JP3041020B2 - Reading device and reading method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a reading apparatus having a plurality of reading sensors, for example, an image sensor, and particularly to a color document having a plurality of reading sensors having different sensitivities. The present invention relates to a reading device and a reading method for reading.

(Prior Art) A color image sensor that separates a color original into red, green, and blue and reads image information of each color has been put to practical use. As the color image sensor, a solid-state color image sensor in which red, green, and blue color separation filters are arranged in a light-receiving element of a solid-state image sensor such as a CCD in which a number of small photoelectric conversion elements are arranged in a light-receiving unit is often used. Can be

(Problems to be Solved by the Invention) The red, green, and blue color image sensors have different sensitivities for each color. In particular, the output of the blue color image sensor is lower in level than the outputs of the other color image sensors. When a color image is reproduced using the output of each sensor as it is, color reproducibility is poor. For this reason, conventionally, the light amount of the light source is set in accordance with the light-sensitive element having low sensitivity, and the element of the color having high sensitivity is provided with a sensitivity correction filter to level out the output level or to reduce the level of sensitivity. The gain of the amplifier of the color element was increased to make the output level of each color uniform.

However, in such a method, since the power of the light source is increased, the amount of heat generated from the light source is also increased, the cooling device of the reader is increased, and the capacity of the buffer memory for the blue CCD sensor must be increased. There was an inconvenience that it had to be done.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a small-sized and low-cost reading apparatus and a reading method while preventing the apparatus from being enlarged.

[Constitution of the Invention] (Means for Solving the Problems) A reading device according to the present invention has a plurality of reading sensors that have different color filters from each other and are reset at predetermined cycles by individually applied reset pulses, and The pulse period of the reset pulse applied to the first reading sensor having a low-sensitivity color filter among the plurality of reading sensors is changed to the first reading sensor among the plurality of reading sensors having high sensitivity in accordance with the sensitivity ratio. Means for driving each reading sensor by setting the pulse period to be longer than the reset pulse given to the other reading sensors, and data accumulated in the first reading sensor and the other reading sensor each time the reset pulse is generated And output data read by the first reading sensor at a lower resolution than output data of the other reading sensor. And having a means for changing the output data of the same resolution of the other reading sensor.

Further, the reading device of the present invention has a plurality of reading sensors that have different color filters from each other and are reset at a predetermined cycle by individually applied reset pulses, and a filter of a low sensitivity color among the plurality of reading sensors. The pulse period of the reset pulse applied to the other read sensors except for the first read sensor among the plurality of read sensors having high sensitivity according to the sensitivity ratio is set to the pulse period of the reset pulse applied to the first read sensor having Means for driving each reading sensor by setting a period longer than a cycle, and means for outputting data accumulated in the first reading sensor and the other reading sensor each time the reset pulse is generated. I do.

Further, the reading device of the present invention has a plurality of reading sensors that have different color filters from each other and are reset at a predetermined cycle by individually applied reset pulses, and a filter of a low sensitivity color among the plurality of reading sensors. The pulse period of the reset pulse applied to the other read sensors except for the first read sensor among the plurality of read sensors having high sensitivity according to the sensitivity ratio is set to the pulse period of the reset pulse applied to the first read sensor having Means for driving each reading sensor by setting it to an integral multiple of the period, means for outputting data accumulated in the first reading sensor and the other reading sensor each time the reset pulse is generated, and The output data read by the reading sensor at a lower resolution than the output data of the other reading sensor is the same as the output data of the other reading sensor. And having a means for changing the resolution.

(Operation) The reading device according to the present invention sets the pulse period of the drive pulse of the reading sensor having a low-sensitivity color filter among a plurality of reading sensors having different color filters from each other according to the sensitivity ratio. Each read sensor is driven by setting it longer than the pulse period of the drive pulse of the read sensor, and the resolution of any one of the output data of the output sensors of the plurality of read sensors is changed, so that the output of the plurality of read sensors is changed. The resolution of the data is the same.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

First, the configuration of an embodiment of a reading apparatus to which the present invention is applied will be schematically described with reference to FIG. In the figure, an original plate made of transparent glass provided on the upper surface of a main body case 9.
A document 12 is placed on the document 10 while being pressed by the document press 11. The original platen 10
Light from a halogen lamp 13 for illumination provided below the light source is irradiated. The light reflected from the original is reflected by mirrors 14 and 1
The light is sequentially reflected at 5, 16 and enters the imaging lens system 17,
An image is formed on the image sensor 18 as a reading sensor.

The first optical system including the halogen lamp 13 and the mirror 14 and the second optical system including the mirrors 15 and 16 are scanned by the motor 19 in the X direction across the document surface. As a result, the original light images are sequentially formed on the image sensor 18.

As shown in FIG. 3 (A), this image sensor 18 has three independent R (red), G (green), and B (blue)
It has a CCD chip 18C in which the CCD line sensors 18R, 18G, 18B are arranged in a direction orthogonal to the X direction. The CCD line sensors 18R, 18G, and 18B are configured as shown in FIG. 3B when the portion in the circle L in FIG. 3A is enlarged. Each of the CCD line sensors 18R, 18G, and 18B is configured by arranging a plurality of light receiving elements such that the pixel pitch is 14 μm and the number of effective pixels is 5000. Each CCD line sensor 1
The intervals between 8R and 18G and between 18G and 18B are set to be 168 μm, respectively. A red filter, a green filter, and a blue filter are applied to the CCD line sensors 18R, 18G, and 18B, respectively.

On the other hand, the total sensitivity of the R, G, and B color separations of the reading device is mainly based on the halogen lamp 13 and the CCD line sensors 18R, 18R.
G and 18B are determined from the spectral sensitivity characteristics, and the characteristic diagram is shown in FIG.

FIG. 4 shows the CCD output level on the vertical axis and the wavelength (nm) on the horizontal axis. As can be seen from this characteristic diagram, the sensitivity ratio of R, G, B is about 1: 2: 2, and blue sensitivity is lower than other colors. As a result, the level of the output signal from the blue CCD line sensor 18B is smaller than those of the other CCD line sensors 18R and 18G, and the S / N ratio is reduced, and as a result, the white balance is also deteriorated.

Here, the block configuration of the electric circuit of this embodiment will be described with reference to FIG. In the figure, the CCD line sensors 18R, 18G, 18B are reset at predetermined intervals by reset pulses φRS, φRS 'output from the CCD drive control circuit 30, respectively. This will be described in detail later.

The read outputs from the CCD line sensors 18B, 18G, and 18R are amplified to optimal levels through amplifiers 31-1, 31-2, and 31-3, respectively, and then A / D converters 32-1 and 32- It is converted to a digital signal in 2, 32-3. Output digital signals of the A / D converters 32-1 and 32-2 are supplied to buffer circuits 33-1 and 33-2, and are delayed by predetermined times, respectively. As described above, the CCD sensor 18
Between G and 18R, there is an interval of 168 μmｍ14 μm = 12, that is, an interval of 12 lines. Therefore, the buffer circuit 33-2 outputs the output signal of the CCD line sensor 18G for the time of the 12 lines. In contrast, the delay causes the CCD line sensors 18G and 18R to read an image on the same line. Here, with respect to the CCD line sensor 18R, the output of the CCD line sensor 18B normally requires a delay of 24 lines, but as will be described in detail later, the output of the CCD line sensor 18B is Since the resolution is halved compared to the outputs of the sensors 18G and 18R, the data for 12 lines was delayed by 12 lines by the buffer circuit 32-1, resulting in a delay of 24 lines. become.

The output of the buffer circuit 33-1 has half the resolution of the output of the other buffer circuits, and this output is restored by the interpolation circuit 34 from adjacent pixels to the same resolution by, for example, a linear interpolation method.

FIG. 5 shows a timing chart of drive signals of the CCD line sensors 18B, 18G, 18R of FIG. FIG. 5 (a),
(B) and (c) are drive signals for the line sensors 18G and 18R. As shown in (e), the reset pulse φRS is supplied for each pixel of the line sensor, and the output thereof is a pulse signal for each pixel. (D) is obtained.

On the other hand, the reset pulse φRS ′ of the blue line sensor 18B
As shown in (g), the pulse rate becomes 1/2 of φRS and is supplied to every other pixel of the line sensor 18B. Therefore, the output is obtained at the timing corresponding to the reset pulse φRS 'as shown in (f). That is, (f), the a charge Q ₁ generated in the first pixel are summed and charge Q ₂ to which was generated in the second pixel is, (Q ₁ + Q ₂₎ as twice the level of the signal is blue From the line sensor 18B. This gives R,
It can be considered that the sensitivity ratios of G and B are equal, the white balance is also equal, and a high-quality color signal with an equalized S / N ratio can be obtained. Further, since it is not necessary to increase the power of the light source for exposing the document in order to increase the blue output, the power consumption does not increase and the temperature rise of the apparatus can be prevented.

In the above embodiment, the sensitivity of the blue CCD line sensor is
Since it is about half of the red and green sensors, the reset rate of the blue sensor is set to half that of the other color sensors, and the charge is accumulated to make the apparent sensitivity almost equal to the other sensors. Are relative, and the sensor with low sensitivity is not limited to blue, but may be a sensor of another color. Also, the sensitivity ratio is 1: 2
The present invention is not limited to this, and may be, for example, 1: 3 or 1: 1.5, and the reset cycle may be variously changed according to the sensitivity ratio.

[Effects of the Invention] As described above, according to the present invention, the period of the reset pulse of a reading sensor having insufficient sensitivity with respect to another reading sensor is set to be longer according to the sensitivity ratio with the other reading sensor. Or set an integer multiple to accumulate the charge,
Since an output of the same level as the output signal level of the other reading sensors is obtained, the white balance is equal and the S /
A high-quality image with an equalized N ratio can be provided. In addition, since a decrease in resolution of the reading sensor when the reset pulse cycle is different can be compensated for by the normal interpolation technique, the output level of each reading sensor is made substantially equal without deteriorating the image quality. Since there is no need to increase the power, an increase in the power consumption of the apparatus and an increase in temperature can be prevented. Further, since the cycle of the reset pulse is set according to the sensitivity ratio of each reading sensor, the capacity of the buffer memory for delaying the output signal from the reading sensor having low sensitivity can be reduced, and the cost can be reduced. Therefore, it is possible to provide a small-sized and low-cost reading apparatus and a reading method while preventing the apparatus from being enlarged.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electric circuit of a reading apparatus according to an embodiment of the present invention, FIG. 2 is a diagram schematically showing the configuration of the embodiment, and FIGS. 3A and 3B are arrangements of CCD line sensors. FIG. 4 is a sensitivity characteristic diagram of R, G, and B, and FIG. 5 is a timing chart of a drive signal of the CCD line sensor of FIG. 11 ... Document holding, 12 ... Document, 13 ... Halogen lamp, 14, 15, 16 ... Mirror, 17 ... Imaging lens system, 18
…… Image sensor, 18R, 18G, 18B …… CCD line sensor, 30 …… Drive control circuit, 31-1, 31-2, 31-3 …… Amplifier, 32-1, 32-2, 32-3… … A / D converter, 33-1, 33-2 ……
Buffer circuit, 34 ... Interpolation circuit.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1 / 028,1 / 04

Claims (4)

(57) [Claims] A plurality of reading sensors having color filters different from each other and reset at predetermined intervals by individually applied reset pulses; and a first sensor having a low-sensitivity color filter among the plurality of reading sensors. The pulse cycle of the reset pulse given to the reading sensor is set longer than the pulse cycle of the reset pulse given to other reading sensors except the first reading sensor among the plurality of reading sensors having high sensitivity according to the sensitivity ratio. Means for driving each read sensor, means for outputting data accumulated in the first read sensor and the other read sensor each time the reset pulse is generated, and means for outputting the other read sensor by the first read sensor. Change the output data read at a lower resolution than the output data of the reading sensor to the same resolution as the output data of the other reading sensor Reader, characterized in that it comprises means that, the. A plurality of reading sensors having color filters different from each other and being reset at a predetermined cycle by individually given reset pulses; and a first sensor having a low-sensitivity filter among the plurality of reading sensors. The pulse cycle of the reset pulse given to the reading sensor is set longer than the pulse cycle of the reset pulse given to other reading sensors except the first reading sensor among the plurality of reading sensors having high sensitivity according to the sensitivity ratio. And a means for driving each of the reading sensors, and means for outputting data accumulated in the first reading sensor and the other reading sensor each time the reset pulse is generated. 3. A reading apparatus comprising a plurality of reading sensors having color filters different from each other and being reset at a predetermined cycle by individually applied reset pulses, wherein the reading sensor comprises: The pulse period of the reset pulse applied to the first read sensor having a filter is determined by changing the pulse period of the reset pulse applied to the other read sensors except the first read sensor among the plurality of read sensors having high sensitivity according to the sensitivity ratio. Each read sensor is driven by setting it longer than the pulse period, and the data stored in the first read sensor and the other read sensor are output each time the reset pulse is generated. The output data output at a lower resolution than the output data of the reading sensor of the same, the same resolution as the output data of the other reading sensor Reading method and performing processing to change. 4. A plurality of reading sensors having color filters different from each other and reset at a predetermined period by individually applied reset pulses, and a first sensor having a low-sensitivity color filter among the plurality of reading sensors. The pulse period of the reset pulse given to the read sensor of the second embodiment is an integer multiple of the pulse period of the reset pulse given to the other read sensors except the first read sensor among the plurality of read sensors having high sensitivity according to the sensitivity ratio. Means for driving each of the read sensors by setting the data to the first read sensor and the other read sensors each time the reset pulse is generated; and The output data read at a lower resolution than the output data of the other reading sensor is changed to the same resolution as the output data of the other reading sensor. Reader and having means for the.