JPH0320951B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reading device for a facsimile machine, etc., and in particular, even if a document is folded or raised above the normal document surface position, the reading of that part is doubled. The present invention relates to a reading device that can be used to read data properly.

Conventionally, as described in Japanese Patent Application Laid-Open No. 55-137767, a solid-state image sensor arranged in the sub-scanning direction in which a document is intermittently fed is moved along with an imaging lens in a direction perpendicular to the main-scanning direction, that is, the sub-scanning direction. It is known that reading and scanning for a plurality of lines can be performed simultaneously in one reciprocating motion.

In FIG. 1, a document 1 is intermittently fed in the direction of arrow 2 (sub-scanning direction). Reference numeral 3 denotes an illumination lamp, which illuminates the slit width regions 6a to 6b of the original 1, and projects the slit width regions 6a to 6b onto a solid-state image pickup device 5 such as a CCD using an imaging lens 4.
be read. The illumination lamp 3, imaging lens 4, and solid-state image sensor 5 together constitute a reading head 7, which reciprocates in the direction of an arrow 8 (main scanning direction).
Therefore, one reciprocating movement of the reading head 7 simultaneously performs reading scanning for a plurality of lines. FIG. 2 is a sectional view taken in the direction of arrow 2 (sub-scanning direction) in FIG. 1.

Here, if the original 1 is at the normal position in the optical axis direction, an area of slit width a is projected by the imaging lens 4 and read by the solid-state image sensor 5, but when the original 1 is at the position 1', for example When the document is folded and that part floats, the slit width projected onto the solid-state image pickup device 5 becomes b instead of a, resulting in the slit being read wider than the predetermined width.

However, since the intermittent feed width in the direction of arrow 2 (sub-scanning direction) is set to a, there is a drawback that the portion b-a is read twice and the portions overlap, disturbing the image.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reading device that eliminates such drawbacks and that can correctly read a document even if it deviates from its normal position in the optical axis direction. The purpose of this is to move the reading head, which is composed of a light source that illuminates the document, an imaging lens, and solid-state image sensors arranged in the sub-scanning direction, in the main scanning direction, which is perpendicular to the sub-scanning direction. , and in a reading device that reads an image of a document by intermittently moving the reading head and the document relative to each other in the sub-scanning direction, the image is formed between an imaging lens included in the reading head and a solid-state image sensor. A diaphragm is provided at the focal point of the lens, and the principal rays emitted from the document travel parallel to the optical axis of the imaging lens, enter the imaging lens, and form an image on the solid-state image sensor through the diaphragm. achieved.

Embodiments of the present invention will be described from FIG. 3 onwards.

FIG. 3 is a diagram showing the principle of the present invention.

11 is a document, 12 is an imaging lens, 13 is an aperture located at the focal position of the imaging lens 12, and 14 is a solid-state image sensor.

The chief ray emitted from the original 11 travels parallel to the optical axis of the imaging lens 12, enters the imaging lens 12, and forms an image on the solid-state image sensor 14 via the aperture 13.

Here, even if the original 11 is displaced in the optical axis direction and reaches the position 11', the principal ray is parallel to the optical axis, so the reading width does not change and there is no overlapped part to be read.

FIG. 4 shows an embodiment in which the present invention is applied to a facsimile machine.

In FIG. 4, a document 21 is intermittently fed in the direction of an arrow 22 (sub-scanning direction). The illumination lamp 23, the imaging lens 24, the diaphragm 27 provided at the focal point of the imaging lens 24, and the solid-state image pickup device 25 provided at the imaging plane of the imaging lens 24 constitute an integrated reading head. (main scanning direction) to move the slit width areas 26a to 2
A plurality of lines within 6b are read simultaneously.

Note that the telecentric imaging lens is not limited to this embodiment, but includes any lens configuration.

As described above, according to the present invention, it is possible to provide a reading device in which the reading width does not differ from the intermittent feed width of the original even if the distance between the original and the reading head changes.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of a conventional reading device, and FIGS. 3 and 4 are explanatory diagrams of an embodiment of the present invention. In the figures, 1, 11, and 21 are original documents, and 3 and 23 are illumination lamps. , 4, 12, 24 are imaging lenses, 13, 2
7 is an aperture, and 5, 14, and 25 are solid-state image sensors.

Claims (1)

[Scope of Claims] 1. A reading head, which is configured by integrating a light source that illuminates the original, an imaging lens, and a solid-state image sensor arranged in the sub-scanning direction, is scanned in the main scanning direction, which is perpendicular to the sub-scanning direction. In a reading device that reads an image of a document by moving the document in the sub-scanning direction and intermittently moving the reading head and the document relative to each other in the sub-scanning direction, the reading device includes: an imaging lens included in the reading head and a solid-state image sensor; A diaphragm is provided at the focal point of the imaging lens, and the principal rays emitted from the original proceed parallel to the optical axis of the imaging lens, enter the imaging lens, and form an image on the solid-state image sensor through the diaphragm. A reading device characterized in that: