JPS61181265A - Image reader - Google Patents

Abstract

PURPOSE:To obtain a stable image reading output without read error by allowing a constant current control section to apply constant current control to a light source current of a light source array section so as to eliminate a change in luminous amount of the light source. CONSTITUTION:An original 2 placed on an original platen 1 is lighted by a light source array section 3 comprising plural light emitting elements. The reflected light including image information from the original is collected by a lens of a lens section 10 and converted into an electric signal according to the reading of a linear image sensor section 7 comprising plural photoelectric converting elements in the main scanning direction. The reading in the main scanning direction of the image sensor section 7 and a light source switching section 4 are synchronized to blink sequentially the light sources of the light source array section 3 and a constant current control section 5 applies constant current control to the light source current. Thus, the current consumption and heat of the light source are reduced and the luminous amount of the light source array 3 is made constant.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an image reading device having a function of reading image information such as characters and figures of a document.

BACKGROUND OF THE INVENTION In recent years, office automation in offices has progressed. In particular, there has been a shift from handwritten document creation to computerized document creation using word processors. Image reading devices are being developed as means for reading and inputting image information such as characters and graphics as input to word processors.

An example of the conventional image reading device described above will be described below with reference to the drawings.

FIG. 2 is a block diagram showing the structure of a conventional image reading device. In FIG. 2, reference numeral 1 denotes an original table on which an original is placed, and 2 represents an original. 9 is a light source section of a light source that illuminates the original; 10 is a lens section that focuses reflected light from the original using a lens; 11
8 is a one-dimensional image sensor section having a plurality of photoelectric conversion elements that read light condensed by a lens section, and 8 is an image reading output of the one-dimensional image sensor section.

The operation of the image reading apparatus configured as described above will be described below.

In FIG. 2, a document 2 is placed on a document table 1, and the document is illuminated by a light aperture 9. The light source section 91d is generally equipped with a fluorescent lamp, a light bulb, an LED, etc., and when it is turned on, the original is illuminated by continuously applying a constant voltage of AC or DC voltage.
The entire reading width of two one-dimensional image sensors is illuminated simultaneously.

The reflected light containing image information from the original is focused by the lens of the lens unit 10, and this focused reflected light is transmitted to the main body of a one-dimensional image sensor consisting of a plurality of photoelectric conversion elements of the one-dimensional image sensor unit 11. It is converted into an electrical signal according to the scanning direction reading.

This electrical signal is the image reading output 8. By scanning in the sub-scanning direction perpendicular to the main-scanning direction of the one-dimensional image sensor, it is possible to read the image of the document on the document table 1''2.

For example, the configuration of the conventional technology is described in Nikkei Electronics, September 10, 1984, pages 161 to 194. ○ Problems to be solved by the invention When conventional image reading devices read image information on a document, During reading by the one-dimensional image sensor section, the entire main scanning direction is simultaneously illuminated, so the light source consumes a large amount of current and generates a lot of heat. Because a constant voltage is applied to the light source,
There is a problem in that a change in the amount of light occurs due to a change in the internal resistance of the light.

In view of the above problems, the present invention does not simultaneously illuminate the entire main scanning direction of the one-dimensional image sensor section, but provides a light source that blinks sequentially in synchronization with the reading of the one-dimensional image sensor section in the main scanning direction, and also reduces the light source current. The present invention provides an image reading device configured to perform constant current control so that the amount of light does not change.

Means for Solving the Problems In order to solve the above problems, the image reading device of the present invention uses a light source switching section to provide a plurality of light sources that blink sequentially in synchronization with reading in the main scanning direction of the one-dimensional image sensor section. In addition to providing a light source array section consisting of a light source array section, the light source current of the light source play section can be controlled at a constant current. A light source is provided, and multiple light sources are switched and blinked in sequence in synchronization with the reading of the main scanning direction of the one-dimensional image sensor section, and the light source current is controlled at a constant current to maintain a constant light amount, stable image reading, and current consumption. Embodiment FIG. 1 is a block diagram showing an embodiment of an image reading apparatus according to the present invention. In FIG. 1, numeral 1 is an original table on which an original is placed, and 2 is an original. Reference numeral 3 denotes a light source array unit consisting of a plurality of light sources that sequentially blinks the original; 6 a constant current control unit that controls the light source current of the light source array unit at a constant current; 6 a lens unit that focuses reflected light from the original with a lens; Reference numeral 7 denotes a one-dimensional image sensor section consisting of a plurality of photoelectric conversion elements that convert light focused by a lens section into electrical signals, and reference numeral 4 denotes a light source array section 3 that synchronizes with reading in the main scanning direction of the one-dimensional image sensor section 7. 8 is an image reading output of a one-dimensional image sensor section.

Regarding the image reading apparatus configured as described above, the case where image information of a document placed on document table 1 is read will be described below with reference to FIG. First, an image reading device is placed on a document placed on a document table 1, and in synchronization with the reading in the main scanning direction of the one-dimensional image sensor section, the light source switching section 4, which switches the light source, illuminates the document while blinking sequentially. The document is illuminated by a light source array section 3 consisting of a plurality of light sources. The light source current of the light source array section 3 is controlled by a constant current control section 5 to keep the amount of light constant.

Reflected light containing image information from the document is focused by the lens of the lens section, and converted into an electrical signal according to reading in the main scanning direction by the one-dimensional image sensor section 7, which consists of a plurality of photoelectric conversion elements. The signal is image reading output 8.

Two-dimensional image reading can be performed by scanning the document table 1 in a sub-scanning direction perpendicular to the main-scanning direction of the one-dimensional image sensor section 7.

As described above, according to this embodiment, the main scanning direction reading of the image sensor 7f and the light source switching unit 4 are synchronized, the light sources of the light source array unit 3 are sequentially blinked, and the light source current is controlled to be constant. The constant current control section 6 reduces the current consumption and heat generation of the light source and makes the sight of the light source array 3 constant, thereby making it possible to read the image information of the document.

Effects of the Invention As described above, in the present invention, since the light source current of the light source array section is controlled by the constant current control section, there is no change in the light amount of the light source, and reading errors can be prevented.
Stable image reading output can be obtained.

Unfortunately, since the light sources in the light source array section are sequentially blinked in synchronization with the reading in the main scanning direction of the one-dimensional image sensor section, the current consumption of the light source is reduced, and since no heat is generated, the cooling mechanism is no longer required. There is no need to take measures such as temperature deterioration of device components and temperature guarantee. That's no good,
The reliability of the image reading device can be made smaller and lighter.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an image reading apparatus according to a first embodiment of the present invention, and FIG. 2 is a block diagram of a conventional image reading apparatus. 3... Light source array section, 4... Light source switching section, 6... Constant current control section. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] A light source array section including a plurality of light sources that illuminates image information of the document; a light source switching section that switches the light sources of the light source array section; a constant current control section that controls the light source current of the light source array section; and a constant current control section that controls the light reflected from the document. It consists of a lens section that collects light with a lens, and a one-dimensional image sensor section that has a plurality of photoelectric conversion elements for reading the focused light, and the plurality of light sources of the light source array section are used for main scanning of the one-dimensional image sensor section. An image reading device configured to blink in synchronization with direction reading.