JPS6248863A - Picture input device - Google Patents

Abstract

PURPOSE:To decrease the required maximum current and the capacity of a lighting power supply by dividing all lamps for picture lighting into proper numbers of groups and shifting the timing of the lighting of each group sequentially. CONSTITUTION:A lighting timing clock signal (b) is outputted from a counter 7. A decoder 8 outputs a signal c1 for lighting lamps L1, L2 to a driver circuit 4 simultaneously with the initial pulse input. Since a start pulse is inputted from a start pulse generator 1 to the circuit 4 at the same time, the signal c1 lights the lamps L1, L2 for a period (t). Further, the decoder 8 outputs a signal c2 lighting lamps L3, L4 when the 4 pulses (b) are inputted to light the lamps L3, L4 for a period (t). In this case, the lamps L1, L2 go off. The lighting of lamps L5, L6 and L7, L8 is executed sequentially by signals c3, c4 from the decoder 8 similarly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an image input device that optically reads image information, converts the read image information into an electrical signal, and outputs the electrical signal.

[Background of the invention]

The image input device illuminates an image, receives reflected light from the image with a photoelectric conversion element, and outputs an electrical signal according to the amount of received light. The output electric hinoki code is converted into a corresponding digital signal and then stored in a storage device, and is used in various forms based on the stored information.

Incidentally, conventionally, fluorescent lamps have been used as light sources for illuminating images, but they have drawbacks such as their large size and the need for correction using slits or the like in order to uniformly illuminate a certain range. On the other hand, L as the light source
There are devices that use multiple EDs (light emitting diodes) or small incandescent lamps, and these devices can be made smaller in size,
Furthermore, by adjusting the brightness of each individual, uniform illumination can be obtained relatively easily. Hereinafter, a device using a small incandescent lamp will be explained with reference to the drawings.

FIG. 4 is a circuit diagram of the illumination circuit of a conventional image input device, in which 1 is a start pulse generator for starting illumination, 2 is a small incandescent lamp for image illumination (hereinafter simply referred to as a lamp), 3 is the power supply for lamp 2. 4 is a driver circuit composed of transistors and the like.

The start pulse generator 1 outputs a start pulse at predetermined time intervals T, and the driver circuits of the two lamps 2 are simultaneously driven to turn on the two lamps 2 at the same time for a predetermined time t. The above period T is the accumulation time of the photoelectric conversion signal,
The time t is the required lighting time of the lamp.

In such a lighting circuit, each lamp 2 is connected in parallel to the power source 3 at the same time, so the required maximum current is large, and the lighting power source 3 also needs to have a large capacity accordingly. There was a drawback.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image input device that eliminates the drawbacks of the above-mentioned prior art and can reduce the maximum current and, in turn, reduce the capacity of the illumination power source.

[Summary of the invention]

In order to achieve the above object, the present invention divides a light source that illuminates an image into a predetermined number of groups, and sequentially drives lighting circuits belonging to each group for a predetermined period using a drive signal that is output at each predetermined period. The present invention is characterized in that the image illumination light sources are turned on sequentially for each group.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a circuit diagram of an illumination circuit of a second image input device according to an embodiment of the present invention, and the same parts as those shown in FIG. 4 are given the same reference numerals and their explanation will be omitted. 6 is a sample pulse generator used in the image input device, and the sample pulse output from this sample pulse generator 6 is used as a clock signal. 7 is a counter that divides the frequency of this clock signal, and 8 is a decoder that uses the output signal from the counter 7 to output a drive signal to the driver circuit 4. L1 to L8 are the same lamps as shown in FIG. 5, and there are four groups I, II,
It is divided into I and IV. Group ■ is 7/P Ll
, L2, group ■ is lamp L s * L 4,
The group ■ consists of the lamp Lm sL6, and the group ■ consists of the lamp L t * La.

Next, the operation of this embodiment will be explained with reference to the time charts shown in FIG. 2 (1 to (j)).

The counter 7 outputs a clock signal for lamp lighting timing as shown in FIG. 2(b). The decoder 8 inputs this clock signal, and at the same time as the input of the first pulse of the clock signal S, as shown in FIG. c1 is output to the driver circuit 4. At this time, the start pulse a is simultaneously output from the start pulse generator 1, and the lamp L is outputted by the signal c1.
1.

L 2 O)" The Raiha circuit enters the driving state. This driving state causes the lamps L1 and L to turn on as shown in FIG.
The output signal dl of the driver circuit 4 for f causes the lamps L 1 e L z of group 2 to be turned on for a period t. The period t is the required lighting time of nine lamps as described above, and in this embodiment is equal to three periods of the clock signal S. This period t can be arbitrarily adjusted by the driver circuit 4.

On the other hand, when the decoder 8 receives the four clocks (response b), it outputs a signal Cat (Cat) which lights up the lamp LseL4 of group H as shown in FIG. The signal d2 shown in FIG. 2(h) is output for Ls*La, and the lamps L a + L 4 are lit for a period t. That is, at the same time as the lamps L 1 + L 2 of group I are turned off, the lamps L a + L 4 of group I are turned off. The lamp La+La (2) will be lit.

Lighting of groups III and IV is done in the same way, and the signal e3*d
3+signal c4. It is executed sequentially by d4. Note that, based on the above operation, the decoder 8 can also be configured with a plurality of counters.

Simultaneously with the end of the lighting period of the lamps Ly+La of group (2), the accumulation period T of the photoelectric conversion device ends, and the next start pulse a is output again, and at the same time, the signal C1dl is output.

In the conventional device shown in FIG.
The output signals of the driver circuit 4 for ...... are output for the same period t from the same time, and this is shown in FIG.
In g) to (j), the signal d! ld! +d
4 is output at the same time and for the same period as the signal d1, a large current is required during this period. However, in this embodiment, the signals d1 to d4 are sequentially shifted and output, so the required maximum current is otherwise small.

Next, the amount of light when all the lamps are lit at the same time for a time t as in the conventional case, and the amount of light when all the lamps are divided into groups of four and the groups are sequentially turned on while being staggered as in this embodiment. Let's compare with. Light g such as COD! , the conversion element obtains the optical 1'# signal by light during a certain fixed time, that is, the accumulation time of the optical'Wt conversion signal, and outputs the previously obtained optical signal as an electrical signal during the next accumulation time.

That is, since the input is performed one by one during the accumulation time, it is expressed as the integral of the total light amount r over the accumulation time. The total lighting time of each lamp is the same whether in the conventional lighting method or in the lighting method of this embodiment, so if the lamps are the same, both the conventional method and the method of this embodiment will be the same. The total light amount (integral value) becomes high and there is no problem with image input. this thing? .

Further, FIGS. 3(a) and 3(b) K will be explained.

FIG. 3(jL) is a lamp arrangement diagram when 20 lamps are used, and FIG. 3(b) is a graph showing the amount of light. 2 each
The amplifiers L1 to LzoVi are arranged in two rows and arranged in a staggered manner. Now, with this kind of lamp arrangement,
When all lamps are turned on simultaneously for a time t as in the conventional method, each lamp emits light as shown in Fig. 3(b) during this time t.
The amount of light shown by the solid line is output, and as a result, the combined amount of light shown by the broken line is obtained. However, when all the lamps are lit in groups as in the method of this embodiment, the amount of light from one start pulse to the next start pulse is The combined light quantity shown by the broken line is obtained only at the period T (accumulation time of the photoelectric conversion signal).

In this way, in this embodiment, all lamps for image illumination are divided into an appropriate number of groups, and the lighting of each group is sequentially staggered, thereby reducing the maximum current required. The capacity of the lighting power source can be reduced. The degree of reduction in the required maximum current compared to the conventional method is as follows. That is, if the lamps are divided so that the lighting times of the lamps in each group do not overlap with each other, the number of divisions n is n≧T/l. As mentioned above, T is the accumulation time of the photoelectric conversion signal,
t is the required lighting time of the lamp. The instantaneous current required in the conventional method is 1. The instantaneous current required in this embodiment is I'.
Then, I: I'= 1: 1/n. That is, the maximum current is reduced by 1/n.

In the description of the above embodiment, an example was given in which the lamp lighting timings of the groups are not equal to each other K1, but it is also possible to make the lighting timings of adjacent groups overlap with each other.

〔Effect of the invention〕

As described above, in the present invention, the light source for image illumination is divided into groups, and the lighting timing of each group is shifted, so that the maximum current required can be reduced.
As a result, the capacity of the lighting power source can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a lamp drive circuit of an image input device according to an embodiment of the present invention, and FIG. 2 (&), (b) (a)-(d)
y(e), (f), (g)-(h), (i), (j) are time charts explaining the operation of the circuit shown in Fig. 1, and Fig. 3 (a) and e(b) are FIG. 4, which is an explanatory diagram for explaining the light amount of the rung, is a circuit diagram of a lamp drive circuit of a conventional image input device. 1... Start pulse generator, 3... Power supply,
4... Drawer 4-rough circuit, 6... Sample pulse generator, 7... Color/return, 8... Decoder. (d)・Representative Patent Attorney Masaru Ogawa 20 (j) 4 Figure 3 Ichigo Figure 4

Claims (1)

[Claims] In an image input device equipped with a large number of photoelectric conversion elements that receive optical signals from an image and output electrical signals according to the amount of received light, there is provided a light source divided into a predetermined number of groups that illuminates the image, and these light sources. An image input device comprising: a lighting circuit that lights up each of the lighting circuits for a predetermined period for each group; and a drive signal generation circuit that outputs a signal that sequentially drives each of the lighting circuits every predetermined period.