JPH02305175A - Variable-speed reading system - Google Patents

Abstract

PURPOSE:To uniform illuminance in the reading view field of a CCD even when the relative moving speed of the CCD is fluctuated by providing a variable control part for quantity of light and a CCD driving circuit with a variable exposure period, and controlling so that the quantity of light of a light source is proportional, and the exposure period is inversely proportional, to the moving speed. CONSTITUTION:Information concerning the moving speed are informed of a control part 100 of the variable quantity of light and a CCD driving circuit of the variable exposure period from a moving speed control part 600. The moving speed control part 600 moves a light source 200 and a CCD 300 at the relative moving speed between an original 100 and the CCD 300. When the moving speed is made 1/p-fold, the CCD driving circuit 500 of the variable exposure period makes the exposure period p-fold. When the quantity of light is made 1/p-fold, the control part 400 of the variable quantity of light makes the quantity of light 1/q-fold. Thus, even when the moving speed is fluctuated and the view field is fluctuated, the equivalent illuminance in the view field is made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] This invention relates to a variable speed reading method that allows the relative moving speed between a CCD and a document to vary.

The purpose is to prevent fluctuations in the moving speed from adversely affecting the reading resolution.

The relative moving speed of the CCD can be controlled by providing a variable light amount control section and a CCD drive circuit with variable exposure period, and by controlling the light amount of the light source to be proportional to the moving speed and the exposure period to be inversely proportional to the moving speed. CC also changes when
The configuration is such that the illuminance within the reading field of view D is made uniform.

[Industrial application field]

The present invention particularly relates to a variable speed reading method that allows the moving speed of a CCD relative to a document read by the CCD to vary, and in which the moving speed does not adversely affect the reading resolution.

[Conventional technology]

Conventionally, in the variable speed reading method, both the light amount of the light source and the exposure period are fixedly determined. Therefore, in order to adjust the amount of data, data is thinned out.

FIG. 4 is an explanatory diagram of the field of view of the CCD. FIG. 4(A) illustrates the field of view when the vehicle is running at a speed (V), and FIG. 4CB) illustrates the field of view when the vehicle is running at a speed (V/3).

In the figure, t represents the exposure period, and a and b represent the vertical and horizontal lengths of one cell of the CCD, respectively. The field of view of one cell of the CCD read during the exposure cycle is the field of view of the CCD itself plus the field of view of the movement.1For example, the field of view when traveling at a speed (V) is.

(a + vt) However, when traveling at speed (v/3), (a+vt)Xb
If you read the field of view three times and output it three times, when you drive at speed (V), you read it once and output it once, but the amount of data will not be the same, so you will have to read it only once.

For example, by outputting only the data of the first reading, it is used instead as image data of an area of (a+vt)xb.

FIG. 5 shows an explanatory diagram of an example of the operation of the conventional variable speed reading method. In this case, the CCD is moved at a speed (v
/ 3) for 1 hour from 3t to 5t, the speed (v/2
) and after 1 hour 5, the vehicle will travel at speed (V), but based on the above principle, when traveling at speed (v/3), output will be 1 for every 3 readings, and when traveling at speed (v/2), output will be 1 for every 3 readings. Two readings result in one output, and when the vehicle is running at a speed (V), one reading results in one output.In this way, so to speak, the data is thinned out.

It is output once for the area of (a+vt)xb, and the amount of output data per unit area is constant regardless of speed fluctuations.

[Invention tries to solve! l! Title]

In the conventional case, the amount of output data of the CCD per unit area is made uniform by thinning out the data, but strictly speaking, the field of view read by the CCD varies depending on the relative moving speed of the CCD. For this reason, the equivalent illuminance within the field of view fluctuates and the sub-scanning resolution deteriorates.

An object of the present invention is to prevent fluctuations in the moving speed of the CCD from adversely affecting the reading resolution.

[Means to solve the problem]

Figure 1 is a diagram showing the principle configuration of the present invention.
0 is a document, and 200 is a light source that illuminates the document.

300 is a CCD for reading; 400 is a variable light amount control unit that controls the amount of light from a light source; and 500 is a variable exposure cycle CCD drive circuit that controls the exposure cycle of the CCD.

Reference numeral 600 represents a movement speed control unit that controls the movement speed of the CCD relative to the document.

The variable light amount control unit 400 controls the moving speed of the CCD.
For example, 1 moving speed is 1/1 so that the amount of light from the light source is proportional.
When the amount of light becomes p times, the amount of light is also controlled to be increased by 1/q times.

The exposure cycle variable CCD drive circuit 500 has an exposure cycle that is inversely proportional to the CCD moving speed.

For example, when the moving speed becomes 1/p times, the exposure period is changed to p.
Controls doubling.

[Effect]

The movement speed control section 600 notifies the variable light amount control section 400 and the variable exposure cycle CCD drive circuit 500 of information regarding the movement speed. Then, the movement speed control section 600
moves the light source 200 and the CCD 300 at the relative movement speed between the document 100 and the CCD 300.

Assuming that the moving speed becomes 1/p times as described above, the CCD drive circuit 500 with variable exposure period increases the exposure period by p times.

If the moving speed becomes f/p times, the light amount is increased by 1/q times.

As a result, even if the moving speed changes and the field of view changes, the equivalent illuminance within the field of view is made uniform, and there is no adverse effect when digitizing the output from the CCD 300.

〔Example〕

Fig. 2 shows the configuration diagram of an embodiment of the present invention with reference numeral 10 in Fig. 0.
0.200.300.400.500.600 correspond to FIG. 1, respectively. Further, 21 is a motor, 22 is a motor drive circuit, 23 is a speed variable section, 32 is an inverter, 33
42 is a light amount variable section, and 42 is a CCD drive circuit.

43 is an exposure period variable section, 60 is an amplifier, and CCD 3
70 represents an A/D converter that amplifies the output from 00.

Based on the information regarding the moving speed from the control unit 600, the speed variable unit 23, the light amount variable unit 33, and the exposure cycle variable unit 4
3, a control amount is generated in a form that matches the moving speed and gives instructions to the motor drive circuit 22, inverter 32, and CCD drive circuit 42, respectively.

FIG. 3 is an explanatory diagram of the operation of the embodiment corresponding to FIG. 2.

In the case shown, it corresponds to the explanatory diagram shown in FIG.
At 1 hour 3t to 5t, the speed (V/2) is 9 hours 5
Hereinafter, it is shown as traveling at a speed (V).

The output of the CCD corresponding to the case of velocity (v/3) is performed at time 3t to 4t, the output of the CCD corresponding to the case of velocity (V/2) is performed at time 5t to 6t, and the output of the CCD corresponding to the case of velocity (V/2) is performed at time 5t to 6t. The output of the CCD corresponding to the case is performed at times 6t to 7t, . . . . Then, the amount of light from one light source 200 is changed in accordance with the speed. Note that when changing the amount of light, the light source 200
It may be considered that the duty ratio in the output from the inverter 32 that drives the is changed.

〔Effect of the invention〕

As explained above, according to the present invention, even when the moving speed changes, the resolution is not affected.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle configuration of the present invention, Fig. 2 is a diagram showing the configuration of an embodiment of the invention, Fig. 3 is an explanatory diagram of the operation of the embodiment corresponding to Fig. 2, and Fig. 4 is an explanatory diagram of the field of view of the CCD. . FIG. 5 shows an explanatory diagram of an example of the operation of the conventional variable speed reading method. In the figure, 100 is a document, 200 is a light source, and 300 is a CCD. 400 is a variable light amount control unit, and 500 is a CC with variable exposure period.
D drive circuit 600 represents a movement speed control section.

Claims (1)

[Claims] In a variable speed reading method that allows the CCD to change its moving speed when reading an image of a document while moving relative to the document, the brightness of a light source irradiating the document is controlled by the CCD. Light amount variable control unit (400) and CCD that adjust in proportion to moving speed
Equipped with a variable exposure cycle CCD drive circuit (500) that exposes the CCD at an exposure cycle that is inversely proportional to the moving speed of the CCD, and even when the moving speed of the CCD fluctuates, the illuminance within the field of view read by the CCD is made uniform. Variable speed reading method.