JPS6298866A - Original reading method - Google Patents

Abstract

PURPOSE:To prevent the deterioration in resolution even if an original deviates from the prescribed position by placing movable parts at plural different positions and deciding the number of changing times of a binarization signal, which can be obtained by reading the same line on the original. CONSTITUTION:An image sensor 4 obtains a read signal D1 with the movable part 52 floating by a distance l1 and a read signal D2 in parallel with a main body part 51. The read signals D1 and D2 are converted into binalization signals E1 and E2 by a comparator 12, stored in the 1st and 2nd RAMs 13 and 14, respectively, and inputted to an up-down counter 15. It counts up how many times the binarization signal E1 changes and counts down how many times the binarization signal E2 changes. If said result is positive, it means that the binarization signal E1 changes more often than the signal E2 and the original is better focused, and vice versa of if the result is negative.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a document reading method using an image reading device using a contact type image sensor.

2. Description of the Related Art Conventionally, as shown in FIG. 4, this type of apparatus has a glass plate 2 on which a document 1 is placed, a sensor unit 7 in which a light source 3, a lens array 5, and an image sensor 4 are optically arranged. , an image processing circuit 6 connected to the image sensor 4, scans the document 1 while moving the document 1 or sensor unit 7 in the sub-scanning direction, and transmits the image signal obtained by the image sensor 4 to the image processing circuit 6. Problem 17 that the invention attempts to solve, which was binarization, is due to this configuration. For example, as shown in Figure 6, if the original 1 is a thick book, the original 1 may float off the glass plate 2, and if the original is read in such a state, it may be difficult to focus. When I made a blurry image +1, I got 2-. .

This 2') problem arises in the following (, due to change, etc.).

That is, as shown in FIGS. 7 and 8, the focal point of the lens array 5 is 17X from the center of the lens array 5.
The depth of focus is so low that even if the document reading position deviates from this focal point by just a few degrees, the modulation transfer function MTF will drop by several tens of factors. This is caused by.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a document reading method in which the resolution is less degraded even if the document is slightly deviated from a predetermined position.

Means for Solving the Problems In order to achieve the above object, the present invention provides a lens array in a movable part that can be displaced relative to the main body of a contact type image sensor that holds a light source for irradiating a document.

Equipped with an image sensor. The image sensor has 2
A valorization means is connected. The binarization means is connected to a means for discriminating the number of changes in the binarized signal obtained by placing the movable part at a plurality of different positions and reading the same line of the document in each state.

The movable portion is set at a plurality of positions in one predetermined line of the working document. The same line of the document is read at a plurality of different positions, and these are binarized by the binarizing means. The binarized read signal is compared with the number of changes by a change number determining means. As a result of the comparison, the read signal with the largest number of changes is selected as the original image signal.

Embodiment FIG. 1 is a schematic configuration diagram showing an example of a document reading apparatus to which a document reading method according to an embodiment of the present invention is applied.

This document reading device includes a glass plate 2 and a contact image sensor 50 provided below the glass plate 2. The contact image sensor 5o includes a main body 51 holding a light source 3 that illuminates the original 1 placed on the glass plate 2;
O includes a light source 3, a lens array 5 optically arranged with respect to the reading section of the document 1, an image sensor 4, and a movable section 52 movably provided with respect to the main body section 51. is connected to the vibration element 8. Vibration element 8
is connected to a drive circuit 9 and a basic clock generation circuit 11, and is moved up and down by the drive circuit 9, which operates in response to a clock signal generated by the basic clock generation circuit 11.

ing. As the vibration element 8 moves up and down, the movable part 52 also moves up and down, and the distance between the movable part 62 and the document 1 is changed.

An image processing circuit 1o to which a basic clock generator 11 is connected is connected to the image sensor 4.

As shown in FIG. 3, the image processing circuit 10 receives the read signal D of the image sensor 4 and a threshold value for binarizing the read signal, and converts the read signal into a binary value. The comparator 12 outputs a converted signal E. In the case of this embodiment, a predetermined voltage ma. is divided by resistors R1 and R2 to create a reference level vc×(R2/R+R2), and a threshold value based on this reference level is input to the comparator 12.

The comparator 12 is connected to a storage means 6Q that temporarily stores the binary signal E, and a selector 1A that inputs the binary signal E stored in the storage means 60. In this example,
The storage means θ0 corresponds to the case where the movable part 62 is displaced to two positions, and stores the binarized signal E at each position.
It includes a RAM 13 and a second RAM 14.

The storage means 60 is provided with a determination means 7Q in parallel. The determining means AQ inputs the binarized signal E equivalent to that outputted to the storage means 60, and calculates the number of changes of each signal. A binary signal E (in the case of this embodiment,
A magnitude determination circuit 16 is provided for outputting a signal for selecting one of the two binary signals E) stored in the first RAM 13 and the second RAM 14 to the selector 1.

Regarding the operation of the document reading device configured as above,
The following description will be made with reference to FIG. 2, which shows the operation timing of the apparatus in FIG. 1.

First, the basic clock generator 11 generates a line synchronization signal T1 for the image sensor 4, as shown in FIG. Every two pulses of this line synchronization signal T1, the second
As shown in FIG. C, a read synchronization signal of 2 is output from the drive circuit 9 to the vibrating element 8. As shown in FIG. 2B, the vibrating element 8 is configured to move up and down in half a cycle after the pulse of the read synchronization signal T2 is generated, and the movable part 62 connected to the vibrating element 8 is In this case, it moves up and down by a distance β1 with respect to the main body 61, as shown in FIG. In this embodiment, this vertical movement is performed for each line of the document 1.

On the other hand, in the sub-scanning direction, step feed 9 is performed in conjunction with the read synchronization signal T2. Then, the same line on the original document 1 is read at two positions on the movable part 52. For example, in this embodiment, the image sensor 4 detects the second
A read signal D1 is obtained as shown in the figure, and a read signal D2 is obtained by the image sensor 4 in a state where the movable part 52 is aligned with the main body part 51 as shown in FIG.

The read signals DI, D2 are converted into binary signals E1, 1! by the comparator 12, respectively, as shown in FIG. 2E. :2, and the first RAM13. While being stored in the second RAM 14,
It is input to the up/down counter 15.

The up/down counter 15 counts up the number of changes in the binary signal E1 and counts down the number of changes in the next binary signal E2. If this result is positive, the binary signal E1 has more changes and is more in focus; on the other hand, if it is negative, the binary signal E2 has more changes. , it can be seen that the image is more in focus. In this embodiment, the binary signal! The magnitude determination circuit 16 determines that the number of changes is greater in the signal E2, and the selector 17 selects a signal for selecting the binary signal E2 stored in the second RAM 14.
Output to.

The selector 17 selects the binary signal E2 and outputs it as a binary image signal.

In this embodiment, a case has been described in which the movable part 52 is displaced twice for each line of the document, but the movable part 52 is displaced twice, once every N lines, and the movable part 52 is displaced twice for each line of the document. The position of the movable part 52 that generates the binary signal is determined by (
It may be held during the N-1) line. By doing so, reading can be performed quickly.

Furthermore, in this embodiment, a case has been described in which the same line is read by displacing the movable part 52 twice, but it is not necessarily limited to two times, and the movable part 52 may be displaced M (M≧3) times. , may be read in each state, converted into a binary signal, and the read signal with the largest number of changes may be output as a binary image signal. By doing so, the document can be read with higher accuracy.

Effects of the Invention As is clear from the above explanation, according to the present invention, a movable part having a lens array and an image sensor is set at each of a plurality of locations, and a line is read and the read signal is binarized. Since the signal with the highest number of changes among the binary A8 signals is output as a binary image signal, the document can be read with almost no deterioration in resolution even if the document is slightly shifted from the specified position. effective.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a document reading device to which a document reading method according to an embodiment of the present invention is applied, FIG. 2 is an operation timing diagram of the device, and FIG. 3 is a diagram similar to that shown in FIG. 4 is a detailed block diagram of an image processing circuit shown in FIG. 4, a schematic configuration diagram showing an example of a conventional document reading device, and FIG. Figure 6,
FIG. 7 is an explanatory diagram showing the depth of focus of the lens array. 4... Image sensor, 5... Lens array, 8... Vibration element, 9... Drive circuit, 10... Image processing circuit, 11...
Basic clock generation circuit, 12... Comparator, 13
...1st RAM, 14...2nd RAM
, 15...up/down counter, 16...
. . . Size determination circuit, 17 . . . Selector, 50
. . . Close contact type image sensor, 51 . . . Main body, 52 . . . Movable part, 6Q . Name of agent: Patent attorney Toshio Nakao and 1 other person4.
- Image 'Se/Pujou 1 Figure
5---- Lens Array δ-Pneumodynamic Cord Preparation Figure 2 published by fAl ([) ■T4 dish 1/l/I 7 E2! “i”; Figure 3 Figure 4

Claims (2)

[Claims] (1) A document is irradiated with illumination light from a light source held in a contact image sensor main body, and a lens array and an image sensor are optically arranged with respect to the light source and the document, and With the movable parts movable at multiple positions set at multiple positions, the image sensor receives reflected light from the same line of the original, converts these light reception signals into binary signals, and determines the number of changes in these binary signals. Compare by means,
A document reading method characterized by outputting a signal having the maximum number of changes as a document reading signal. (2) Displace the movable part every predetermined number of lines, read the same line at multiple positions, create a binary signal, and set it at the position that shows the greatest number of changes. A method for reading a manuscript according to claim 1.