JPH02111158A - Original reader - Google Patents

Abstract

PURPOSE:To improve the convenience of handling an original reader by distinguishing a face of a press plate at the side of an original platen from a background of a usual original, detecting the tilt of the set original depending on the density difference between the background of the original and the background of the press plate and turning a photoelectric conversion means in matching with the tilt of the original. CONSTITUTION:A color with a density more or less blacky than white color is applied to a face (reference face) 5a of a press plate 5 at the side of the original platen 3 and the density of the color of the reference face 5a is set to a density whity more than a threshold level used for binarizing a read data of a scanner 1. Thus, a tilt of the original 4 set on the original platen 3 is detected at pre-scan and the angle of a CCD is adjusted in matching with the tilt of the original 4 to make the read picture to an upright picture without any tilt.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a document reading device, and in particular to an electronic file and an O.
The present invention relates to a book-type document reading device applied to CR (optical character recognition device), facsimile machines, digital copiers, and the like.

(Prior Art) Conventionally, in a so-called book-type document reading device in which a document set on a document table is irradiated with light and the reflected light is introduced into a photoelectric conversion means through an optical system and read, the document set on the document table is read. scan the loaded original as it is set.

Therefore, if a document is set crooked (tilted) on the document table, it will be read in the tilted state, and the read image will also be outputted in the tilted state.

Conventionally, document reading devices that output read images to a host computer, etc.
A device with a function to rotate the camera by ° has been proposed.

(Problem to be Solved by the Invention) However, in such conventional document reading devices, image rotation is performed on software using a host computer, so it is difficult to rotate a single image. It takes a long time of 5 to 30 minutes to complete the rotation, and the rotation angle can only be roughly set, so when the original is set at a slightly crooked angle in an electronic file, etc., and you want to adjust it, or when you want to adjust the set angle of the original in OCR. This cannot be applied when you want to make adjustments because the character recognition rate has decreased due to a slight crookedness of the original, and the operator has to place the original on the original table again, causing the original reading device to It was not suitable for use.

(Purpose of the Invention) Therefore, the invention of the present application makes it possible to distinguish the background of the pressure plate that presses the original onto the document table from the background of the original, detects the inclination of the original in the prescan mode, and uses a photoelectric sensor based on this detection result. By adjusting the tilt of the conversion means, we offer an inexpensive document reading device that can output a tilt-free scanned image that corrects the tilt of the document at high speed without rotating the image on software. The aim is to further improve the convenience of the above.

(Structure of the Invention) In order to achieve the above object, the invention according to claim 1 includes a document table on which a document is set, a pressure plate that presses the document placed on the document table, and a pressure plate that applies light to the document set on the document table. In a document reading device including a light source for projecting light, a photoelectric conversion means for photoelectrically converting incident light, and an optical system that guides reflected light from the document to the photoelectric conversion means, the surface of the pressure plate on the document table side is The background is distinguishable from the background of the original and has a predetermined density on the white level side than the threshold value during binary output, and in prescan mode, the skew of the set original is determined from the difference in density between the background of the original and the background of the pressure plate. The invention according to claim 2 is characterized in that the size is detected, and the invention according to claim 2 is characterized in that the photoelectric conversion means comprises:
It is equipped with a photoelectric conversion element for one line in the main scanning direction, one end of which is rotatably supported in the main scanning direction, and the other end is connected to a drive mechanism, and the inclination of the document detected in the prescan mode is The drive mechanism is operated based on the size, and the photoelectric conversion means is rotated in accordance with the amount of inclination of the document.

Hereinafter, a detailed description will be given based on examples.

1 to 12 are diagrams showing an embodiment of the invention as claimed in claim 1, which is applied to a scanner.

In FIG. 1, reference numeral 1 denotes a scanner as a document reading device, and the scanner 1 has a document table 3 formed above its main body 2. As shown in FIG. The document table 3 is made of transparent glass, and the document 4 is set on the document table 3 with its original surface facing the document table 3 side. A pressure plate 5 is also rotatably attached to the upper part of the main body 2, and the pressure plate 5 presses the document 4 set on the document table 3 against the document table 3. Document table 3 of pressure plate 5
The side surface (reference surface) 5a is coated with a color that is a little darker than white, for example, the background color of a new newspaper (I.

D=0.1), and the color density of this reference surface 5a is set to a value on the white side than the threshold value used for binarizing the data read by the scanner 1. There is.

As shown in FIG. 2, the main body 2 of the scanner l houses a light source 6, a first mirror 7, a second mirror 8, a third mirror 9, a lens 10, a photoelectric conversion unit 11, etc. 6 and mirrors 7, 8, and 9 move from the reading start position shown by the solid line in FIG. 2 to the reading end position shown by the broken line for sub-scanning. The light source 6 projects light onto the original 4 through the original platen 3, and the reflected light from the original 4 is sequentially reflected by the first mirror 7, second mirror 8, and third mirror 9, and enters the photoelectric conversion unit 11 through the lens 10. be done.

The light source 6 and the first mirror 7 are mounted on the same carriage (not shown) and move together in the sub-scanning direction.

The second mirror 8 and the third mirror 9 are mounted on the same carriage (not shown) and move together in the sub-scanning direction. However, the moving speed of the second mirror 8 and the third mirror 9 is slower than the moving speed of the light source 6 and the first mirror 7.
The mirror 9 moves so as to keep the optical path length from the light source 6 to the photoelectric conversion unit 11 constant. Note that the first mirror 7
, the second mirror 8 , the third mirror 9 , and the lens 10 constitute an optical system that warms the reflected light from the original to the photoelectric conversion section 11 .

The lens 10 and the photoelectric conversion section 11 are constructed as shown in FIG. That is, the lens 10 is held by a lens block 12 fixed to the main body 2, and the photoelectric conversion section 11 is a COD (Char
ge Coupled Device) 13, board 14, cover 15, worm gear 16, driven gear 17
, and a step motor 18. C.C.
D13 is provided on the substrate 14, and photoelectrically converts the light incident through the lens 10 and outputs it as image data. The substrate 14 is fixed to the cover 15 with fixing screws 19, and one end of the cover 15 is attached to the lens block 12 with stepped screws 20, as shown in FIG. That is, holes 15 a 1 are formed at one end of the cover 15 and at the same position on the board 14 .
4a are formed, and the stepped screw 20 is inserted into these holes 15.
a, 14a and is screwed into the lens block 12. Therefore, the cover 15 and the substrate 14 are rotatably supported by the stepped screw 20 around the stepped screw 20.

A driven gear 17 is fixed to the other end of the cover 15, and the driven gear 17 meshes with the worm gear 16, as shown in FIG. The worm gear 16 has spiral teeth and is fixed to the shaft 18a of the step motor 18. Therefore, when the worm gear 16 is rotated by the step motor 18, the driven gear 17 moves in the vertical direction (arrow direction) in FIG.
The cover 15 rotates around the stepped screw 20.

Next, the action will be explained.

The present invention detects the inclination of the document 4 placed on the document table 3 during pre-scanning, and detects the inclination of the document 4 on the CCD 1 according to the inclination of the document 4.
The feature is that the angle of step 3 is adjusted to make the read image a straight image with no tilt.

This angle adjustment process will be explained below based on the flowchart shown in FIG.

When reading an image, the operator sets the original 4 on the original table 3, closes the pressure plate 5, and presses the original 4 against the original table 3. When the operator presses the start button of the scanner 1, the scanner 1 performs a pre-scan to correct for variations in the light source 6 itself, variations in the CCD 13, and the like.

During this pre-scan, the tilt of the document 4 is detected and CC'D
Perform angle adjustment in step 13.

Assume that the document table 3 is tilted and centered with the left shoulder of the document table 3 raised upward, as shown in FIG.

When the operator presses the start button, the
The scanner 1 enters the prescan mode (steer knob S) and starts prescanning. During pre-scanning, the scanner 1 starts reading from a reading start position and performs main scanning and sub-scanning. Now, on the nth line, document 4
The reading output of the CCD 13 is shown in Fig. 8 (
As shown in a), it is assumed that the background portion of the document 4 is output in white. Note that the line indicated by the dashed dotted line in FIG. 8(a) indicates the threshold level of binarization at the time of main reading. Also, in the next n+1 line, the document 4
It is assumed that the scanning is performed including the image-described portion of the document 4, and the reading output of the CCD 13 is an output including the background and image of the original 4, as shown in FIG. 8(b). Now, in the n-th line, the dot position in the main scanning direction that has changed from the CCD 13 output based on the color of the reference surface 5a of the pressure plate 5 to the CCD 13 output based on the background color of the original 4 is changed from the background of the original 4 to the color of the reference surface 5a. The changed dot position is x1□, the dot position that changed from the color of the reference surface 5a to the background of the document 4 on the n+1th line is Xz, and the dot position that changed from the background of the document 4 to the color of the reference surface 5a is defined as X22. , the dot difference Xl5X2 in the change position between the nth line and the n+lth line is X+ =X++ Xz+ --(1)X2 =X
+z Xzz --(2)

When the dot differences X, , X2 are found, the dot differences X1, X
2 are equal (X+ = XZ) (step S2), and when the dot differences (Step S9).

When the dot difference X+ and Xz are not equal, the dot difference X,
It is checked which of the dot difference and the dot difference X2 is larger (step SZ). Now, as shown in FIG. 7, the left shoulder of the original 4 is raised, so xi>xZ, and the larger Xl is selected and adopted (step S5), and the original 4
Calculate the cent deviation amount (inclination amount) Y of (step 3
6).

That is, convert the value of Xl to the value of tan (tan α1
), and if the maximum reading width of the scanner 1 is P, then the inclination IY of the original 4 is determined by the following equation.

Y=P-tan α+ +++++ (3> Once the amount of inclination Y of document 4 is determined, the reduction rate (scanner 1
(depending on the maximum reading width P), the adjustment amount (movement amount) y of the CCD 13 from the reference position (position where the original 4 is not tilted) is determined (step S7). When the adjustment my of the CCD 13 is determined, a number of drive pulses corresponding to the adjustment ff1y are output to the step motor 18 to rotate the step motor 18. The worm gear 16 is rotated by the rotation of the step motor 18, and the driven gear 17 is moved in the vertical direction by an amount of adjustment ff1y, thereby adjusting the angle of the CCD 13 (step Sa). When the angle 1) of the CCD 13 is completed, the main reading process is executed (step S
,).

In this way, when the document 4 is being read, the CCD 13
The reason why the image read by the CCD 13 of the document 4 becomes a straight image without any texture is due to the following reason.

When the original 4 is set correctly, if there is a positional deviation of the incident light on the CCD 13 between the main scanning start position and the main scanning end position in the main scanning direction, this positional deviation will cause the CCD
13, this appears as a vertical deviation of the incident light between the main scanning start position and the main scanning end position. Considering the assembly accuracy of the scanner 1, this deviation in the main scanning direction generally does not change between the reading start position and the reading end position in the sub-scanning direction. Therefore, when assembling the scanner I, the deviation (tilt) in the main scanning direction can be adjusted by adjusting the mounting positions of the first mirror 7 to the third mirror 9 and the CCD 13.

Therefore, when the original 4 is main-scanned from a to a2 as shown in FIG. a1 and reading end position a2 as shown in FIG.
Assuming that there is a deviation by ΔA, by adjusting the mounting angle of the CCD 13 by an angle ΔB corresponding to the amount of deviation ΔA, the image read by the CCD 13 can be made straight without any inclination.

In the above embodiment, if the document 4 is sent with its right shoulder raised as shown in FIG. 11, the CCD 13 as shown in FIG.
The output shown in Figure 12 (
The output of the CCD 13 as shown in b) is obtained. From the output of the CCD 13, dot differences X+ and Xz are determined from the above equations (1) and (2), and the dot differences χ1 and X2 are compared, as in the case of FIG. 7.8. In this case, the 11th
As shown in the figure, the right shoulder of document 4 is raised, so
<X2, the larger X2 is selected and adopted (step S4), and the misalignment amount (inclination ff1) Y of the set of original documents 4 is calculated in the same manner as described above (step S).

In this way, in the pre-scan mode, the amount of inclination (amount of deviation) of the original 4 is detected with a simple structure from the density difference between the background of the original 4 and the base surface 5a of the pressure plate 5, and the amount of inclination is handled accordingly. CC
Since the inclination angle of D13 can be adjusted, the read image during book reading can be made straight without any inclination, without rotating the image on software as in the conventional case.

Therefore, a document reading device that can output a read image without tilt can be made inexpensive, and the handling convenience of the document reading device can be further improved.

In the above embodiment, when the background color of the document 4 is darker than the color of the reference surface 5a, the inclination of the document 4 cannot be detected. Please check that the original is set.'' is displayed.

(Effects) According to the present invention, it is possible to detect the inclination of a document with a simple configuration, and to output a read image without inclination in which the inclination of the document is corrected at high speed without rotating the image on software. Can be done. As a result, a document reading device capable of outputting a read image without tilting can be made inexpensive, and the convenience in handling the document reading device can be further improved.

[Brief explanation of the drawing]

Figures 1 to 12 show the invention of claim 1 and claim 2.
FIG. 1 is a perspective view of a scanner as the document reading device, FIG. 2 is a front view of its optical system, and FIG. 3 is a front view of its optical system. FIG. 4 is an exploded perspective view of the photoelectric conversion section, FIG. 5 is a front view of the worm gear section, FIG. 6 is a flowchart showing the angle adjustment process, and FIG. 7 is an exploded perspective view of the photoelectric conversion section. Diagram showing the document set on the document table with the left shoulder raised.
Figure 8 is a diagram showing the COD output during pre-scanning when set as shown in Figure 7, Figure 9 is a diagram showing the main scanning direction of the original, and Figure 10 is a diagram showing the deviation in the main scanning direction. CCD
Figure 11 is a diagram showing the state in which the original is set on the original table with its right shoulder raised; Figure 12 is a diagram showing the relationship between the
The figure shows the output of the CCD during blisscanning when set as shown in FIG. 11. 1...Scanner, 2...Main body, 3...Original table, 4...Original, 5...Press plate, 5a... ... Reference plane, 6 ... Light source, 11 ... Photoelectric conversion section, 12 ... Lens block, 13 ... CCD (photoelectric conversion means), 14...
.... Board, 15 .... Cover 16 .... Worm gear, 17 .... Driven gear, 18 .... Step motor, 19 .... Fixing screw, 20...Stepped screw.

Claims (2)

[Claims] (1) A document table on which a document is set, a pressure plate that presses the document placed on the document table, a light source that projects light onto the document set on the document table, and a photoelectric conversion means that photoelectrically converts incident light; In a document reading device equipped with an optical system that guides reflected light from a document to a photoelectric conversion means, the surface of the pressure plate on the document table side can be distinguished from the background of a normal document, and the threshold value at the time of binary output is The document reading device is characterized in that the background has a predetermined density on the white level side, and in a prescan mode, the magnitude of the tilt of the set document is detected from the density difference between the background of the document and the background of the pressure plate. (2) The photoelectric conversion means includes one line of photoelectric conversion elements in the main scanning direction, one end of which in the main scanning direction is rotatably supported, the other end is connected to a drive mechanism, and the photoelectric conversion means includes one line of photoelectric conversion elements in the main scanning direction. Claim 1 characterized in that the drive mechanism is operated based on the amount of inclination of the document detected during the scan mode, and the photoelectric conversion means is rotated in accordance with the amount of inclination of the document.
The manuscript reading device described.