JPH0458664A - Picture reader - Google Patents

Abstract

PURPOSE:To obtain a proper picture at a proper location by varying a read timing based on a quantitative behavior data when a subscanning system representing an unequal behavior and controlling luminous quantity simultaneously. CONSTITUTION:At first a stop signal is sent from a CPU 9 to a pulse motor 10. The CPU 109 gives a command to a clock generator 12 so as to make reading in a read timing based on a behavior data 11 from that time to vary a generation interval of shift pulses SH fed to a close contact sensor in a read section 14. Simultaneously, a current flowing to a lamp 13 is controlled so as to obtain a luminous quantity in matching with the read timing. This is implemented till a time reaching standstill. Thus, a proper picture at a proper position is read even in an unequal speed state to improve the picture quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device, and particularly to an image reading device of a type that repeatedly stops and restarts in sub-scanning.

[Prior Art] In conventional image reading devices, when the data transfer time of one image reading device exceeds the transfer time from the interface to the host, it becomes impossible to read images in real time. Images were read by intermittent scanning, which was repeatedly stopped and restarted.

[The problem that the invention is trying to solve] However,
In the above-mentioned conventional example, due to the influence of inertia, friction, etc. of the sub-scanning system, there were parts of non-uniform speed near the time of stopping or starting.

Even at the non-uniform speed locations, one image was read at evenly spaced reading timings, so
This poses a problem in that the image cannot be read at an appropriate position, and as a result, the image locally expands or contracts, resulting in deterioration of image quality.

[Means for Solving the Problems] According to the present invention, the behavior of the sub-scanning system when stopped and started is investigated, behavior data is obtained, and the reading timing is determined at an appropriate reading timing based on the data. By changing the amount of light to an appropriate amount of light for reading, it is possible to obtain an appropriate image at an appropriate position.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the structure and operation of an image reading device according to the present invention, FIG. 2 is a perspective view showing the overall structure of the image reading device in an embodiment of the invention, and FIG. 3 is a sub-scanning system. FIG. 4 is a diagram showing behavior data when the apparatus is stopped and changes in reading timing and light amount based on the behavior data, and FIG. 4 is a diagram showing a control procedure for the reading operation.

In Fig. 2, l is a contact sensor, 2 is an LED array,
3 is a sliding shaft, 4 is a timing belt, 5 is a pulley, 6 is a drive gear unit, 7 is a pulse motor, and 8 is a document table.

The operation of this image reading device will be explained.

First, a document is set on the document table 8. Next, a start switch (not shown) is used to instruct the start of reading. As a result, the CPU rotates the pulse motor 7 (step 101).
), and simultaneously lights up LED3 (step 102
), the image is read in synchronization with the shift pulse SH (step 103).

However, due to the data transfer time, it becomes necessary to temporarily stop the sub-scanning system. However, an overrun may occur due to inertia or the like.

Here, in order to avoid data loss, it is also necessary to read the data during the Oatesian-run, but since the speed is non-uniform during the overrun, the problem described above occurs.

After the motor is stopped there (step 104),
Reading at the time of stop is performed (step 105). As a result, behavior data after the stop signal is generated is obtained. That's why the third
Behavioral data as shown in Figure (a) was obtained. Figure 3 (
In the example of b), there are five lines of overrun. Then, the time t corresponding to the overrun of each line.

Find ~t5.

Then, based on these t to t5, the generation interval of the shift pulse SH is changed as shown in FIG. 3(b), and the reading timing is changed (step 108), thereby making it possible to read at an appropriate position. However, if reading is performed by changing the reading timing while the light amount remains constant, the amount of light will be excessive, causing image deterioration. This is because the amount of light accumulated in a CCD is [light accumulation time] x [light amount].
This is because the amount of light accumulation changes by changing the reading timing, that is, the light amount accumulation time.

Therefore, as shown in FIG. 3(C), the light amount is controlled so that the amount of light accumulation (area) at each reading timing is always constant (step 109), that is, the light amount is changed according to the reading timing. let Furthermore, the amount of light is controlled by changing the current flowing through the LED 3.

To summarize the above using Figure 1, first, CPU9
Stop signal (hold signal) from to pulse motor lO
will be sent.

From this point on, the CPU 9 instructs the clock generator 12 to read at the reading timing based on the behavior data 11, and changes the generation interval of the shift pulse SH supplied to the contact sensor in the reading section 14. At the same time, the current flowing through the lamp 13 is controlled so that the amount of light matches the reading timing. This is done for the time T until it comes to rest.
This makes it possible to read an appropriate image at an appropriate position even at non-uniform speeds, leading to improved image quality.

The explanation above is about stopping, but even when restarting, the sub-scanning system exhibits inconstant speed behavior near the time of startup, so data on the behavior at startup is obtained and the reading timing and lamp light intensity are controlled based on that data. A similar effect can be obtained by reading the data as follows.

In the above embodiment, the optical system uses an a'' arrival sensor, but the same effect can be obtained even if a reduction optical system using a CCD is used.

Furthermore, in the lighting system, if it is easy to control the amount of light,
Any optical system may be used, and the control method is not particularly limited.

[Effects of the Invention] As described above, when the sub-scanning system exhibits inconstant speed behavior, by obtaining quantitative behavior data, changing the reading timing based on that data, and controlling the light amount at the same time, An appropriate image at an appropriate position can be obtained, which has the effect of improving image quality.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration and operation of an image device according to the present invention, FIG. 2 is a perspective view showing the overall configuration of an image reading device in an embodiment of the present invention, and FIG. 3 is a sub-scanning system. FIG. 4 is a flowchart showing the control procedure of the reading operation. 1... Contact sensor 2... LED array 3... Sliding shaft 4... Timing belt 5... Pulley 6... Drive gear unit 7... Pulse motor 8... Document table 9 ...CPU 0...Pulse motor & dry pigeon...Behavior data 2...Clock generator 3...Ramp time

Claims (1)

[Claims] In an image reading device that illuminates a document with a lamp and uses the reflected light to photoelectrically scan the document image using a one-dimensional image sensor consisting of an array of photoelectric conversion elements, the document image is read by mechanically performing sub-scanning. An image reading device that controls reading timing and lamp light amount based on falling and rising behavior data when stopping and restarting the image reading device.