JPH02159166A - Image reading device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image reading device that reads image information on a document by manually scanning the document.

(Prior Art) Conventionally, in this type of image reading device, an opening or a window fitted with a transparent plate such as glass is provided at the document reading position on the bottom surface of the main body, and light is directed onto the document surface through the opening or window. An image is reproduced after illuminating the light and guiding the optical information to a photoelectric conversion element such as a COD and converting it into an electrical signal.

(Problem to be Solved by the Invention) However, the above-mentioned image reading device needs to be made small so that it can be easily scanned manually, and it compensates for variations in the light intensity distribution of the lighting unit, non-uniformity in sensitivity of the photoelectric conversion element, etc. A white reference means for (shading correction) was not provided, and it was not possible to improve the gradation reproducibility of the original image.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a manual scanning type image reading device that can perform shading correction without increasing the size of the main body of the device.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an image reading device that reads image information on a document by manually scanning the document and illuminating the document with an illumination unit.
Outside of the document reading operation, a cover is provided that blocks the optical path between the document reading position and the photoelectric conversion element and has a white reference surface on the inside, and illuminates the white reference surface before reading the document to perform photoelectric conversion during document reading. The structure is such that the output of the element can be corrected.

(Function) The function of the present invention based on the above configuration is that the white reference surface of the cover is illuminated before reading the original to memorize the ideal output, the cover is opened when reading the original, and the photoelectric conversion element is activated based on the ideal output. Correct the output. Further, the cover can be closed when the document reading operation is not performed.

(Example) Next, the present invention will be described based on an example shown in the accompanying drawings.

FIGS. 1 and 2 show a first embodiment, and in the figures, l is an image reading device, and a document P is illuminated by an illumination unit 11.
A light image of the document is formed by a lens 13 via a reflecting mirror 12 on a plurality of photoelectric conversion elements 14 arranged in the main scanning direction. 15 is a roller that rotates around a shaft 15'.

16 is a reading switch provided on the top surface of the image reading device 1;
When the reading switch 16 is turned ON-OFF, illumination of the illumination unit 11 onto the original P and image reading are started. The reading switch 16 is provided with a protrusion 16a on the upper surface side, and the protrusion 16a can slide left and right along the guide groove 1a of the image reading device 1.

A cover 17 blocks and opens an optical path a between the original P and the photoelectric conversion element 14, and the cover 17 is provided integrally with the reading switch 16. A white reference surface 18 is formed on the inner surface of the cover 17.

19 is an interface cable, and the interface cable 19 is connected to an external device such as a personal computer (not shown).

Next, the operation of the present invention will be explained based on the block diagram shown in FIG. 3 and the flow chart shown in FIG. 4.

First, when the document reading operation is not performed, the cover 17 is
As shown in the figure, the document reading opening is covered.

When an external device (such as a personal computer) (not shown) connected via the interface cable 19 is ready to receive image data from the image reading device 1, the image reading device t1 is placed on the document P to be read. and slide the cover 17 in the direction of arrow A (step ■) to remove the second
When moved to the position indicated by the two-dot chain line in the figure, the reading switch 16 is interlocked and changed from the OFF state to the ON state (step ■).
, the image reading device l enters the reading operation state. At this time, since the cover 17 is still blocking the reading opening, the light a from the two illumination units 11 does not illuminate the document P, and the cover 17
is reflected on the white reference surface 18 of the reflecting mirror 12. lens 1
3 and reaches the photoelectric conversion element 14 (step 2), which is stored as reference white information in the storage device 24 of FIG. 2 (step 2), and used as a reference for shading correction.

Furthermore, when the cover 17 is slid to the position shown by the solid line in FIG. 1(b), the reading switch circuit 31 is activated, and the cover 17
opens the optical path a and also opens the timing signal generation circuit 29.
The photoelectric conversion element drive circuit 21 is operated via. Then, in step (2), the light a from the illumination unit 11 passes through the document reading opening and reaches the surface of the document P, and the light image is formed on the reflecting mirror 12. Photoelectric conversion element 14 via lens 13
image is formed. The one-line original optical image formed on the photoelectric conversion element 14 is converted into an electric signal, passed through an amplifier 22, and converted into a digital signal by an A/D converter 23.
Step (2) After shading correction is performed by the shading correction circuit 25 based on the reference white information stored in the storage device (step (2)), the image is binarized by the binarization circuit 26 (step (2)).

When the image reading device 1 scans the document P, the image reading device 1 scans the document P via the interface circuit 27 based on the amount of movement of the image reading device 1 in the sub-scanning direction obtained from the output of the rotary encoder 30 connected to the shaft 15a of the roller 15. hand,
Only the necessary image information is transmitted to the external device as one line of image data (step ■). After the above operation is continued and the scanning range of the original P has been scanned, the cover 17 is moved to the position shown in FIG. The return reading operation is ended (step o).

5 and 6 show a second embodiment of the invention.

In the figure, reference numeral 16 denotes a reading switch provided on the lower surface (reading surface) of the image reading device 1. The reading switch 16 can be slid in the vertical direction and has a wedge-shaped tip. 17 is a cover, and a white reference surface 18 is formed on the inner surface of the cover 17. 17a is a hole provided in the cover 17, and the tip of the read switch 16 is inserted into the chain hole 17a. Reference numeral 50 denotes a tension spring; one end of the tension spring 50 is fixed to the tip of the cover 17, and the other end is fixed to a proper position within the device 1. Therefore, the cover 17 is attached to the tension spring 5
0, it is always biased in the direction of arrow B.

Note that 51 is a passage through which the cover 17 slides.

Next, the operation of the second embodiment will be explained.

First, when the document is not being read, the switch 16 is in the state shown in FIG. When pressed against the document surface as shown in FIG. 6, the switch 16 slides upward to turn ON, and the image reading device 1 enters the reading operation state. At this time, since the cover 17 still keeps the reading opening cold (double-dashed line), the illumination unit 11
The light from the document P is not illuminated on the document P, but is reflected on the white reference surface 18 of the cover 17, and is reflected on the reflection mirror 12. The light passes through the lens 13 and reaches the photoelectric conversion element 14 . This is stored as reference white information in the storage circuit 24 of FIG. 2, and used as a reference for shading correction.

Furthermore, when the image reading device l is pressed completely against the document surface,
A cover 17 linked to the tip of the switch 16 is a tension spring 5
0 in the direction of the arrow, the reading opening opens and the light from the illumination unit 11 reaches the surface of the document P, and the reflected light a is sent to the reflecting mirror 12. It is led to the photoelectric conversion element 14 via the lens 13. In this state, the image reading device 1 is caused to scan the document P, and the image data is transmitted to an external device in the same manner as in the above embodiment. After scanning the reading range of the original P, when the image reading device l is separated from the second side of the original, the switch 16 slides downward to 0FFL, and the tension spring 50 causes the cover 17 to slide in the direction of arrow B to close the reading opening. cut off the section.

(Effects of the Invention) As described above, the present invention provides an image reading device that manually scans a document and reads image information on the document by illuminating the document with a lighting unit. A cover is provided that blocks the optical path between the document reading position and the photoelectric conversion element and has a white reference surface on the inside, and the white reference surface is illuminated before the document is read to correct the output of the photoelectric conversion element when the document is read. Because of this feature, it was possible to form a white reference surface for shading correction without increasing the size of a small image reading device that manually scans the surface of a document.

Therefore, it is possible to prevent deterioration in image quality caused by variations in the light amount distribution of the illumination unit during manual scanning, uneven sensitivity of the photoelectric conversion elements, etc., and to provide an image reading device with excellent gradation reproducibility.

[Brief explanation of the drawing]

The figures show embodiments of the present invention; FIG. 1 is a schematic sectional view of the first embodiment, FIG. 2 is a sectional view of the main parts, FIG. 3 is a block diagram of the main circuit configuration, and FIG. The figures are a flowchart, FIG. 5 is a schematic sectional view of the second embodiment, and FIG. 6 is a sectional view of the main parts. Symbol 1... Image reading device 1 14... Photoelectric conversion element 1 17... Cover l Description 1... Lighting unit 6... Reading switch 8... White reference plane Fig. 4

Claims (3)

[Claims] (1) In an image reading device that reads image information on a document by manually scanning the document and illuminating the document with a lighting unit, the optical path between the document reading position and the photoelectric conversion element is What is claimed is: 1. An image reading device comprising: a cover that blocks out the light and has a white reference surface on the inner surface; the white reference surface is illuminated before reading a document; and the output of a photoelectric conversion element during reading the document is corrected. (2) The image reading device according to claim 1, wherein the cover opens and closes in conjunction with ON/OFF of a reading switch provided on the image reading device. (3) The image reading device according to claim 1, wherein the cover opens and closes in conjunction with pressing and separating the image reading device from a document reading surface.