JPH0429273B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention can be applied to handy scanners, handy transfer machines, handy copying machines, and the like. More specifically, the present invention relates to a manual image reading device that manually scans and reads images and the like.

Prior Art This type of image reading device allows the image to be read at any length (in the sub-scanning direction), but the reading width (in the main scanning direction) is constant, so it does not read unnecessary information other than the necessary information. It is necessary to adjust it so that it does not occur.
Conventionally, this adjustment has been done by the following method.

An image reading window is provided with a shutter mechanism that can be partially opened and closed, and the image reading window is covered with a shutter to prevent unnecessary information from being read.

The light source corresponding to the unnecessary information part is turned off so that only that part cannot be read.

Problems to be Solved by the Invention However, there were problems in that the mechanism was complicated and shading was difficult.

An object of the present invention is to enable the reading width to be adjusted simply and inexpensively using an electric circuit.

Means for Solving the Problems Therefore, the image reading device of the present invention includes a pixel number counter that counts the number of pixels from the start of reading in each main scanning period of an image scanner, and an analog A digital-to-analog converter that outputs a voltage V _p , a reading width setting means that sets an arbitrary reading width, a reference voltage generation circuit that generates a voltage V _w that is proportional to the set reading width, and the voltage V a comparator that compares _w with the analog voltage V _p , and a gate circuit that performs an OR or AND of the output of the comparator and the image data read and binarized by the image sensor. It is something.

Operation While the output of the image sensor is being binarized, the number of pixels is counted by a pixel number counter for each main scanning period. This count number is converted into an analog voltage V _p and compared with a reference voltage V _w corresponding to an arbitrarily set reading width. The analog voltage V _p corresponding to the number of pixels is the reference voltage V _w corresponding to the reading width.
When the above value is reached, the gate circuit is opened, AND or OR is performed, and the number of pixels of the set reading width is written into, for example, a memory.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the drawings.

In FIG. 1, an image is read by an image sensor 10. In FIG. For example, a linear CCD sensor is used as the image sensor 10, and pixel columns are output in series each time a group of photoelectric conversion elements arranged on a sensor chip is electrically scanned. This one scan is called a main scan, and the main scan is repeated at regular intervals. The analog image data for each main scan is input to the binarization circuit 11. A pixel clock φ is supplied to the image sensor 10 and the binarization circuit 11 from a read timing generation circuit 12.

In FIG. 2, the main scanning period is represented by φTG. During this period, the analog image data is synchronized with the pixel clock φ from the read timing generation circuit 12.
It is output from the image sensor 10 at a rate of 1 pixel per 1φ clock pulse, converted into digital image data by the binarization circuit 11 as shown in FIG. 2, and stored in a memory (not shown) via the data buffer 13 as described later. transferred and written. This writing is performed only during the reading period by the write enable signal WRG in FIG. 2 in order to remove dummy pixels and redundant pixels. The time length is (1φ clock time Tφ) × (image sensor reading density)
Calculated by x (maximum reading width). Here, (image sensor reading density) x (maximum reading width) is the number of pixels written to the memory. For example, if the reading density is 8 dots/mm and the maximum reading width is 40 mm,
The number of pixels written to memory in one main scan is 8 x 40
=320. At this time, the reading period is 320×Tφ
(seconds).

The pixel clock φ is also supplied to the pixel number counter 14 from the time WRG becomes active. The counter 14 starts counting from 0, counts the number of pixels using the pixel clock φ during the reading period, and is reset to 0 at the end of the reading period. In the example above, 0 to 320 (101000000 in binary)
Count (integrate) up to. Note that the pixel number counter 14 may be a subtraction counter that subtracts from a preset value.

The digital output of the pixel number counter 14 is sent to the digital-to-analog converter 1 with linear input/output characteristics.
5 and is converted into an analog voltage V _p proportional to the number of counts. Assuming that the maximum value of this analog voltage V _p is V _p (max), to find out how many mm from the reading start point a certain pixel is located during the reading period, let its width be X and correspond to the pixel in question. voltage to
When V _p is used, the relationship with the maximum reading width becomes X=40V _p /V _p (max) in the above example. V _p is compared with a reference voltage V _w from a reference voltage generation circuit 17 by a comparator 16 .

The reference voltage generation circuit 17 constitutes a voltage dividing circuit with a manually adjusted volume 18, and by adjusting the volume 18, it can generate any voltage between the full range of the analog voltage V _p from 0 to _{V p} (max) volts. This is then input to the comparator 16 as a reference voltage. In the above example, if you want to set the desired reading width from the edge of the image to XR (mm), set the reference voltage V _w to the volume 18, and calculate V _w = (XR/40) × V _p (max). If adjusted to volts, voltage V _p intersects V _w at XR from the end, as shown in Figure 2, and at that point comparator 1
The output of No. 6 is inverted and remains in this state until the end of the reading period. This output of the comparator 16 is input to the data buffer 13. The data buffer 13 includes a gate circuit, and the binarization circuit 1
The digital image data from 1 is ANDed or ORed with the output of comparator 16. In the above example, a logical product is performed, and the output of the data buffer 13 is written to the memory as write image data as shown in FIG. At this time, among the digital image data from the binarization circuit 11, the width XR from the image edge
The data up to this point becomes the written image data as it is, but after that it becomes data 0 (white data).
Virtually unreadable. Therefore, the reading width in the main scanning direction can be arbitrarily adjusted by using the volume 18 as a reading width setting means.

It should be noted that whether the + or - input terminal of the comparator 16 is set to V _p or V _w , and the H of the image data.
Depending on how to determine whether the level or the L level is to be used as white data, it may be determined as appropriate whether to perform a logical product or a logical sum inside the data buffer 13.

Effect of the invention According to the present invention, there are the following effects.

It is easy to adjust the reading of only the desired portion of image information.

No software is required to adjust the reading width.

A complicated mechanism such as a mechanical shutter mechanism is not required.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
The figure shows the timing chart. 10... Image sensor, 11... Binarization circuit, 12... Read timing generation circuit, 13...
Data buffer including gate circuit, 14... Pixel number counter, 15... Digital-to-analog converter, 16... Comparator, 17... Reference voltage generation circuit, 18... Volume (reading width setting means).

Claims (1)

[Claims] 1. A pixel number counter that counts the number of pixels from the reading start point in each main scanning period of the image scanner, and an analog voltage corresponding to the counted number.
A digital-to-analog converter that outputs V _p , a reading width setting means that sets an arbitrary reading width, a reference voltage generation circuit that generates a voltage V _w proportional to the set reading width, and the voltage V _w and the analog voltage _Vp , and a gate circuit that performs an OR or AND of the output of the comparator and the image data read and binarized by the image sensor. A manual image reading device featuring: 2. The pixel number counter is an integration counter;
A manual image reading device according to claim 1. 3. The manual image reading device according to claim 1, wherein the pixel number counter is a subtraction counter.