JPH05100110A - Image pickup device - Google Patents

Abstract

PURPOSE:To provide an image pickup device which is expanded in an operation range. CONSTITUTION:Constitution units of a color filter 39 are composed of cyan color transmission filter elements (Cy) C111, C131, and C151, yellow color transmission filter elements (Ye) C112, C132, and C151, magenta color transmission filter elements (Mg) C121 and C142, and green color transmission filters (G) C122 and C141. A signal A obtained by forming an image on the image pickup surface of a solid image pickup element 27 through the color filter 39 passes through a band-pass filter 30 to obtain a color difference signal (G-2B) or (G-2R). Color difference signals (G-2R) and (G-2B) are obtained by a changeover switch 37 at each one-horizontal-scanning period(1H) from a signal which is delayed by 1H by a one-horizontal-scanning-period(1H) delay circuit 36 and a signal which is supplied without being supplied. A brightness signal (Y) is obtained by passing the signal A through a low-pass filter 28. An encoder 38 generates a composite video signal by using those signals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device, and more particularly to a color solid-state image pickup device.

[0002]

As is well known, in color television image transmission / reception systems, NTSC system, PAL system, SEC
The AM method is adopted in each country. The interlace scanning method is the standard for detecting and drawing these image information.

In order to reproduce an image on a general color television receiver, the solid-state image pickup device also needs to comply with these systems.

FIG. 4 is a diagram for explaining interlace scanning. When, for example, the character A is imaged on the image pickup surface of the solid-state image pickup device and a video signal is taken out, photoelectric conversion is performed in accordance with each scan from left to right and from top to bottom, and a video signal corresponding to an image is generated. To be detected. Since interlace scanning is actually performed, at first, 1A, 2A,
3A, ..., MA are interlaced to complete the scanning of the A field, and then the B field is scanned in the order of 1B, 2B, 3B ,. Complete. Thus, a complete image A, that is, the entire screen (one frame) is formed by scanning the A field and the B field. In the NTSC system, the television image is 30 / s by the interlace scanning as described above.
The number of frames is 30, that is, the sum of A field scanning 30 times per second and B field scanning 30 times per second.
The signal is detected once per second. Reading such a signal is called frame reading.

On the other hand, as a method used in the image pickup field of an image pickup apparatus having a solid-state image pickup element, the following method is considered.

In FIG. 4, this is (1A, 1
B), (2A, 2B), (3A, 3B), ... Simultaneous scanning is performed with each combination of two rows, and the signals obtained through the respective signal lines are mixed by an external circuit to perform A field scanning. After performing, (1B, 2A), (2B, 3
A), (3B, 4A), ..., B-field scanning is performed by performing mixed reading in a combination shifted by one row, and one frame scanning is completed.
In this case, signal detection is performed once for every field, that is, every 1/60 seconds for all the light receiving elements. This is called a field read. In particular, the solid-state image sensor has a characteristic that it does not cause a burn-in phenomenon in principle and has a low afterimage as compared with an image pickup tube. In order to make the best use of this feature, interlaced scanning by field reading is often desired even if the vertical resolution is somewhat sacrificed.

By the way, in order to construct a single-plate color camera by using one solid-state image sensor, as shown in FIG.
The light receiving element of the solid-state imaging device 11 and the color filter element of the color filter must be adjusted and mounted so as to correspond to each other 1: 1. That is, the light receiving elements A ₁₁ , A ₁₂ , ...
..., A ₂₁ , A ₂₂ , ..., A _mn , ... and the color filter elements C ₁₁ , C ₁₂ , ..., C ₂₁ , C ₂₂ , ..., C _mn , ... are exactly Must be arranged correspondingly.

After the light 13 from the outside passes through each color filter element C ₁₁ , C ₁₂ , ..., C _mn , ... Of the color filter ₁₂ , each light receiving element A ₁₁ , A ₁₂ ,. _mn ,
...... is irradiated and converted into signal charges. This signal charge is generated by A ₁₁ and A ₂₁ in the field reading, for example, in reading the rows 21 and 22 in the A field.
Like A ₁₂ and A ₂₂ , the signal charges of two light receiving elements are mixed and read. When reading rows 23 and 24, A ₃₁ and A ₄₁ , A ₃₂ and A ₄₂ , A ₃₃ and A ₄₃ , ..., And when reading rows 25 and 26, A ₅₁ and A ₆₁ , A ₅₂ and A ₄₂ , respectively. The signal charges for two light receiving elements are mixed and read out, such as ₆₂ , A ₅₃ and A ₆₃ .

Next, line 22 and line 2 in the B field
When reading 3,_{twenty one}And A₃₁, A _{twenty two}And A₃₂, A_{twenty three}And A
₃₃, ..., the signal charges of two light receiving elements are mixed.
Read out.

FIG. 6 shows a structural unit of a color filter using the field reading method. The constituent units of this color filter are all-color transmission filter elements (W) C ₁₁ , C ₃₁ , C
₅₁ , and green transmission filter element (G) C ₁₂ , C ₃₂ , C
₅₂ , yellow transmission filter elements (Ye) C ₂₁ and C ₄₂ , and cyan transmission filter elements (Cy) C ₂₂ and C ₄₁ . In the figure, 21 to 25 indicate rows.

The all-color transmission filter element (W) is red,
The blue and green primary color components are transmitted, the yellow transmission filter element (Ye) transmits red and green primary color components, and the cyan transmission filter element (Cy) transmits blue and green primary components. Make it transparent.

[0012]

In this color filter, since the all-color transmission filter element (W) having a high light transmittance is used in its constituent elements, the element portion has high sensitivity characteristics. There is an advantage called. However, Cy, Ye, W, which are the components of the color filter,
Since the G color filter transmittances are different, the signal currents from the pixels corresponding to them are largely different. That is, since the green transmission filter element (G) has the lowest light utilization rate, the green transmission filter element (G) requires about three times as much light amount as the all-color transmission filter element (W) to saturate. .. Therefore, compared with an ideal color filter in which the transmitted light amount of all filter constituent units is equal to each other,
In the image pickup device using the color filter shown in FIG.
The operating range is determined by the portion of the all-color transmission filter element (W), and the operating range of each pixel of the solid-state image sensor, particularly the green transmission filter element (G) cannot be used sufficiently, so the operating range is narrow. It has become a thing.

An object of the present invention is to eliminate the inconvenience caused by the color filter and to provide an image pickup apparatus having an expanded operation range.

[0014]

The image pickup apparatus of the present invention comprises:
A solid-state image sensor having a light-receiving element group that is two-dimensionally arrayed in the horizontal direction and the vertical direction, in which outputs of two vertically adjacent light-receiving elements are mixed and read, and a filter element arranged in front of the solid-state image sensor. Are arranged in a matrix, and the unit array has a two-dimensionally arranged color filter, and the unit arrays in the filter element of the color filter are arranged in two columns and four rows. The filter element comprises a fourth filter element, and the first, second, first and third filter elements are sequentially arranged in the first column of the unit array, and the fourth, third and third filter elements are arranged in the second column. 4 and a second filter element are sequentially arranged, and these first, second, and
The third and fourth filter elements are selected from the group consisting of cyan, magenta, green, and yellow and have different colors.

[0015]

In the image pickup apparatus according to the present invention, a single color and two colors are used.
Since the color filter in which the color filter elements are arranged in the specific positional relationship as described above is arranged on the front surface of the solid-state image sensor, the difference in the amount of light passing through each filter element is reduced and the operation range is expanded. It Then, from the solid-state image sensor in which this color filter is arranged on the front surface, the outputs of two vertically adjacent light receiving elements of the light receiving element group two-dimensionally arranged in the horizontal direction and the vertical direction are mixed and read out. It becomes possible to easily obtain the color difference signal.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The color filter used in the image pickup apparatus of the present invention has a magenta color transmission filter element, a cyan color transmission filter element, a green transmission filter element, and a cyan color transmission filter element arranged in two columns and four rows. A unit is constructed and is used in the field read system.

FIG. 1B shows an example of a structural unit of a color filter used in the image pickup apparatus of the present invention. This constituent unit is a cyan transmission filter element (Cy) C ₁₁₁ , C
₁₃₁ , C ₁₅₁ , yellow transmission filter element (Ye) C ₁₁₂ , C
₁₃₂ , C ₁₅₂ , magenta color transmission filter element (Mg) C
₁₂₁ , C ₁₄₂ , and green transmission filters (G) C ₁₂₂ , C ₁₄₁ . In the figure, 121 to 125 indicate each row.

The cyan transmission filter element (Cy)
Transmits the light of the blue and green primary color components, the yellow transmission filter element (Ye) transmits the light of the red and green primary color components, and the magenta color transmission filter element (Mg) transmits the light of the blue and red primary color components. Each is transparent.

Next, an electric output signal taken out from the solid-state image pickup device having the color filter shown in FIG. 1B will be described.

FIG. 2A shows an odd-numbered row (for example, the row shown in FIG. 1B) in the A field when the two light-receiving elements of the color filter shown in FIG. Simultaneous reading of 121 and 122,
Here, the two rows are collectively referred to as an odd row). FIG. 2B similarly shows the electrical output of the even rows (simultaneous reading of the rows 123 and 124 of FIG. 1B) in the A field. FIG. 2C shows the electric output of the odd rows in the B field (simultaneous reading of the rows 122 and 123 of FIG. 1B). FIG. 2D shows the electrical output of the even rows (simultaneous reading of the rows 124 and 125 of FIG. 1B) in the B field. In these figures, the vertical axis represents the voltage v and the horizontal axis represents the time t.
However, for easy understanding of the output waveform, red, green, and blue of the primary color components of the color filter corresponding to each light receiving element are shown by R, G, and B, respectively.

2A to 2D, respectively,
By passing through a bandpass filter to produce a color difference signal, for example, the following color difference signals are obtained in each row of the A field and the B field.

Odd row of A field (FIG. 2A): (Cy + Mg) − (Ye + G) = (R + G + 2B) − (R + 2G) = 2B−G Even row of A field (FIG. 2 (b)): (Cy + G) )-(Ye + Mg) = (2G + B)-(2R + G + B) = G-2RB Odd row of field (FIG. 2 (c)): (Mg + Cy)-(G + Ye) = (R + G + 2B)-(R + 2G) = 2B-GB Even rows of field (FIG. 2 (d)): (G + Cy) − (Mg + Ye) = (2G + B) − (2R + G + B) = G−2R For the luminance signal (Y), the signals of FIGS. Is passed through a low pass filter,
The luminance signals (Y) of all lines are as follows.

Y = 4R + 6G + 4B Next, a solid-state image pickup device according to an embodiment of the present invention will be described with reference to FIG. In this embodiment, the filter shown in FIG. 1B is used as the color filter 39, and the solid-state image sensor 27 has 380 pixels in the horizontal direction.
A solid-state image pickup device of the two-light-receiving element simultaneous readout system of 512 pixels in the vertical direction was used.

When an image is formed on the image pickup surface of the solid-state image pickup device 27 through the color filter 39, the above-mentioned signal A is output from this device 27. Center frequency of signal A is 3.58 MH
z, band 1 MHz band pass filter 30, and detection circuit 31 to pass (G-2B) or (G-
2R) color difference signal is obtained. Color difference signals (G-2B), (G
-2R) is (G-2B), (G-2B), (G-2B)
-2R) to obtain the process circuit 32
The signal which is delayed by 1H in the 1H scanning period (1H) delay circuit 36 and the signal which is supplied without delay are processed by the switch 37 for every 1H scanning period (1H). -2R) and (G-2B) color difference signals are obtained at the same time. The two types of color difference signals (G-2R) and (G-2B) thus obtained are supplied to the encoder 38.

On the other hand, for the luminance signal (Y), the signal A
Can be obtained by filtering with a low-pass filter 28 having a band of 3.58 MHz, and an output signal thereof is appropriately processed by a process circuit 29 as necessary and then supplied to an encoder 38, and the encoder 38 causes the color difference signal to be obtained. A composite signal is obtained with (G-2R) and (G-2B).

As described above, the luminance signal Y that determines the camera sensitivity in the filter in this embodiment is given by the following equation.

Y = 2R + 3G + 2B On the other hand, the luminance signal Y of the filter shown in FIG. 6 is given by the following equation.

Y = 2R + 4G + 2B As is clear from these comparisons, with respect to the sensitivity itself, the filter in this embodiment is slightly lower than the filter shown in FIG.

However, in the filter in this embodiment, the respective constituent elements are the green transmission filter element (G), the magenta transmission filter element (Mg), the yellow transmission filter element (Ye) and the cyan transmission filter element (Cy). ,
Since it is composed of monochromatic or bicolor color filter elements, the difference in the amount of light passing through the respective filter elements is reduced, and the operating range as a color solid-state image pickup element is expanded by about 3 dB.

That is, the operating range of the filter element in this embodiment is the magenta color transmission filter element (M
g), a yellow transmission filter element (Ye), and a cyan transmission filter element (Cy), which are determined by two color filter elements. The light amount of these color filter elements is a green transmission filter element which is a monochromatic color filter element. It is about twice the amount of light of (G), which in particular widens the operating range of the green transmission filter element (G) and expands the overall operating range.

FIG. 3 shows another example of the filter element. As shown in the figure, the unit array of filter elements of 2 columns and 4 rows is two-dimensionally arranged, and the first column of the unit array is magenta (Mg), cyan (Cy), magenta (M
g) and yellow (Ye), and the second row is green (G), yellow (Ye), green (G), cyan (Cy).
It is arranged by repeating.

Also in this color filter, as shown in FIG.
Similar to the color filter of (b), color difference signals (G-2R) and (G-2B) can be obtained by applying the above-mentioned embodiment.

As the solid-state image pickup device, the solid-state image pickup device of the two-light-receiving element simultaneous reading system has been described in the above embodiment, but the solid-state image pickup device of the two-row simultaneous reading system is also used.
It goes without saying that the color separation filter and processing circuit described above can be used.

[0034]

According to the image pickup apparatus of the present invention, the unit array is composed of first, second, third and fourth filter elements arranged in two columns and four rows, and the first column of the unit array is the first column. , The second, first and third filter elements are sequentially arranged, and the second column is the fourth, third, fourth and second filter elements are sequentially arranged. The first, second, third and fourth filter elements are cyan
The color filter is selected from the group consisting of magenta, green, and yellow, and each color is different. This color filter is arranged in front of the solid-state image sensor and the output of the light receiving element is read out. Because there is
The difference in the amount of light passing through each filter element is reduced,
The operating range can be expanded. Then, the color difference signals can be easily obtained by mixing and reading the outputs of the two light receiving elements adjacent in one direction of the light receiving element group of the solid-state image sensor.

[Brief description of drawings]

FIG. 1A is a block diagram of a solid-state imaging device according to an embodiment of the present invention, and FIG. 1B is a diagram showing an example of a structural unit of a color filter used in this embodiment.

2A to 2D are views for explaining primary color components of the color filter shown in FIG. 1B.

FIG. 3 is a diagram showing another structural unit example of a color filter used in the image pickup apparatus of the present invention.

FIG. 4 is a diagram for explaining interlace scanning in a television scanning system.

FIG. 5 is a diagram for explaining a relationship between a light receiving element of a solid-state image sensor and a color filter element of a color filter.

FIG. 6 is a diagram for explaining a constituent unit of a color filter used in a field reading method.

[Explanation of symbols]

27 solid-state image pickup device 28 low-pass filter 29 process circuit 30 band filter 31 detection circuit 32 process circuit 36 1 horizontal scanning period (1H) delay circuit 37 1 horizontal scanning period (1H) changeover switch 38 encoder 39 color filter C ₁₁₁ , C ₁₃₁ , C ₁₅₁ cyan transmission filter element C ₁₁₂ , C ₁₃₂ , C ₁₅₂ yellow transmission filter element C ₁₂₁ , C ₁₄₂ magenta transmission filter element C ₁₂₂ , C ₁₄₁ green transmission filter element

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Hashimoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Masao Hiramoto 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A solid-state image sensor having a light-receiving element group which is two-dimensionally arrayed in the horizontal direction and the vertical direction, in which outputs of two vertically adjacent light-receiving elements are mixed and read, and the solid-state image sensor. A color filter in which filter elements are arranged in a matrix and unit arrays are arranged two-dimensionally, and the unit arrays in the filter elements of the color filter are arranged in 2 columns and 4 rows. First done
The first column of the unit array is composed of second, third and fourth filter elements, and the first, second, first and third filter elements are sequentially arranged, and the unit array The second column of is constructed by sequentially arranging the fourth, third, fourth and second filter elements.
An imaging device in which the second, third, and fourth filter elements are selected from the group consisting of cyan, magenta, green, and yellow, and the respective colors are different. 2. The image pickup apparatus according to claim 1, wherein the first, second, third and fourth filter elements are cyan color, magenta color, green color and yellow color, respectively. 3. The image pickup apparatus according to claim 1, wherein the first, second, third and fourth filter elements are green, yellow, cyan and magenta colors, respectively.