JPH0630193A - Picture reader - Google Patents

Abstract

PURPOSE:To attain the low power consumption and the miniaturization of a device while securing required illuminance by lighting selectively only a light emitting unit optically corresponding to the reading and scanning position of an image sensor. CONSTITUTION:Respective light emitting units L1 to Ln of a lighting source 5 is lighted selectively by a picture element synchronizing clock CK1 and a line synchronizing clock CK2 so that only the unit optically corresponding to the reading and scanning position of the line image sensor 3 is lighted. Namely, when the line image sensor 3 reads and scans a range irradiated by some specific light emitting unit, only the light emitting unit to contribute to the irradiation of that reading and scanning position is lighted selectively, and the light emitting units other than this are extinguished. Thus, while the light emitting unit to be lighted is replaced successively as being coincided with the reading and scanning position of the image sensor 3, and the whole reading and scanning range of the image sensor 3 is irradiated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for reading an original or the like while illuminating a portion to be read in a facsimile apparatus or the like.

[0002]

2. Description of the Related Art In an image reading apparatus used in a facsimile apparatus or the like, as shown in FIG. 3, a light source 5 for illuminating a reading scanning range 4 of the image sensor 3 together with an optical system 2 and a line image sensor 3. The original 1 which is driven and driven in the sub-scanning direction Y is read line by line from the main scanning direction X.

As shown in FIG. 4, the illumination light source 4 is composed of a plurality of light emitting units L1 to Ln, and each of the light emitting units L1 to Ln is composed of one or a plurality of LEDs (light emitting diodes). Each of the light emitting units L1 to Ln is driven to be turned on by the drive circuit 81.

Here, in this conventional device, as shown in FIG. 5, the light emitting units L1 to Ln forming the illumination light source 4 are
When the reading operation of the image sensor 3 is performed, the reading scanning range of the image sensor 3 is illuminated by being turned on all at once by the drive circuit 81.

[0005]

However, according to such a configuration, the power consumption of the illumination light source is large, which is a major factor inhibiting the reduction of power consumption of this type of device. was there.

The above-mentioned problems occur for the following reasons. That is, since the illumination light source 5 needs to illuminate at least the entire reading scanning range of the line image sensor 3, it is configured by using a large number of light emitting elements such as LEDs (light emitting diodes). A considerable amount of power is consumed.

However, in order to ensure the reading of the image sensor 3, it is necessary to illuminate the reading portion with a certain brightness or more.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an image reading apparatus in which the necessary illuminance is given to the reading portion of the image sensor and the power consumption is significantly reduced. .

[0009]

In order to solve the above-mentioned problems, the present invention, when illuminating a reading scanning range of an image sensor with a plurality of light emitting units, emits light which optically corresponds to the reading scanning position of the image sensor. It has a configuration that selectively lights only the unit.

[0010]

According to the present invention, since the light-emitting units that are simultaneously turned on are limited to only the portion necessary for reading the image sensor by the above-described configuration, the illuminance required for the reading portion of the image sensor is provided, and the device is largely It is possible to achieve low power consumption.

[0011]

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

In the figures, the same reference numerals indicate the same or corresponding parts. FIG. 1 shows a schematic configuration of an image reading apparatus according to an embodiment of the present invention. Reference numeral 3 denotes a line image sensor for reading and scanning a document 1 fed and driven in the sub-scanning direction in the main scanning direction. Is a reading scanning range (main scanning range) of the image sensor 3, 5 is a light source for illuminating the reading portion of the image sensor 3, 6 is a reading control circuit for controlling the reading operation of the line image sensor 21, and CK1 and CK2 are A pixel synchronizing clock and a line synchronizing clock that define the reading operation timing of the sensor 6, a counter 7 that counts the reading scanning position on the main scanning line of the line image sensor 3 by the clocks CK1 and CK2, and 8 is the above Depending on the count value of the counter 7, that is, the reading scanning position of the image sensor 3, the light emitting units L1 to L A selection drive circuit for selectively lighting the.

Here, the counter 7 is incremented (Cin) by the pixel synchronization clock CK1 and reset (R) by the line synchronization clock CK2, thereby indicating the actual read scanning position of the line image sensor 3. The data is output as a binary-coded count value. Selective drive circuit 8
Decodes the count value output from the counter 7 into an alternative selection signal, and outputs each light emitting unit L1 of the illumination light source 5.
Ln are selectively driven to light.

The operation of the image reading apparatus configured as described above will be described below. In the above-mentioned device, as shown in FIG. 2, the light emitting units L1 to L of the illumination light source 5 are arranged.
Only the pixels n which are optically corresponding to the reading / scanning position of the line image sensor 3 are selectively turned on by the pixel synchronizing clock CK1 and the line synchronizing clock CK2. That is, when the line image sensor 3 is reading and scanning the range illuminated by a specific light emitting unit, only the light emitting units that contribute to the illumination of the reading and scanning position are selectively turned on, and All other light emitting units are turned off. In this way
While the light emitting units that are turned on are sequentially changed according to the reading scanning position of the image sensor, the entire reading scanning range of the image sensor is illuminated.

As a result, the light-emitting units that are turned on at the same time are limited to the portions necessary for the reading operation of the image sensor while providing the necessary illuminance to the reading portion of the image sensor, and the power for illumination is significantly increased. Can be reduced. At the same time, since the number of light emitting units that are turned on at the same time is small, the output current capacity of the power supply device need only be prepared for the number of light emitting units that are turned on at the same time, which enables downsizing of the device.

The lighting of the light emitting units L1 to Ln is as follows.
In order to eliminate variations in illuminance depending on the reading and scanning position, for example, as shown in FIG. 2, adjacent light emitting units (L1
And L2, L2 and L3, ...) may be partially overlapped and lighted. Further, as the illumination light source, a light emitting element or unit other than the LED can be used as long as it can be instantly activated.

[0017]

As is apparent from the above description, according to the present invention, when the reading and scanning range of the image sensor is illuminated by the plurality of light emitting units, only the light emitting unit optically corresponding to the reading and scanning position of the image sensor is used. By selectively turning on, the light emitting units that are turned on at the same time are limited to only the part necessary for reading the image sensor, and while providing the necessary illuminance to the reading part of the image sensor, the device consumes significantly less power. This has the effect that power and size can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart showing a lighting state of each light emitting unit of the illumination light source in the device of the present invention.

FIG. 3 is a schematic diagram showing an arrangement example of an image sensor and an illumination light source.

FIG. 4 is a schematic configuration diagram of a conventional image reading device.

FIG. 5 is a timing chart showing a lighting state of each light emitting unit of the illumination light source in the conventional device.

[Explanation of symbols]

 1 Document 3 Line Image Sensor 4 Scanning Range 5 Illumination Light Source L1 to Ln Light Emitting Unit 6 Scanning Control Circuit 7 Counter 8 Selection Drive Circuit

Claims (2)

[Claims] 1. An image sensor for reading and scanning a document or the like, a light source for illuminating the reading and scanning range of the image sensor with a plurality of light emitting units, and a light emitting unit that optically corresponds to the reading and scanning position of the image sensor. An image reading apparatus comprising: a selection driving unit that selectively lights. 2. An image sensor for reading and scanning a document or the like, a light source for illuminating the reading and scanning range of the image sensor with a plurality of light emitting units, a counter for counting the reading and scanning position of the image sensor, and a counter for counting the reading and scanning positions. An image reading apparatus comprising: a selection driving unit that selectively lights the light emitting unit according to a numerical value.