JPH0522531A - Picture reader - Google Patents

Abstract

PURPOSE:To enable the reading speed selection between the first speed reading with relatively low speed capable of preventing the missing of a picture even when multilevel image picture or the like with large amount of information is temporarily stopped because of the conditions of the personal computer such as I/F data transfer speed and the writing to a disk and the second speed reading capable of high speed reading even though the missing of picture is generated when document information to be read at a high speed with binarization is temporarily stopped. CONSTITUTION:The speed of a stepping motor 21 is switched to either the first speed or the second speed speedier than the first speed, and when the driving of the stepping motor 21 is stopped during the subscanning at the first speed, the data of line numbers read by a line sensor 5 from the driving stop to the moving stop of the line sensor 5 is stored in a RAM buffer memory 28. At the time of restarting, the reading data stored in a RAM buffer memory 28 is read out in order of writing from a CPU 31, and the subscanning of the line sensor 5 is started by the CPU 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device for reading the contents of books, photographs, documents and the like as image information and sending it as digital signals to a personal computer, a workstation or the like.

[0002]

2. Description of the Related Art Today, there are various purposes for reading characters and images into an information processing device such as a personal computer. For example, when inserting a picture or photograph in a created document, transmitting the read information as it is or storing it as an electronic file, character recognition that encodes the read character information, image processing of the read image, etc. There is a case to do. Therefore, there are various ways of reading in a processing device that requires image information. For example, a device that wants to process a large amount of binary information in a short time, such as an electronic file, a device that sequentially recognizes the read character information, or a large amount of information such as a color multi-value image image. There is. Therefore, it is desirable that the image reading apparatus can support various reading methods.

[0003]

There are cases where it is desired to input a large amount of image information in a short time for processing, and there are cases where it is desired to input while sequentially processing partial image information. In the method of reading an image by moving the document or the optical system in the sub-scanning direction when reading an image, whichever method is used, inertial force acts on the object that moves at high speed, causing a step in the image information of the sudden stop point. Is inevitable.

A reading unit moving in the sub-scanning direction cannot stop suddenly due to a considerable inertial force when moving at high speed. It stops at a certain distance up to a certain moving speed, but at a higher speed, there is a large variation in the distance until it stops due to the load at the place where it stops. If the reading is temporarily stopped during the reading, the scanning line of the image is missing in the read image, and the image becomes a step.

Various means have been proposed for avoiding the step of the image information caused by the stop of the reading operation due to the memory limitation on the information processing apparatus side. However, if the reading speed is increased to some extent, the effect is lost. The current situation.

The present invention has been made in view of the above points, and an object of the present invention is to provide a first speed capable of preventing the image scanning line from being lost when the reading is once stopped. An object of the present invention is to provide an image reading apparatus capable of performing reading suitable for various purposes by making it possible to select a second speed at which high speed reading is possible, but it is impossible to lose an image when stopped.

[0007]

In order to achieve the above object, the present invention provides an image reading apparatus having a line sensor and a sub-scanning unit for sub-scanning the line sensor,
Switching means for switching the sub-scanning speed of the sub-scanning means to either a first speed or a second speed faster than the first speed; and a case where the driving of the sub-scanning means is stopped during the sub-scanning at the first speed. , Storage means for storing the data of the number of lines read by the line sensor from the stop of driving to the stop of movement of the line sensor, and the read data stored in the storage means are read in the order of writing at the time of restarting. And a control unit for starting sub-scanning of the line sensor later.

[0008]

In the present invention, the sub-scanning speed of the sub-scanning means is switched to either the first speed or the second speed faster than the first speed by the switching means, and the sub-scanning means is driven during the sub-scanning at the first speed. Is stopped, the data of the number of lines read by the line sensor from the stop of driving to the stop of movement of the line sensor is stored in the storage means, and when the restart is started, the read data stored in the storage means is controlled by the control means. After reading the data in the order of writing, the control unit starts the sub-scan of the line sensor.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and FIG. 2 shows the structure of an image reading apparatus according to the embodiment. In FIG. 2, 1
Is an original to be read and is placed on the original placing table 2 made of glass. Reference numeral 3 is a light source for illuminating the original 1 and 4 is a rod lens for forming an image of reflected light from the original 1 on the line sensor 5. These are held on a shaft 7 as an integrated reading unit 6 so as to be movable in the sub-scanning direction. The reading unit 6 is scanningly driven in the sub-scanning direction on the shaft 7 by a driving stepping motor 21 (not shown) (FIG. 1), and 10 connected to the control board 9 by a flexible cable 8 is a housing. Is.

In FIG. 1, reference numeral 5 denotes the same portion as in FIG. Reference numeral 21 is a stepping motor. Reference numeral 23 denotes a shading correction circuit, which corrects shading of the image signal from the line sensor 5. An A / D converter 24 converts an analog signal from the shading correction circuit 23 into a digital signal. Reference numeral 25 is a binarizing circuit, which binarizes the digital signal converted by the A / D converter 24. A drive timing generation / switching circuit 26 drives the line sensor 5 and drives and controls the stepping motor drive circuit 27. 28 is a RAM buffer memory, 29 is I /
It is an F circuit. A ROM 30 stores a control program. Reference numeral 31 denotes a CPU, which controls each unit.

Next, the processing when the reading is stopped during reading will be described with reference to FIG.

FIG. 3A shows a signal indicating the period of the scanning line. Now, as shown in FIG. 3B, when the reading is interrupted on the nth line, the drive signal to the stepping motor 21 is stopped as shown in FIG. 3C. Figure 3 now
The image data read by the line sensor 5 shown in (d) is transferred to the host during the reading of the next line as shown in FIG. 3 (e). Since the image data is stopped at the n-th line, the image data at the n-th line remains untransferred. Further, although the reading is stopped at the n-th line, the reading unit 6 moves a certain distance until it is completely stopped due to inertial force or the like. This distance changes depending on the weight of the reading unit 6, the moving speed, the load on the mechanism, etc., but for the sake of simplicity of explanation, the distance is equivalent to one line. Therefore, since the reading unit 6 is moving despite the absence of this drive signal, the reading operation by the line sensor 5 continues, the (n + 1) th line is read, and the data is stored in the RAM buffer memory 28.

Then, in response to a read start command, first the RAM
After the data of the nth line stored in the buffer memory 28 is transferred, the drive signal of the reading unit 6 is issued, and the reading operation of the n + 2th line and the transfer operation of the data of the n + 1th line are resumed. Normally, the moving distance to the stop is a little longer, reaching the n + 2 and n + 3 lines. By doing so, it is possible to prevent a disconnection at the time of stopping during reading.

Further, as shown in FIGS. 3 (f) and 3 (g),
Although the reading can be performed at a high speed of 1/4 in the reading cycle and the reading period, the reading is performed at a speed with a small inertial force with an interval between the reading lines.

FIG. 4 is a flow chart showing a control program stored in the ROM 30 shown in FIG.

In response to a reading start command, preprocessing such as data collection for shading correction is performed in step S1, and the reading unit 6 is moved by one line in the sub-scanning direction in step S2. Then, in step S3,
It is checked whether the specified number of lines have been moved, and if the result of the check is that the specified number of lines has been reached, the process ends.
On the other hand, if the specified number of lines is not reached, step S4
In parallel with the reading operation for one line, if there is already read data, the previous line data is also transferred to the host. Then, in step S5, the host REA
It is checked whether or not it is in the DY state, and if it is in the READY state, the process returns to step S2 to continue the processing of the next line. On the other hand, if the host is not in the READY state, it is confirmed in step S6 whether the current reading is the reading in the standard mode or the high-speed reading mode. As a result of confirmation, if it is high-speed reading, the reading ends as an error. On the other hand, in the standard reading mode, after the start / stop buffer processing is performed in step S7, the normal reading operation is continued.

The example of a typical image reading apparatus has been described above. In practice, however, the high-speed reading mode is optimally applied during continuous high-speed image reading by an automatic document feeder, which is abbreviated as ADF. Is.

As a method of reducing the inertial force of the reading unit, it is usual to lengthen the drive signal to the stepping motor as shown in FIG. 5B as compared with the high-speed reading shown in FIG. 5A. Done. Also, it is convenient that the ratio is an integral multiple because of the ease of making a signal.

[0020]

As described above, according to the present invention,
Since it is configured as described above, binary high speed input like an electronic file can be achieved by having both the first speed reading and the high speed reading that can prevent the missing of the image scanning line when the reading is temporarily stopped. It becomes possible to select the one that is convenient for two types of reading such as multi-value sequential reading such as a color image.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a structure of an image reading apparatus according to an embodiment of the present invention.

FIG. 3 is a timing chart for explaining buffer processing at the time of start / stop.

FIG. 4 is a flowchart showing a control program stored in the ROM shown in FIG.

FIG. 5 is a timing diagram for explaining a drive signal of a stepping motor that changes the reading speed.

[Explanation of symbols]

 21 stepping motor 22 image sensor 23 shading correction circuit 24 A / D converter 25 binarization circuit 26 drive timing generation / switching circuit 27 stepping motor drive circuit 28 RAM buffer memory 29 I / F circuit 30 ROM 31 CPU

Claims (1)

1. An image reading apparatus having a line sensor and a sub-scanning unit for sub-scanning the line sensor, wherein a sub-scanning speed of the sub-scanning unit is a first speed or the first speed. Switching means for switching to one of the higher second speeds;
When the driving of the sub-scanning unit is stopped during the sub-scanning at the first speed, a storage unit for storing the data of the number of lines read by the line sensor from the driving stop to the movement stop of the line sensor, An image reading apparatus comprising: a control unit that starts sub-scanning of the line sensor after reading the read data stored in the storage unit in a writing order at the start of activation.