JP2000032328A - Image input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image input device using stroboscopic light emission so as to enable focal point detecting processing or the like at high speed. SOLUTION: This image input device is composed of a two-dimensional pixel array L with which non-destructive read is enabled, vertical and horizontal scanning circuits 2 and 3, a first line memory 5-1 for reading and storing video signals on the specified row of the pixel array in the manner of no destruction before the light emission of a stroboscopic light emitting device, a second line memory 5-2 for reading and storing video signals on the same specified row of the pixel array in the manner of no destruction just after the light emission of the stroboscopic light emitting device, a line processing circuit 6 for forming the differential signal of video signals stored in the first and second line memories before and just after the stroboscopic light emission, and a control circuit 7 for controlling the operation of the said respective components, performing focal point detecting processing operation, based on the differential signal of the video signals and outputting an exposure control signal and a white balance control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input apparatus using a non-destructive readable two-dimensional solid-state imaging device, and more particularly to a focus detection using a non-destructive readable two-dimensional solid-state imaging device and strobe auxiliary light. The present invention relates to an image input device capable of speeding up processing and the like.

[0002]

2. Description of the Related Art Hitherto, various proposals have been made for an image input device using an auxiliary strobe light. For example, Japanese Patent Application Laid-Open No. 7-23302 discloses an image input device which is synchronized with the input of a trigger signal indicating a flash emission timing. The charge accumulation operation and the accumulated charge readout operation of the solid-state imaging device are sequentially performed, and this is caused by avoiding the overlap of the strobe light emission timing and the accumulated charge readout timing by prohibiting strobe light emission or shifting the light emission period. There is disclosed a solid-state imaging device for capturing a strobe image, which is configured to prevent omission of capturing of a subject image and displacement of a subject.

Japanese Patent Application Laid-Open No. 9-327799 discloses a solid-state image pickup device that photoelectrically converts incident light from a subject and outputs it as an electric signal, a strobe light emitting tube for irradiating the subject with light, A control unit for causing the strobe light emitting tube to emit light during the vertical blanking period of the image pickup device, so that even when a solid-state image pickup device of an XY address type such as CMD and a strobe light emitting tube emitting light for a short time are used, proper exposure can be performed. An imaging device capable of obtaining an amount of images is disclosed.

On the other hand, processing such as setting of an exposure amount and focusing is generally performed by focusing on a partial area of an image. Japanese Patent Application Laid-Open No. 7-162767 discloses a two-dimensional image sensor. There is disclosed an image sensor in which a part of the circuit configuration is used as a one-dimensional image sensor, and the cost is reduced by sharing parts.

[0005]

However, Japanese Patent Application Laid-Open No. 7-23302 and Japanese Patent Application Laid-Open No. 9-312799 have been disclosed.
The technology disclosed in Japanese Patent Application Laid-Open Publication No. H11-107421 aims to obtain a proper strobe image, and no consideration is given to focus detection when obtaining a strobe image. There is no disclosure about signal processing when used as light. Further, the technology disclosed in Japanese Patent Application Laid-Open No. 7-162767 is for extracting a signal in an arbitrary row or an arbitrary column of a two-dimensional image sensor and causing the signal to function as a line sensor, and is effective in reducing the size and cost of the device. However, during the period of functioning as a line sensor, imaging, which is the original function of the two-dimensional image sensor, cannot be performed. Therefore, there is a major problem in using the apparatus, such as the need for re-exposure after a pass determination of focusing. However, no consideration has been given to improving this point.

The present invention has been made in view of this point, and when obtaining a strobe image, it is possible to perform a focus detection process using an arbitrary region of the image at a high speed, and to output a video signal even during the process. It is an object of the present invention to provide an image input device using strobe light emission enabled.

[0007]

In order to solve the above-mentioned problems, the present invention provides a two-dimensional solid-state imaging device capable of non-destructively reading out a video signal obtained by photoelectrically converting light from a subject. A strobe light emitting means for irradiating the subject with auxiliary light, a line memory means capable of storing video signals of arbitrary plural rows of the two-dimensional solid-state imaging device, and before and immediately after light emission of the strobe light emitting means Non-destructively reading out at least one line or more of the same line of the video signal of the two-dimensional solid-state imaging device and storing it in the line memory means;
The image input device is constituted by the difference processing means for performing the difference processing between the video signal before light emission and the video signal immediately after light emission stored in the line memory means.

As described above, the video signal of at least one line of the two-dimensional solid-state image sensor before and immediately after the light emission of the strobe light emitting means is read nondestructively and stored in the line memory means, and the stored light emission is stored. By performing difference processing of the previous and next video signals, it is possible to read out image signals for focus detection processing etc. at high speed and with high accuracy based on the video signal of a specific row from which external light components and offset components have been removed. In addition, the video information is held in the pixels by non-destructively reading the video signal when stored in the line memory means, and the video signal is scanned and output even after reading the signal to the line memory means. In addition, since an external line memory element is not required for a signal processing system and the like, and processing can be performed during a video scanning period, processing can be performed. Adoption of a slow CPU becomes possible, it is possible to realize an image input device suitable for miniaturization and cost reduction.

[0009]

Next, an embodiment will be described. FIG. 1 is a block diagram showing a first embodiment of the image input apparatus according to the present invention. In FIG. 1, 1 is m
A non-destructive readable two-dimensional pixel array composed of × n (vertical × horizontal) pixels, 2 is a vertical scanning circuit, 3 is a horizontal scanning circuit, and a video output is obtained from the horizontal scanning circuit 3 in the same manner as a normal image sensor. It has become. Reference numeral 4 denotes a strobe light emitting device, and 5-1 denotes a first line memory for reading and storing a video signal of a specific row (i-th row) of the pixel array 1 before emission of the strobe light emitting device 4, and 5-2 denotes a strobe light emitting device 4.
Is a second line memory for reading and storing the video signal of the same specific row (i-th row) of the pixel array 1 immediately after the light emission of the i-th row, and before the flash emission of the i-th row stored in the first line memory 5-1. A line processing circuit for reading out the video signal of the i-th row stored in the second line memory 5-2 immediately after the flash emission and forming a difference signal between them.
Controls the operation of each of the above components, and detects a focus (A) based on the difference signal formed by the line processing circuit 6.
F) A control circuit (CPU) that outputs a signal, an exposure (AE) control signal, and a white balance (WB) control signal. The first and second line memories 5-1 and 5
-2 are provided in parallel for each column of the two-dimensional pixel array 1, and are on-chip together with the line processing circuit.

Next, the operation of the thus configured image input apparatus will be described with reference to the timing chart shown in FIG. This image input device causes the strobe light emitting device 4 to emit light and output a video signal based on the strobe light. Prior to the output of the video signal, before and after the strobe light emission of a specific row (i-th row) of the pixel array 1 is performed. The video signal immediately after is read nondestructively and stored in the first line memory 5-1 and the second line memory 5-2, respectively.
That is, in the first strobe light emission prior to the time t _01, the video signal of the i-th row in the first line memory 5-1 are written and stored by the write control pulse SH-1 sent from the control circuit 7. Next, at time t ₀₂ , strobe light emission is performed under the control of the control circuit 7 of the strobe light emitting device 4. Subsequently, at time t ₀₃ immediately after the strobe light emission,
Write control pulse S also sent from control circuit 7
The video signal of the i-th row is written and stored in the second line memory 5-2 by H-2.

Next, at time t ₁ , scanning for outputting a video signal is started, and before and immediately after the strobe light emission of the same row stored in the first and second line memories 5-1 and 5-2. And a line processing circuit 6 performs difference processing to generate a difference signal between them, thereby forming a video signal of a specific row based on the strobe light from which an external light component and an offset component have been removed, and a time t ₂ in on the basis of the video signal, focus detection (focus determination processing) operation or the control circuit 7, an exposure control signal, forming a white balance control signal, and outputs at time t ₃ ~t ₄ as a feedback signal, the following Correct the focus of the optical system and the setting of the light source intensity before the flash fires.

As described above, the video signal of a specific row before and immediately after the strobe light emission is stored in the image sensor without being output to the outside, and based on the video signal, a focus detection signal, an exposure control signal, a white balance control signal, and the like. So that a video signal for focus detection can be stored at a higher speed than when a focus detection signal, an exposure control signal, and a white balance control signal are formed using a normal video signal. Even when the position of the specific row on the image is changed, the video signal of the specific row can be stored at the same timing. Further, since the video signal of the specific row is read nondestructively, image information can be obtained without loss of image information for subsequent scanning for video signals.

Further, as described above, video information for focus detection and the like is taken in based on the video signal of a specific row immediately before and immediately after the flash emission in which the flash operation is performed at the beginning of one frame. Since the writing of the video signal read before and after the light emission to the line memory is performed in parallel and does not require any extra time, the time during which the video signal is scanned after storing the video signal of the specific row is used as the processing time. This makes it possible to use a CPU with a low processing speed as a control device.

Further, in the above-described embodiment, a description has been given of a case where the specific row of the pixel array to be read before and immediately after the emission of the strobe light is one row. Alternatively, video signals immediately after the light emission may be read, and based on these video signals, the focus detection processing operation and the formation processing of the exposure control signal and the white balance control signal may be performed. In this case, a line memory is configured corresponding to the number of read lines.

Next, a second embodiment will be described. FIG. 3 is a block diagram showing a second embodiment.
In this embodiment, there is a case where it is desired to capture a video signal obtained by strobe light more accurately, that is, a case where it is desired to capture a video signal of only a strobe light emission component. Even if a difference signal from the previous video signal is formed, the external light component during the flash emission will enter, so the external light component during the flash emission is removed, and the external light removal accuracy is further improved. It is to make it.

That is, as shown in FIG. 3, a third line memory 5-3 is additionally provided in addition to the first and second line memories 5-1 and 5-2. as shown, in the first line memory 5-1, the first embodiment and the same timing t ₀₁ in the video signal read from a particular row of the pixel array 1 (i line) before emission of the flash device 4 Is stored in the second line memory 5-2.
The video signal read from the same row of the pixel array 1 is stored at time t ₀₂ immediately before the flash device 4 emits light, and then the flash light is emitted at time t ₀₃ , and the third line memory 5-3 stores the video signal. Immediately after the flash device 4 emits light t ₀₄
, The video signal read from the same row of the pixel array 1 is stored.

Then, the video signal stored in the first line memory 5-1 is transferred to the SIG _SH1 and the second line memory 5
Assuming that the video signal stored in -2 is SIG _SH2 and the video signal stored in the third line memory 5-3 is SIG _SH3 , the following expressions (1) and (2) can be obtained. . SIG _SH2 = SIG _SH1 + E _DARK × (t _02- t ₀₁ ) ... (1) SIG _SH3 = SIG _SH1 + E _DARK × (t _04- t ₀₁ ) + E _SIG ... () 2) Here, E _DARK × t represents a signal component due to external light, and E _SIG represents a signal component due to strobe exposure. The above (1),
When E _SIG is obtained from the equation (2), the following equation (3) is obtained. E _SIG = SIG _SH3 -{(t ₀₄ -t ₀₁ ) / (t ₀₂ -t ₀₁ )} x SIG _SH2 + {(t ₀₄ -t ₀₁ ) / (t ₀₂ -t ₀₁ )} x SIG _SH1 ... (3) By performing the difference processing of the above equation (3) in the line processing circuit 6, the external light component during the emission of the strobe light is also removed, and a video signal based on only the strobe light with improved external light removal accuracy is generated. can do.

Also in this embodiment, the number of lines of the pixel array to be read before, immediately before, and immediately after the emission of the strobe light is a plurality of lines, and the video signals in the plurality of line regions are read out, and the focus detection processing operation is performed based on the readout. Alternatively, a process of forming an exposure control signal and a white balance control signal may be performed.

[0019]

As described above with reference to the embodiments, according to the present invention, a strobe light emitting device and a non-destructive readable two-dimensional solid-state imaging device are used, and before and immediately after the strobe light emitting device emits light. The non-destructive read-out video signal of at least one or more specific lines of the two-dimensional solid-state imaging device is stored in the line memory means, and the difference processing of the stored video signals before and after light emission is performed. It is possible to perform focus detection, exposure control, and auto white balance control at high speed and with high accuracy based on a video signal of a specific row from which an external light component and an offset component have been removed, and store it in the line memory means. The video information is held in the pixels by non-destructively reading out the video signal when performing the operation. It is possible to scan and output signals, and furthermore, an external line memory element is not required for the signal processing system and the like, and processing can be performed during the video scanning period, so that a CPU with a slow processing speed can be adopted, and the size can be reduced. An image input device suitable for cost reduction and cost reduction can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of an image input device according to the present invention.

FIG. 2 is a timing chart for explaining the operation of the first embodiment shown in FIG.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a timing chart for explaining the operation of the second embodiment shown in FIG. 3;

[Explanation of symbols]

 Reference Signs List 1 pixel array 2 vertical scanning circuit 3 horizontal scanning circuit 4 strobe light emitting device 5-1 first line memory 5-2 second line memory 5-3 third line memory 6 line processing circuit 7 control circuit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/335 H04N 5/335 Z 9/04 9/04 BF Term (Reference) 2H002 DB02 DB20 HA05 HA24 JA07 2H053 BA82 DA03 5C022 AB00 AB06 AB15 AB26 AC42 5C024 AA05 CA19 DA01 FA01 HA18 HA24 5C065 BB02 BB11 BB41 DD01 GG22 GG30

Claims (4)

[Claims] 1. A two-dimensional solid-state imaging device capable of non-destructively reading a video signal obtained by photoelectrically converting light from a subject, and a strobe light emitting unit for irradiating the subject with auxiliary light. Line memory means capable of storing video signals of an arbitrary plurality of rows of the two-dimensional solid-state image sensor, and images of at least one or more lines of the two-dimensional solid-state image sensor before and immediately after light emission of the strobe light emitting means Reading the signal non-destructively and storing it in the line memory means,
An image input device comprising: a difference processing unit that performs a difference process between a video signal before light emission and a video signal immediately after light emission stored in the line memory unit. 2. The image processing apparatus according to claim 1, further comprising signal processing means for performing at least one signal processing of focus detection, exposure control, and white balance adjustment based on the signal subjected to the difference processing by the difference processing means. The image input device according to claim 1. 3. The image input device according to claim 2, wherein the signal processing unit is configured to perform the signal processing during one frame scanning period of the two-dimensional solid-state imaging device. 4. A memory element constituting said line memory means is provided in parallel for each column of said two-dimensional solid-state image pickup device, and said memory element is provided before and after light emission of said strobe light emitting means.
When non-destructively reading out video signals of at least one line of the same line of the three-dimensional solid-state imaging device, the image data is stored in the memory element in parallel on a row-by-row basis to perform difference processing. Item 4. The image input device according to any one of Items 1 to 3.