RU2686053C1 - Method of forming video signal of circular frame in television camera for panoramic computer surveillance in conditions of high illumination and/or complex brightness of objects - Google Patents

Abstract

FIELD: physics.SUBSTANCE: invention relates to the panoramic computer observation, which is performed using the circular view monochrome or colour television camera in the close to the hemisphere region, made on the basis of an “annular” sensor (“annular” photodetector). Result is achieved by the fact that photodetector "circular" target is divided into isolated from each other photoreceiving areas, which, in parallel control of photo reception and scanning processes have shape in form of part of circular ring, wherein the value of the automatic accumulation time (AAT) automatic voltage control voltage and the charge accumulation duration, respectively, are determined separately for each said target from the video signal peak value, and the "circular" output register is made in the form of two adjacent "circular" registers acting alternately on a two-channel unit of charge-voltage conversion.EFFECT: technical result is to automatically increase sensitivity for fragments of a "circular" frame with low illumination by increasing accumulation time for them with simultaneous implementation of saving power consumption of the photodetector.1 cl, 8 dwg

Description

The present invention is a technical solution for the category "method" and is related to panoramic computer monitoring, which is performed using a monochrome or color television camera with a circular view in an area close to a hemisphere made on the basis of a "ring" sensor ("ring" photodetector).

The closest to the technical nature of the claimed invention should be considered a method of forming a video signal "ring" frame [1], in a monochrome or color television camera for panoramic computer surveillance, which consists in installing a television camera in a fixed position, capture the optical image in a television a camera with an angular field in the space of objects 360 ° in azimuth in the "annular" photodetector of a television camera, manufactured according to the technology of devices with charges The second connection (CCD), which is made on a crystal in the form of a circular ring, has a ring-shaped line transfer circuit and consists of a ring-shaped photo-receiving region (target) and a ring-shaped output register connected in series with a charge coupling; - voltage ”(BPSN) with the organization“ floating diffusion ”, while on the target of the line of photosensitive elements, alternating with the lines of elements shielded from light, are located along the radial directions from the center of the circular ring to its outer periphery and the “ring” output register located there, and the number of elements in each “ring” line of the target is equal to the number of elements in the “ring” output register, and the area of the photosensitive elements on the target and the area of the screened elements equal to it from line to line, increasing as it moves to the outer periphery up to a maximum value not exceeding the area of the element of the “ring” output register; accumulate the charge image of the information frame on the photosensitive elements of the target in accordance with the control voltage for automatic adjustment of the accumulation time (ARVN) of the photodetector; carry out a "ring" scan of the charge image on the target with subsequent element-by-element reading of charge packets in the "ring" output register and forming the voltage of the analog image signal of the observed space at the BPSN output, while in the process of receiving the sensor video signal the reading aperture area is controlled due to the fact that to the line change the period of control pulses T _r , (reset pulses) for BPSN according to the relation:

where T _p - the period of reading the element in the "ring"photodetector;

n _m - coefficient, integer, the value of which for the current reading line in the “ring” photodetector is equal to the ratio:

where Δ ₁ and Δ _m are, respectively, the area of the photosensitive element for the first and current lines of reading in the “ring” photodetector, providing the same value of the area of the reading aperture within the entire “ring” raster of the photodetector; convert analog video to digital video.

The method of forming the video signal in the prototype [1] ensures the alignment of the resolution of the “ring” image, and, consequently, the “rectangular” images offered to computer operators-users. This is achieved by controlling the area of the reading aperture.

Note that for this the BPSR of the photodetector of the prototype [1] is organized as a “floating diffusion region”, and therefore has a control input that provides element-by-voltage voltage drop of the generated video signal.

As applied to a single line in the prototype [1], traditional loading by charge packets of the “ring” output register is performed within the time interval, which, according to the television standard, occupies the interval τ _oxc - the duration of the horizontal sweep.

However, when working in conditions of complex illumination and / or complex brightness of objects, when high illumination (brightness) in some areas of the field of view is accompanied by low illumination (brightness) in other areas, the prototype video signal generation method [1] implemented in a television camera does not cope with by the situation.

This is because under these conditions, ARVN, by performing a control voltage reading with an amplitude detector, peak or average value of a video signal proportional to the illumination of a photodetector target, spreads its result, namely, the accumulation time, to all elements (pixels) target

The disadvantage of the video signal generation method in the prototype [1] is that a limited accumulation mode (in time) occurs for those sections of the panoramic image that are controlled at low illumination (brightness) of the objects corresponding to them.

The objective of the invention is the organization in the automatic mode of increasing the sensitivity for these fragments of the “ring” frame by increasing the accumulation time for them with the simultaneous implementation of energy saving of the photodetector.

The task of increasing the sensitivity in the proposed method of forming a video signal "ring" frame, which is based on the fact that the television camera is installed in a fixed position, capture an optical image in a television camera with an angular field in the space of 360 ° azimuth in the "circular" photodetector television cameras made by the technology of charge-coupled devices (CCD), which is made on a crystal in the form of a circular ring, has a circuit It consists of a ring-connected target connected in series with a ring and a ring output register ending with a BSCR with floating diffusion organization, while the targets of the photosensitive elements alternating with the lines of light-shielded elements are located along the radial directions from the imaginary center of the circular ring to its outer periphery and the “circular” output register located there, and the number of elements in each “circular” line of the target is equal to the number elements in the “ring” register, with the area of the photosensitive elements on the target and the area of the screened elements equal to it vary from line to line, increasing as they move to the outer periphery to a maximum value not exceeding the area of the element of the “ring” output register; accumulate charge image information frame on the photosensitive elements of the target in accordance with the control voltage for ARVN photodetector; carry out a "ring" scan of the charge image on the target with subsequent element-by-element reading of charge packets in the "ring" output register and forming the voltage of the analog image signal of the observed space at the BPSN output, while in the process of receiving the sensor video signal the reading aperture area is controlled due to the fact that to the line change the period of control pulses T _r for BPSN according to the relations (1, 2), providing the same value of the area of the reading aperture within the whole " ring "raster of photodetector; convert the analog video signal into a digital video signal, is solved by the fact that the “ring” target of the photodetector is divided into isolated photodetector areas, which, when operating in parallel with the photoreceiving and scanning processes, have a form as a part of a circular ring, and their number k is determined by the ratio:

where γ _g is the horizontal angle of the field of view in degrees of the expected and proposed “rectangular” image to the computer operator,

wherein the magnitude of the control voltage ARVN and accordingly the duration of accumulation of charges for a frame are determined separately for each of the individual target by the peak value of the video signal generated at the sensor output during a respective time interval within the forward stroke of the frame, the bitmap transfer frequency ƒ _e " the ring "photodetector on the CCD is halved, and the" ring "output register is performed as two adjacent" ring "registers acting alternately on dual-channel B PZN, each of these "ring" registers contains half of the elements of the number of pixels for each photodetector row, and in the interval τ _oxc load the charge packets of the current information line both ring registers successively in time and separately for odd and even pixels of this line , moreover, for charge packets arriving at the second input of the BSPN, the area of the readout aperture of the video signal, as well as at the first input, is performed, and the number of phase electrodes for a single pixel in both the “ring” s "registers must be even, constituting component 2 or 4.

Comparative analysis of the prototype [1] shows that the claimed method is characterized by the presence of the following features:

- condition for the implementation of actions on the formation in the television camera of the original analog video signal, namely: dividing the “ring” target of the photodetector into k isolated targets that are shaped as part of a circular ring on which the photoreception and sweep processes are carried out in parallel;

- performing in a television camera parallel and autonomous actions to install the device ARVN duration of accumulation of charges per frame for each of the k targets of the sensor in accordance with the light (brightness) of the observed scene;

- performing energy savings by reducing the photodetector doubled frequency ƒ _e bitmap transfer as well as a new organization therein the constituent units: output register and BPZN. According to the claimed method, the output “ring” register consists of two parallel “ring” registers, and the BPS from the single-channel block becomes two-channel. In this case, the charge signals will be recorded by the BPSS in the correct phase ratio due to the choice of an even indicator for the number of phase electrodes as applied to an individual element of these registers.

Here it is important to note the following. From the monograph [2, p. 153] it is known that in an n-channel CCD with a cell size of 30 μm, operating at a frequency of 1 MHz, a charge packet of 0.5 pC consumes a specific power of about 2.8 nW / cell. And this value grows as the square of the working frequency!

When organizing such a mode of element-by-element transfer of charge packets for the “ring” photodetector, the resolution of the video signal of the panoramic plot remains unchanged, and the power consumption of a television camera based on such a sensor is “decelerated”, compensating for the full or partial associated energy costs.

The combination of known and new features is not known from the prior art, therefore, the claimed method meets the requirement of novelty.

It is obvious that the proposed method can be used both in “ring” photo detectors of a monochrome image and in “ring” photo receivers of a color video signal obtained by covering the sensor target with a color mosaic filter in the form of a ring.

The technical result and the method of its achievement the proposed technical solution meets the criterion of the presence of inventive step.

FIG. 1 shows the circuit organization of the “ring” photodetector on a CCD (by the method of “ring line transfer”) with six isolated targets (k = 6); in fig. 2 - the circuit organization of an isolated target with control inputs; in fig. 3 shows a block diagram of the device, explaining the implementation of the proposed method of forming a video signal and which is, in essence, the design pattern of ARVN photodetector; in fig. 4 shows an example of the implementation of a peak detector concept; six of which are taken (marked) in FIG. 3; in fig. 5b-5g relative to the temporary position of the damping pulse of the lines shown in FIG. 5a shows diagrams of control signals for obtaining the necessary areas ("windows") of photometry of the charge relief of a photodetector; in fig. 6b is a plot illustrating the temporal position of the output signal of an ARVN device (relative to the personnel damping pulse shown in Fig. 6a; Fig. 7 shows the position of six photometric windows for six rectangular frames on a ring photodetector under conditions of its complex illumination and / or complex brightness; and Fig. 8 are diagrams explaining the control of the first and second “ring” photodetector registers.

Note that the formation of these "rectangular" frames, as in the prototype [1], is assumed in the server of the computer system by the video signal of the "ring" frame coming from the television camera monitoring the panoramic scene.

The “ring” photo detector in FIG. 1 is made on a crystal in the form of a circular ring, has a ring-shaped line transfer circuit organization and consists of a ring-shaped photo-receiving region (target) 1-1 connected in series by a charge coupling, the first ring-type register 1-2-1, the second ring-shaped "Registers 1-2-2 and BPSN 1-1-3 with the organization" floating diffusion ", the output of which is the output of the" video "" ring "photodetector, while on the target 1-1 radially arranged lines of photosensitive elements alternate with radial shielded lines from with eta elements, and the number of elements in each “circular” line of the target 1-1 is equal to the number of elements in the “circular” registers 1-2-1 and 1-2-2, and the area of photosensitive elements on the target varies from line to line, increasing to the extent of movement to the outer periphery to a maximum value not exceeding the area of the element in the “ring” registers. The dash-dotted lines in FIG. 1 shows the selection of six isolated targets (i.e., k = 6) shaped like a part of a circular ring and equipped with an electronic shutter on the “ring” target 1-1 of the photodetector. We introduce the designation of these sensors, respectively, as: 1-1-1, 1-1-2, 1-1-3, 1-1-4, 1-1-5 and 1-1-6.

It is assumed that for all six isolated targets (see Fig. 2) there is a parallel control, which provides:

- the process of charge relief accumulation in accordance with the duration specified by the output pulse ARVN at the input of the electronic shutter of the sensor;

- the process of progressive transfer of accumulated charges towards the “ring” registers 1-2-1 and 1-2-2.

The organization of this parallel control can be carried out by “multiplying” the pulse signals with the help of external buffer stages for ready-made circuits that implement a set (set) of necessary control voltages.

Note that each of these two “ring” registers has an input control through its load gate, which can be opened by a pulse signal, ensuring the flow of charge packets into the cells of its register, or vice versa - is closed, thereby isolating the cells of its register from charging . The loading gates of the “ring” registers 1-2-1 and 1-2-2 are shown in FIG. 1 ... 2 thickened lines.

Let us consider in more detail the “mechanism” of this charge loading using the time diagrams of the signals presented in FIG. eight.

FIG. 8a shows a signal plot for a horizontal quenching pulse of a television scan, which is active during the interval τ _o.h.s. with a period of lines T _with .

FIG. 8b, fig. 8c shows the diagrams of pulse signals that control the loading gates of the second “ring” register 1-2–2 and the first “ring” register 1-2–1, respectively.

Note that the first “ring” register 1-2-1 is universal, ensuring the transfer of charge packets in two directions, namely: both along the register and across (through), i.e. in the cells of the second "ring register 1-2-2.

FIG. 8g, fig. 8d are diagrams of pulsed signals that control the operation of both “ring” registers in parallel as applied to a two-phase charge transfer charge system, where T _e = 1 / ƒ _e is the element charge transfer period of charge packets.

τ_о.x.c. - интервале активного действия импульса на фиг. 8б через открытый затвор загрузки в «кольцевой» регистр 1-2-2 будут поступать заряды первой, третьей, пятой и других нечетных элементов строки.In the interim

τ _о.xc is the interval of the active action of the pulse in FIG. 8b through the open gate of the load in the "ring" register 1-2-2 will receive the charges of the first, third, fifth and other odd elements of the line.

τ_o.х.с. - интервале активного действия импульса, изображенного на фиг. 8в, через открытый затвор будет загружаться зарядами «кольцевой» регистр 1-2-1, но применительно для второго, четвертого, шестого и других четных элементов этой строки.And in the subsequent interval

τ _oh.s. - the interval of active action of the pulse depicted in FIG. 8b, through the open gate, the charges will be loaded with a “ring” register 1-2-1, but with reference to the second, fourth, sixth, and other even-numbered elements of this line.

Note that in this time interval, the charge packets loaded earlier in the “ring” register 1-2–2 remain “in their places”, being in the cells (potential wells) of the register in storage mode.

Now let us return to the previously announced structural scheme of ARVN in FIG. 3. It contains the shaper 2 signals "windows" for photometric measurement of the sensor, serially connected the first peak detector 3 and the first pulse-width modulator (PWM) 4, sequentially connected the second peak detector 5 and the second PWM 6, sequentially connected the third peak detector 7 and the third PWM 8, the fourth peak detector 9 and the fourth PWM 10 sequentially connected, the fifth peak detector 11 and the fifth PWM 12 sequentially connected, as well as the sixth peak detector 13 and the sixth PWM 14 sequentially connected. Inform The operational inputs of all six peak detectors (3, 5, 7, 9, 11, 13) are connected to the output of the photodetector video 1, and the control inputs of these peak detectors are respectively to the first, second, third, fourth, fifth and sixth outputs of the driver 2. The seventh output of the driver 2 is connected to the reset inputs of all six peak detectors (3, 5, 7, 9, 11, 13).

The output of block 4 is connected to the electronic gate of target 1-1-1, the output of block 6 to the electronic gate of target 1-1-2, the output of block 8 to the electronic gate of target 1-1-3, the output of block 10 to the electronic gate of the target 1-1-4, the output of block 12 to the electronic gate of the target 1-1-5, and the output of block 14 to the electronic gate of the target 1-1-6. It is assumed that in the television camera from its microcontroller to the input of the shaper 2 signals of the "windows" are fed start and synchronization pulses.

Shaper 2 is designed to implement six pulse signals (see Fig. 5b ... 5g), which are fed to the control inputs of peak detectors. A three-bit binary counter can be used to obtain these signals [see, for example, 3, p. 168-170].

Broadcasting through the shaper 2 from the television camera microcontroller provides a frame sync pulse of positive polarity for zeroing (resetting) all six peak detectors (3, 5, 7, 9, 11, 13) at the beginning of each frame.

Peak detectors are designed to register the maximum level of an analog video signal arriving at their information inputs in the presence of a high level of a pulse signal at their control inputs.

Each of the peak detectors can be made on the basis of two operational amplifiers (OA) according to the scheme proposed in [4, p. 301]. The feature of the circuit shown in FIG. 4, is the selection of the first (input) op-amp. This OU must additionally have a control input for implementing external control of the reserve power and operating point using an external bias voltage. An example of such an opamp is a CA3078T chip from RCA (USA). The pulse signals that need to be applied to the control inputs of all six peak detectors (3, 5, 7, 9, 11, 13) are shown in the time diagrams, shown respectively in FIG. 5b, 5b, 5g, 5d, 5e, 5g.

The devices shown in FIG. 1 ... 3, work as follows.

As in the prototype [1], it is assumed that the television camera is installed in a fixed position, for example with the help of a photo stick (everything is not shown here).

The optical image of the observed panoramic scene in conditions of complex illumination and / or complex brightness is projected onto the entire target 1-1 of the “ring” photodetector 1, and, consequently, onto all six of its constituent targets 1-1-1, 1-1-2, 1-1-3, 1-1-4, 1-1-5 and 1-1-6.

In our example shown in FIG. 7, in the conditions of high illumination of the observed plot, there appears an area occupied by the “Window” 1; in low light conditions - “Window” 2 and “Window” 5; in conditions of moderately low illumination - “Window” 3 and “Window” 6, and in conditions of significantly reduced illumination - “Window” 4.

In the interval of the direct course of each television frame, an optimized charge accumulation process takes place in the photosensitive pixels of all six targets 1-1-1, 1-1-2, 1-1-3, 1-1-4, 1-1-5 and 1- 1-6 is proportional to the illumination of the controlled panoramic plot.

During the short period of the subsequent interval of the reverse frame sweep, a photo gate is opened, and the charges of all the “ring” lines participating in the accumulation are transferred (in one rotation step) to pixels shielded from light located on the same targets.

Then photogate each of the six targets is closed and a new frame cycle is performed another charge accumulation "pattern", and saved in the previous frame, charge packets are transported in radial directions to the periphery of the photodetector chip loaded in the interval τ _o.h.s new charges sequentially the first 1-2-1 and second 1-2-2 "ring" registers.

For all rows of each of the six photodetector targets in BPSN 1-1-3, as in the prototype [1], the area of the reading aperture is the same across the field, which guarantees the same sensitivity for all elements of the “unified” target while maintaining the same spatial gaps between adjacent pixels.

Thus, alignment of the resolution of the “ring” image over the entire area of the “unified” sensor target is provided.

Then, as in the prototype [1], the generated analog video signal is converted into a digital television signal (PZT) of the “ring” frame at the output of the television camera. Next, the PLC over the interface (for example, USB 2.0) is transmitted to the server of the computer system, where video information is recorded in its operational memory per frame. In a server, the video signal of each current “ring” frame is converted (converted) into six “rectangular” frames, also shown in FIG. 7

The technical result of the proposed solution is ensured by the fact that the optimal performance for the accumulation time (T _n ) for all k areas of the “ring” target of the photodetector will be obtained in the television camera in a fully automatic mode.

Therefore, in comparison with the prototype [1], an increased signal-to-noise ratio (ψ) of the generated video signal and, accordingly, an increase in sensitivity for those sections of the panoramic image, which are recorded at low illumination (brightness) of their corresponding objects, and, equally important, will be achieved. , - with the implementation of energy saving sensor.

It is obvious that the method of video signal generation proposed in this technical solution can be successfully implemented for the other two variants of the circuit design of the “ring” photodetector, namely: the “ring personnel transfer” method [5] and the “ring line-frame transfer” method "[6].

At present, all the elements of the circuit organization of the aforementioned “ring” photoreceivers, as well as blocks and elements of a commented structural block diagram of an ARVN sensor device, implement the proposed method of forming a “ring” frame in a television camera for panoramic computer observation in complex illumination and / or brightness of objects, mastered or can be mastered by domestic industry.

Therefore, the intended invention should be considered as meeting the requirement of industrial applicability.

INFORMATION SOURCES

1. RF patent №2633758. IPC H04N 5/00. Sensitive TV camera for panoramic computer surveillance. / V.M. Smelkov // B.I. - 2017. - №29.

2. Seken K., Tompset M. Charge transfer devices. Translation from English - "The World", 1978.

3. Tokheim R. Basics of digital electronics. Translation from English - M .: Mir, 1988.

4. Peyton A.J., Volsh V. Analog electronics on operational amplifiers. Translation from English - M .: "BINOM", 1994.

5. RF patent №2625163. IPC H04N 7/00. Television camera and its "ring" photodetector for a computer system for panoramic surveillance. / V.M. Smelkov // B.I. - 2017. - №20.

6. RF patent №2611422. IPC H04N 7/00. A television camera of increased sensitivity and its “ring” photodetector for a computer system for panoramic surveillance. / V.M. Smelkov // B.I. - 2017. - №6.

Claims (10)

The method of generating the video signal of the “ring” frame in a television camera for panoramic computer surveillance in conditions of complex illumination and / or complex brightness of objects when high illumination (brightness) in some areas of the field of view is accompanied by low illumination (brightness) in other areas, that set the television camera in a fixed position, carry out the capture of the optical image in the television camera with an angular field in the space of objects 360 ° azimuth in the "ring" From the receiver of a television camera, manufactured using charge-coupled device (CCD) technology, which is made on a crystal in the form of a circular ring, it has a ring-shaped line transfer circuit and consists of a ring-shaped photo-receiving region (target) and a ring-shaped "An output register ending in a charge-voltage conversion unit (BOPZN) with the organization of floating diffusion, with the target of the line of photosensitive elements alternating with the rulers elements shielded from light are located along radial directions from the imaginary center of the circular ring to its outer periphery and the “ring” output register located there, and the number of elements in each “ring” target line is equal to the number of elements in the “ring” register, and the target area photosensitive elements and the equal area of shielded elements are different from line to line, increasing as they move to the outer periphery up to a maximum value not exceeding the area of the element “ring the target register accumulate the charge image of the information frame on the photosensitive elements of the target in accordance with the control voltage to automatically adjust the accumulation time (ARVN) of the photoreceiver, perform a “ring” scan of the charge image on the target, followed by element-wise reading of the charge packets in the “ring” output register and the formation of the output voltage BPSR analog signal of the image of the observed space, and in the process of obtaining video sensor pa controlled area reading aperture by the fact that from line to line changing period of control pulses T _r, (reset pulse) for BPZN by the relation:

where T _p - the period of reading the element in the "ring"photodetector; n _m - coefficient, integer, the value of which for the current reading line in the “ring” photodetector is equal to the ratio:

where Δ _l and Δ _m - respectively, the area of the photosensitive element for the first and current lines of reading in the "ring" photodetector, providing the same area of the readout aperture within the entire “ring” raster of the photodetector, convert the analog video signal to a digital video signal, characterized in that the “ring” target of the photodetector is divided into isolated photodetection areas, which, when operating in parallel with the photoreceiving and scanning, have parallel the shape as a part of a circular ring, and their number k is determined by the relation:

where γ _g is the horizontal angle of the field of view in degrees of the expected and proposed “rectangular” image to the computer operator, wherein the magnitude of the control voltage ARVN and accordingly the duration of accumulation of charges for a frame are determined separately for each of the individual target by the peak value of the video signal generated at the sensor output during a respective time interval within the forward stroke of the frame, the bitmap transfer frequency ƒ _e " the ring "photodetector on the CCD is halved, and the" ring "output register is performed as two adjacent" ring "registers acting alternately on dual-channel B PZN, each of these "ring" registers contains half of the elements of the number of pixels for each photodetector line, and in the reverse horizontal sweep interval τ _oh.s. the charge packets of the current information line are loaded with both “ring” registers sequentially in time and separately for odd and even pixels of this line, and for charge packets arriving at the second input of BPSN, the area of the reading aperture of the video signal is controlled, as well as the number of phase electrodes for a single pixel in both "ring" registers must be even, making a measure of 2 or 4.

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