JP3069908B2 - Image reading device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, and more particularly to an image reading apparatus that uses a light emitting diode array as a light source when an original image is read by an image mencer.

[Conventional technology]

6 and 7 show the configuration of a contact image sensor using a light emitting diode array and an optical sensor provided in a conventional image reading apparatus.

6 and 7, reference numeral 1 denotes an image reading device, 3 denotes a contact image sensor (hereinafter, referred to as a sensor), 5 denotes a reading roller, 21 denotes a light emitting diode array (hereinafter, referred to as an LED array), and 22 denotes a rod. A lens array, 23 is an optical sensor, and S is a sheet-shaped image document (hereinafter, referred to as a document).

 Next, the operation will be described.

When the image reading apparatus starts reading the document S, a plurality of lines from D1 to DN are linearly formed in the main scanning direction as shown in FIG.
The LED array 21 in which the LEDs are arranged is turned on collectively, the document S is sandwiched between the sensor 3 and the reading roller 5, and the image of the document S is read by the sensor 3.

At this time, the reflected light from the document S irradiated by the LED array 21 is image-formed on the optical sensor 23 by the rod lens array 22 and the image is read. The LED array 21 is controlled by a voltage control and a pulse lighting method.

[Problems to be solved by the invention]

However, conventionally, the LED array 21
Is controlled, the LEDs of the LED array 21 are turned on at the same time when the image document S is read, so that all the LEDs are turned on even when performing partial reading in the main scanning direction. There is a problem in that the lighting of the LED outside the reading range is wasted, thereby wasting power. In particular, at present, in which the miniaturization, energy saving and cost reduction of the device are strictly required, not only the waste of power consumption but also the heat generation by unnecessary LED lighting affects the life of the sensor 3 and the device parts adjacent thereto. And the reliability of the quality of the image reading apparatus is reduced.

[Means for solving the problem]

The present invention has been made in order to solve the problems of the conventional example as described above, and detects light reflected from an image document illuminated by the light emitting means arranged in an array and illuminated by the light emitting means. An image sensor for reading an image, an interface circuit for receiving a read range control signal by the image sensor from an external device, and latch means for storing a read range control signal from the external device received by the interface circuit; A timing generation circuit that generates a lighting pulse based on a read range control signal from the external device received by the interface circuit; and an output of the latch unit and the array-shaped light emitting unit based on the lighting pulse from the timing generation circuit. Control means for controlling a lighting range in the main scanning direction and the sub-scanning direction. By the, it is intended to achieve the object.

[Action]

The image reading device according to the present invention having the above-described configuration includes a light emitting unit arranged in an array, an image sensor that reads an image by detecting reflected light from an image document illuminated by the light emitting unit, An interface circuit for receiving a read range control signal by the image sensor from an external device; a latch unit for storing a read range control signal from the external device received by the interface circuit; and the latch circuit received by the interface circuit. A timing generation circuit for generating a lighting pulse based on a reading range control signal from an external device; and a main scanning direction and a sub-scanning direction of the array-shaped light emitting means based on an output of the latch means and a lighting pulse from the timing generation circuit. And control means for controlling the lighting range of the external device. Even when only a desired portion of a document is selectively read based on these reading range control signals, light emission in a useless range of the light emitting means can be minimized, and power consumption and heat generation are minimized. can do.

Therefore, it is possible to significantly extend the life of the portion, improve reliability, and reduce thermal noise as compared with the related art.

〔Example〕

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

(Structure) FIG. 1 is a light emitting diode array lighting circuit diagram of an image reading apparatus according to an embodiment of the present invention, FIG. 2 is a light emitting diode array lighting control block diagram of the above embodiment, and FIG. It is principal part structure sectional drawing.

The same or corresponding parts as in the conventional example are denoted by the same reference numerals.

In FIG. 3, 1A is an image reading device, 2 is a body of the image reading device 1A, 3A is a contact type image sensor for reading an image, and the image sensors (hereinafter, referred to as sensors) 3A are arranged in an array. A light emitting diode array (hereinafter, referred to as an LED array) 2 which is an example of the light emitting means L.
1A, a rod lens array 22 and an optical sensor 23. Reference numeral 5 denotes a reading roller that presses and adheres the sheet document S to the lower side of the sensor 3A, and reference numeral 6 denotes a discharge device that discharges the document S read by the sensor 3A.

The discharge device 6 includes a discharge roller 9 that forms an inner guide surface of the reversing path 12 and a sheet S that contacts the discharge roller 9 and contacts the discharge roller 9.
Flexible holding plate constituted by a leaf spring for holding and discharging
10 and have.

The body 2 in the horizontal direction of the holding plate 10 has a paper discharge port.
11 and the body 2 above the discharge roller 9
In FIG. 2, reference numeral 201 denotes an amplifier (AMP) for amplifying the image signal from the optical sensor 22; 202, an A / D converter;
03 is an image signal processing circuit, 204 is an interface circuit with an external device (not shown), 205 is a CPU (central processing unit), 206
Is a timing signal generation circuit controlled by the CPU 205,
Reference numeral 207 denotes an LED array lighting circuit controlled by the CPU 205. The document S is illuminated by the LED array 21A lit by the LED array lighting circuit 207. Then, the CPU 205, the timing signal generation circuit 206, and the LE
The D array lighting circuit 207 constitutes control means A for controlling the lighting range of the LED array 21A.

Further, in FIG. 1, in the LED array 21A, in the sub-scanning direction, four LEDs, that is, LEDs D1-D4 form one set of light-emitting element blocks. It is arranged in a line in the direction. 101 is LED
This is a latch circuit provided in the array lighting circuit 207.

(Operation) An operation will be described based on the above configuration. 2 to 4, first, a CPU 205 is connected to a timing signal generation circuit 206 via an interface circuit 204 from an external device such as a digital printer or a personal computer.
A control signal is output to the LED array lighting circuit 207 in advance for initial setting. In this state, if a document reading start command is input from the external device in step S501, then in step S502
Then, the CPU 205 receives the input signal and stores the reading range in the latch circuit 101, thereby setting the lighting range of the LED array 21A. When the document S is supplied to the image reading apparatus 1A, a lighting pulse is output from the timing signal generation circuit 206 in step S503, an LED in the set reading range is turned on, and is held between the reading roller 5 and the sensor 3A. Image reading of the document S is started. (Step S504). The document S read by the rotation of the reading roller 5 driven by a motor and a drive gear (not shown) is conveyed to a discharge roller 9 and discharged from a discharge port 11 or 13 provided in the body 2.

At this time, the image analog signal read by the optical sensor 23 in the sensor 3A is compared and amplified by the amplifier 201 and input to the A / D converter 202. A / D converter 202
The image signal is converted into an 8-bit digital signal, sent to an image signal processing circuit 203, subjected to image processing, and output to an external device via an interface circuit 204.
When the CPU 205 detects that the reading of the document S has been completed (step S505), the lighting pulse of the LED array lighting circuit 207 is turned off (step S506), the LED array 21A is turned off, and the reading ends.

As described above, the LEDs in the LED array 21A arranged in the main scanning direction are illuminated only by turning on the LEDs in the range necessary for reading the document S, thereby preventing the power consumption of the LED array 21A from being wasted. Thus, it is possible to prevent the life of the device components from being shortened due to heat generated by unnecessary illumination.

Further, in this embodiment, a control unit B for controlling the lighting range according to the reading range of the document S also in the sub-scanning direction is provided. The conventional image reading section shown in FIG.
Compared with the timing of the sub-scanning section signal a and the lighting pulse b, the scanning section in which the LED array 21A is turned on matches the actual document as indicated by the actual image reading section C and the timing of the corresponding lighting pulse d. As a result, the power consumption is further reduced, the life of device components is prevented from being shortened due to heat generated by unnecessary illumination, and the reliability of the quality of the image reading apparatus can be further improved.

〔The invention's effect〕

As described above, according to the image reading apparatus of the present invention, a light emitting unit arranged in an array, an image sensor that reads an image by detecting reflected light from an image document illuminated by the light emitting unit, An interface circuit for receiving a read range control signal by the image sensor from an external device; a latch unit for storing a read range control signal from the external device received by the interface circuit; and the latch circuit received by the interface circuit. A timing generation circuit for generating a lighting pulse based on a reading range control signal from an external device; and a main scanning direction and a sub-scanning direction of the array-shaped light emitting means based on an output of the latch means and a lighting pulse from the timing generation circuit. And control means for controlling the lighting range of the external device. Even when only a desired portion of a document is selectively read based on these reading range control signals, light emission in a useless range of the light emitting means can be minimized, and power consumption and heat generation are minimized. can do.

Therefore, it is possible to significantly extend the life of the portion, improve reliability, and reduce thermal noise as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a light emitting diode array lighting circuit diagram of an image reading apparatus showing one embodiment of the present invention, FIG. 2 is a light emitting diode array lighting control block diagram of the above embodiment, and FIG. 3 is an embodiment of the present invention. 4 is a sectional view of a main part of an image reading apparatus,
FIG. 5 is a flowchart showing the operation of reading an image document, FIG. 5 is a timing chart of a section signal and a lighting pulse in the sub-scanning direction, FIG. 6 is a sectional view of a main part of a conventional image reading apparatus, and FIG. It is a lineblock diagram of an example of a contact type image sensor. 1,1A image reading device 3,3A image sensor 21,21A light emitting diode array 101 latch circuit 205 CPU 206 timing signal generating circuit 207 light emitting diode array lighting circuit A, B ... Control means L... Array-like light emitting means l... Light emitting means S... Iconographic document In the drawings, the same or corresponding parts are denoted by the same reference numerals.

Claims (2)

(57) [Claims] 1. A light emitting means arranged in an array, an image sensor for detecting reflected light from an image original illuminated by the light emitting means to read an image, and a reading range control signal from an external device by the image sensor. An interface circuit for receiving a read range control signal from the external device received by the interface circuit; and a light based on a read range control signal from the external device received by the interface circuit. A timing generation circuit for generating a pulse; and a control means for controlling a lighting range in the main scanning direction and the sub-scanning direction of the array of light emitting means based on an output of the latch means and a lighting pulse from the timing generation circuit. An image reading device, comprising: 2. The image reading apparatus according to claim 1, wherein said control means controls the lighting of said light emitting means periodically in said sub-scanning direction.