JP3854455B2 - Viewfinder device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a viewfinder device for a television camera.
[0002]
More specifically, the present invention relates to a novel viewfinder device that displays a video signal read from an area-divided parallel readout image sensor.
[0003]
[Prior art]
In general, a viewfinder device of a television camera displays a video signal having the same standard as the standard (horizontal, vertical drive frequency, etc.) of a signal output from the television camera.
[0004]
On the other hand, an area-divided parallel readout image sensor is known as an image sensor for performing ultrahigh-definition imaging. For example, a paper by Smith et al. (C. Smith el al .: “An 8M-CCD for an Ultra High Definition TV Camera”, 1999 IEEE Workshop on Charge-Coupled Devices and Advanced Image Sensors, pp. 175-178 (1999)) Announced an ultra-high-definition image sensor with 8 million pixels.
[0005]
101 of FIG. 1 is a diagram schematically illustrating an area-divided parallel readout image sensor. This area-divided parallel readout imaging device 101 divides the imaging surface into 16 and reads out signals through different output channels. By doing so, it is possible to avoid the limitation of the number of pixels due to the reading speed per output channel of the imaging device, and it is possible to perform ultrahigh-definition imaging by combining a plurality of outputs.
[0006]
[Problems to be solved by the invention]
When a conventionally known viewfinder technique is applied to this type of region-divided parallel readout image sensor, the entire image output is synthesized and then displayed on the viewfinder display.
[0007]
However, a viewfinder device for a television camera using this type of area-divided parallel readout image sensor has not been realized yet.
[0008]
The reason is as follows: (1) Ultra high-definition video signals obtained by synthesizing signals from area-divided parallel readout elements have a very high data rate, so that they can be applied as they are to conventional view funders that have been known so far. (2) Even if the display pixel number is simply reduced, the details of the subject cannot be displayed on the viewfinder, and focusing becomes impossible. is there.
[0009]
In particular, it is clear from the comparison between the NTSC system and the high vision system that focusing becomes difficult in a multi-pixel camera. In conventional viewfinders, as a method to solve this problem, a method of substituting spatial high frequency components by spatial offset sub-Nyquist sampling to temporal frequency to assist focusing (Okano et al .: “Focus Indicator”, TV Science and Technology Bulletin, Vol.11, No.10, pp.1-5, (1987)) has been proposed. However, it can be said that this method has room for further improvement from the viewpoint of a simple device configuration or a simple circuit configuration.
[0010]
Accordingly, an object of the present invention is to provide a viewfinder device that enables a reliable and easy focusing operation despite a simple circuit configuration in which the number of display pixels is reduced in view of the above points.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, the display data amount of a television camera using a region-divided parallel readout element is reduced by performing sub-Nyquist sampling between field offset spaces, and at the same time By making a sub-Nyquist sample, the flicker phenomenon that occurs in the outline / stripe pattern portion of the viewfinder screen can be used for focusing of an ultra-high-definition television camera.
[0012]
That is, the present invention is a viewfinder device that displays a video signal read from a region-divided parallel readout image sensor, and reads out the video signal in parallel from each imaging region of the region-divided parallel readout image sensor. And sampling means for sampling the inter-field offset space sub-Nyquist sampling for each imaging region, and sampling data for each imaging region output from the sampling means. And combining means for forming a single image and display means for visually displaying the signal output from the combining means.
[0013]
Here, the sampling means may include an AD converter that converts an analog video signal read from each imaging region of the region-divided parallel readout imaging device into a digital signal.
[0014]
The inter-field offset space sub-Nyquist sampling for each imaging region is performed by using a first field clock pulse and a second field clock formed by thinning out every other pixel clock pulse as a drive clock pulse of the AD converter. This can be done by using pulses.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0016]
FIG. 1 is a circuit diagram showing a viewfinder device to which the present invention is applied. In this figure, 101 is a region-divided parallel readout imaging device having regions a to p, 102a is an output signal from the region a, 103 is an AD converter, 104 is a first-in first-out (FIFO) memory, 105 Is a timing pulse generator (TGW) for AD conversion processing and memory writing, 106 is a timing pulse generator (TGR) for memory reading, 108a is a converted signal of region a, 108b to 108p are regions b to The converted signal in the region p, 109 is a multiplexer, 110 is a timing pulse generator (TGM) for switching the multiplexer, 111 is a DA converter, and 112 is a display.
[0017]
Here, it is assumed that the area-divided parallel readout image sensor 101 is divided into two in the vertical direction and eight in the horizontal direction and has 16 outputs. Each region is labeled with a to p. Since the video output from each of the areas a to p is processed in parallel, the following description will describe the process for the output signal 102a from the area a. That is, the remaining signals 108b to 108p input to the multiplexer 109 are all subjected to the same processing, and thus description thereof is omitted.
[0018]
The output signal 102 a is sampled and quantized by the AD converter 103 and stored in the FIFO memory 104. At that time, the timing pulse generator (TGW) 105 supplies the AD converter 103 and the FIFO memory 104 with the timing pulse shown in FIG. 3 so that the sampling pattern shown in FIG.
[0019]
Here, 201 in FIG. 2 indicates a sampling structure of an area-divided parallel readout imaging device 8 × 8 pixels, 202 indicates a sampling point in the first field, 203 indicates a sampling point in the second field, and 204 indicates a point that is not sampled. . In FIG. 3, 301 is a vertical synchronizing signal, 302 is a vertical output waveform of TGW (timing pulse generator 105), 303 is a horizontal synchronizing signal, 304 is a horizontal output waveform of TGW, and 305 is a pixel clock (= system clock). 306 is a first field odd line waveform, 307 is a second field odd line waveform, and 308 is an even line waveform.
[0020]
Thereby, the signal of area | region a is stored in the FIFO memory 104 which is a frame memory. Note that in the case where signals are output in the reverse order to the scanning of the image displayed in the region a of the region-divided parallel readout image sensor 101, the FIFO memory 104 may be replaced with a LIFO (Last-In First-Out) memory.
[0021]
In the next frame, the signal stored in the FIFO memory 104 is read according to the pulse shown in FIG. 4 provided by the timing pulse generator (TGR) 106, and becomes a signal 108a.
[0022]
4, 401 is a vertical synchronization signal, 402 is a vertical output waveform of TGR (timing pulse generator 106), 403 is a horizontal synchronization signal, 404 is a horizontal output waveform of TGR, 405 is a pixel clock, and 406 is a TGR signal. It is an output waveform.
[0023]
The other areas b to p are also read out by pulses corresponding to the positions of the respective areas in the screen (indicated by broken lines in FIG. 4B), and become signals 108b to 108p.
[0024]
These signals 108 a to 108 p are input to the multiplexer 109 in parallel. The switching timing of the multiplexer 109 is determined by a timing pulse generator (TGM) 110 that generates the timing shown in FIG.
[0025]
5, 501 is a vertical synchronization signal, 502 is a vertical output waveform of TGM (timing pulse generator 110), 502a is a region a to h selection unit, 502b is a region i to p selection unit, and 503 is a horizontal synchronization signal. 504 is a TGM horizontal output waveform, 504a is a region a or i selection unit, 504b is a region b or j selection unit, 504c is a region c or k selection unit, 504d is a region d or l selection unit, and 504e is a region e or m selection unit, 504f is a region f or n selection unit, 504g is a region g or o selection unit, and 504h is a region h or p selection unit.
[0026]
The output of the multiplexer 109 is converted into an analog signal by the DA converter 111 and displayed on the display 112.
[0027]
Effect of the present embodiment Through the above operation, the output of the area-divided parallel readout image sensor 101 is subsampled and displayed on the display (display) 112. Thereby, the number of pixels of the display for viewfinder can be reduced to 1/4 of the number of pixels of the TV camera, the signal band can be set to 1/8 of the signal output from the TV camera, and the horizontal drive frequency can be set to 1/4. .
[0028]
In addition, since the high frequency component of the spatial frequency in the TV camera signal is converted to the time frequency and flickers (flickering), the lens is adjusted so that the flickering of the displayed contour / striped pattern is maximized. Photographers can easily focus. That is, since the sample point 202 (white circle) and the sample point 203 (black circle) shown in FIG. 2 are displayed at different times, the subject image that is changing at a spatially high frequency is represented by time. If you look at the axis, it will be displayed at a different timing. Accordingly, when there is a high frequency component in the vertical direction, it becomes flicker and is displayed as an image that changes in the time axis direction. For focusing, it is only necessary to adjust so that the high frequency component is maximized. Therefore, the cameraman may adjust the flicker to the maximum while looking through the viewfinder (display device).
[0029]
Also, if there is a time delay in the video displayed on the viewfinder (display), the cameraman becomes difficult to operate, but the signal delay of this apparatus shown in FIG. 1 is one field, which affects the operability of the cameraman. Does not give. That is, in this apparatus, only a delay of one field occurs due to writing / reading of the FIFO memory 104.
[0030]
【The invention's effect】
As described above, according to the viewfinder device according to the present invention, it is possible to perform the focusing operation reliably and easily despite the simple circuit configuration in which the number of display pixels is reduced.
[0031]
More specifically, in an ultra-high-definition camera using an area-divided parallel readout image sensor, each output from the image sensor is converted into an inter-field offset space sub-Nyquist sample and combined to obtain the number of pixels. It is possible to realize a small number of viewfinder devices, and at the same time, it is possible to assist focusing by visually checking flicker generated by the sampling.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a viewfinder device to which the present invention is applied.
FIG. 2 is a diagram showing sample points of an image displayed on the viewfinder device.
FIG. 3 is a diagram illustrating timing (AD conversion and memory write unit) for obtaining an image to be displayed on the viewfinder device from an image sensor output.
FIG. 4 is a diagram illustrating timing (memory read unit) for obtaining an image to be displayed on the viewfinder device from an image sensor output.
FIG. 5 is a diagram illustrating timing (multiplexer unit) for obtaining an image to be displayed on the viewfinder device from an image sensor output.
[Explanation of symbols]
101 Region-Division Parallel Reading Image Sensor 102a Output Signal 103 of Region a 103 AD Converter 104 FIFO Memory 105 Timing Pulse Generator (TGW) for AD Conversion Processing and Memory Writing
106 Timing Pulse Generator (TGR) for Memory Reading
108a to 108p Converted signal 109 in region a to region p 109 Multiplexer 110 Timing pulse generator (TGM) for multiplexer switching
111 DA converter 112 Display (display)
201 Sampling Structure of Image Sensor 8 × 8 202 First Field Sampling Point 203 Second Field Sampling Point 204 Non-sampling Point 301 Vertical Synchronization Signal 302 TGW Vertical Output Waveform 303 Horizontal Synchronization Signal 304 TGW Horizontal Output Waveform 305 Pixel clock (system clock)
306 First field odd line waveform 307 Second field odd line waveform 308 Even line waveform 401 Vertical synchronization signal 402 TGR vertical output waveform 403 Horizontal synchronization signal 404 TGR horizontal output waveform 405 Pixel clock 406 TGR output waveform 501 Vertical synchronization signal 502 TGM vertical output waveform 502a region a to h selection unit 502b region i to p selection unit 503 horizontal synchronization signal 504 TGM horizontal output waveform 504a region a or i selection unit 504b region b or j selection unit 504c region c or k selection Unit 504d region d or l selection unit 504e region e or m selection unit 504f region f or n selection unit 504g region g or o selection unit 504h region h or p selection unit

Claims (3)

A viewfinder device for displaying a video signal read from an area-divided parallel readout imaging device,
Reading means for reading video signals in parallel from each imaging region of the region-divided parallel readout imaging device;
Sampling means for sampling the inter-field offset space sub-Nyquist for each imaging region, the signals read in parallel;
Synthesizing means for synthesizing sampling data for each imaging region output from the sampling means to form a single image;
A viewfinder device comprising display means for visually displaying a signal output from the synthesizing means. The viewfinder device according to claim 1,
The viewfinder device, wherein the sampling means includes an AD converter that converts an analog video signal read from each imaging region of the region-divided parallel readout imaging device into a digital signal. The viewfinder device according to claim 2,
By using the first field clock pulse and the second field clock pulse formed by thinning out every other pixel clock pulse as the drive clock pulse of the AD converter, the inter-field offset space for each imaging region is used. A viewfinder device that performs sub-Nyquist sampling.

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