JP3299295B2 - Camera and its operation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera provided with a solid-state electronic image sensor and an operation method thereof.

[0002]

2. Description of the Related Art FIG. 2 is a schematic diagram of a solid-state electronic image pickup device of a frame interline transfer system.

The solid-state electronic image pickup device shown in FIG. 2 includes a large number of photodiodes 5 arranged in a row direction and a column direction, and a signal charge stored in the photodiodes 5 arranged adjacent to the photodiodes 5 in a column direction. It comprises a vertical transfer path 6 for transferring in the vertical direction, and a horizontal transfer path 7 for further transferring the signal charges transferred by the vertical transfer path 6 in the horizontal direction. Solid-state electronic imaging devices are characterized by their small size and light weight, and are therefore effectively used in cameras.

[0004]

In a digital electronic still camera, a solid-state electronic imaging device having a vertical resolution of 525 scanning lines is used so that it can be used in the standard television system of the NTSC system. On the other hand, a solid-state electronic image sensor having a vertical resolution of 1000 scanning lines has been developed due to a demand for a high-definition television system. When an image of a subject is captured using a solid-state electronic imaging device having a high vertical resolution, a field for forming one screen by four fields is used instead of a conventional field scan for forming one screen by two fields in order to prevent flickering of the screen. Scanning is required.

When one screen is constituted by four fields, the photodiodes 5 in the A1 row every three rows in the vertical direction
Is read out via the vertical transfer path 2 and the horizontal transfer path to obtain a first field video signal.
The signal charges stored in the photodiodes 5 in one row are read out as a second field video signal, then the signal charges stored in the photodiodes 5 in row A2 are read out as a third field video signal, and then the row B2 is read. The signal charge stored in the photodiode 5 is read out to be a fourth field video signal. One screen is composed of the first to fourth field video signals.

FIG. 3 is a time chart for reading out signal charges stored in the photodiode 5. Here, VD is a vertical blanking signal.

The photodiode 5 is exposed during the period Δt, and signal charges are accumulated in the photodiode 5. There are several methods for reading the signal charges stored in the photodiode 5. As a first reading method, there is a method of reading immediately after the end of exposure. This is to start reading out the stored signal charges from the photodiode 5 to which a field shift pulse is applied immediately after exposure. In the example shown in FIG. 3, the field shift pulse F3
Is applied first after the end of the exposure, so that the signal charges accumulated in the photodiodes 5 in the row to which the field shift pulse F3 is applied are read out. Next, the photodiodes 5 in the row to which the field shift pulse F4 is applied
Is read out, and the photodiode 5 in the row to which the field shift pulse F1 is next applied is read out.
The signal charge stored in the
The signal charges stored in the photodiodes 5 in the row to which the shift pulse F2 is applied are read.

When the signal charges stored in the photodiode 5 are read by such a reading method, most of the smear charges generated during the exposure period are added to the signal charges read first. Can be For this reason, a difference is generated between the signal charge amount read out at the first time and the signal charge amount read out at other times, which causes flicker in a reproduced image.

As a second reading method, it is conceivable that only smear charges are once swept after exposure to prevent flicker due to smear charges.

This method uses a photodiode 5 immediately after exposure.
The field shift pulse F3 to be given to
The reading of the signal charge is delayed for 1 V without being applied to the photodiode 5, and the smear charge is swept out during the delayed 1 V. In the case shown in FIG. 3, data is read from the fourth field video signal. However, the fourth, first and second field video signals,
In the reading of and, signal charges due to dark current during a 4 V (V is one vertical scanning period) period during which field shift pulses F4, F1 and F2 are applied are accumulated in the photodiodes 5 of each row. Since the field shift pulse F3 immediately after the exposure is removed (FS mask on) in the reading of the third field signal indicated by the code C, the photodiode 1 in the row to which the field shift pulse F3 is applied is supplied. In this case, signal charges due to dark current during a period of 8 V, which is twice the period of 4 V of the field shift pulse F3, are accumulated.

As a result, a level difference occurs between the fourth, first and second field video signals, and the third field video signal, and the read method 1
As in the case of (1), flicker occurs in the reproduced image.

Further, as a third reading method, in order to prevent flicker due to the difference in the amount of signal charge accumulated by smear charge and dark current, only the smear charge is swept once after exposure, and the accumulation of signal charge by dark current is performed. It is possible to make them all equal.

This method uses field shift pulses FS1 to FS to be applied to the photodiode 5 after exposure.
The reading of the signal charge is delayed for 4 V without applying S4 to the photodiode 5, and the smear charge is swept out within the delayed 4 V period. Since the field shift pulse is not applied to the photodiodes 1 of all the rows once, the period in which the dark current is accumulated is all 8V periods. For this reason, it is possible to correct the level difference of the signal charges in each reading, and to prevent flicker.

However, according to the third reading method, a relatively long time is required from the exposure to the start of reading.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the influence of a dark current generated due to a difference in output timing of each field of a video signal even if the period from the exposure to the start of reading is short.

[0016]

A camera according to a first aspect of the present invention includes a plurality of photoelectric conversion elements arranged in a row direction and a column direction, and a plurality of photoelectric conversion elements arranged adjacent to the photoelectric conversion elements in a column direction. A vertical transfer path for vertically transferring the accumulated signal charges; and a horizontal transfer path for further horizontally transferring the signal charges vertically transferred by the vertical transfer paths.
A video signal representing the object on the screen in four fields
A solid-state electronic imaging device that outputs the first, second, third, and fourth fields in order, and a level difference between fields based on a dark current caused by a difference in output timing of a video signal from the solid-state electronic imaging device for each field. Correction values for each field to be corrected, the first correction value corresponding to the first field, the second correction value corresponding to the second field, the third correction value corresponding to the third field, and the fourth field Storage means for storing a fourth correction value corresponding to the first correction value, the second correction value, the third correction value, and the fourth correction value stored in the storage means. Correction data generating means for generating the first correction data, the second correction data, the third correction data, and the fourth correction data, and the first field image sequentially output from the solid-state electronic imaging device No., second field image signal, third
To the field video signal and the fourth field video signal,
An adding circuit for adding the first correction data, the second correction data, the third correction data, and the fourth correction data generated by the correction data generating means; The first field video signal, the second field video signal, the third field video signal and the fourth field video signal to which the first correction data, the second correction data, the third correction data, and the fourth correction data are respectively added. A recording control means for recording a field video signal on a recording medium is provided.

The first invention also provides an operation method suitable for the camera. That is, this method comprises a plurality of photoelectric conversion elements arranged in a row direction and a column direction, and a vertical transfer that is arranged adjacent to the photoelectric conversion elements in a column direction and vertically transfers signal charges accumulated in the photoelectric conversion elements. And a horizontal transfer path for further horizontally transferring the signal charges vertically transferred by the vertical transfer path. The video signals representing the subject on one screen in four fields are represented by first, second, third and fourth fields. In a camera provided with a solid-state electronic imaging device for outputting in the order of the fourth field, for each field for correcting a level difference between fields based on a dark current caused by a difference in output timing of a video signal from the solid-state electronic imaging device for each field. , The first correction value corresponding to the first field, the second correction value corresponding to the second field, and the third correction value. The third correction value and the fourth correction value corresponding to the fourth field are stored, and the stored first correction value, second correction value, third correction value, and fourth correction value are stored. Based on the values, first correction data, second correction data, third correction data, and fourth correction data are generated, and the first field video signal, the second field data signal, and the second field data sequentially output from the solid-state electronic imaging device are generated. Field video signal, third field video signal and fourth
The generated first correction data, the second correction data, the third correction data, and the fourth correction data are respectively added to the field video signal, and the first correction data and the second correction data are added. The first field video signal, the second field video signal, the third field video signal, and the fourth field video signal to which the correction data, the third correction data, and the fourth correction data are respectively added are recorded on a recording medium. Things.

According to the first aspect, each of the first field, the second field, the third field, and the fourth field based on a dark current caused by a difference in output timing of the video signal from the solid-state electronic imaging device for each field. A correction value for each field for correcting a level between the first field and a second correction value corresponding to the first field.
A second correction value corresponding to the field, a third correction value corresponding to the third field, and a fourth correction value corresponding to the fourth field are stored for each field. The stored first correction value, second correction value, and third correction value
And the fourth correction value are read. Based on the read first correction value, the second correction value, the third correction value, and the fourth correction value, the first correction value
, The second correction data, the third correction data, and the fourth correction data are generated. The first correction data, the second correction data, and the second correction data generated in the first field video signal, the second field video signal, the third field video signal, and the fourth field video signal output from the solid-state electronic imaging device. The third correction data and the fourth correction data are respectively added. The first field video signal, the second field video signal, the third field video signal, and the fourth
Is recorded on the recording medium.

According to the first aspect, it is possible to eliminate the influence of the dark current generated based on the difference in the output timing of the video signal from the solid-state electronic image sensor for each field. In particular, according to the first invention, the stored first correction value, second correction value, third correction value and fourth correction value are stored.
, The first correction data, the second correction data, the third correction data, and the fourth correction data are generated. The generated first correction data, second correction data, third correction data, and fourth correction data are stored in the first correction data.
It is added to the video signal of the field, the video signal of the second field, the video signal of the third field, and the video signal of the fourth field. By this addition processing, the video signal of the first field, the second field, and the third field to which the correction data has been added can be matched with the video signal of the fourth field to which the correction data has been added. Can be eliminated.

According to a second aspect of the present invention, there is provided a camera comprising: a plurality of photoelectric conversion elements arranged in a row direction and a column direction; and a signal charge disposed adjacent to the photoelectric conversion element in a column direction and accumulated in the photoelectric conversion element. A vertical transfer path for vertical transfer, and a horizontal transfer path for further horizontally transferring the signal charges vertically transferred by the vertical transfer path. A video signal representing a subject on one screen in a plurality of fields is sequentially provided for each field. A solid-state image pickup device for outputting, and a correction value for each field for correcting a level difference between field images based on a dark current caused by a difference in output timing of a video signal from the solid-state image pickup device for each field. Storage means for storing a plurality of correction values corresponding to a plurality of correction values, and a plurality of correction values based on the plurality of correction values stored in the storage means. Correction data generating means for generating data, and adding the corresponding correction data among the plurality of correction data generated by the correction data generating means to the video signals of a plurality of fields sequentially output from the solid-state electronic imaging device. And a recording control means for recording, on a recording medium, a plurality of field video signals to which the correction data has been added by the adding circuit.

The second invention also provides an operation method suitable for the camera. That is, this method comprises a plurality of photoelectric conversion elements arranged in a row direction and a column direction, and a vertical transfer that is arranged adjacent to the photoelectric conversion elements in a column direction and vertically transfers signal charges accumulated in the photoelectric conversion elements. And a horizontal transfer path for further horizontally transferring the signal charges vertically transferred by the vertical transfer path. The solid-state electronic imaging device sequentially outputs a video signal representing a subject on one screen in a plurality of fields for each field. A correction value for each field for correcting a level difference between field images based on a dark current caused by a difference in output timing for each field of a video signal from the solid-state electronic imaging device in the camera having the elements. Stores a plurality of correction values corresponding to a plurality of correction values, and generates a plurality of correction data based on the stored plurality of correction values. The corresponding correction data among a plurality of generated correction data is respectively added to a plurality of fields of video signals sequentially output from the solid-state electronic imaging device, and a plurality of field video signals to which the correction data is added are recorded on a recording medium. It is to be recorded.

In the second invention, a correction value for each field for correcting a level difference between a plurality of fields based on a dark current caused by a difference in output timing for each field of a video signal from a solid-state electronic imaging device is used. In addition, a plurality of correction values corresponding to each field are stored. A plurality of correction data corresponding to the stored plurality of correction values are generated. Corresponding correction data among a plurality of generated correction data is respectively added to the plurality of field video signals output from the solid-state electronic imaging device.
A plurality of field video signals to which respective corresponding correction data are added are recorded on a recording medium.

According to the second aspect of the present invention, it is possible to eliminate the influence of the dark current generated due to the difference in the output timing of the video signal from the solid-state electronic image sensor for each field.

[0024]

FIG. 1 shows an embodiment of the present invention and is a block diagram showing an electric configuration of a digital electronic still camera.

The overall operation of the digital electronic still camera 10 is controlled by an overall control unit 20.

The digital electronic still camera 10 includes a CCD 12 as an image pickup device. A schematic diagram of the CCD 12 is shown in FIG.

As shown in FIG. 2, the CCD 12 has a large number of photodiodes 5 arranged in a row direction (vertical direction) and a column direction (horizontal direction). In FIG. 2, (4i + 1)
(I is an integer of 0 or more) The photodiodes 5 in the row
1, the photodiode 5 in the (4i + 2) -th row uses the code B1, the photodiode 5 in the (4i + 3) -th row uses the code A2, and the photodiode 5 in the (4i + 4) -th row uses the code B2. Respectively.

The CCD 12 outputs four field video signals. The photodiode A in the (4i + 1) th row
The field video signal represented by the signal charge accumulated in the first field video signal is the first field video signal, (4i + 2)
The field video signal represented by the signal charge stored in the photodiode B1 in the row is a second field video signal, and the field video signal represented by the signal charge stored in the photodiode A2 in the (4i + 3) th row is a third field video signal. The signal, a field video signal represented by the signal charge stored in the photodiode B2 in the (4i + 4) th row is defined as a fourth field video signal.

The first to fourth field image signals output from the CCD 12 have different output timings of the CCD 12, and therefore have different amounts of smear charge and signal charge generated by the dark current accumulated in the photodiode 5. For this reason, a level difference occurs for each field video signal, which causes flicker. In the digital electronic still camera 10 of this embodiment, C is used to correct the level difference for each field video signal.
The correction data corresponding to the field is added to the video signal output from the CD 12. For this purpose, the digital electronic still camera 10 includes an addition circuit 14, a correction value memory 17 storing correction values, and a correction data generation circuit 18 for generating correction data. The correction value memory 17 stores correction values corresponding to each field.

A subject image is formed by a CCD 12 by an imaging lens 11.
Imaged on top. The CCD 12 is an element which is read out by four-field scanning, and reads out first to fourth field video signals. This reading method will be described in the section of the prior art, and is based on the first reading method as shown in the time chart of FIG.

Referring to FIGS. 2 and 3, when the CCD 12 is exposed, a field shift pulse FS3 is given to the photodiode 5 indicated by reference numeral A2. As a result, the signal charges stored in the photodiode 5 indicated by the symbol A2 are transferred to the vertical transfer path 6.

Subsequently, a vertical transfer pulse is applied to the vertical transfer path 6, and the signal charge is transferred vertically in the vertical transfer path 6 to the horizontal transfer path 7. The signal charge transferred to the horizontal transfer path 7 is output as a third field video signal by applying a horizontal transfer pulse to the horizontal transfer path 7.

The signal charge output from the CCD 12 is supplied as an analog video signal to an analog / digital (A / D) conversion circuit 13 as shown in FIG. The digital image data converted by the A / D conversion circuit 13 is supplied to an addition circuit 14.

When digital image data corresponding to the third field video signal is supplied to the adding circuit 14, a correction value for correcting the level of the third field video signal is stored in the memory controller 15 from the correction value memory 17.
And is provided to the correction data generation circuit 18. Data for correcting digital image data corresponding to the third field video signal is generated in the correction data generation circuit 18 and supplied to the addition circuit 14. The third field image data is obtained by adding the correction data to the image data corresponding to the third field video signal by the adding circuit 14. The third field image data is temporarily stored by being applied to the frame memory 16 via the memory controller 15.

Subsequently, a field shift pulse F is supplied from the CCD 12 to the photodiode 5 indicated by the symbol B2.
S4 is given, and the signal charge stored in the photodiode 5 indicated by the reference B2 is transferred to the vertical transfer path 6.
This signal charge is output as a fourth field video signal via a vertical transfer path 6 and a horizontal transfer path 7, applied to an A / D conversion circuit 13, converted into digital image data, and applied to an addition circuit 14.

At this time, a correction value for correcting the level of the fourth field video signal is read from the correction value memory 17 and supplied to the correction data generation circuit 18. The correction data generation circuit 18 generates correction data to be added to the image data corresponding to the fourth field video signal. The generated correction data is supplied to an addition circuit 14 and added to the digitally converted fourth field video signal. The added data is provided to the frame memory 16 via the memory controller 15 as image data of the fourth field, and is temporarily stored.

Subsequently, the signal charges stored in the photodiode 5 indicated by the symbol A1 are read out from the CCD 12 as a first field video signal in the same manner as described above, converted into digital signals, and supplied to the addition circuit 14. Data for correcting the first field video signal is supplied from the correction data generating circuit 18 to the adding circuit 14 in the same manner as described above. In the adding circuit 14, correction data is added to the image data of the first field. The first field image data to which the correction data has been added is stored in a memory controller.
The data is provided to the frame memory 16 via the memory 15 and is temporarily stored.

Further, the signal charges stored in the photodiode 5 indicated by the symbol B1 are read out from the CCD 12 as a second field video signal, converted into digital signals, and supplied to the adding circuit 14. Further, data for correcting the image data of the second field is supplied from the correction data generation circuit 18 to the addition circuit 14 in the same manner as described above. In the adder circuit 14, correction data is added to the data of the second field. The second field image data to which the correction data has been added is provided to the frame memory 16 via the memory controller 15 and is temporarily stored.

As described above, the frame memory 16 has the first
To the fourth field are stored.

The first to fourth field image data are read from the frame memory 16 and are read by the memory controller.
The signal is supplied to a compression circuit 19 through 15. The compression circuit 19 is a circuit for compressing data by Huffman coding, run-length coding or the like. The first to fourth field image data data compressed by the compression circuit 19 are interfaced.
The data is provided to the memory card 30 through the memory 21 and recorded. One screen is constituted by the first to fourth field image data recorded on the memory card 30.

The first to fourth data recorded on the memory card 30
By reading and reproducing the field image data and displaying it on the monitor display device, the screen represented by the image data can be viewed. In the first to fourth field image data, since the level difference between the respective fields due to the electric charge generated by the dark current or the like is corrected,
It is possible to prevent flicker from occurring on the playback screen.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a block diagram illustrating an electrical configuration of a digital electronic still camera.

FIG. 2 is a schematic diagram of a CCD.

FIG. 3 is a flowchart showing reading of signal charges from a CCD.

[Explanation of symbols]

 12 CCD 14 Addition circuit 17 Correction value memory 18 Correction data generation circuit 20 Overall control unit

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-288686 (JP, A) JP-A-55-163959 (JP, A) JP-A-3-231580 (JP, A) JP-A 62-288 159579 (JP, A) JP-A-3-238984 (JP, A) JP-A-3-248687 (JP, A) JP-A-2-822771 (JP, A)

Claims (4)

(57) [Claims] 1. A photoelectric conversion element arranged in a large number in a row direction and a column direction, and a vertical transfer path arranged adjacent to the photoelectric conversion element in a column direction and vertically transferring signal charges accumulated in the photoelectric conversion element. And a horizontal transfer path for further horizontally transferring the signal charges vertically transferred by the vertical transfer path. A video signal representing a subject on one screen in four fields is provided by first, second, third and fourth video signals. A solid-state image sensor that outputs in the order of four fields, and a correction value for each field for correcting a level difference between fields based on a dark current caused by a difference in output timing of each field of a video signal from the solid-state image sensor. , A first correction value corresponding to the first field, a second correction value corresponding to the second field, a third correction value corresponding to the third field, and a fourth correction value. Storage means for storing the fourth correction value corresponding to Rudo, the first correction value stored in the storage means, a second auxiliary
On the basis of the positive value, the third correction value and the fourth correction value,
First correction data, second correction data, third correction data
Correction data generating means for generating the fourth correction data
Stage, the first field video signals sequentially outputted from the solid-state electronic image sensing device, the second field image signal, the third field picture signal and a fourth field video signal, said correction de
The first correction data generated in the data generation means ,
An adding circuit for adding the second correction data , the third correction data, and the fourth correction data , respectively; and the first correction data and the second correction data by the adding circuit.
The first field video signal, the second field video signal, the third field video signal, and the fourth field video signal to which the third correction data , the third correction data, and the fourth correction data are respectively added are recorded on a recording medium. Camera with recording control means. 2. A photoelectric transfer device according to claim 1, further comprising: a plurality of photoelectric conversion elements arranged in rows and columns; and a vertical transfer path disposed adjacent to said photoelectric conversion elements in a column direction and vertically transferring signal charges accumulated in said photoelectric conversion elements. And a horizontal transfer path for further horizontally transferring the signal charges vertically transferred by the vertical transfer path. A video signal representing a subject on one screen in four fields is provided by first, second, third and fourth video signals. In a camera provided with a solid-state image pickup device that outputs in the order of four fields, in each field, a level difference between fields based on a dark current caused by a difference in output timing of each field of a video signal from the solid-state image pickup device is corrected. A first correction value corresponding to the first field, a second correction value corresponding to the second field, and a second correction value corresponding to the third field. The correction value and the fourth stores the fourth correction value corresponding to the field, first correction value stored, the second correction value, the third auxiliary
The first correction data is calculated based on the positive value and the fourth correction value.
Data, the second correction data, the third correction data and the fourth correction data.
Generates the correction data, the first field video signals sequentially outputted from the solid-state electronic image sensing device, the second field image signal, the third field picture signal and a fourth field video signal, generated in the first correction data, The second correction data , the third correction data
Correction data and adds the fourth correction data respectively, said first correction data, the second correction data, the third first field correction data and the fourth correction data are added each An operation method of a camera, wherein a video signal, a second field video signal, a third field video signal, and a fourth field video signal are recorded on a recording medium. 3. A plurality of photoelectric conversion elements arranged in a row direction and a column direction, and a vertical transfer path arranged adjacent to the photoelectric conversion elements in a column direction and vertically transferring signal charges accumulated in the photoelectric conversion elements. And a horizontal transfer path for further horizontally transferring signal charges vertically transferred by the vertical transfer path, and a solid-state electronic image pickup device for sequentially outputting a video signal representing a subject on one screen in a plurality of fields for each field. A correction value for each field for correcting a level difference between field images based on a dark current caused by a difference in output timing of a video signal from the solid-state electronic imaging device for each field, and a plurality of correction values corresponding to each field. Storage means for storing values, based on a plurality of correction values stored in the storage means
Te, the correction data generating means for generating a plurality of correction data, the video signals of a plurality of fields that are sequentially outputted from the solid-state electronic image sensing device, generated in the correction data generating means
A camera comprising: an adder circuit for respectively adding correction data corresponding to the plurality of correction data , and recording control means for recording, on a recording medium, a plurality of field video signals to which the correction data has been added by the addition circuit. 4. A plurality of photoelectric conversion elements arranged in a row direction and a column direction, and a vertical transfer path arranged adjacent to the photoelectric conversion elements in a column direction and vertically transferring signal charges accumulated in the photoelectric conversion elements. And a horizontal transfer path for further horizontally transferring signal charges vertically transferred by the vertical transfer path, and a solid-state electronic image pickup device for sequentially outputting a video signal representing a subject on one screen in a plurality of fields for each field. A correction value for each field for correcting a level difference between field images based on a dark current caused by a difference in output timing for each field of a video signal from the solid-state electronic imaging device. A plurality of corresponding correction values are stored, and a plurality of correction values are stored based on the stored plurality of correction values.
Generates data, the video signals of a plurality of fields that are sequentially outputted from the solid-state electronic image sensing device, the generated plurality of the corresponding correction data of correction data respectively added, a plurality of field image signals corrected data is added Method of operating a camera that records images on a recording medium.