JPH0630204A - Scanner - Google Patents

Abstract

PURPOSE:To improve picture quality until prescribed speed can be obtained by performing line thinning-out in accordance with speed less than prescribed speed while travel in a direction of sub operation is performed at such speed. CONSTITUTION:Low acceleration of reading speed is applied to image data E2 from an image reading part 22 immediately after reading is started, therefore, the image data to be read as the one of (n) lines originally is extended to the one of (m), (m+1), or (m+2) lines. A read control part 20 outputs an effective line designation signal E5 in accordance with the reading speed, and thins-out the data on (m+1)th and (m+2)th lines leaving the one on the (m)-th line, and stores it in buffer memory 27 as the data of (n) lines. Thenceforth, the image data on the (m+4)th line is thinned-out from the image data extended to the one of (m+3) and (m+4) lines by the effective line designation signal E5 leaving the data on the (m+3)th line, and is stored in the buffer memory 27 as the data of (n+1) lines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanner using a one-dimensional sensor.

[0002]

2. Description of the Related Art Currently, scanners are widely used in devices capable of image processing such as personal computers and optical document file systems. However, the speed at which the image data of the host device (image processing device such as a personal computer) connected to the scanner is taken in is almost lower than the image reading speed of the scanner.

Therefore, a conventional scanner is equipped with a memory capable of storing several tens of lines of image data in the main scanning direction inside the scanner, reads at a speed higher than the data fetching speed of the host device, and the read image data is stored in the memory. Once, the data is output according to the capture speed of the connected host device, and when the memory usage exceeds a specified value, the movement in the sub-scanning direction is stopped and the read image data When the memory usage amount drops below a specified value, the drive in the sub-scanning direction is restarted from the stopped state, and the read image data is stored again in the memory. Method was used.

However, when the above-mentioned intermittent drive reading is used, there is a problem in that the read image is distorted due to the vibration caused by the rapid speed change between the stop and start of the drive. Therefore, the scanner is equipped with a memory capable of storing several tens of lines of image data in the main scanning direction, and reading is performed at a speed higher than the data acquisition speed of the host device, and the read image data is temporarily stored in the memory and connected. Data is output according to the capture speed of the host device, and when the memory usage exceeds a specified value, the movement in the sub-scanning direction is gradually decelerated and stopped, and the read image data is stored in memory. When the storage is stopped and the memory usage falls below a specified value, the drive in the sub-scanning direction is gradually accelerated from the stopped state and restarted, and the read image data is stored again in the memory. Driven reading methods have been considered.

In the latter intermittent drive, as shown in FIG. 1, in order to reduce vibration caused by a rapid speed change at the time of starting and stopping the drive, at the start, the stop state 1 is changed to a predetermined speed 2. Gradually increase the speed to 2
When the speed reaches, the driving is performed at a constant speed, and in the case of the stop, the speed is gradually reduced from the predetermined speed 2 to the stop state 3 to stop.

When the original shown in FIG. 2 is read by using the latter scanner having the intermittent drive, the image data as shown in FIG. 3 is read when the original is read only at a predetermined speed. If this is done, the distorted image data as shown in FIG. 4 will result.

[0007]

When the latter intermittent drive reading method is used, the speed is gradually increased from the stopped state to the predetermined speed, and the predetermined speed is changed to the stopped state. During this period, the speed is gradually reduced,
If the reading is performed at a constant timing, the read image becomes a distorted image.

The present invention has been made in view of the above-mentioned problems, and during the period from the stopped state at the time of intermittent drive reading to a predetermined speed, or from the predetermined speed to the stopped state. The object is to make the read image have a good image quality and read the image.

[0009]

An original placing table on which an original is placed, a line sensor for exposing the original placed on the original placing stand, and reading in the main scanning direction for each line, and the original. Of the image data read by the line sensor, which has an optical system capable of relatively moving with respect to the original with respect to the sub-scanning direction, and drive means for relatively moving the original and the optical system. A buffer memory that can store and sequentially output to the outside at a speed lower than the storage speed, and when the memory usage amount of the buffer memory becomes a predetermined value or more, the driving unit moves the optical system in the sub-scanning direction. The relative movement is gradually decelerated to a stopped state, the storage of the image data read by the line sensor in the buffer memory is stopped, and the memory usage of the buffer memory is a predetermined value. When it goes down, the relative movement of the optical system in the sub-scanning direction is gradually accelerated from the stopped state to a predetermined speed by the driving means, and the image data read by the line sensor is stored again in the buffer memory. In the scanner, while the original is being read at a speed at which the drive speed of the drive means is less than a predetermined speed,
The feature is that line thinning is performed corresponding to a speed lower than the predetermined speed.

[0010]

When the scanner of the present invention is used, the thinning corresponding to the reading speed is performed when the intermittent driving is performed.
It is possible to obtain good read image quality in which image distortion is corrected.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A scanner of the present invention will be described with reference to FIGS. 5, 6 and 7. FIG. 5 is a diagram showing an embodiment of a mechanism system for performing intermittent drive. In FIG. 5, reference numeral 10 is a light source, and 13 is a light source 10 for irradiating the light. The first light reflects light reflected by a document (not shown) placed on the document table to a second mirror 7 described later. Mirror, 7 is the first mirror 1
A second mirror that reflects the light reflected from the third mirror 8 to a third mirror 8 described later, 8 is a third mirror that reflects the light reflected from the second mirror 7 to a CCD 9 described later, and 9 is a third mirror
It is a CCD that receives the light reflected from the mirror 8 and converts it into an electric signal.

The power generated by the stepping motor 1 which operates based on the frequency of the input signal is the small pulley 15, belt 14, large pulley 2, drive pulley 3, wire 4, wire pulley 5, tension pulley 11, etc. The first mirror unit 12 composed of the light source 10 and the first mirror 13 and the second mirror unit 6 composed of the second mirror 7 and the third mirror 8 are driven via the.

In the scanner of the present invention, the CCD 9 reads the main scanning direction of the image, and the first mirror unit 12 and the second mirror unit 6 (the first mirror unit 12 and the second mirror unit 6 are referred to as an optical system). Reading is performed while driving in the sub-scanning direction. FIG. 6 is a diagram showing an embodiment of the functional blocks of the scanner of the present invention.

In FIG. 6, the image reading in the main scanning direction is performed by an image reading unit 22 composed of a CCD or the like in synchronization with a clock E1 from a timing generating unit 21 which generates various timings. It is output as data E2. While E1 shown in the timing chart of FIG. 7 is high, electric charges are stored in the CCD of the image reading unit 22 and transferred to a transfer register (not shown) of the image reading unit 22 at a low timing. That is, the transferred data is the image data E for one line read in the main scanning direction.
It is 2.

The image data E2 output from the image reading section 22 contains invalid data, as indicated by the hatched portion of E2 shown in FIG. The invalid data is, for example, CCD dummy data or data of a portion exceeding the width of the document. Of the image data E2 output from the image reading unit 22, what is indicated as valid data is the low active signal of E3 shown in FIG.

The various timing generators 21 use the clock E1 generated when the reading is started to notify the reading controller 20 composed of a CPU or the like of the reading start for each line in the main scanning direction (each). Read start signal for each line). The reading control unit 20 determines the number of read lines by counting the reading start signal for each line from the various timing generation units 21. Further, the reading control unit 2
0 receives the clock E1 for notifying the start of reading, and then outputs the effective line designation signal E5 for thinning out for a predetermined fixed time, that is, for the time during which the reading speed is gradually accelerated. This effective line signal E5
Is gated by the gate unit 24 and a low active signal of E3 indicating that the image data E2 output from the image reading unit 22 is valid data.
It is output as a signal E11 that controls the gate unit 26 that controls the writing of image data to the. At this time, the effective line designation signal E5 output from the reading control unit 20 corresponds to the reading speed.

When reading the original with the slanted lines shown in FIG. 2 with such a configuration, the image data E2 output from the image reading unit 22 becomes as shown by 41 in FIG. Immediately after the start of reading, the acceleration of the reading speed is small and the read image data is in a stretched state. Image data originally read as n lines extends to m, m + 1, m + 2 lines. The reading control unit 20 outputs the valid line designation signal E5 corresponding to the reading speed, invalidates (thinning) the data of the m + 1 and m + 2 lines, leaving the m lines, and stores them in the buffer memory 27 as the n lines. Strictly speaking, n
Although m and m are different data, they are approximate values within a short time until the reading speed reaches a predetermined constant speed state (predetermined speed), which is within the allowable range in view of the overall image quality. Similarly, the image data extending to the m + 3 and m + 4 lines is invalidated (thinning out) with the valid line designation signal E5 leaving the m + 3 lines.
And stores it in the buffer memory 27 as line n + 1. From the m + 5 line, since the reading speed is a predetermined constant speed (predetermined speed), it is not necessary to invalidate the line by the valid line signal E5.
Buffer memory 2 with line data as n + 2 lines
Store in 7.

That is, as the reading speed approaches a predetermined constant speed (predetermined speed), the number of lines for invalidating (decimating) the read data is reduced. The reading control unit 20 outputs the free space of the buffer memory 27 for communication with the host device (not shown) connected to the scanner of the present invention from the buffer memory 27 when starting the line reading in the main scanning direction. Judging from the signal E12 indicating the available free space, when the buffer approaches full,
The frequency of the signal output to the motor 1 is reduced and the instruction signal E8 for gradually decelerating the movement in the sub-scanning direction is continuously sent to the motor drive pulse generator 23 until it is completely stopped. At this time, the image data E2 output from the image reading unit 22 is as shown by 42 in FIG. Immediately after deceleration of the reading speed, that is, at a speed slightly slower than a predetermined constant speed, the image originally read as k lines extends to j, j + 1 lines. Read control unit 2
When 0, the valid line designation signal E5 corresponding to the reading speed is output, the k + 1 lines are left and the data of the j + 1 line is invalidated (thinned), and stored in the buffer memory 27 as the k line. Strictly speaking, j and k are different data, but the reading speed is an approximate value within a short time from a predetermined constant speed (predetermined speed) to a stop state, and when viewed from the overall image quality. It is within the allowable range. Thereafter, similarly, the image data extending to the j + 2, j + 3, j + 4 lines is j + 2 by the effective line designation signal E5.
The j + 3 and j + 4th lines are invalidated (thinned) while leaving the lines and stored in the buffer memory 27 as the k + 1th line.

That is, as the reading speed approaches a stop mode from a predetermined constant speed (predetermined speed), the number of lines for invalidating (decimating) the read data is increased. While the reading is stopped, the host device fetches the image data from the buffer memory 27 through the communication I / F 28, and when a sufficient space is generated in the buffer memory 27, the above-described reading operation is performed and the reading is restarted. .

When the memory usage amount of the buffer memory 27 shown above exceeds a predetermined value, the movement in the sub-scanning direction is stopped, and the image data read by the image reading unit 22 is stored in the buffer memory 27. Stop doing,
Further, when the memory usage amount of the buffer memory 27 becomes equal to or less than a predetermined value, the driving in the sub-scanning direction is restarted from the stopped state, and the image data read by the image reading unit 22 is stored again in the buffer memory 27. Is called intermittent drive.

By the above control, when performing intermittent driving reading, it is possible to correct image distortion due to a change in reading speed.

[0022]

According to the scanner of the present invention, when intermittent driving is performed, thinning corresponding to the reading speed is performed to obtain a good read image quality in which image distortion is corrected.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a change in speed of reading drive.

FIG. 2 is a diagram showing a document to be read.

FIG. 3 is a diagram showing an image when a document is read only by reading drive at a predetermined speed.

FIG. 4 is a diagram showing an image when a document is read by intermittent driving.

FIG. 5 is a diagram showing an embodiment of a mechanical system that performs intermittent drive.

FIG. 6 is a diagram showing an embodiment of functional blocks of the scanner of the present invention.

FIG. 7 is a time chart showing each output signal.

[Explanation of symbols]

 20 Reading Control Unit 21 Various Timing Generation Unit 22 Image Reading Unit 23 Motor Drive Pulse Generation Unit 24, 26 Gate Unit 27 Buffer Memory 28 Communication I / F

Claims (1)

[Claims] 1. An original placing table on which an original is placed, a line sensor for exposing the original placed on the original placing stand and reading in the main scanning direction for each line, and a sub-scanning direction of the original. A drive means for relatively moving the original and the optical system relative to each other, and temporarily storing image data read by the line sensor, A buffer memory that can be sequentially output to the outside at a speed lower than the storage speed, and when the memory usage amount of the buffer memory exceeds a predetermined value, the drive means gradually moves the optical system in the sub-scanning direction. When decelerating to a stop state, stopping the storage of the image data read by the line sensor in the buffer memory, and when the memory usage of the buffer memory falls below a predetermined value. In the scanner, the relative movement of the optical system in the sub-scanning direction is gradually accelerated from a stopped state to a predetermined speed by the driving unit, and the image data read by the line sensor is stored again in the buffer memory. A scanner, wherein line thinning corresponding to a speed lower than the predetermined speed is performed while the original is being read at a speed lower than a predetermined speed by the driving unit.