JPH0228945B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a crosstalk correction circuit for an image reading device, and in particular, it uses a CCD sensor in which a plurality of elements are integrated at high density, and a CCD sensor using a fluorescent lamp as a light source.
In an image reading device that blinks sequentially in accordance with the scanning period of the sensor, the CCD sensor detects the reflected light from the image, and performs color separation.
The present invention relates to a crosstalk correction circuit that corrects crosstalk components occurring between adjacent elements in a sensor.

2. Prior Art FIGS. 1 to 3 are diagrams showing an optical system in an image reading device, which is the background of the present invention.

In the example shown in FIG. 1, an R fluorescent lamp 2 emits red light, a G fluorescent lamp 3 emits green light, and a B fluorescent lamp emits blue light on a color document 1. A light 4 is provided. The reflected light from the color original 1 based on the light from these fluorescent lamps 2 to 4 is converged by a lens 6 via a mirror 5.
It is input to the CCD sensor 7.

In the example shown in FIG. 2, only a normal color fluorescent lamp 8 is provided for a color original 1, and the light reflected from the color original 1 based on the light from this fluorescent lamp 8 is reflected by a mirror 5. The color original 1 is separated into red, green, and blue light components by the filter disk 9 and input to the CCD sensor 7 via the lens 6.

In the example shown in FIG. 3, a dichroic mirror 10 is arranged behind the lens 6 in place of the filter disc 9 shown in FIG. , the blue light component is separated and each is connected to an R-reading CCD sensor 11,
G reading CCD sensor 12 and B reading CCD sensor 1
3 is input.

Figure 4 is shown in Figures 1 to 3 above.
3 is a sectional view of the main parts of each of CCD sensors 7, 11, 12, and 13. FIG. This figure 4 shows CCD sensor 7
As the wavelength of light from the light source input to the becomes longer,
This shows that the generation of electrons by photons occurs deep within the CCD chip. In other words, for example, when light with a wavelength λ = 450 nm is input to the CCD sensor 7, the electrons due to the photons are transferred to the CCD sensor 7.
It occurs relatively shallowly in the chip. However, when the wavelength of light becomes λ = 550nm, the electrons
It occurs deeper than the CCD chip, and the wavelength λ
= 650nm, electrons will be generated even deeper than the CCD chip. In this way, as the wavelength of light becomes longer, electrons are generated deeper than the CCD chip, so the generated electrons are not captured by the element directly above.
The probability of being detected by the sensors on both sides increases. For this reason, a crosstalk phenomenon occurs between each element in the CCD sensor. In a CCD sensor, if crosstalk occurs between each element, there is a problem that it becomes impossible to output clear read data when reading reflected light from an image.

Purpose of the Invention Therefore, the main purpose of this invention is to
It is an object of the present invention to provide a crosstalk correction circuit for an image reading device that can output clear read data by correcting adjacent crosstalk components between adjacent elements in a sensor.

Structure of the Invention To summarize the invention, analog signals output from each element of a CCD sensor are converted into digital signals as read data, and stored.
Data for each element of the CCD sensor is temporarily stored in a first temporary storage means at a first timing, and data for each element stored in the first temporary storage means is further stored in a second temporary storage at a second timing. Store it in your means. The read data of a certain element read from the storage means, the read data of an adjacent element as output from the first temporary storage means, and the read data of an adjacent element outputted from the second temporary storage means. The configuration is such that each crosstalk component is corrected based on a predetermined constant.

The above objects and other objects and features of the present invention will become more apparent from the detailed description given below with reference to the drawings.

DESCRIPTION OF THE EMBODIMENT FIG. 5 is a schematic block diagram of an embodiment of the present invention. First, the configuration of an embodiment of the present invention will be described with reference to FIG. CCD sensor 21
For example, M light receiving elements are integrated and output read signals corresponding to red, green, and blue as analog signals. this
The output of the CCD sensor 21 is output from the A/D converter 22.
and the read output as an analog signal is N
It is converted into a bit digital signal. This N-bit data is stored in the R memory 23, G memory 24, and B
memory 25. The R memory 23 stores red reading data, and the G memory 2
4 is for storing the green read data, and B
The memory 25 stores blue reading data.

R memory 23, G memory 24 and B memory 2
5 is supplied with an address signal and a read/write signal from a control circuit 26, and read/write control is performed by this control circuit 26. That is, R
When red read data is written in the memory 23, green read data is read out from the G memory 24. These memories 23, 24 and 2
The N-bit read data sequentially read from the control circuit 26 is temporarily stored in the latch circuit 27 as a first temporary storage means at a first timing by the timing signal T _L output from the control circuit 26. The read data temporarily stored in the latch circuit 27 is temporarily stored in a latch circuit 28 as a second temporary storage means at a second timing. That is, N in a certain element of the CCD sensor 21 from the R memory 23
When the bit read data is read, the latch circuit 27 temporarily stores the read data of the element adjacent to the element corresponding to the read data read from the R memory 23, and the latch circuit 28 stores the read data of the element adjacent to the element corresponding to the read data read from the R memory 23. The read data of the element adjacent to the element corresponding to the read data temporarily stored in the latch circuit 27 is temporarily stored.

R memory 23, G memory 24 and B memory 2
The read data of N bits read from any one of the latch circuits 27, 27, and 28 are supplied to a correction circuit 29. The correction circuit 29 receives a correction coefficient switching signal given from the control circuit 26.
Each crosstalk component is corrected by T ₀ and T ₁ .

FIG. 6 is a diagram for explaining the operation when the crosstalk correction circuit shown in FIG. 5 corrects a crosstalk component.

Next, the operation shown in FIG. 5 will be explained with reference to FIG. For example, typical wavelengths of blue, green, and red
Suppose that, for example, the n-th light receiving element of the CCD sensor 21 is irradiated with light of 450 nm, 550 nm, and 650 nm in such an amount that the output of the CCD sensor 21 becomes level 1 as shown in FIG. 6a. Then, when irradiating light with a wavelength of 450 nm, the output level of the nth light receiving element in the CCD sensor 21 is
0.9, and 0.05 minutes are leaked to the n-1 and n+1-th light receiving elements on both sides. Also, the wavelength
When 550 nm light is irradiated, the output level of the n-th light receiving element is 0.85, as shown in FIG. 6d, and only 0.075 is leaked to the n-1 and n+1-th light receiving elements on both sides. Furthermore, in the case of light with a wavelength of 650 nm, the output level of the n-th light receiving element is 0.8, as shown in Figure 6 f, and the n-1,
Only 0.1 minute is leaked to the n+1th light receiving element.

Conventionally, due to such crosstalk phenomenon,
The output of the light receiving element is focused on the output of the CCD sensor.
Let v _o be the output of the elements on both sides of this element, v _o-1 ,
It is well known that when v _o+1 is set and the output level of the target element after correction is V _o , correction is performed using the following equation.

V _o = v _o / (1 - α) - (v _{o -1} + v _{o +1} ) α / 2 (1 - α
) This invention sets the correction coefficient α in the above formula to red,
When reading green and blue data, the correction values are changed for each. For example, if the read data is blue, α=0.1, and in this case, the output of the light receiving element shown in FIG. 6b is corrected as shown in FIG. 6c. Further, if the read data is green, α=0.15, and in this case, the output level of the light receiving element shown in FIG. 6d is corrected as shown in FIG. 6e. Furthermore, if the read data is red, α
=0.2, and in this case, the output level of the light receiving element shown in FIG. 6f is corrected as shown in FIG. 6g.

For this purpose, the correction circuit 29 shown in FIG. 5 is constituted by, for example, a large-capacity ROM, and correction data is written in advance so that the output V _o is corrected based on the above-mentioned correction formula. If the correction coefficient switching signals T ₀ and T ₁ given from the control circuit 26 to the correction circuit 29 are both “0”, α=
The data is corrected using a correction coefficient based on 0.1 and output. Further, if the correction coefficient switching signal T ₀ is "1" and T ₁ is "0", correction is performed based on α=0.15. In addition, a correction coefficient switching signal
If T ₀ is “1” and T ₁ is “1” then α=
Corrected by a factor of 0.2.

Effects of the Invention As described above, according to the present invention, analog signals output from each element of a CCD sensor are converted into digital signals as read data and stored.
The stored data for each element in the CCD sensor is temporarily stored in a first temporary storage means at a first timing, and the output of the first temporary storage means is further stored in a second temporary storage means at a second timing. Based on predetermined constants, the data of the element that is temporarily stored and read out from the storage means, the data of the adjacent element as the output of the first temporary storage means, and the data of the further adjacent element as the output of the second temporary storage means. Since the configuration is configured to correct the crosstalk components that occur between adjacent elements of the CCD sensor, it is possible to correct the crosstalk components that occur between adjacent elements of the CCD sensor.
Therefore, clear image data can be output by this corrected output.

[Brief explanation of drawings]

FIG. 1, FIG. 2, and FIG. 3 are diagrams showing an optical system in an image reading device, which is the background of the present invention. Figure 4 is shown in Figures 1 to 3 above.
FIG. 2 is a cross-sectional view of a main part of a CCD sensor. FIG. 5 is a schematic block diagram of one embodiment of the present invention. FIG. 6 is a diagram illustrating an operation for correcting crosstalk components according to an embodiment of the present invention. In the figure, 21 is a CCD sensor, 22 is an A/D
converter, 23 is R memory, 24 is G memory,
25 is a B memory, 26 is a control circuit, 27 and 28 are latch circuits, and 29 is a correction circuit.

Claims (1)

[Claims] 1. An image reading device that detects light from a light source reflected by an image using a CCD sensor in which a plurality of elements are integrated at high density, and thereby reads the image,
A crosstalk correction circuit for correcting crosstalk between adjacent elements in the CCD sensor, A/D conversion means for converting an analog signal output from each element of the CCD sensor into a digital signal as read data. , storage means for storing read data sequentially output from the A/D conversion means, first temporary storage means for temporarily storing data for each element of the CCD read from the storage means at a first timing. , second temporary storage means for temporarily storing the output of the first temporary storage means at a second timing; and data for each element of the CCD sensor read from the storage means and the first temporary storage means. The device is provided with an output of the device and an output of the second temporary storage device, and is provided with a correction device for correcting a crosstalk component occurring between adjacent elements in the read data given from each based on a predetermined constant. , Crosstalk correction circuit for image reading device.