CN1041485C - TV camera - Google Patents

Abstract

A television camera capable of processing a wide illumination range of an image object without an optical iris diaphragm device on an imaging lens, includes a CCD imaging device (2) for generating a video signal and shutter control means (13, 22) for generating a discharge pulse in synchronization with a horizontal synchronizing signal of the video signal during an image period of the video signal, the discharge pulse being supplied to the CCD at a timing of an integral multiple of the horizontal synchronizing signal during a vertical blanking period, determining a shutter time, and controlling an incident light amount of the object. The television camera also has brightness/color flicker extraction means (23).

Description

TV camera

The present invention relates to a television camera apparatus capable of controlling and correcting the gain of the intensity of a light source for illuminating an object to be imaged, and periodically changing the intensity of the light.

Fig. 2 is a block diagram showing the main structure of a video (image) signal system used in a conventional television camera.

As shown in Figure 2, in the video signal system of the TV camera, the incident light sent from the imaged object (not shown) is incident on the imaging lens 1, and passes through the variable focal length lens used to control the angle of view and used to The focusing lens system, which controls the focal length, reaches the imaging plane of the imaging device 2 . The imaging lens 1 is arranged such that an aperture 14 for controlling the amount of light reaching the imaging device 2 according to the intensity of incident light can be provided, and, if necessary, can output information about a zoom lens system (not shown) and a focusing lens. The position information of the system (also not shown) and the information of the light amount control condition of the aperture device 14 . In the imaging device (hereinafter referred to as "CCD") 2, the image of the object reaching the imaging plane is converted into a line-sequential image (video) signal under the control of the CCD drive control device 13 (hereinafter referred to as "CCD driver"), and the CCD Drivers are discussed below.

It should be understood that the above-mentioned CCD 2 is a solid-state imaging device generally called a CCD, and its detailed description is omitted because its structure and operation are in the prior art. In order to explain the present invention, only a brief description of the term CCD is required.

A CCD is assembled from photoelectric conversion elements in which the screen is divided into a large number of pixels, electron charges whose amount depends on incident light to each pixel are introduced, and the introduced charges are accumulated during an instant. CCDs also have horizontal and vertical transfer paths (using a type of register known as a "charge-coupled device") that are used to extract electronic charges accumulated on the elements as line-sequential image signals. In normal operation, all electronic charge accumulated on the element is transferred to the vertical transfer path in response to an applied control signal during each field of the line sequential video signal, and immediately thereafter, the electronic charge is stored in the order of to the incident light emitted from the object corresponding to the next field. In such a CCD with a built-in shutter function, when the shutter is selected to be operated (that is, a discharge pulse is output from the CCD driver 13), the electronic charge accumulated on the element responds to the discharge pulse through a preparatory channel different from the transfer path. The access is released (extracted), and the discharge pulse is applied for a preselected time period during the field period (this discharge operation can be performed several times during a field). Then, the electron charge stored just after this discharge operation is transferred to the vertical transfer path for a period corresponding to the opening of the shutter (a time interval during which the shutter is opened).

It should be noted that the electron charges that have been transferred to the vertical transfer path are transferred to the horizontal transfer path of each pixel array arranged in the horizontal direction during each horizontal scanning period, and are output as line-sequential video signals.

The line-sequential video signal converted by the CCD 2 is sent to a signal processing device 3 (hereinafter referred to as "CDS/AGC") to remove a noise signal specific to the CCD itself and adjust the video signal to generate a video signal of a predetermined amplitude. The signal output from the CDS/AGC is sent to the brightness (Y)/color (C) signal separation device 4 (hereinafter referred to as "Y/C separator), and the output is separated into a brightness signal and a color signal. In the Y/C In the separator 4, the high-frequency component (Yh) of the luminance signal, the low-frequency component (Ye) of the luminance signal, and the red component (R) and blue component (B) of the main color signal are separated by means of frequency band separation, and synchronously detected The signal is also disclosed. Then, the high-frequency component (Yh) and the low-frequency component (Ye) of the luminance signal are sent to the luminance signal processing device 5 (hereinafter referred to as "Y processor"), in which, for example, linear correction (ca horse correction), horizontal/vertical contour correction and other preselected signal processing operations to generate a luminance signal.

On the other hand, the low-frequency component (Ye) of the luminance signal and the red component (R)/blue component (B) of the original color signal are supplied to a white balance control device 6 (hereinafter referred to as "WB controller"), in which , the respective amplitudes of these signals are adjusted to control reproduction of white, and the white balance signal is sent to a color signal processing device 7 (hereinafter referred to as "C processor"). Then, the C processor 7 produces two color difference signals (R-Ye) and (B-Ye), and the two color difference signals are converted into a form having a carrier color signal (C) by means of an encoder 8 (hereinafter referred to as "ENC") signal of.

The signal processing operation described above is the basic configuration/operation of a television camera. Next, a description of additional configuration/operation of the television camera is made.

In the case where the television camera has a function of automatically controlling the opening of the aperture device 14 in response to the intensity of incident light from an object to be imaged, the luminance signal (Y) output from the Y processor 5 is sent to the aperture control device 15 to thereby This way automatically controls the opening of the aperture device 14 so that the value of the luminance signal (Y) is limited within a predetermined range.

In the case that the television camera has a function of being able to set white reproduction according to the light source illuminating the object, the two color difference signals (R-Ye) and (B-Ye) are locked back to the WB control device 6, and then, when the white When reproduction is adjusted (ie, an operation in which the values of the color difference signals (R-Ye) and (B-Ye) are substantially equal to zero and the color of the imaged object is white), it is used as a signal to be controlled.

A so-called "flicker" phenomenon is corrected when television cameras have an automatic flicker detection/correction function and when the brightness of the light source illuminating the object changes periodically with a period twice the period of the AC power supply for the light source, This flicker phenomenon is caused by the amplitude of the video signal changing at a period equal to the difference (beat period) between the field period of the video signal and the luminance change period.

In this automatic flicker detection/correction type TV camera, the luminance signal (Y) output from the Y processor is sent to the flicker detection device 11, in which there is an amplitude change component of a certain period included in the luminance signal Y is taken out, and the amplitude of the changed component is compared with a predetermined reference value to determine whether there is flicker. Then the comparison result signal is supplied to the fixed shutter device 12, which sends a signal corresponding to the predetermined shutter opening time to the CCD driver 13, and then the driver 13 supplies the discharge pulse corresponding to the preselected shutter opening time to the CCD2. It should be noted that although this predetermined shutter opening time can be determined by the above-mentioned beat period, when the frequency of the AC power source driving the light source is 50 H ₂ (that is, the brightness change frequency is H ₂ ), and the field frequency of the video signal is 60 H ₂ , this shutter opening time is generally set to 1/100 second (0.01 second).

Furthermore, in a television camera having other shutter functions, when a fast moving object is photographed, a blurring phenomenon of a still image (single image of a fast moving object) can be prevented in field units. In this TV camera, fixed shutter device 12 supplies a signal corresponding to a shutter opening time selected by an operation unit (not shown), and CCD driver 13 supplies a discharge pulse corresponding to the selected shutter opening signal to CCD2.

In the above-mentioned conventional television cameras, there are problems as follows.

That is, in order to improve the performance of the imaging lens 1, the aperture device 14 generally must be located on such a position, that is to say, this aperture device 14 is positioned on the optical axis of the imaging lens 1, and the light from the imaging object is substantially parallel to the This optical axis travels.

This can hinder the miniaturization of the imaging lens 1, and in addition, the shape of the hole of the opening device is also imaged on the imaging screen to form a so-called "ghost image", and when the area of the hole is small (that is, the number of stops increases), due to Diffraction can degrade the sharpness of the imaging lens.

As described in detail below, when a CCD device having a shutter function is installed, the shutter function of the television camera can be used in place of the aperture device 14 from the viewpoint that the basic amount of incident light converted photoelectrically by the CCD2 is controllable. function, so there are TV cameras in which the shutter function of the CCD2 is used instead of being equipped with the aperture device 14 under certain imaging conditions. However, the controllable shutter opening time (the smallest unit of operating time) is not short enough to cover a bright object. Also, there is no CCD device that has a full variable range (dynamic range) sufficient to cover the amount of incident light from an imaged object. Therefore, in the case of providing a large amount of incident light, flicker phenomenon occurs under this imaging condition, because in order to reduce the amount of incident light, a high-speed shutter operation is selected, which makes the amount of flicker of the luminance signal (Y) and color signal (C) increase (reasons to be stated). In this case, a television camera that replaces the aperture device 14 with the CCD2 shutter function cannot be realized.

Also, in a conventional television camera, when flickering caused by a driving power source of a light source illuminating an imaging object is detected, the shutter operating speed of the CCD 2 is changed to a general shutter operating speed, thereby eliminating the flickering. In such a television camera, there is another problem. That is, the amount of electron charges accumulated on the elements of the CCD 2 is reduced, thereby reducing the brightness sensitivity to the imaged object at the selected shutter operating speed compared with the normal shutter operating speed.

FIG. 1 schematically shows the basic structure of a conventional WB control 6 . In this conventional WB control 6, when the light source illuminating the object is changed, the white balance readjustment is performed under the condition that the imaged object is taken as white by the television camera. In the structure of Fig. 1, the color difference signals (R-Ye) and (B-Ye) output from the C processor 7 are respectively fed back to the averaging means 61 and 62, where these color difference signals are respectively integrated in the time domain to obtain the averaged signal . This average signal is supplied to comparison means 63 and 64, in which these average color difference signals (R-Ye) and (B-Ye) are compared with an automatic white reference voltage (EW). The automatic white reference voltage (EW) has a value corresponding to the color difference signals (R-Ye) and (B-Ye) for achromatic color. Through the switch means 65 and 66, the result signal of the comparison (respective difference components) carried out in the comparison means 63, 64 is sent to the gain control means 67.68, whose gain is controlled and maintained in such a way that the average color difference signal (R-Ye ) and (B-Ye) are matched with the automatic white reference voltage (EW) respectively.

It should be noted that this control is initiated by turning on switches 65 and 66, and that switches 65, 66 are opened when the average color difference signals (R-Ye) and (B-Ye) match the automatic white reference voltage (EW) . The actual adjustment operation and release of these switches 65 and 66 is accomplished and terminated automatically, generally after this operation has been manually initiated.

In order to solve the problems referred to above, the invention provides following device:

In a television camera so set according to the shutter operation of the imaging device, the imaging device is used to photoelectrically convert the optical image focused on the imaging plane by means of an optical lens, so that the photoelectrically converted optical image signal is used as a line sequence video signal output, the amplitude of the video signal output from the imaging device is controlled so that the amplitude of the video signal is maintained within a predetermined range which is related to changes in the amount of incident light from the imaged object, said television Cameras include at least:

A normal discharge pulse generator, used to generate a pulse sequence with predetermined timing synchronously with the horizontal synchronization signal of the video signal in the horizontal blank period;

N-times discharge pulse generating means for generating a pulse sequence equal to a value obtained by multiplying an integer by a horizontal synchronizing signal of the video signal during at least a vertical blanking period of the video signal; and

A shutter time determining device for determining a shutter time in response to a luminance signal of the video signal, wherein:

When the timing of the discharge pulse determined by the shutter time determining means occurs within the image period of the video signal, and the discharge pulse is used to release unnecessary photoelectric When converting the electron charge in the means, the discharge pulse is supplied to the imaging means at every timing or several timings of the output pulse from the normal discharge pulse generating means, and when the timing of the discharge pulse determined by the shutter time determining means is at the video signal During the vertical blank period of , the discharge pulse is supplied to the image forming device at every timing or at several timings of the output pulse from the N-fold discharge pulse generating device.

In addition, in the television camera so configured according to the shutter operation of the imaging device, the imaging device is used to photoelectrically convert the optical image focused on the imaging plane by the optical lens, so that the photoelectrically converted optical image is used as a line Sequential video signal output, and the amplitude of the video signal output from the imaging device is controlled so that the amplitude of the video signal is maintained within a predetermined range related to the amount of incident light from the imaging object, the television camera includes at least:

Integrating means for a preselected number of fields, and a corresponding period of variation of the field scanning frequency of the video signal and the amount of incident light from the imaged object are provided;

input switching means for switching the video signal for each field and for sequentially distributing the converted video signal into integrating means for a predetermined number of fields;

output switching means for sequentially switching the output of the integrating means for a predetermined number of fields to be output;

shutter time determining means for determining the shutter time in response to the value of the output signal from the output switching means, wherein:

each field integrating means integrates the luminance signal by a predetermined timing constant during a predetermined number of fields connected to the input switching means, thereby outputting an average value of the luminance signal during the occurrence of a preselected number of fields; and

Output switching means for sequentially switching the output of the integrating means for a predetermined number of fields for each field, thereby outputting a continuous signal, whereby the timing of the discharge pulse determined by the shutter time determining means is controlled, which releases the memory stored in the image forming means Unwanted electronic charges in the corresponding photoelectric conversion elements of each pixel.

Moreover, in the television camera so arranged according to the shutter operation of the imaging device, wherein the imaging device is used to photoelectrically convert the optical image focused on the imaging plane by the optical lens, so that the photoelectrically converted optical image is used as A line-sequential video signal is output, and the amplitude of the video signal output from the imaging device is controlled, whereby the reproduction of the color of the video signal is maintained within a predetermined range related to changes in the amount of incident light from the imaging object , the television camera includes at least:

Two sets of integrating means for predetermined field numbers are provided according to the field scanning frequency of the video signal and the period of change of the amount of incident light from the imaging object;

Two sets of input conversion means are used to convert the two input color difference signals (R-Ye) and (B-Ye), and distribute the two color difference signals to the predetermined field number integration means; and

output converting means for sequentially converting outputs to be outputted from the integrating means of a predetermined number of lines, wherein:

Each field integration device integrates the color difference signals (E-Ye) and (B-Ye) in cooperation with the operation of the input conversion device within a selected field number with a predetermined time constant, so as to output the preselected field number the mean value of the color-difference signal during the occurrence;

two output converting means for sequentially converting the output of each field from the integrating means for a preselected number of fields, thereby outputting a continuous signal; and

Comparing the mean value of the two color difference signals (R-Ye) and (B-Ye) per field from the two output conversion devices with a preselected reference value, and controlling the color difference for the original color signal in response to the result of the comparison Gain Controls the gain of the device.

Fig. 1 schematically represents the basic structure (block diagram) of conventional white balance control device;

Fig. 2 schematically represents the main circuit structure of the video signal system of conventional TV camera;

Fig. 3 shows schematically the main circuit structure of the video signal system used in the television camera of the present invention;

Fig. 4 schematically represents the main circuit structure of the wide shutter device used in the television camera of the present invention;

Fig. 5 (a) to (d) schematically represents the relation between the shutter operating time of the television camera of the present invention and the discharge pulse;

6(a) to (g) are shaped timing diagrams illustrating the operation of the flicker extraction device and the flicker phenomenon;

Fig. 7 is the main circuit structure of the flicker extraction device used in the television camera of the present invention; and

Fig. 8 is the main circuit structure of the color flicker extraction device used in the television camera of the present invention;

Embodiments of the television camera of the present invention will now be described with reference to the accompanying drawings. It should be noted that the same reference numerals in the conventional TV camera denote the same devices and structures of the TV camera of the embodiment, and their detailed descriptions are omitted.

It should also be noted that, according to the television camera of the present invention, the field frequency of the video signal is chosen to be 60H ₂ , and the frequency of the AC power source for driving the light source illuminating the object to be imaged is 50H ₂ . These conditions can be understood, for example, as an example case where an NTSC system TV camera is used in an AC power supply of 50H ₂ . Even when these structural schemes are changed, if part of the structure (block diagram) of this television camera is also changed, the inventive concept can obviously be applied to any form of television camera while maintaining the same inventive concept.

Fig. 3 schematically shows the main circuit configuration of the video (picture) signal system used in the embodiment of the present invention.

In the television camera of the embodiment of the present invention shown in Fig. 3, the incident light from the object to be imaged (not shown) is incident on the imaging lens 10, then passes through the variable focal length lens system and the A focusing system (neither shown but included in imaging lens 10) for adjusting focus enters the imaging plane of CCD2. This incoming light is converted into a line-sequential video signal by the CCD2. The line-sequential video signal converted by CCD2 is processed by CDS/AGC3, Y/C splitter 4, and Y processor 5 in a manner similar to conventional video signal processing, thereby generating and outputting a luminance signal (Y), and Two sets of color difference signals (R-Ye) and (B-Ye) are generated by the WB controller 16 and the C processor 7 . Also, these color difference signals are converted into the color carrier signal "C" by the ENC8, whereby the color carrier signal "C" is output.

Then, the luminance signal (Y) is supplied to the Y flicker extracting means 21 to generate a luminance level signal (YS) (discussed later), and the luminance level signal (YS) is sent to the wide shutter means 22. These two sets of color difference signals (R-Ye) and (B-Ye) are sent to the color flicker extracting device 23 to generate two average color difference signal levels, namely RS and BS. These average color difference signals are sent to WB controller 16 (to be discussed later).

First, the wide shutter device 22 will be discussed with reference to the main structure shown in FIG. 4 .

The wide shutter device 22 is composed of a shutter time determining device 221 , a normal discharge pulse generating device 222 , an N-times discharge pulse generating device 223 , and a discharge pulse output device 224 . In the wide shutter device 22, a luminance level signal (YS), a clock pulse (HD), which is generated in synchronization with a horizontal synchronizing signal of a video signal by a reference pulse generator (not shown), and Vertical synchronization signal (VD) of the video signal. These circuit arrangements are connected in such a way that the signal flow shown in FIG. 4 is established. The normal discharge pulse generating means 222 generates and outputs a normal discharge pulse (RP) which is a pulse train having a predetermined timing within a horizontal blank period and coincides with a horizontal synchronizing signal of a clock (HD) based video signal. The N-times discharge pulse generator 223 generates and outputs N-times discharge pulses (ND), and the number of pulses in the pulse train is equal to a value obtained by multiplying an integer, such as 25, by the horizontal synchronization signal of the video signal. The shutter time determining means 221 compares the incoming luminance signal (YS) with a predetermined luminance reference level (ES), thereby determining that when the luminance level signal (YS) is greater than the luminance reference level, the shutter time is set to be short (high speed). ), in order to respond to the difference therebetween for successive shutter actions, and when the luminance level signal (YS) is less than the luminance reference level (ES), the shutter time is set to be long (low speed) in order to respond to the difference therebetween with The successive shutter actions immediately follow the state processed by the previous shutter time. And the determined shutter time is output as shutter time information (ST). For example, assuming that the current luminance reference level (ES) is set to the level of an imaged object with a luminance of 2000 lux, when the previous shutter time is 0.005 seconds (1/200 second), the response to the shutter being output Temporal information (ST), successive shutter times are changed in such a way that the contrast of the imaged object increases, (brightens). When the brightness level signal (YS) is changed from the previous level corresponding to the object brightness of 2000 lux to a new level corresponding to 2500 lux, because the brightness of the imaged object is increased by 25%, one reduces the shutter time by 25%. Information. That is, shutter time information (ST) for setting the shutter time to 0.004 second (1/250 second) is output.

Thus, the determined shutter time information (ST) is sent to the discharge pulse output means 224, which is also supplied with a normal discharge pulse (RP), an N times discharge pulse (NP), and a vertical synchronization signal (VD). In this case, a discharge pulse PP is output from the discharge pulse output means 224 as follows:

5(a) to (d) schematically show the relationship between the shutter time and the discharge pulse (PP). The position of the horizontal synchronizing signal is shown on the waveform diagram of the image period and the vertical blank period of the video signal generated based on the vertical synchronizing signal (VD) in FIG. 5(a). In Fig. 5 (a), when using the NTSC type video signal, 1 field is equal to 1/60 second (about 0.0167 second) during which the number of horizontal synchronization periods is 262.5 (will be expressed as 262.5H as a time interval), and The vertical blank period is approximately 1.27ms, during which the number of horizontal sync periods is equal to 20 (time interval of 20H).

In general, in order to avoid the side effect of deteriorating the periodic signal due to the discharge of unnecessary electron charges, the discharge pulse (PP) must be output during the blank period (horizontal blank period) of the horizontal sync signal.

For ease of illustration, it is assumed that the readout of the effective electronic charge from each pixel of CCD2 ends at the end of the vertical blank period, and the shutter time is expressed as the corresponding number of horizontal synchronous cycles, that is, at the end of the vertical blank period and at the end of the vertical blank period The number of synchronization pulse periods between the moments when discharge pulses (PP) are supplied (output) in the field. Because 1H is equivalent to about 63.5ms, assuming that the discharge pulse (PP) is equal to the point "A" that is 52H from the end point of the vertical blank period in Fig. 5 (a), the shutter time then becomes about 3.3ms (about 1/ 300 seconds). According to the same principle, when the discharge pulse (PP) is provided at point B corresponding to 9H in Fig. 5(a), the shutter time is approximately 0.57ms (1/1750 second).

It should be noted that the charge accumulated on the pixel until the moment of the discharge pulse input is discharged, so these charges are not used to generate the video signal. On the other hand, if the discharge pulse (PP) is not applied before the end of the vertical blank period , the shutter time becomes 1/60 second, and all the electronic charges accumulated during one field are used as an effective output to generate a video signal.

Also, the description of the minimum variable unit of the shutter time is now performed in order to deal with a wide range of luminance changes of the imaged object by means of the shutter operation.

First, as an initial condition, a discharge pulse (PP) is applied to the CCD only during the blank period of the horizontal sync pulse, as is done in conventional television cameras. For example, in a TV camera with a shutter time of 1/60 second (equivalent to no shutter operation in one field period), under the condition that the brightness of an imaged object at 100 lux is adjusted to the brightest signal, when the object When the brightness becomes 500 lux, the shutter time must be 1/300 second. The shutter operation can be adjusted such that the discharge pulse (PP) is output at the above-mentioned point "A", that is, point 52H. If the discharge pulse is output at a point close to 52H, the minimum variable unit of 1H of the shutter time becomes 2% which is equivalent to less than 1/300 second. Thus, there is no problem in the shutter changing operation. On the contrary, when the brightness of the object becomes 3000 lux in the same TV camera, the shutter time is required to be equal to 1/1800 second, that is, the above-mentioned point "B", that is, 9H point or 8H point. The minimum variable unit of the shutter time becomes 11% or more of 1/1800 second when the shutter time corresponding to 1H is changed around the point "B". In addition, when the brightness of the object is 20000 lux, the shutter time must be 1/12000 second, which is equivalent to a little over 1H. This means that when the shutter time is changed in increments of 1H as the smallest variable unit, it becomes as much as 50% of 1/12000 second. If this were the case, the variation induced in the luminance signal level when the shutter time is varied during the imaging operation would be too large to be practical.

Returning to the description of the present invention, Figure 5(b) represents a pulse train (RP) of normal discharge pulses. This normal discharge pulse (RP) is a pulse occurring every horizontal blank period. Fig. 5(c) shows a pulse train of N times discharge pulses (NP). An N-times discharge pulse (NP) is a pulse train that occurs at N times the frequency of a normal discharge pulse (RP). Discharge pulse output device 224, according to the shutter time information (ST) that enters, obtains the moment that discharge pulse (PP) should be output from the end point of previous vertical blank period, and selects such a pulse as discharge pulse (PP), and it has The output timing closest to the output timing of the pulse train of the normal discharge pulse (RP) generated from the normal discharge pulse generating means 222, whereby this pulse is output as the discharge pulse (PP). The discharge pulse output means 224 selects a pulse having an output timing close to the output timing of the pulse train of the N times discharge pulse (NP) generated from the N times discharge pulse generating means 223, and outputs this pulse as the discharge pulse (PP), If the timing of outputting the discharge pulse (PP) is within the vertical blank period of the video signal. As a result, a pulse train representing the timing that can be used by the discharge pulse (PP) is shown in FIG. 5(d). When the number of N times the discharge pulse (NP) is as much as 25 times the normal discharge pulse (RP), even if the shutter time of the above example is selected to be 11 equal to 1/12000 second, the shutter time can be set at (different from the selected) 1 /25H increments, so the minimum variable shutter time unit can be as small as 4%.

The means and method of generating the luminance level signal (YS) in the Y flicker extracting means 21 will be described below, and the flicker phenomenon during shutter operation will also be described.

6(a) to (g) are illustrations illustrating the operation of the Y flicker extracting means 21 and the flicker phenomenon occurring during the shutter operation period. Among them, the abscissa is the time axis, which is divided according to the field period of the video signal, and the ordinate represents the level of each signal. As mentioned above, in this television camera, the field frequency of the video signal is chosen to be 60H ₂ , and the frequency of the AC power source for illuminating the light source to be imaged is 50H ₂ .

As described in the prior art, the flicker phenomenon will occur at the highest intensity when the brightness of the light source is changed at a period twice that of the AC power supply. This is caused by the AC power of the light source that illuminates the imaged object. Figure 6(a) represents the variation in brightness of this light source used to illuminate the imaged object.

In FIG. 6( a ), the width of the hatched portion represents the shutter time T. In FIG. CCD2 converts the electronic charge accumulated on the pixel into a line-sequential video signal proportional to its equal area and outputs the converted signal. The amount of incident light converted into a video signal by CCD2 is shown in FIG. 6(b).

In Fig. 6(c), the luminance signal (Y) output sequentially from the CCD2 is represented by a solid line, and the average value of the luminance signal segment of each field is represented by a horizontal dotted line, and its level change between different fields is caused by changes in the image. In this case, the periodic change of the average luminance electric value every three fields is peculiar, which may be the cause of the flicker. In FIGS. 6(a) to 6(g), the relative phase between the shutter operation and the change in the luminance of the light source is shown as an example. Apparently, the amount of change in luminance value for each field is affected by this phase relationship and the shutter time.

Next, the Y flicker extraction means 21 will be described.

As shown by the horizontal dotted line in FIG. 6(C), as a general method of extracting the change in the average luminance value, integration is performed in the time domain during signal processing. However, when the luminance signal (Y) shown by the solid line in FIG. Integration introduces a time lag, making it impossible to extract fundamental changes in real time within a field.

The Y flicker extraction device 21 of the present invention is designed in consideration of this difficulty, and its circuit structure is shown in FIG. 7 .

In FIG. 7, the main structure of the Y flicker extraction means 21 includes an input conversion means 211, three groups of luminance signal field integration means (hereinafter referred to as "YF integrators") 212 to 214, and an output conversion means 215, the luminance signal (Y ) and a field switching signal (FC) synchronized with a vertical synchronizing signal from a device (not shown in detail) are input to the Y flicker extraction device 21, and these circuit devices are connected such that the signal flow shown in the figure is established .

Meanwhile, referring to FIG. 6, the present Y flicker extracting device 21 will be described. The input luminance signal (Y) is converted by input conversion means 211 in response to a field conversion signal (FC). The luminance signal (Y) of the first field (11F) shown in Fig. 6 (a) to (g) is converted to the YF integrator 212, and the luminance signal of the next field (12F) is converted to the YF integrator 213 , the luminance signal of the adjacent field ( 13F ) is converted to the YF integrator 214 , and thus the luminance signal (Y) of the next field ( 21F ) is converted to the YF integrator 212 . These luminance signals are continuously and sequentially supplied to the corresponding YF integrators 212 to 214 . The YF integrators 212 to 214 integrate the selected input luminance signal (Y) with a predetermined time constant sufficiently longer than the field period, thereby outputting the signals of FIGS. 6(d) to 6(f). 6( d ) shows the signal output from the YF integrator 212 , FIG. 6( e ) shows the signal output from the YF integrator 213 , and FIG. 6( f ) shows the signal output from the YF integrator 214 . Then, the signals output from the YF integrators 212 to 214 are converted by the output changeover switch 215 in the same order as the input changeover means 211, thereby generating a continuous signal as shown in FIG. ) output, which is equivalent to the horizontal dashed line in Figure 6(C).

Thus, the generated luminance value signal (YS) is sent to the wide shutter device 22, where this luminance value signal is compared with the aforementioned luminance reference value (ES), and the shutter time is adjusted according to each average value of each field. Real-time control. Thus flicker can be corrected.

A supplementary explanation will now be given as to why several luminance signal field integrating means are required. In the above embodiment, a three-level luminance signal field integration device is used because the frequency of the AC power source of the light source is assumed to be 50H ₂ , the luminance change occurs at 100H ₂ , and the field frequency of the video signal of the TV camera is 60H ₂ , so a flicker occurs every third field. Since this flicker period is equal to the smallest common denominator between the luminance variation period and the field period, it is convenient to calculate the required number of stages of the luminance signal field integration means when the calculated flicker period is divided by the field period. As another example, assuming that the power source frequency of the light source is 60H ₂ , the luminance change frequency is 120H ₂ , and the field frequency of the video signal output from the TV camera is 50H ₂ , since a flicker occurs every 5 fields, a 5-level luminance signal is required field integration device. It should be noted that the number of contacts of the input/output conversion means must be suitable for the corresponding 5-level luminance signal field integration means.

Correction of the color flicker phenomenon will now be described.

Similar to the flicker phenomenon of the luminance signal, as mentioned earlier, another flicker phenomenon occurs due to color condensation, which is caused by the AC power of the light source. The color-condensed flicker phenomenon is caused by a change in color temperature of a light source driven by an AC power source, which is different from the above-mentioned change in luminance of the light source, which causes a flicker phenomenon related to a luminance signal (Y). This color flicker occurs in the color signal waveform, and when the shutter speed is high, it is increased and thus more harmful than the luminance flicker phenomenon. By reading the ordinates of Figure 6(a) as color temperature and the ordinates of Figures 6(b) to 6(g) as color signal values, the occurrence of color flicker can be explained similarly to brightness flicker . A detailed explanation of color flickering is therefore omitted. As a special point, the average value of the two color difference signals (R-Ye) and (B-Ye) in one field changes periodically, which becomes a color flicker, as shown in Figure 6(c).

Furthermore, with respect to color flicker, when the color difference signal (R-Ye) or the color difference signal (B-Ye) is integrated in the time domain, the fundamental change in the color signal value averaged over these fields is difficult to extract due to the and The brightness flicker phenomenon is the same reason.

The color flicker extraction device 23 of the present invention is designed in consideration of the above problems, and its circuit structure is shown in FIG. 8 .

Fig. 8 is the main structure of color flicker extraction device 23, and it comprises two sets of such devices: each set includes input conversion device 231, three groups of color signal field integration devices (hereinafter referred to as "CF integrators") 232 to 234, and An output conversion device 235. Two color difference signals (R-Ye) and (B-Ye) and a field conversion signal (FC) synchronized with a vertical synchronizing signal generated from a device (not shown) are input to this color flicker extracting device 23, and The above-mentioned circuit elements are connected such that the signal flow shown in FIG. 8 can be generated. The operation of this color flicker extraction means 23 is practically the same as that of the luminance flicker extraction means, except that the coordinates of Figs. 6(a) to 6(g) should be changed for the signal to be processed, as described above. Therefore, a detailed description of the color flicker extracting means 23 need not be given.

With respect to the two color-difference signals (R-Ys) and (B-Ye), the average color-difference signal values (RS) and (BS) within each field can be taken out independently, as shown in FIG. 6(g). Thus, the resulting average color difference signal values (RS) and (BS) are sent to the WB control 16, where these signal values are used as signals for the operation of correcting the color flicker phenomenon, which will be described later.

Although the conventional adjustment of color reproduction performed in the conventional WB control 6 has been briefly described, a detailed description of the WB control of the present invention is now required.

FIG. 9 is a basic structure of the WB control 16 of the present invention. Referring to Fig. 1, it can be seen that the difference with the conventional WB control 6 is that it includes the color flicker extraction device 23 used in the embodiment shown in Fig. 3, the comparison device 69.70 and the conversion device 71.72 to replace the conversion device 65.66.

One of the functions of the WB control 16 of the present invention is as follows. When the light source illuminating the object is changed, the white balance by taking a white object is initialized by switching the switching devices 71 and 72 to the "a" contact, and the rest of the operation is similar to the conventional WB control 6. After finishing the adjustment operation, these switching means 71.72 are switched back to point "b".

On the other hand, during normal imaging operation, the two averaged color difference signal values (RS) and (BS) from the color flicker extraction means 23 are respectively fed back to the comparison means 69.70. Therein these average color difference signal values (RS), (BS) are compared with the automatic white reference voltage (EW) to generate difference signals respectively, which are sent to gain control means 67.68 through conversion means 71.72. In which the red component value (R) and the blue component value (B) in the original color signal input from the Y/C separator 4 are controlled so that the two color difference signal values (RS), (BS) are always the same as the automatic white Reference voltage matching. With this control operation, the values of the red component (R) and the blue component (B) in the original color signal are adjusted in response to the average color temperature per field, with the result that color flicker is corrected.

It should be understood that the above-mentioned basic structure of the WB control 16 of the present invention, as shown in FIG. 23, and the conversion device 71.72 can be located on the output side of the comparison device 69.70, so that the comparison device 63.64 is omitted.

With the structure of the television camera of the present invention as described above, since the optical variable aperture device is replaced by the shutter capable of handling a wide range of change (dynamic range) of the incident light quantity emitted from the imaging object, the imaging lens can be made compact , in addition to preventing deterioration of sharpness, which may otherwise result in so-called "ghosting", which is caused by the shape of the outer edges of the aperture of the optical variable aperture device, and may also be caused when the area of the aperture is reduced. caused by the diffraction phenomenon that occurs. Furthermore, since the luminance flicker and the color flicker caused by the power supply of the light source are extracted in real time in each field, the extracted flicker components are fed back to correct these luminance/color flicker phenomena. Therefore, it is possible to provide a television camera that operates stably even when the brightness and color temperature of a light source for illuminating an imaged object are periodically changed.

Claims (1)

1. television camera with image device, described image device is used for to the image formation of object by a variable intensity light source irradiation, and output row preface vision signal, described capable preface vision signal only is maintained at color rendering in the preset range by means of control capable preface vision signal amplitude by the shutter operation of image device, thereby the change that opposing is caused by described variable intensity light source from the incident light of object, described capable preface vision signal comprises two color difference signals (R-Y1) and (B-Y1), and described television camera comprises:

The empty system of a pair of gain device is used for controlling respectively the gain of described two color difference signals;

A pair of first and second integrating gears, each comprises the preselected number integrator, described predetermined number is determined by the field-scanning period of row preface vision signal with from the change cycle of the incident light of object;

A pair of input conversion apparatus is used for changing respectively described two color difference signals that are transfused to, thereby makes each color difference signal of two color difference signals be assigned to described preselected number integrator to each field; And

A pair of output conversion device is connected respectively on described first, second integrating gear, and each output conversion device is sequentially changed the output of coupled described predetermined number integrator, wherein:

Each described predetermined number integrator is by means of with the scheduled time constant integration being carried out in each field of described color difference signal, thereby the mean value of the described color difference signal of each that output is transfused to, and each of wherein said a pair of output conversion device is from the single continuous signal of the color difference signal mean value of described preselected number integrator, and, wherein have from two color difference signals and a preliminary election reference value of the mean value of described a pair of output conversion device output and compare, thereby export first, second gain control signal is so as to responding described first, first gain control signal is controlled the gain of described gain control respectively.

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