JPH04225675A - Device for reading color image - Google Patents

Abstract

PURPOSE:To provide a device for reading a color image which can read the image at high speed though it is a small-size. CONSTITUTION:A color filter 40 is arranged between an image formation lens 16 and CCD 18 and, at the same time, in the neighborhood of CCD 18. Piezo elements 42 and 44 which move the color filter 40 are provided. A voltage applied to the piezo elements 42 and 44 is changed at every reading of the original image of respective color components, a B light transparent part 22, a G light transparent part 24 and an R light transparent part 26 which are corresponding to the color components which should be read are moved to be on an optical axis 28 and the original images of the respective color components are read. The color filter 40 can be miniatuarized owing to the position of the color filter and because the piezo elements are small-size. Since the piezo elements 42 and 44 can move the color filter 40 at high speed, the images can be read at speed. Furthermore, the price of the device is reduced since only inexpensive piezo elements are used.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a color image reading device such as a color scanner, and in particular, the present invention relates to a color image reading device such as a color scanner, and in particular, the original image of a color original is converted into blue (B), green (G), and red (R) color components using a color filter. The present invention relates to an image sensor that separates each color component and reads the original image of each color component using an image sensor.

0002

2. Description of the Related Art FIG. 6 shows a color image reading device that separates an original image into colors using conventional color filters. In this color image reading device, a color original 2 is reflected and illuminated by a fluorescent lamp 4 serving as a white light source, and is relatively moved in a sub-scanning direction 6 indicated by an arrow. The original image of the light reflected by the original 2 enters the imaging lens 16 via the reflecting mirrors 8 , 10 , 12 , and 14 . The original image that enters the imaging lens 16 is focused on a predetermined position on the optical axis. On this imaging surface, there is a line-type CC that reads the image as a line.
D18 is placed. In addition, the imaging lens 16 and the CCD 1
8 is integrally fixed to the frame 20 to prevent out-of-focus.

Between the reflecting mirror 12 and the reflecting mirror 14,
That is, a color filter 102 is provided between the color original 2 and the imaging lens 16. The color filter 102 has a B light transmitting section 22 that transmits B light, a G light transmitting section 24 that transmits G light, and an R light transmitting section 26 that transmits R light. The color filter 102 is slid in a direction 104 indicated by an arrow by a conveyance mechanism including a motor, an actuator, etc. (not shown) in accordance with the line-sequential or field-sequential scanning of the original image of each color component.

When the color filter 102 is slid to align the B light transmitting section 22 with the optical axis 28, a B color component original image is provided to the CCD 18 via the imaging lens 16. C.C.
D18 reads this B color component document image. Similarly, by aligning the G light transmitting section 24 and the R light transmitting section 26 with the optical axis 28, the original image of the G color component and the R color component is read.

FIG. 7 shows a color image reading device that separates the original image into colors using another conventional color filter.

In this color image reading device, between the reflecting mirror 14 and the imaging lens 16, that is, the color original 2
A disc-shaped color filter 106 is provided between the image forming lens 16 and the imaging lens 16 . This color filter 106 is rotated in a direction 110 indicated by an arrow by a motor 108 in accordance with the line-sequential or field-sequential scanning of the original image of each color component.

When the color filter 106 is rotated by the motor 108 and the B light transmitting section 22 is aligned with the optical axis 28, the B light
A color component original image is provided to the CCD 18 via the imaging lens 16. The CCD 18 reads this B color component document image. Similarly, by aligning the G light transmitting section 24 and the R light transmitting section 26 with the optical axis 28, the original image of the G color component and the R color component is read.

[0008]

[Problems to be Solved by the Invention] In the conventional color image reading device shown in FIGS. 6 and 7, a color filter is provided between the color document and the imaging lens, so that the color filter is not visible from the imaging surface. It was getting far away. In order to separate the original image incident on the imaging lens 16 into B, G, and R color components, as the color filter becomes farther from the imaging surface, the B light transmitting part and the G light transmitting part become separated.
The area of the light transmitting portion and the R light transmitting portion must be increased. For this reason, in conventional devices, the color filters had to be large. Furthermore, since it is necessary to move large color filters, the transport mechanism and motor have become large. Therefore, it has not been possible to realize a compact color image reading device. Furthermore, since the color filters are large and it takes time to switch between them, there is also the problem that the reading speed becomes slow.

In addition to the above-mentioned color filter switching method, conventional color image reading devices include a light source switching method, a dichroic mirror method, and a color image sensor method depending on the color separation method.

The light source switching method uses three fluorescent lamps as color light sources: a B-color fluorescent lamp, a G-color fluorescent lamp, and an R-color fluorescent lamp. In this light source switching method, three fluorescent lamps are sequentially turned on in a time-division manner, and colors are separated using color light sources. However, since this light source switching method requires three light sources, it has not been possible to downsize and reduce costs. In addition, the reading speed is limited because it is necessary to consider the time from when each light source is turned on until the amount of light becomes stable, and the time from when the light source is turned off until the influence of afterglow disappears.

The dichroic mirror method uses a dichroic prism and three image sensors. In this dichroic mirror method, the original image formed by the imaging lens is transferred to B and G by dichroic prisms.
, R, and the color-separated original image is read separately by each image sensor. Therefore, three image sensors are required, but each sensor not only requires focus adjustment, but also causes positional deviation in the main scanning direction and the sub-scanning direction with respect to the read image. As a result, a shift occurs in the B, G, and R images,
Color shifts and blurring occur in the resulting image, and a lot of time is spent adjusting the positional shift. Furthermore, one pixel of a CCD is on the order of several μm, and it is difficult to detect and correct a shift of one pixel or less.

The color image sensor method uses a color image sensor in which the image sensor itself is provided with a color filter. In this color image sensor method, color separation is performed by the color image sensor itself. However, since the B, G, and R reading light receiving sections are located at different positions (in the sub-scanning direction), deviations occur in the B, G, and R read images. Since this deviation is large, on the order of several hundred μm, it must be electrically corrected at a later stage. Furthermore, due to problems in CCD manufacturing technology, the number of pixels is smaller than that of a regular 1-line CCD (without a color filter), which is disadvantageous for increasing the resolution of images read by a scanner and for increasing the size of originals.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned technical problems and to provide a color image reading device that is small in size and capable of reading images at high speed.

[0014]

[Means for Solving the Problems] In order to solve the above-mentioned technical problems, the present invention takes the following configuration.

That is, the color image reading device according to claim 1 includes: a white light source that transmits or reflects a color original; A lens, an image sensor placed on the imaging surface and reading the original image, a B light transmitting section that transmits B light, a G light transmitting section that transmits G light, and an R transmitting section that transmits R light.
In a device that is equipped with a color filter having a light transmitting part, the color filter separates the original image of a color original into B, G, and R color components, and the original image of each color component is read by an image sensor. A piezo element is disposed between the image lens and the image sensor and near the image sensor, and moves the color filter in a direction intersecting the optical axis, and a voltage is applied to the piezo element each time a document image of each color component is read. The method is characterized in that the transmissive portion corresponding to the color component to be read is moved along the optical axis by changing the voltage, and the document image of each color component is read.

[0016]

[Operation] The color filter is arranged between the imaging lens and the image sensor and near the image sensor. A piezo element is provided to move the color filter. Each time the original image of each color component is read, the voltage applied to the piezo element is changed to move the transparent part corresponding to the color component to be read onto the optical axis, and the original image of each color component is read. Since the color filter is disposed between the imaging lens and the image sensor and near the image sensor, the area of each transmitting portion of the color filter can be small. Therefore, the color filter can be downsized. Furthermore, since the piezo element is small, it can be downsized. Furthermore, the color filter can be made smaller and the piezo element can move the color filter at high speed, so images can be read at high speed.

[0017]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

FIG. 1 is a diagram showing a color image reading device according to an embodiment of the present invention, and parts corresponding to those of a conventional color image reading device are given the same reference numerals.

In this color image reading apparatus, the color original 2 is held and fixed between transparent original mounting tables 32 and 34. When the color original 2 is a positive film, photographic paper, or the like, a fluorescent lamp 4 serving as a white light source illuminates the original with a constant amount of white light reflected in a line shape. Color manuscript 2
When the film is a negative film or the like, it is transmitted and illuminated in a line with a constant amount of white light by a fluorescent lamp 5 as a white light source. The color original 2 is relatively moved in the sub-scanning direction 6 shown by the arrow while being held between the original placing tables 32 and 34. The original image of the light reflected or transmitted by the original 2 is
The light enters the imaging lens 16 via the reflection mirror 8. The original image incident on the imaging lens 16 is focused on a predetermined position on the optical axis 28 . A line-type CCD 18 (image sensor) that reads images as lines is arranged on this imaging plane. In addition, the imaging lens 16 and the CCD 18
are integrally fixed to the frame 20 via fixtures 36 and 38, respectively, to prevent out-of-focus.

A color filter 40 is arranged between the imaging lens 16 and the CCD 18 and near the CCD 18. The color filter 40 includes a B light transmitting section 22 that transmits B light;
It has a G light transmitting section 24 that transmits G light and an R light transmitting section 26 that transmits R light. Each transparent part 22, 24, 26 has a C
They are arranged in a band shape almost parallel to the arrangement direction of the CDs 18 (see FIG. 2). Since the color filter 40 is placed near the CCD 18, it is close to the image plane. As a result, the width D of each of the transparent parts 22, 24, and 26 can be small, and the area of each transparent part 22 can also be small. Therefore, color filter 4
0 can be made smaller.

One ends of piezo elements 42 and 44 are fixed to both ends of the lower end of the color filter 40, respectively. The other ends of the piezo elements 42 and 44 are fixed to the frame 20. The piezo elements 42 and 44 change their length L depending on the applied voltage, and the piezo elements 42 and 44 change their length L in a direction 4 intersecting the optical axis 28.
Expands and contracts to 6. Therefore, by changing the voltages applied to the piezo elements 42 and 44, it is possible to move each of the transmission parts 22, 24, and 26 at high speed to match the optical axis 28, and then stop them. The voltage applied to the piezo elements 42 and 44 is controlled by a control circuit 50.

FIG. 3 is a specific circuit diagram of the control circuit 50.

The bus 52 includes a CPU 54, a ROM 56,
Lookup memory 58 and D/A converters 60, 6
2 are connected. The lookup memory 58 stores in advance a lookup table 64 for color separation switching.

In the lookup table 64, addresses A1 and A2 contain data for expanding and contracting the lengths L of the piezo elements 42 and 44, respectively, to align the B light transmitting section 22 with the optical axis 28 when reading the B color component original image. D1 and D2 are respectively stored (see FIG. 1). Address A3, A4
, piezo elements 42 and 44 are activated when reading the original image of the G color component.
The length L of G is expanded and contracted respectively, and the G light transmission section 24 is moved to the optical axis 28.
Data D3 and D4 are respectively stored to match the data (see FIG. 1). Addresses A5 and A6 store data D5 and D6, respectively, for expanding and contracting the length L of the piezo elements 42 and 44 and aligning the R light transmitting section 26 with the optical axis 28 when reading an image of the R color component ( (See Figure 1)
.

[0025] The ROM 56 stores in advance a program for operating the CPU 54. According to the program stored in the ROM 56, the CPU 54 first specifies the address A1 and transfers the data D1 to D/D.
The data D2 is sent to the D/A converter 62 by specifying the address A2. D/A converter 6
0 and 62 convert the sent data D1 and D2 into analog voltages, respectively, and apply the converted voltages to the piezo element 42.
, 44, respectively. Therefore, the piezo elements 42 and 44 expand and contract, and their lengths L change, causing the B light transmitting portion 22 of the color filter 40 to
coincides with the optical axis 28 (see FIG. 4(1)). As a result, the CCD 18 receives one line of the original image of the B color component. Therefore, at this time, image reading is performed by the CCD 18.

[0026] Next, the CPU 54 selects addresses A3, A
4 are sequentially addressed and data D3 and D4 are sent to D/A converters 60 and 62, respectively. Therefore, the piezo elements 42 and 44 expand and contract, and their lengths L change.
The G light transmitting portion 24 coincides with the optical axis 28 (see FIG. 4(2)). As a result, the CCD 18 receives one line of the original image of the G color component. Therefore, at this time, the CCD
Image reading is performed at 18.

[0027] Next, the CPU 54 selects addresses A5, A
6 are sequentially addressed and data D5 and D6 are sent to D/A converters 60 and 62, respectively. Therefore, the piezo elements 42 and 44 expand and contract, and their lengths L change.
The R light transmitting portion 26 coincides with the optical axis 28 (see FIG. 4(3)). As a result, the CCD 18 receives one line of the original image of the R color component. Therefore, at this time, the CCD
Image reading is performed at 18.

Next, the color original 2 is moved 1 in the sub-scanning direction 6.
The above-mentioned operation is performed by moving relatively by a line. In this way, the operation of reading the original image for each color component of BGR is repeated line by line (line sequentially).

In this embodiment, the color filter 40 is moved by piezo elements 42, 44, and the color separation by each transmitting section 22, 24, 26 is switched. therefore,
Documents can be read at high speed. Furthermore, since the piezo elements 42 and 44 are small, the device can be made smaller. Also, a color filter 40 and piezo elements 42, 44
are small, so these, the imaging lens 16 and the CCD 18
can be integrated into a unit. Unitization improves positional accuracy, and since it can be made in advance, the manufacturing process can be simplified and adjustment can be made easier.

[0030] There is no need for a motor or transport mechanism to slide or rotate the color filter, no separate color separation prism or color image sensor, and only one fluorescent lamp 4 or fluorescent lamp 5 and one CCD 18 are required. A compact color image reading device can be realized.

In the above embodiment, the CCD 18 that reads the image as lines is used to carry out the process, but as shown in FIG. 5, the CCD 70 that reads the image as points may also be used. . In the case of this embodiment, the color original 2 may also be relatively moved in the main scanning direction perpendicular to the sub-scanning direction 6.

In this case, the CCD 70 can be made smaller. In addition, each transmitting portion 22, 2 of the color filter 40
Since the area of the color filters 4 and 26 only needs to correspond to one pixel of the CCD 70, the color filter 40 can be further miniaturized. Furthermore, only one piezo element 42 is required, and the size can be reduced.

In the above-described embodiment, the process is performed line-sequentially, but instead of line-sequentially, the entire document image is processed using BGR.
It is also possible to carry out the reading in a plane-sequential manner in which each color component is read.

Further, although the embodiment shown in FIG. 1 uses two piezo elements and the embodiment shown in FIG. good.

Furthermore, a plurality of color filters may be used. Furthermore, although a fluorescent lamp is used as the white light source, other white light sources such as a halogen lamp or a xenon lamp may be used.

Furthermore, although the CCD is used as the image sensor, other image sensors such as MOS and photomultipliers may be used. Further, in this embodiment, since it is sufficient to use an inexpensive piezo element in place of the transport mechanism, motor, etc., the cost of the apparatus can be reduced.

[0037]

Effects of the Invention Since the color filter is disposed between the imaging lens and the image sensor and near the image sensor, the area of each transmitting portion of the color filter can be small. Therefore, the color filter can be downsized. Furthermore, since the piezo element is small, the device can be downsized. Furthermore, since the color filter can be moved at high speed using the piezo element, images can be read at high speed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a color image reading device according to an embodiment of the present invention.

[Fig. 2] CCD 18, color filter 40, and piezo element 4
2. It is a perspective view of the vicinity of 44.

FIG. 3 is a specific circuit diagram of the control circuit 50.

FIG. 4 is a diagram for explaining the operation.

FIG. 5 is a diagram showing a part of a color image reading device according to another embodiment of the present invention.

FIG. 6 is a diagram showing a conventional color image reading device.

FIG. 7 is a diagram showing a conventional color image reading device.

[Explanation of symbols]

2...Color manuscript 4, 5...Fluorescent light 16...Imaging lens 18,70...CCD 22...B light transmission section 24...G light transmission section 26...R light transmission section 40...Color filter 42, 44...piezo element

Claims (1)

[Claims] 1. A white light source for transmitting or reflecting illuminating a color original, an imaging lens for forming an image of the original of light transmitted or reflected from the color original on an optical axis, and disposed on an imaging surface,
It is equipped with an image sensor that reads an original image, and a color filter that has a B light transmitting section that transmits B light, a G light transmitting section that transmits G light, and an R light transmitting section that transmits R light, and reads the original image of a color document. In a color image reading device that separates each color into B, G, and R color components using a color filter and reads an original image of each color component using an image sensor, the color filter is placed between an imaging lens and an image sensor, and the color filter is placed between an imaging lens and an image sensor. A piezo element is placed near the color filter and moves the color filter in a direction intersecting the optical axis.The voltage applied to the piezo element is changed each time the original image of each color component is read, and the transmission signal corresponding to the color component to be read is changed. 1. A color image reading device that reads an original image of each color component by moving a portion on an optical axis.