JPH10229471A - Color image scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain high read speed in the case of reading an original as a color image, while ensuring a light emission time from a light source and to attain a high speed of a read time in the case of reading the original as a monochromatic image. SOLUTION: This scanner is provided with a cylindrical color filter 11, colored in three RGB colors in a circumferential direction and a filter motor 14 that drives the color filter 11 around a fluorescent tube inserted in the color filter 11. In the case of the color read mode reading an original as a color image, the color filter 11 is driven to read the original, so that the time emitted in one color of the color filter 11 is longer than the storage time of the image sensor required for an least one color. In the case of a monochromatic read mode where the original is read as a monochromatic image, the color filter is driven to read the original, such that the time emitting one filter of the color filter 11 is a time obtained by dividing the storage time of the image sensor by 3n.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image scanner for optically reading a document image.

[0002]

2. Description of the Related Art Conventionally, as a color image scanner, a technique as disclosed in JP-A-63-184456 is known. In this color image scanner, as shown in FIGS. 6 and 7, a red (R) filter 1a, a green (G) filter 1b, a blue (B) filter 1c, which are color filters for color separation, are provided on each surface of the rectangular tube. And a color filter 1 in which a transparent filter 1d as a colorless filter is arranged. A fluorescent tube 2 as a light source is inserted into the color filter 1, and a gear 3 provided at an end of the color filter 1 is provided. By rotating the color filter 1 around the fluorescent tube 2 by the motor 4 at a predetermined speed in the direction of the arrow in the figure, the light from the fluorescent tube 2 is changed to red (R), green (G), and blue (B). Was converted to light.

When reading the original 5 as a color image, the color filter 1 is rotated and set at a predetermined position so that the light from the fluorescent tube 2 becomes red (R), and the original 5 is irradiated with the light. Then, the reflected light is captured by an image sensor 7 provided with a photoelectric conversion element via a condenser lens 6. Next, the color filter 1 is rotated and set at a predetermined position so that the light from the fluorescent tube 2 becomes green (G), the light is irradiated on the original, and the reflected light is transmitted to the image sensor 7.
Take in. Subsequently, the color filter 1 is rotated and set at a predetermined position so that the light from the fluorescent tube 2 becomes blue (B), the light is irradiated on the original, and the reflected light is captured by the image sensor 7. . Thus, color data converted into an electric signal for each color component can be obtained from the image sensor 7.

When the original 5 is read as a monochrome image (black and white image), the color filter 1 is rotated and set at a predetermined position so that the light from the fluorescent tube 2 passes through the colorless transparent portion 1d, and the light is set on the original. And the reflected light is taken in by the image sensor 7 to obtain monochrome data converted into an electric signal.

[0005]

However, in such a color image scanner, when the original 5 is read, the color filter 1 is rotated and set at a predetermined position, and then the reflected light from the original 5 is imaged. Since the reading is performed by the sensor 7, there is a problem that it takes time to read the document. In particular, when the original 5 is read as a color image, each of the red (R), green (G), and blue (B)
It has been necessary to rotate the color filter 1 and set it at a predetermined position, which takes a lot of time.

In this case, in order to reduce the reading time, the color filter 1 is rotated at a predetermined speed so that the light of the fluorescent tube 2 is accumulated in the photoelectric conversion element of the image sensor 7 at the timing of passing through each color. Control for continuously converting to an electric signal is also conceivable.

However, in such a control, when the original 5 is read as a color image, the slit width of other colors is reduced by the colorless transparent portion 1d in the color filter 1, so that the rotation of the color filter 1 is reduced. When the speed is high, the light irradiation time of each color decreases, and the accumulation time of the photoelectric conversion element for each color must be shortened. In this case, it is considered that the light amount of the light source cannot be sufficiently used.

When reading the original 5 as a monochrome image, it is sufficient to use only the colorless transparent portion 1d of the color filter 1. Therefore, in this case, the color filter 1 is rotated at a predetermined speed. Then all the other color parts need to be skipped,
It is considered that reading time is wastefully taken.

Therefore, the present invention can increase the reading speed while securing the light irradiation time from the light source when reading a document as a color image, and can shorten the reading time when reading a document as a monochrome image. It is an object of the present invention to provide a color image scanner which can be realized.

[0010]

SUMMARY OF THE INVENTION The present invention relates to an image scanner for irradiating an original with light from a light source through filters of a plurality of colors, taking in reflected light by a photoelectric conversion element, and converting the reflected light into an electric signal. A cylindrical color filter that is color-coded into a plurality of colors in the circumferential direction, color filter driving means for rotating the color filter around a light source inserted in the color filter, and a color reading mode for reading a document as a color image. A reading mode determining unit that determines which one of a monochrome reading mode and a monochrome reading mode for reading a document as a monochrome image. When the reading mode determining unit determines a color reading mode, the reading mode is determined via one color of a color filter. The irradiation time should be longer than the accumulation time of the photoelectric conversion element required for at least one color. When the color filter is rotated by controlling the filter driving means and the monochrome reading mode is determined by the reading mode determining means, the time for continuously irradiating through one color of the color filter is determined by the accumulation time of the photoelectric conversion element. N times the number of filter colors (n
Is an integer of 1 or more) and a color filter control unit that controls the color filter driving unit and rotates the color filter so that the time is divided.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a configuration of a light irradiation unit in a color image scanner according to the present embodiment, and 11 is a color filter. The color filter 11 is formed by dividing the circumferential direction of a cylindrical glass tube into three parts, and coating the surfaces of the three parts with red (R) 11a, green (G) 11b, and blue (B) 11c, respectively. It is composed. A fluorescent tube 12 as a light source is inserted into the color filter 11. A gear 3 is provided at an end of the color filter 11.
The filter motor 14 is connected via the. The filter motor 14 is driven to rotate the color filter 11 around the fluorescent tube 12 at a predetermined speed in a direction indicated by an arrow in the drawing, so that the light from the fluorescent tube 12 is changed to red (R), green (G), The light is converted into blue (B) light and can be irradiated on the document. The fluorescent tube 12, the color filter 11, and the like are unitized together with an image sensor 25 described later, and the image sensor unit is disposed at a predetermined position in the image scanner apparatus.

FIG. 2 is a block diagram showing the overall configuration of a color image scanner having the color filter 11, and reference numeral 21 denotes a CPU (central processing unit) constituting a control unit main body. The CPU 21 has a ROM storing program data and the like for the CPU 21 to control each unit.
(Read only memory) 22 and a RAM (random access memory) 23 provided with a memory and the like used for data processing are connected. The CPU 21;
The ROM 22 and the RAM 23 are mutually connected by bus lines 24 such as a data bus, an address bus, and a control bus.

An image sensor 25 is connected to the bus line 24 via a sensor drive circuit 26 and a sensor control circuit 27. The image sensor 25 takes in the reflected light when the light from the fluorescent tube 12 is applied to the original via the color filter 11, and converts the density of the original into an electric signal (photoelectric conversion) depending on the intensity of the reflected light. .

The image sensor 25 is constructed by arranging a plurality of photoelectric conversion elements in a line in the main scanning direction. The sensor drive circuit 26 is driven based on a control signal from the sensor control circuit 27, and controls the accumulation time of each photoelectric conversion element.

The electric signal converted by the image sensor 25 is supplied to a shading correction circuit 29 via an A / D conversion circuit 28. The output from the shading correction circuit 29 is used for image processing. Circuit 30
Is temporarily stored in the image buffer 31 via the.

The electric signal from the image sensor 25 is converted from analog to digital (A / D) by an A / D conversion circuit 28.
/ D conversion), and the shading correction circuit 29 corrects density level unevenness (shading). afterwards,
The image processing circuit 30 performs predetermined image processing, and stores the image data in the image buffer 31.

The image data stored in the image buffer 31 is transferred to the host computer 3 connected to the interface 32 via the interface 32 by a communication cable.
3 is transferred. The interface 32, the shading correction circuit 29, the image processing circuit 30, and the image buffer 31 are also connected to the bus line 24, respectively.

The bus line 24 is connected to an inverter circuit 34 having a dimming function for controlling on / off of the fluorescent tube 12 and controlling light intensity. It is desirable to use a fluorescent tube having a high light intensity in order to increase the amount of light to the image sensor 25. For example, an aperture type fluorescent tube having a narrow slit for transmitting light is used.

Further, a motor control circuit 36 for controlling a motor driver 35 for driving the filter motor 14 is provided on the bus line 24, and conveys (sucks), feeds, and discharges a document to a position facing the image sensor unit. A motor control circuit 39 for controlling a motor driver 38 for driving the transport motor 37 is connected. Other, bus line 2
Reference numeral 4 denotes various sensors 42 such as a paper sensor via a sensor circuit 41, and various operations such as setting input of a reading mode (a color reading mode for reading a document as a color image and a monochrome reading mode for reading a document as a monochrome image). Are connected via an operation panel control circuit 44.

When the power of the main body is turned on, the CPU 21 performs a reading control as shown in FIG. That is, the CPU 21 first clears the memory or initializes various settings in ST (step) 1 as initial settings. At this time, the number of rotations of the color filter 11 is set as a default value for color reading. In other words, the speed is set such that the time of irradiation from the fluorescent tube 12 through one color of the color filter 11 is longer than at least the accumulation time of the photoelectric conversion element of the image sensor 25 required for each color. The reading mode is set to the color reading mode as a default value.

Next, in ST2, it is determined whether or not the monochrome reading mode has been set (reading mode determination means). At this time, if the reading mode has not been changed by the setting from the operation panel or the instruction from the host device side, it is determined that the color reading mode is the default value, and the reading mode has been changed to the monochrome reading mode. In this case, it is determined that the mode is the monochrome reading mode. Since the monochrome reading mode is a reading mode in which the read result is a monochrome image, the original image itself may be a monochrome image or a color image.

If it is determined in ST2 that the mode is the color reading mode, the convey motor 37 is controlled in ST3 to suck in the original. Subsequently, in ST4, the fluorescent lamp 12 is turned on by controlling the inverter circuit 34 with the dimming function, and the filter motor 14 is controlled to rotate the color filter 11 (color filter control means). At this time, the color filter 11 rotates at the rotation speed for color reading.

Next, a reading process is performed by the image sensor 25 for each color in ST5. That is, first, the fluorescent tube 12 is turned on, and subsequently, photoelectric conversion is performed for each color line by line in accordance with the switching timing of each color of the color filter 11, and a predetermined process is performed on the obtained electric signal to obtain image data. It is stored in the image buffer 31.

The timing of the photoelectric conversion is, specifically, as shown in FIG. 4 (a), while the light from the fluorescent tube 12 is irradiated through the red (R) 1a of the color filter 11 at a predetermined timing. The image sensor 25 is controlled by the accumulation time TR to photoelectrically convert the reflected light, and the light from the fluorescent tube 12 is radiated through the green (G) 1b of the color filter 11 while the image is imaged for a predetermined accumulation time TG. By controlling the sensor 25 to photoelectrically convert the reflected light, the image sensor 25 is controlled for a predetermined accumulation time TB while the light from the fluorescent tube 12 is irradiated through the blue (B) 1c of the color filter 11. To perform photoelectric conversion of the reflected light. Thereby, the photoelectric conversion processing can be continuously performed according to the rotation speed of the color filter 11, and the reading speed is increased. Then, when the process of ST5 ends, the reading control ends.

If it is determined in ST2 that the monochrome reading mode is set, the color filter 11 is determined in ST6.
Is set for monochrome reading. And S
At T7, the transport motor 37 is controlled to suck the original. Subsequently, in ST8, the control unit controls the inverter circuit 34 with the dimming function to turn on the fluorescent tube 12, and the filter motor 1
4 to rotate the color filter 11 (color filter control means).

At this time, the number of rotations of the color filter 11 is set to a value obtained by dividing a preset storage time of the image sensor 25 by n times the number of filter colors of the color filter 11 (n is an integer of 1 or more). That is, since the rotation is performed at the rotation speed for monochrome reading, the rotation speed is higher than the rotation speed when rotating at the rotation speed for color reading. Specifically, the color filter 11 in the present embodiment
The image sensor 25 is rotated at a speed such that the image sensor 25 rotates n times during a preset accumulation time.

Subsequently, in ST9, a reading process is performed on the image sensor 25 for a preset accumulation time. At this time, red (R) 11a, green (G) 11b, blue (B)
The reflected light from the original when illuminated via 11c is input to the image sensor 25 at equal time intervals, accumulated and photoelectrically converted. The electric signal thus obtained is subjected to predetermined processing and stored in the image buffer 31 as image data. As a result, by color reading, the red (R) 11a,
The same data as in the case of creating monochrome image data by adding all the data read separately for green (G) 11b and blue (B) 11c is obtained.

The storage time of the image sensor 25 when reading as a monochrome image may be the same as the storage time for one color when reading as a monochrome image. It may be longer than the accumulation time for one color.

In the embodiment of the present invention having such a configuration, when reading a document as a color image, the reading mode is left at the default value, or when the reading mode is changed, the reading mode is changed again. When the color reading mode is set, at the time of reading, the color filter 11 rotates at the rotation speed for color reading. Then, photoelectric conversion is performed by accumulating the light of each color of the image sensor 25 in accordance with the timing at which the color of the light from the fluorescent tube 12 is switched by the color filter 11. Thereby, the reading process for each color can be continuously performed, and the reading process is performed at a higher speed than in the conventional case where the color filter 11 is set at a predetermined position for each color and the photoelectric conversion is performed. be able to.

When a document is read as a monochrome image, the reading mode is set to the monochrome reading mode. At the time of reading, the color filter 11 is rotated at the rotation speed for monochrome reading, so that the accumulation time of the image sensor 11 is reduced. rotate n times. Then, red (R)
The reflected light from the original when illuminated via the green (G) 11b and blue (B) 11c is uniformly input to the image sensor 25, accumulated and photoelectrically converted. The image data obtained in this manner is read in red (R) 1 by color reading.
1a, green (G) 11b, and blue (B) 11c are the same data as in the case of creating monochrome image data by adding all the data read separately.

That is, the color (R) 11
a, monochrome image data can be created faster than the case of adding image data obtained by separately reading green (G) 11b and blue (B) 11c.

Further, the slit width of other colors can be widened by the absence of the colorless transparent portion in the color filter 11, so that the light irradiation time of each color can be reduced even if the rotation speed of the color filter 11 is kept high. Can be secured.
Accordingly, high-speed reading can be performed, and the accumulation time of the photoelectric conversion element of the image sensor 25 for each color can be extended.

Further, since the color filter 11 is not provided with a colorless and transparent portion and the rotation speed of the color filter 11 is increased to enable monochrome reading, all other color portions are skipped as in the prior art. Wasteful time can be saved, and monochrome reading can be performed at higher speed.

The color filter 11 shown in FIG.
One line may be read by rotating. Thereby, filters having the same color but different (for example, red filter 1)
When the transmittances are different between 1a and 11d), averaging is performed. Therefore, it is possible to prevent image unevenness between the odd-numbered lines and the even-numbered lines as compared with the case where two lines are read by rotating the color filter 11 once.

In the embodiment of the present invention, the case where the image is read by fixing the image sensor unit and conveying the original in the sub-scanning direction has been described. However, the present invention is not necessarily limited to this. Alternatively, the present invention may be applied to an apparatus in which a document is placed on a reading glass and the image sensor unit is transported in the sub-scanning direction.

In the embodiment of the present invention, the color filter 11 is divided into three parts in the circumferential direction of a cylindrical glass tube as shown in FIG. 11a, green (G) 11b, blue (B) 11
In the above description, the color filter 11 is formed by coating with different colors. However, the present invention is not limited to this.
(M is an integer of 2 or more).
Green (G), blue (B), red (R), green (G) ...,
It may be applied to those which are configured by coating with colors.

For example, the color filter 11 is divided into six parts in the circumferential direction of a cylindrical glass tube, and the red (R) 1
FIG. 5 shows a configuration in which coating is performed by classifying into 1a, green (G) 11b, blue (B) 11c, red (R) 11d, green (G) 11e, and blue (B) 11f.

Thus, as the circumferential direction of the glass tube of the color filter 11 is divided into a large number, the slit width per color can be reduced, and the rotation angle of the color filter 11 per color can be reduced. Therefore, the entire reading time can be reduced.

That is, when reading as a color image, a larger slit width per color is more convenient because a larger amount of light can be secured, even if the rotation speed of the color filter 11 is the same. If the slit width is too large, it takes time until each color is switched unless the color filter 11 is rotated at a higher speed. Therefore, if the circumferential direction of the glass tube of the color filter 11 is divided into a large number, the entire reading time can be reduced without increasing the rotation speed of the color filter 11 so much.

Also, when reading as a monochrome image, it is possible to switch the colors more quickly by dividing the circumferential direction of the glass tube of the color filter 11 into a large number, so that the rotation speed of the color filter 11 does not need to be so high. Can also read monochrome images.

[0041]

As described above in detail, according to the present invention, since the colorless and transparent portion of the color filter can be dispensed with, the slit width of other colors can be increased by that amount, so that the original The reading speed can be increased while securing the light irradiation time from the light source when reading as a color image. When reading a document as a monochrome image, the reading time in monochrome reading can be shortened by rotating the color filter at a speed that satisfies a predetermined condition (faster than in color reading). it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a light irradiation unit of a color image scanner according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the overall configuration of the color image scanner according to the embodiment;

FIG. 3 is a flowchart showing reading control performed by a CPU shown in FIG. 2;

4A and 4B are diagrams showing a timing relationship between an irradiation time from a fluorescent tube and an accumulation time of an image sensor in the reading control shown in FIG. 3; FIG. 4A shows a case of a color reading mode, and FIG. This is the case of the monochrome reading mode.

FIG. 5 is a perspective view showing a modification of the color filter shown in FIG. 1;

FIG. 6 is a perspective view illustrating a configuration of a color filter of a conventional color image scanner.

FIG. 7 is a diagram illustrating a reading mechanism of a conventional color image scanner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Color filter 12 ... Fluorescent tube (light source) 14 ... Filter motor (color filter drive means) 25 ... Image sensor

Claims (1)

[Claims] 1. An image scanner that irradiates a document with light from a light source through respective filters of a plurality of colors, takes reflected light of the document by a photoelectric conversion element, and converts the reflected light into an electric signal. A color filter, a color filter driving means for rotating the color filter around the light source inserted in the color filter, a color reading mode for reading a document as a color image, and reading a document as a monochrome image Reading mode determining means for determining which of the monochrome reading mode and the reading mode, and when the reading mode determining means determines the color reading mode, at least the irradiation time through one color of the color filter The color buffer is set to be longer than the storage time of the photoelectric conversion element required for one color. When the color filter is rotated by controlling the filter driving means and the monochrome reading mode is determined by the reading mode determination means, the time for continuously irradiating one color of the color filter is stored in the photoelectric conversion element. Color filter control means for controlling the color filter driving means to rotate the color filter so that the time is divided by n times the number of filter colors of the color filter (n is an integer of 1 or more). A color image scanner.