed on the document table 2. In FIG. 3a and 3b are two linear light sources, and the light emitted from the linear light sources 3a and 3b illuminates the surface of the original 1, and the reflected light is arranged perpendicularly to the original table 2. It is guided to a focusing rod lens array 4. Original paper placed in the focusing rod lens array 4
The four beams of light travel in the direction of the light through the focusing rod lens array 4, and when they exit the focusing rod lens array 4 into the air, they are focused and imaged on the image sensor 5. Since the image sensor 5 is composed of a CCD or the like, the image of the document is converted into an electrical signal and read and viewed by the image sensor 5.

The linear light sources 3a and 3b, the focusing rod lens array 4, and the image sensor 5 described above are housed in a document reading unit 6. The document reading unit 6 is intermittently transported in the sub-scanning direction of the document at appropriate timing by a drive device (not shown). Therefore, all information on the original document 1 is converted into electrical signals by the image sensor 5 and read out.

(Problems to be Solved by the Invention) The above-described conventional techniques had the following problems.

In other words, as is clear from FIG. 5, since the convergent rod lens array 4 is disposed in a direction perpendicular to the document table 2, the convergent rod lens array 4 has a convergent lens 6. There was a problem in that it was not possible to make the optical rod lens array 4 thinner than the sum of the focal lengths (conjugate lengths) on the incident side and the output side, and it was not possible to make a compact, particularly thin image reading device.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate and improve the drawbacks of the prior art described above, provide a thin document reading unit, and provide a document reading unit in which the components of the document reading unit 1 to 1 can be arranged at optimal positions. It is something.

(Means and Effects for Solving the Problems) In order to solve the above problems, the present invention provides a rectangular prism into which the reflected light of the original is incident, and a convergent rod lens array arranged parallel to the original table. By installing these in sequence and guiding the reflected light whose direction has been changed by 90' by the right angle prism to the focusing rod lens array, the document reading unit that houses these can be made thinner, and the entire image reading device can be made thinner. It is characterized by its miniaturization.

(Example) The present invention will be described in detail below with reference to the drawings. 1st
The figure is a schematic configuration diagram of an embodiment of the present invention. In the figure, the same reference numerals as in FIG. 5 represent the same or equivalent parts. Further, 11 and ]2 are first and second prisms, and 13 is a document reading unit.

d3, the distance between the light reflection point on the document and the incident surface of the focusing rod lens array 4, and the distance between the outgoing surface of the focusing rod lens array 4 and the image sensor 5, respectively. The focal lengths are made equal to the focal lengths of the entrance side and the exit side of the lens array 4.

Reading of document information in this embodiment is generally carried out as follows.

The light emitted from the linear light sources 3a and 3b is irradiated onto the original 1, and the reflected light is incident on the first right angle prism 11. The first right-angle prism 11 changes the direction of the emitted light by 90' and guides it to the focusing rod lens array 4. The light guided to the convergent rod lens array 4 travels through the convergent rod lens array 4 in its length direction, and exits from the convergent rod lens array 4 to the right angle prism 1 of the rear tube 2.
2. The reflected light is transmitted through the convergent rod lens array 4
The beam is focused upon exiting the beam, and after its traveling direction is changed by 180 degrees by the second right-angle prism 12, an image is formed on the image sensor 5. In this way, the optical image formed on the image sensor 5 is converted into an electrical signal by the photoelectric conversion function of the image sensor 5 and output as an image signal.

As described above, in this embodiment, the optical path is folded back using total internal reflection of the first right-angle prism 1, and the optical path is returned to the focusing rod lens array 4 arranged in a direction parallel to the surface of the document table 2. Since the reflected light is guided, the document reading unit 13 can be made thinner.

Further, according to this embodiment, the first right-angle prism 11 and the second right-angle prism 12 can be fixed to a support (not shown) at the surfaces 11a and 12a, and the angles of their attachment can be the same. , Prism attachment can improve the processing accuracy of the part. Therefore, the angle and position of the prism can be set accurately, and the focusing rod lens array can also be installed on the prism mount in a predetermined positional relationship with the prism, so that the reflected light from the original can be transferred to the image sensor 5.
can be accurately imaged.

In addition, the first right-angle prism 11 and the second right-angle prism 12 have a higher defect rate than a flat mirror made of vacuum-deposited metal, are easy to support, and are easy to remove dirt from the surface. Therefore, the performance of the image reading device can be improved and maintenance is also easy.

FIG. 2 shows a schematic configuration diagram of a second embodiment of the present invention. In the figures, the same reference numerals as in FIG. 1 indicate the same or equivalent parts.

This embodiment differs from the first embodiment in that only one light source is used, and the rest is the same as the first embodiment.

FIG. 3 shows a schematic configuration diagram of a third embodiment of the present invention. In the figure, the same reference numerals as in FIG. 1 represent the same or equivalent parts.

The difference between this embodiment and the second embodiment is that a third right-angle prism 14 is provided on the output side of the convergent rod lens array 4 to change the optical path by 90 degrees. The point is that the image of the original document is formed on the image sensor 5.

Further, FIG. 4 shows a schematic configuration diagram of a fourth embodiment of the present invention. In the figure, the same reference numerals as in FIG. 2 represent the same or equivalent parts.

This embodiment differs from the second and third embodiments in that the light emitted from the convergent rod lens array 4 is directly imaged onto the image sensor 5 without passing through a right-angle prism.

Needless to say, the second to fourth embodiments are similar to the first embodiment.
It will be clear that this example has the same effect as the example. According to the fourth embodiment, although the width of the document reading unit 13 in the lateral direction is slightly longer than that of the first to third embodiments, the advantage is that the document reading unit 13 can be made thinner. is.

In addition, in each of the above embodiments, the linear light sources 3a and 3b
As a light source, a fluorescent lamp, an LED (light diode), or the like can be used.

(Effects of the Invention) As is clear from the above description, according to the present invention, the following effects are achieved.

(1) The reflected light from the original is redirected by 90 degrees using a right-angle prism, guided into a focusing rod lens array arranged in a direction parallel to the original table, and then imaged on the image sensor. The original reading unit l~ can be made significantly thinner than the conventional one.

(2) Since the right-angle prism and the focusing rod lens array can be accurately and easily positioned and mounted on the table, the performance of the image reading device is improved and manufacturing is simple.

(3) Maintenance is easy because dirt on the right-angle prism etc. can be easily removed.

[Brief explanation of drawings]

FIG. 1, FIG. 2, FIG. 3, and FIG. 4 are schematic configuration diagrams of the first, second, third, and fourth embodiments of the present invention, respectively;
Figure 5 shows f! of the conventional device. 1118 configuration diagram. DESCRIPTION OF SYMBOLS 1... Original document, 2... Document table, 3a, 3b... Linear light source, 4... Focusing rod lens array, 5... Image sensor, 11.12.14... Right angle prism Figure 1 Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) A document table, a right-angle prism into which the reflected light from the document placed on the document table is incident, and a rectangular prism that is approximately parallel to the document table, into which the reflected light whose direction has been changed by the right-angle prism is incident. A focusing rod lens array installed, an image sensor on which the reflected light focused by the focusing rod lens array is formed, and a thin type housing at least the right angle prism, the focusing rod lens array, and the image sensor. An image reading device comprising: a document reading unit; (2) The image reading device according to claim 1, further comprising a right angle prism between the convergent rod lens array and the image sensor.