JPS6390267A - Color picture reader - Google Patents

Abstract

PURPOSE:To simplify the construction of the entirely of a device by irradiating the reading position of an original with the light beams of at least three colors through a rotating filter from the light transmission part of white color light source, separating the color of the reflected light beams synchronously with the rotation of the rotating filter and obtaining the read output correspondingly to a color picture. CONSTITUTION:At the time of moving to the original 1, a roller 9 is rotated according to a friction with the original 1. This rotation is transferred to the rotating filter 7 and an encoder 17 to rotate the rotating filter 7 and the encoder 17. These rotating operations cause the rotating filter 7 to rotate once and the light beams of the three colors of red, blue, green to irradiate on the original 1 through color filters 7a, 7b, 7c when the roller 9 executes a rotation corresponding to the movement of one line on the original according to the gear ratio between the respective gears. The rotating operation of the roller 9 and the rotating filter 7 is detected by the encoder 17 and the color the output signal of an image sensor 3 is separated synchronous with the light irradiation operation of the three colors of the rotating filter 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a color image reading device that reads color images using a monochrome image sensor.

(Prior Art) A color image reading device that reads a color image of a document and converts it into an electrical signal for use in a facsimile or a copying machine, for example, conventionally uses a solid-state image sensor such as an image pickup tube or COD and a color film. A combination of these is common. However, those using R@ tubes are large and expensive, and those using solid-state image sensors require at least three times as many pixels, or segments, as in the case of monochrome, corresponding to at least three primary colors. As the device density increases, it is difficult to increase the yield, and the device also ends up being expensive.

On the other hand, in recent years, devices that use a small Rondo lens in the lens system and read images with an image sensor that is 1:1 in size with the document surface have attracted attention, and color image reading devices using this type of configuration have been developed. It's coming.

(Problems to be Solved by the Invention) As described above, when a color image is separated and read using an image sensor of actual size that is one-to-one with the document surface, at least Three times as many photoreceptor segments are required, and the total light-receiving area of the image sensor is the same as that for monochrome, so the amount of light received per pixel is one-third that of that for monochrome. Since the area is reduced to 1/9, the detection sensitivity is reduced to 1/27, resulting in a problem that the read output becomes extremely small.

The present invention has been made in view of the above, and an object thereof is to provide a color image reading device that can read color images with high sensitivity using a monochrome image sensor with a simple configuration.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention provides a color image reading device that reads a color image of a document while moving relative to the document. , a cylindrical white light source that irradiates the document from the cylindrical circumferential surface, and a cylindrical circumferential surface of the white light source that
rotating filter means for selectively and sequentially disposing at least three types of color filters in the circumferential direction at υ and rotating around a cylindrical peripheral surface of the white light source; The circumferential surface of the white light source except for a circumferential portion facing the reading position is shielded from light so that the light is irradiated only to the reading position of the document, and the light is transmitted only from the circumferential portion. a light transmitting portion having the circumferential portion formed in a light transmitting shape, and receiving reflected light from the document that illuminates the reading position of the document through the light transmitting portion, and outputting an output signal corresponding to the reflected light. The gist of the present invention is to include a light receiving means for generating light, and a color separation means for color-separating the output signal of the light receiving means periodically with the rotation of the rotary filter means.

(Function) In the color image reading device of the present invention, the reading position of the original is irradiated with at least three colors of light from the light transmitting portion of the white light source via the rotating filter means, and the light reflected by the original is reflected by the rotating filter means. Color separation is performed in synchronization with rotation to obtain readout output corresponding to a color image.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a configuration diagram of a color image reading position according to an embodiment of the present invention. The color image reading device shown in the figure is -
As an example, a hand scan method is shown, in which one end of a rod lens array 2 is disposed facing the document 1, and an image sensor 3 is disposed facing the other end of the rod lens array 2. ing. This image sensor 3 is formed by arranging in a line a large number of photoconductor segments 5 made of a photoelectric conversion film, that is, a film having a photovoltaic effect or a film having a photoconductive effect, on a substrate 4.
The length of photoreceptor segment 5 is approximately equal to the width of document 1. That is, the image sensor 3 has the same actual dimensions as the monochrome image sensor.

A white light source 6 made of, for example, a cylindrical rare gas discharge tube is disposed close to one end of the rod lens array 2, and a cylindrical rotating filter 7 is disposed around the white light source 6. It is set up. This rotary filter 7 is divided into 6 parts in the circumferential direction, and every other 3 parts of the 6 parts are divided into red, green, and blue color filters 7a, respectively.
7b and 7C are provided, and there is no filter in every third divided area of the square, and the light from the white light source 6 may or may not be blocked.

The color filters 7a, 7b, and 7c each have wavelengths λr of the three primary colors of red, green, and blue as shown in FIG.

It has transmission characteristics with peaks at λg and λb.

The light output from the white light source 6 passes through a rotating filter 7 and illuminates the reading position of the document 1 facing one end of the rod lens array 2. A light transmitting portion 28 is formed only in the portion shown in FIG. 2, and a peripheral wall 29 of the white light source 6 other than the light transmitting portion 28 is subjected to a light shielding treatment to form a light shielding surface 29 to prevent light from leaking.

The light transmitting portion 28 has a length approximately corresponding to the width of the original 1,
The color filters 7a, 7b, and 70 are formed to have a width slightly larger than the width of light passing through the light transmitting portion 28 thereof.

When the rotating filter 7 configured as described above is rotated in the circumferential direction as shown by the arrow 31 around the axis of the white light source 6, the light from the white light source 6 passing through the light transmitting section 28 is transmitted through the rotating filter. Color filters 7a and 7b formed in 7
, 7c, the reading position of the original 1 is irradiated as red, green, and blue light as shown by the arrow 8a while changing sequentially in a time-divisional manner in synchronization with the rotation of the rotary filter 7. The reflected light is focused through the rod lens array 2 as shown by the arrow 8b, and is imaged on the photoreceptor segment 5 on the image sensor 3 as shown by the arrow 8c.

The image sensor 3 detects red from the original fi1 color image,
The reflected light corresponding to the green and blue color information is sequentially received in time series, and the received light signal is converted into a corresponding electric signal. Therefore, the electric signal output from the image sensor 3 is separated into colors in synchronization with the red, green, and blue light irradiation operation caused by the rotation of the rotary filter 7, and information on each of the red, green, and blue colors is extracted. It is possible to obtain a read output corresponding to a color image. , 7)-cIi, 6゜In this way, in this color image reading device, each color information of the color image of the document 1 is read in a time-division manner, so the image sensor 3 has the number of photoreceptor segments 5 for monochrome use. It could be something as simple as .

When reading the color image of the original N1 while moving the color image reading device configured as described above in the direction of the arrow 33 in FIG. However, since the image sensor 3 needs to obtain red, green, and blue color information for the same image on the same line of the original m1, the rotary filter 7 is attached to the original m1. and image sensor 3
At the same time, when the image sensor 3 is imaging approximately the same line of the document 1, the rotating filter 7 is rotated once to image red, green, and blue for approximately the same line. It is necessary to configure the device so that it is irradiated with three colors of light.

In FIGS. 3, 4, and 5, the rotating filter 7 is rotated in synchronization with the relative movement between the document 1 and the image sensor 3.
This shows the structure that rotates the .

As shown in FIG. 3, the color image scanning device shown in FIG.
and rollers 21 are provided, and these rollers 9, 21
By sliding the roller 9 over the document 1,
The rotation is transmitted to the rotary filter 7 to rotate the rotary filter 7, and an encoder 17, which will be described later, is rotated to identify the moving position, and the above-mentioned synchronization is achieved by these related operations.

With reference to FIG. 4, the structure of the white light source 6 made of a rare gas discharge tube and the rotating filter 7 will be described. white light source 6
A base portion 10 thereof is held so as not to rotate relative to a holder 12 made of an insulating material such as plastic, and a hollow lN 16a is integrally attached to the holder 12. The white light source 6 is turned on when a voltage is applied to 27a and 27b drawn out through the inside of the hollow shaft 6a.

Further, around the hollow shaft 6a for the white light source 6, a rotary filter 7 is provided which protrudes from both ends of the rotary filter 7 via a bearing 24.
A hollow rotary support portion 25 is rotatably attached, and a gear 14 is integrally attached to one end of the rotary support portion 25.

Rotating filter 7 and encoder 17 relative to roller 9
The structure of the rotary filter 7 is as shown in FIG.
The gear 14 is connected to the gear 16a via the timing belt 19.
The gear 16a is connected to the roller 9 via a support shaft 15, and the rotation of the row 59 is transmitted via the gear 16a, the belt 19, and the gear 14 to the rotating filter 7.
has been communicated to. Also, a gear 16 is provided at the other end of the roller 9.
b is integrally attached, and this gear 16b is connected to the gear 18 of the encoder 17 via the timing belt 20, whereby the rotation of the roller 9 is transmitted to the encoder 17 via the gear 16b1 belt 20 and gear 18. It looks like this.

In the device configured as described above, when the present color image reading device is moved relative to the original 1, the roller 9 rotates due to friction with the original 1. This rotation is the rotation filter 7
The rotational filter 7 and the encoder 17 are also rotated by being transmitted to the encoder 17. When the roller 9 performs a rotation corresponding to the movement of one line on the original 1 according to the gear ratio between each gear, the rotating filter 7 rotates once and the color filter 7a is rotated as described above. , 7b, 7c, the document 1 is set to be irradiated with light in three colors of red, green, and blue through the rollers 9 and 7c, and the rotational movement of the roller 9 and the rotary filter 7 is detected by the encoder 17, and the rotation is controlled by this detection signal. The output signal of the image sensor 3 is separated into colors in synchronization with the three-color light irradiation operation of the filter 7.

Specifically, if this color image reading device moves and reads the document 1 in the direction shown by the arrow 33 at an areal density of 8 lines/mm, the image sensor 3 finishes reading one line and starts reading the next line. The rollers 9 and 21 will have rotated through an angle corresponding to 1/8 mm of movement distance until reaching the point. And the rotating filter 7 has this 1/8 ma+
It rotates once during the travel distance equivalent to the original 8X light of three colors.
All you have to do is irradiate 1. In particular, in the case of the hand scan method, after reading one line, the roller continues to rotate without stopping, making it impossible to accurately read the same line. Since the period in which the three colors of light are sequentially irradiated via the rotary filter 7 is a very short distance of ⅛ square, the image of the document 1 does not actually change, so there is no problem.

Note that the rollers 9 and 21 and the support shaft for the discharge tube 6 are rotatably attached to the housing 22.

[Effects of the Invention] As described above, according to the present invention, the reading position of the document is irradiated with at least three colors of light from the light transmitting portion of the white light source via the rotating filter means, and the light reflected by the document is Since the colors are separated in synchronization with the rotation of the rotary filter means and read output is obtained corresponding to a color image, the overall structure of the apparatus is simplified and economical.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a color image reading device according to an embodiment of the present invention, FIG. 2 is a diagram of luminescence characteristics of a phosphor used in the device shown in FIG. 1, and FIG. Schematic sectional view, 4th
The figure is a cross-sectional view showing the structure of the white light source and rotating filter used in the device shown in FIG. 1, and FIG. 5 is a perspective view showing the rotation transmission structure between the roller, discharge tube, and encoder used in the device shown in FIG. It is a diagram. 1... Document 2... Rod lens array 3... Image sensor 5... Photoreceptor segment 6... White light source 7... Rotating filters 7a, 7b, 7c... Color filter 9...・Roller 17...Encoder

Claims (1)

[Claims] A color image reading device that reads a color image of a document while moving relative to the document, and includes a cylindrical white light source that irradiates the document from a cylindrical circumferential surface, and a light source that surrounds the cylindrical circumferential surface of the white light source. rotary filter means for rotating around the cylindrical circumferential surface of the white light source, in which at least three types of color filters are selectively and sequentially disposed in the circumferential direction; A circumferential surface of the white light source excluding a circumferential portion facing the reading position is shielded from light so that the light is irradiated only to the reading position of the document, and the light is transmitted only from the circumferential portion. A light transmitting portion having the circumferential portion formed in a light transmitting shape, and receiving reflected light from the document that illuminates the reading position of the document through the light transmitting portion, and generates an output signal corresponding to the reflected light. 1. A color image reading device comprising: a light receiving means for color-separating the output signals of the light-receiving means in synchronization with the rotation of the rotary filter means.