JPS59223059A - Picture reader - Google Patents

Abstract

PURPOSE:To suppress the heating value of a light source and to make the light source part and the whole device small-sized and light by providing a control means for holding the lighting of a light source adjacent to the light source concerned, in case of turning on each light source of a picture reader for turning on successively plural light sources which are placed adjacently. CONSTITUTION:When an START pulse is inputted, a light source block 5 is turned on. When a counter 12 counts a clock pulse corresponding to a T1 time, namely, a time-up to the sense timing of a sensor block SB 1, FFs 9, 10 are reset and set, respectively, and a counter 13 starts counting. When the pulse corresponding to a T2 time is counted, a decoder DCD 14 sets an FF 16 by an output phi1, and light source block 6 is turned on. This turn-on timing is generated when the original scanning position is in a middle point of the SB 1. Subsequently, after a T3 time elapses, the light source block 5 is turned off and 7 is turned on by an output phi2. Thereafter, the turn-off and turn-on are repeated in the same way.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an image reading device, and particularly to an image reading device used for reading originals in facsimile machines and the like.

BACKGROUND OF THE INVENTION In recent years, image reading sensors have been known that are used in facsimile machines or input devices for characters, images, etc., in which optical sensors such as CCPs (charge coupled devices) are arranged side by side across the entire width of a document. Such a reading sensor is
Similarly, an image reading device is configured together with a light source arranged across the width of the document, and the image on the document is read by light reflected from the light source through the document. In recent years, in order to reduce the size and weight of devices, a configuration in which a large number of LEDs are arranged in a line near a reading sensor as a light source is often used.

In the case of such a light source using an LED, the light source is often arranged beyond the width of the document in consideration of a decrease in the amount of light at both ends of the document. For example, if the original size is A4 (210
mm width), the light source is arranged with a margin of about 10 mm at both ends than the arrangement width of the reading sensor, which is equal to the original width, so the total length of the LED light source is 23On+
It will be about m.

In this case, in order to prevent the light intensity distribution characteristics from deteriorating due to variations in the light intensity of each LED, the arrangement and pitch of the LEDs should be set to 1.2.
If the size is reduced to about 5 mm and arranged, a total of 184 LEDs will be required. At this time, 4 per LEo
Assuming that 0mW of power is consumed, lighting up all the LEDs generates a total of just over 7W of heat.

Normally, when the luminous intensity deterioration of an LED is 1 when the environmental temperature is 25°C, the luminous intensity deterioration at 50°C is about 20%, and in addition, the heat generation itself causes a decrease in the lighting intensity, so this type of LED A heat sink is usually attached to the LED light source to suppress the effects of heat. Therefore, the size of the light source portion inevitably becomes large, which poses a problem in reducing the size and weight of the device.

In view of the above drawbacks, conventional devices often perform light source control as shown in FIGS. 1 to 3.

That is, what is indicated by the symbol 1 in FIG. 1 is CO
This optical sensor 1 is arranged so that its optical axis coincides with that of the lens 2. Also, the reference numeral 4 is a document from which an image such as a document is to be read. Light is irradiated onto the reading point P on the document 4 by a light source 3.3 using an LED, and the reflected light is transmitted through the lens 2 to become a light source. sensor 1
to converge.

As shown in FIG. 2, the light source 3 and optical sensor 1 are each divided into four blocks. Here, the optical sensor 1 is composed of sensor elements S1 to S40, which are divided into sensor blocks SB1 to SB4. Further, the light source 3 is divided into four parts, a light source block 5 to a light source block 8.

The above optical sensor 1 and light source 3 are controlled at the timing shown in FIG. As shown in the top row of FIG. 3, the optical sensor 1 is sequentially enabled for each of the blocks SBI to SB4, one block at a time, and in synchronization with this, the light source blocks 5 to 8 are also sequentially controlled to turn on. (However, at this time, each sensor block SBI to SB4 is strobed block by block, but within a block, each optical sensor element is enabled sequentially.) 2. When such lighting control is performed, the heat generation of the light source Although this has the advantage of being able to suppress the amount of light, the lack of light intensity that occurs at both ends of the light source when all light sources are turned on simultaneously occurs at both ends of each block, and the signal read by the optical sensor l is converted into a binary signal at the subsequent stage. The disadvantage is that errors are likely to occur during processing.

Purpose The present invention has been made in view of the above points, and it suppresses the amount of heat generated by a light source, prevents deterioration of characteristics of a light emitting element, and
It is an object of the present invention to provide an image reading device in which the light source section or the entire device employed can be made small and lightweight.

EXAMPLES Hereinafter, the present invention will be explained in detail based on examples shown in the drawings. However, in the following explanation, an image reading device used in a facsimile machine etc. will be explained as an example, and the reading sensor and light source are assumed to have the same configuration as shown in FIGS. 1 and 2. .

FIG. 4 shows the configuration of a light source control device used in the present invention.

In FIG. 4, reference numerals 9, 10 and 15 to 18 indicate R, S flip-flops, which are constructed by a combination of flip-flop elements or gate elements. Among these, as shown in the figure, flip-flops 15 to 1
Reference numeral 8 uses a device having a plurality of set or reset input terminals.

This circuit has the symbols CLOCK, 5TART, RE
It has three input terminals of SET, and input terminals CLOCK and CLOCK.

The pulse is input to counter 12 and AND gate 19.

In addition, a reset pulse for starting new light source control from the beginning is input from the input terminal RESET-, and this reset pulse resets the counter 12.13 and flip-flops 15 to 18, and each light source block turns off. will be reset.

A set pulse for starting light source control is input from the input terminal 5TART to the set terminals of the flip-flop 9 and the flip-flop 15. The output of this flip-flop 9 is input to the counter 12, and the counter 12 is placed in a count enable state. When the counter 12 has counted a predetermined number of clock pulses, the output of the counter 12 is sent to the flip-flop 9 through the decoder 11.
is reset, and flip-flop 10 is set.

By setting the flip-flop 10, the AND gate 19 is opened and the counter 13 starts counting clock pulses. A decoder 14 is controlled by counting the predetermined value of the counter 13, and flip-flops 15 to 18 are controlled to be set and reset by the five outputs of the decoder 14 according to the count number of the counter 13.

That is, the output φ1 of the decoder 14 sets the flip-flop 16, the output φ2 resets the flip-flop 15, and sets the flip-flop 17. In addition, the output φ3 resets the flip-flop 16, sets the Noritsubu flop 18, and outputs φ4.
flip-flop 15 is set, flip-flop,
, -7' l 7 are reset, and the flip-flop 18 is further reset by the output φ5.

Light source blocks 5 to 8 using LEDs are connected between the output terminals of each flip-flop 15 to 18 and ground, respectively, and the connection between each output terminal and the light source block is pulled up to the power supply voltage +V via a resistor R. . At this time, it is assumed that each light source processor 5 is arranged with respect to the optical sensor 1 as shown in FIG. 2, as in the conventional example, as described above.

Next, the operation of the above configuration will be described in detail with reference to FIG. 5, which is a timing chart of lighting control similar to FIG. 3.

First, when starting new light source control, input terminal R
A reset pulse is input from ESET to reset each Noritsu flop and counters 12 and 13.

Next, when a start pulse is input from the input terminal 5TART, flip-flops 9 and 15 are set, and the counter 12 is thereby enabled to count.
The light source block 5 lights up.

The counter 12 is Tl shown in the timing chart of FIG.
After counting the clock pulses corresponding to the time interval i, that is, the time i until the sensing timing of the sensor block 1, the control flops 9 and 10 are reset and set via the decoder 11, respectively. This setting of flip-flop 10 opens AND gate 19, and counter 13 starts calculating clock pulses.

When the counter 13 counts clock pulses corresponding to 12 hours in FIG. 5, the decoder 14 sets the clip-flop 16 with the output φ1 and lights up the light source block 6. It is preferable that the lighting timing of the light source block 6 is determined so that the document scanning position reaches the middle point of the sensor block SBL, as shown in the figure.

Subsequently, when the counter 13 counts clock pulses corresponding to the time T3 when the light source block 6 is turned on, that is, the time when the scanning position comes to the center position of the following sensor block SB2, the decoder 14 outputs the output φ2 to the flip-flop 15.
is reset and flip-flop 17 is set. As a result, the light source block 5 is turned off and the light source block 7 is turned on. At this time, the light source block 6 remains lit because the flip-flop 16 remains set.

Next, when the counter 13 counts clock pulses corresponding to the same 13 hours, the decoder 14 resets the flip-flop 16 with the output φ3, and the flip-flop 1
Set 8. As a result, the light source block 7 remains lit, the light source block 6 is turned off, and the light source block 8 is lit.

Subsequently, when the counter 13 similarly counts clock pulses for 13 hours, the flip-flop 17 is reset to 1 by the output φ4 of the decoder 14, the flip-flop 15 is set, and the light source block 8 remains lit. is turned off, and the light source block 5 is turned on.

Furthermore, when the counter 13 counts clock pulses corresponding to 13 hours, the flip-flop 18 is reset by the output φ5 of the decoder 14.

The light source block 8 is turned off. Subsequently, when counting for 13 hours is performed, the decoder 14 sequentially outputs the output φl, and the light source blocks are controlled for each block in the same manner as described above.

According to the embodiment described above, since the adjacent light source block on the side closer to the scanning position is always illuminated during scanning, there is no shortage of light at the end of the light source block as in the conventional case. Furthermore, compared to a method in which all light sources are turned on simultaneously, the amount of heat generated can be significantly reduced, and power consumption can be reduced. This is because in the above explanation, the light source and optical sensor are divided into four blocks for the sake of simplicity, and half of the blocks are always lit, so the power consumption or heat generation is lower than that of the all-light source lighting method. Although this is only half the size, dividing the light source into a larger number of blocks would reduce heat generation and power consumption, prevent the deterioration of elements such as LEDs used in the light source, or reduce the amount of light emitted, and prevent The light source section can be made smaller by omitting the additional heat dissipation means, and the power supply section can also be made smaller, which contributes to the miniaturization of the entire device employed.

Effects As is clear from the above description, according to the present invention, in an image reading device having means for illuminating an image by sequentially lighting a plurality of adjacent light sources for image reading, each light source is Since the structure includes a fl control means that keeps one light source adjacent to the light source turned on when the light source is turned on, the amount of heat generated by the light source is suppressed, and characteristic deterioration of the light emitting element is prevented. It is possible to provide an excellent image reading device in which the light source section or the entire device employed can be made small and lightweight.

[Brief explanation of the drawing]

95. FIG. 1 is a schematic diagram showing the arrangement of the image reading device, and FIG. 2 is an explanatory diagram showing the arrangement of the image reading device.
3 is a timing chart diagram illustrating image reading and light source control operations in a conventional image reading device, FIG. 4 is a block diagram showing the configuration of a light source control device in an image reading device according to the present invention, and FIG. FIG. 3 is a timing chart diagram illustrating image reading and light source lighting timing in the image reading device. 5-8...Light source block 9.10. j5-16...Flip-flop 11.1
4...Decoder

Claims (1)

[Claims] In an image reading device having means for illuminating an image by sequentially lighting a plurality of light sources arranged adjacently for image reading, when each light source is turned on, at least one light source adjacent to the light source is turned on. An image reading device characterized in that it is provided with a control means for holding the image.