JP3670367B2 - CCD signal readout control device for CCD television camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a CCD television camera that uses a CCD (Charge Transfer Device) as an imaging device, and more particularly to a CCD signal readout control device including an electronic shutter.
[0002]
[Prior art]
As is well known, a CCD signal readout control device used for a CCD television camera is incident on the CCD for about 1/60 second or about 1/50 second (depending on the television system such as NTSC, PAL, SECAM, etc.). Light is accumulated and read out as a video signal during the vertical blanking period. Hereinafter, the NTSC system will be described as an example.
[0003]
By the way, in the CCD signal readout control device, when an object moving at high speed is picked up, incident light is accumulated for 1/60 second, so that the images overlap (blur) and a clear image cannot be obtained. Therefore, an electronic shutter is used so that the light accumulation time can be shortened appropriately so that the images do not overlap even if the subject moves at high speed.
[0004]
On the other hand, in a CCD television camera device, two pixels in the vertical direction are added to prevent line flicker (if the pixels in the vertical direction of the CCD are read as they are, the resolution becomes too high and flicker is generated). Therefore, the vertical resolution is lower than the number of vertical scanning lines.
[0005]
That is, since the number of vertical scanning lines in the NTSC system is about 483, if the CCD is read out as it is, the vertical resolution is about 483. However, since reading is performed by adding two pixels, the number of scanning lines is about 360 and the vertical resolution is lowered. The reason why the vertical resolution does not decrease up to 240 lines is that the combination of pixels is changed by the field offset method.
[0006]
Therefore, conventionally, the above-described electronic shutter is used to improve the vertical resolution.
That is, in order to increase the vertical resolution, pixels between the pixel readout of the n-th line and the pixel readout of the (n + 1) -th line may be read out and used in consideration of the balance between the line flicker and the vertical resolution. To read out one pixel and a pixel that is a fraction of one pixel, read one pixel normally, read the other pixel with a shutter, and add (reduce the light accumulation time). Thus, pixel readout between one and two scanning lines can be performed, and the vertical resolution can be improved as compared with normal readout.
[0007]
However, in the CCD signal readout control device of the conventional CCD television camera device having the electronic shutter as described above, when the vertical resolution is improved by using the electronic shutter, the electronic shutter inherent high-speed subject blurring prevention function is exhibited. It becomes impossible. On the other hand, if the high-speed subject is prevented from being shaken by the electronic shutter, the vertical resolution cannot be improved.
[0008]
[Problems to be solved by the invention]
As described above, the CCD signal readout control device of the conventional CCD television camera has a problem that the electronic shutter can perform only one of either high-speed subject blur prevention or vertical resolution improvement.
[0009]
An object of the present invention is to provide a CCD signal readout control device for a CCD television camera that can solve the above-described problems and can simultaneously realize high-speed subject blur prevention and vertical resolution improvement using an electronic shutter. It is in.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is a CCD that is incorporated in a television camera and controls charge readout of an imaging CCD (charge transfer device) driven on the basis of a vertical synchronization signal and a horizontal synchronization signal in a field unit. In a CCD signal readout control device for a television camera, an electronic shutter that controls the incident light accumulation time of the imaging CCD according to a shutter speed, and a maximum allowable time of the light accumulation time for the CCD within the field period As the time, shutter speed control means for controlling the shutter speed of the electronic shutter independently and independently in the first field and the second field that are repeated continuously, and different sets in the first field and the second field Accumulated in each pixel arranged in the vertical direction for two adjacent lines And an addition reading means for adding and reading the load, wherein the shutter speed control means is adapted to a normal shooting mode for taking an image at a shutter speed for obtaining a light accumulation time corresponding to the reference time in each of the first and second fields. The shutter speed of the first field is made to correspond to the high-speed subject photographing mode by controlling the shutter speed of the first field so that the light accumulation time becomes shorter than the reference time, and the shutter speed of the second field is set to the shutter speed of the first field. It was made to correspond to the vertical high-resolution shooting mode by controlling to be shorter .
[0011]
In particular, the shutter speed control means sets the shutter speed of each field based on a horizontal synchronization signal and a vertical synchronization signal for driving the CCD.
The shutter speed control means counts the clock pulse, a clock pulse generator that generates a clock pulse synchronized with the horizontal synchronization signal, a reset pulse generator that generates a reset pulse synchronized with the vertical synchronization signal, and and a counter for outputting a light accumulation control signal to the CCD to the from the time the count value reaches the preset value reset pulse is input, detects the vertical blanking period from the vertical synchronizing signal, said that period the first field in the preset corresponding to the shutter speed during fast object shooting value, such that the in the second field and a preset means for preset preset value corresponding to the shutter speed during vertical high resolution photography to the counter did.
[0012]
Alternatively, the shutter speed control means includes a clock pulse generator that generates a clock pulse synchronized with the horizontal synchronization signal, a reset pulse generator that generates a reset pulse synchronized with the vertical synchronization signal, Counting, and detecting a vertical blanking period from the vertical synchronization signal, and first and second counters that output an optical accumulation control signal from when the count value reaches a preset value until the reset pulse is input , A preset value corresponding to the shutter speed at the time of high-speed subject shooting used in the first field is preset in the first counter during that period, and the preset value corresponding to the shutter speed at the time of vertical high-resolution shooting used in the second field. Preset means for presetting a value in the second counter; Was set to and a switching means for deriving the output of said first and second counter alternately every the vertical blanking period in accordance with the first and second fields.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows the configuration of the CCD readout control apparatus of the first embodiment. In FIG. 1, reference numeral 11 denotes a synchronizing signal generating circuit which generates a horizontal synchronizing signal HD and a vertical synchronizing signal VD of a television signal. The horizontal synchronization signal HD is supplied to the clock pulse generation circuit 12, and the vertical synchronization signal VD is supplied to the MPU (microprocessor) 13 and the reset pulse generation circuit 14.
[0014]
The clock pulse generation circuit 12 generates a horizontal synchronization pulse using the horizontal synchronization signal HD as a trigger, and the reset pulse generation circuit 14 generates a reset pulse using the vertical synchronization signal VD as a trigger. Both the horizontal synchronization pulse and the reset pulse are supplied to the counter 15.
[0015]
This counter 15 is a presettable counter for determining the CCD light accumulation time, stores the preset value given from the preset circuit 16, counts the horizontal synchronization pulse, and counts up and outputs when the count value reaches the preset value. Set the level to high level. Further, the count value is reset by inputting a reset pulse, and the output level is returned to the low level.
[0016]
The output of the counter 15 is supplied to the CCD drive circuit 17. The CCD driving circuit 17 drives and controls the charge transfer of the CCD 18 based on the vertical synchronizing signal VD and the horizontal synchronizing signal HD, and controls the period when the output of the counter 15 is high with respect to the CCD 18 as the light accumulation time. The charge of each pixel of the nth line and the (n + 1) th line is added and outputted.
[0017]
On the other hand, this CCD signal readout control device includes a mode selection / shutter speed switching circuit 19. This circuit 19 selects one of four modes: (1) normal shooting mode, (2) high-speed subject shooting mode, (3) high-resolution mode, and (4) high-speed subject shooting + high-resolution mode, and (2 ) To (4) have a function of manually or automatically selecting the shutter speed.
[0018]
The MPU 13 calculates a counter preset value corresponding to the CCD light accumulation time from the mode and shutter speed set by the mode selection / shutter speed switching circuit 19 and stores the calculation result in the preset circuit 16. Then, the vertical synchronization signal VD is monitored to determine the vertical blanking period. For example, the first preset value during the vertical blanking period of the odd field and the second preset value during the vertical blanking period of the even field. Is given to the preset circuit 16 so as to be preset in the counter 15.
[0019]
In the above configuration, the operation for each mode will be described below with reference to FIG. Here, it is assumed that the television camera adopts the NSTC system. In FIG. 2, (a) is a normal shooting mode, (b) is a high-speed subject shooting mode, (c) is a high-resolution mode, and (d) is light in odd and even fields in the case of high-speed subject shooting + high-resolution mode. The accumulation time is shown.
[0020]
Although the light accumulation time in the normal photographing mode is strictly shorter than 1/60, for the sake of simplicity, the light accumulation time will be described below as 1/60 seconds.
First, when the normal shooting mode is selected by the mode selection / shutter speed switching circuit 19, the MPU 13 stores the preset values P1 and P2 as "0" in the odd number field and even number field in the preset circuit 16, and the vertical blanking period. The preset value P1 = "0" and P2 = "0" are sequentially preset in the counter 15.
[0021]
Therefore, the counter 15 counts up from the end of the vertical blanking period in each field, and keeps the output level high until a reset pulse is given by the next vertical synchronization signal. As a result, as shown in FIG. 2A, the light accumulation time is 1/60 seconds in both the odd field and the even field, and the maximum allowable time is set.
[0022]
Next, when the high-speed subject photographing mode is selected, the MPU 13 calculates preset values P1 and P2 (P1 = P2) corresponding to the shutter speed setting values in both the odd field and the even field, and stores them in the preset circuit 16. The preset values P1 and P2 stored during the vertical blanking period are sequentially preset by the counter 15.
[0023]
The counter 15 counts the vertical synchronization pulse at P1 and P2 in each field and sets the CCD 18 as the light accumulation time through the CCD drive circuit 16 until the vertical synchronization signal is reset. In this case, since P1 = P2, as shown in FIG. 2B, the light accumulation time is the same for both the odd field and the even field, and both are shortened by an amount corresponding to the shutter speed setting value with respect to 1/60 seconds. .
[0024]
Subsequently, when the high resolution mode is selected, the MPU 13 calculates a preset value P2 corresponding to the shutter speed setting value for the even field and sets the preset value P1 to “0” for the odd field, Store. Then, the preset values P1 and P2 stored during the vertical blanking period are sequentially preset by the counter 15.
[0025]
The counter 15 counts up from the end of the vertical blanking period because P1 = “0” in the odd field, but counts up when the count value reaches the preset value P2 in the even field. Therefore, as shown in FIG. 2C, the light accumulation time is 1/60 second in the odd field, but is shortened by an amount corresponding to the shutter speed setting value in the even field.
[0026]
When the high-speed subject photographing + high resolution mode is selected, the MPU 13 obtains preset values P1, P2 corresponding to the shutter speed setting value for high-speed subject photographing and the shutter speed setting value for high resolution, respectively, and the preset circuit 16 The counter 15 is preset to P1 in the odd field and P2 in the even field.
[0027]
As a result, since an arbitrary preset value is set in the counter 15 for each field, the light accumulation time of the CCD 17 is equivalent to the shutter speed setting value individually set for each field as shown in FIG. Shorter.
[0028]
Therefore, since the CCD signal readout control device having the above configuration can control the light accumulation time of the odd field and the even field for each mode, in addition to normal shooting, high-speed subject shooting, high-resolution shooting, and high-speed subject + high-resolution shooting are all available It can be realized in an optimal state.
[0029]
In the above-described embodiment, the odd field is used as a reference. However, the present invention can be similarly implemented using the even field as a reference. Although the shutter is read for a time shorter than 1/60 seconds, there is a method of obtaining a shutter speed slower than 1/60 seconds by changing the CCD reading method.
[0030]
FIG. 3 shows the configuration of the second embodiment according to the present invention. In FIG. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted here.
[0031]
This CCD signal readout control device includes two counters 151 and 152. One counter 151 is used for high-speed subject shooting, and the other counter 152 is used for high-resolution shooting. Both counters count the horizontal synchronization pulse from the clock pulse generation circuit 12 described above, and the counter pulse from the reset pulse generation circuit 14. The count value is cleared by a reset pulse.
[0032]
The counters 151 and 152 are presettable counters, which store preset values from the corresponding preset circuits 161 and 162. When the count values reach the preset values, the counters 151 and 152 are incremented and a reset pulse is input. Until the output level is high.
[0033]
On the other hand, the MPU 13 calculates a counter preset value corresponding to the CCD light accumulation time in each of the odd field and the even field from the mode and shutter speed set by the mode selection / shutter speed switching circuit 19, and the calculation result is the preset circuit. 161 and 162. Then, the vertical synchronizing signal VD is monitored to determine the vertical blanking period, and during the vertical blanking period of the odd field, the preset circuit 161 is activated to execute the data preset to the counter 151, and the vertical blanking of the even field is performed. During the ranking period, the preset circuit 162 is activated to execute data preset to the counter 152.
[0034]
The outputs of the counters 151 and 152 are selectively sent to the CCD drive circuit 17 by the switch 20. The switch 20 is sequentially switched by the switching control circuit 21 at the input timing of the vertical synchronizing signal VD. That is, the output of the counter 151 is sent to the CCD drive circuit 17 in the odd field, and the output of the counter 152 is sent to the CCD drive circuit 17 in the even field.
[0035]
In the CCD readout control apparatus having the above-described configuration, the light accumulation time of the odd field can be set by the counter 151, and the comparative accumulation time of the even field can be set by the counter 152. Therefore, as in the first embodiment, the normal photographing mode and the high speed The light accumulation time can be freely set as shown in FIGS. 2A to 2D for each of the four modes of the subject photographing mode, the high resolution mode, and the high speed subject photographing + high resolution mode.
Although the NTSC system has been described in the above embodiment, the present invention can be similarly applied to other television systems.
[0036]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a CCD signal readout control device for a CCD television camera that can simultaneously achieve high-speed subject blurring and improved vertical resolution using an electronic shutter. .
[Brief description of the drawings]
FIG. 1 is a block circuit diagram showing a configuration of a first embodiment of a CCD signal readout control device of a CCD television camera according to the present invention.
FIG. 2 is a timing diagram for explaining the operation of each mode according to the embodiment, in which (a) is a normal shooting mode, (b) is a high-speed subject shooting mode, (c) is a high-resolution mode, and (d) is a high-speed mode. It is a figure which shows the light accumulation time of the odd number field and the even number field in the case of subject photographing + high resolution mode.
FIG. 3 is a block circuit diagram showing a configuration of a second embodiment of a CCD signal readout control device of a CCD television camera according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Synchronization signal generation circuit 12 ... Clock pulse generation circuit 13 ... Microprocessor (MPU)
14 ... Reset pulse generation circuit 15, 151, 152 ... Counter 16, 161, 162 ... Preset circuit 17 ... CCD drive circuit 18 ... CCD
19: Mode selection / shutter speed switching circuit 20 ... Switch 21 ... Switching control circuit

Claims (4)

In a CCD signal readout control device of a CCD television camera that controls charge readout of an imaging CCD (charge transfer device) incorporated in a television camera and driven based on a vertical synchronization signal and a horizontal synchronization signal.
An electronic shutter for controlling the incident light accumulation time of the imaging CCD according to the shutter speed;
A shutter speed for controlling the shutter speed of the electronic shutter independently and independently between the first field and the second field, which are repeated continuously, with the maximum allowable time of light accumulation time for the CCD within the period of the field as a reference time. Control means;
Addition reading means for adding and reading out charges accumulated in each of the pixels arranged in the vertical direction for two adjacent lines of different sets in the first field and the second field;
The shutter speed control means sets the shutter speed of the first field to the light accumulation time for the normal shooting mode in which the first and second fields are photographed at a shutter speed that obtains the light accumulation time corresponding to the reference time. By controlling so that the shutter speed of the second field is shorter than the shutter speed of the first field while controlling the shutter speed to be shorter than the reference time, the shutter speed of the second field is controlled to be shorter than the shutter speed of the first field. A CCD signal readout control device for a CCD television camera, characterized in that it corresponds to a mode . 2. The CCD signal readout control device for a CCD television camera according to claim 1, wherein the shutter speed control means sets the shutter speed of each field based on a horizontal synchronization signal and a vertical synchronization signal for driving the CCD. . The shutter speed control means counts the clock pulse, a clock pulse generator that generates a clock pulse synchronized with the horizontal synchronization signal, a reset pulse generator that generates a reset pulse synchronized with the vertical synchronization signal, A counter that outputs a light accumulation control signal to the CCD from when the count value reaches a preset value until the reset pulse is input, and a vertical blanking period is detected from the vertical synchronization signal, and the first blanking period is detected during that period . preset field corresponding to the shutter speed during high-speed shooting an object value, and in the second field and characterized in that it comprises a preset means for preset preset value corresponding to the shutter speed during vertical high resolution photography to the counter The CC of the CCD television camera according to claim 1 Signal readout controller. The shutter speed control means counts the clock pulse, respectively, a clock pulse generator that generates a clock pulse synchronized with the horizontal synchronization signal, and a reset pulse generator that generates a reset pulse synchronized with the vertical synchronization signal. Detecting a vertical blanking period from the first and second counters that output an optical accumulation control signal from the time when the count value reaches a preset value until the reset pulse is input, and the vertical synchronization signal; The preset value corresponding to the shutter speed at the time of high-speed subject shooting used in the first field is preset in the first counter, and the preset value corresponding to the shutter speed at the time of vertical high-resolution shooting used in the second field is set. Preset means for presetting the second counter; Beauty second counter outputs of said first and CCD television camera according to claim 1, wherein in accordance with the second field, characterized in that it comprises a switching means for deriving alternately every the vertical blanking period CCD signal readout control device.

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