RU2362275C1 - Television camera for suveillance in conditions of complex illumination and/or complex brightness of objects - Google Patents

Abstract

FIELD: electronic engineering.

SUBSTANCE: invention relates to television cameras which work in conditions of complex illumination and/or complex brightness of objects, when in the field of vision there can be strong and weakly illuminated objects and/or objects with sharp difference in brightness at the same time. The technical outcome of the invention is achieved due to that, the television camera includes a frame delay unit, second comparator, OR element and an AND element.

EFFECT: wider dynamic range for tone gradation of the image created by the television camera, independent of spatial distribution in the field of vision of objects with sharp difference of illumination or brightness.

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Description

The invention relates to cameras operating in conditions of complex illumination and / or complex brightness of objects, when in the field of view of the camera there may be simultaneously highly and dimly lit objects and / or objects with a sharp difference in brightness.

The closest in technical essence to the claimed invention should be considered a camera [1], containing sequentially located and optically coupled lens and a beam splitter, the first output of which is optically connected with the photo target of the first sensor of the television signal, and the second output of the beam splitter - with the photo target of the second sensor of the television signal, the geometric dimensions of the photographic targets of the first and second sensors are the same, and the projections of the optical frame of the lens on the photographic targets coincide, as well as sequentially with unity selector clock and driver "window" signal, the switch-mixer serially coupled peak detector and a comparator, the reference input of which is connected to a threshold voltage U _n, the counter, the switch and the RS-flip-flop, the input S of which is connected respectively to the input "reset" peak detector and counter cleaning input, the control input of which is connected to the output of the comparator, the clock input of the counter is connected to the second output of the clock selector, and the output of the bits of the counter is connected to the information input of the comm signal generator 11, the control input of which is connected to the direct output of the RS-trigger and connected to the first control input of the first sensor, the second control input of which is connected to the output of the switch, the Synchro output of the first sensor is connected to the synchro input of the second sensor, and the output is video ”of the first sensors - to the input of the clock selector, to the first information input of the mixer-mixer and to the information input of the peak detector, the“ Strobe ”input of which is connected to the output of the“ window ”signal conditioner and connected to the control the input of the switch-mixer, the second information input of which is connected to the “video” output of the second sensor, and the output of the switch-mixer is the “video” output of the television camera, while the input S of the RS-trigger is the “Start” input of the camera, and the input is RS RS -trigger - the entrance of the “Stop” camera.

When operating the prototype camera, conditions of complex lighting and / or complex brightness of the observed plots and objects are possible. Examples of complex lighting conditions include:

- observation of the launch of a rocket with a bright torch from running engines;

- observation through a window or against the background of open doors, when you need to simultaneously distinguish between objects on the street and in the room;

- observation against diffused sunlight;

- observation against the background of glare, lighting lamps and more.

A typical example of complex brightness conditions for industrial television is the monitoring of the hot-rolled zone in metallurgy, as well as the control of arc or electron-beam welding processes in automatic or semi-automatic mode.

The prototype camera provides an extension of the dynamic range of gradations of brightness of the images of the observed scene by forming a combined image, which is the result of the synthesis of video signals generated by the first and second sensors. In the centrally located “window” of the combined image, bright and light objects of the observed scene are transmitted by the video signal of the first sensor. Within the remaining area of the combined image (outside the “window”), dark and / or low-lit scene details are transmitted by the video signal of the second sensor.

The disadvantage of the prototype is the restriction on the spatial placement in the field of view of the camera of objects and details of the observed scene with a sharp difference in illumination or brightness.

The objective of the invention is the expansion of the dynamic range of gradations of brightness generated by the camera image, regardless of the spatial placement in the field of view of objects and details of the observed scene with a sharp difference in illumination or brightness.

The problem is solved in that in the inventive camera, which contains a lens, a serially connected television signal sensor, a clock selector, a counter-divider and a switch, as well as an RS-trigger, the first comparator, the reference input of which is connected to a threshold voltage, and a switch-mixer moreover, the first control input of the television signal sensor is connected to the control input of the switch and connected to the direct output of the RS-flip-flop, the second control input of the television signal sensor is connected to the output of the com a mutator, the information input of which is connected to the output of the counter-divider, and the “Video” output of the television signal sensor is connected to the first information input of the mixer-mixer, the S-input of the RS-trigger is the input “Start” of the camera, the R-input of the RS-trigger is the input “Stop” the camera, and the output of the switch-mixer is the “Video” output of the camera, an “And” element is introduced and a delay unit per frame consisting of a series-connected analog-to-digital converter (ADC), random access memory (RAM), and numbers analog converter (DAC), the second comparator and the OR element, while the output of the delay unit per frame is connected to the second information input of the switch-mixer, the first control input of the switch-mixer is connected to the output of the And element, the first and second inputs of which are connected respectively to the direct output RS-trigger and the output of the counter-divider, the second control input of the switch-mixer is connected to the output of the OR element, the second input of which is connected to the output of the first comparator, the gate inputs of the first and second to The comparators are combined and connected to the direct output of the RS-flip-flop, the clock input of which is connected to the output of the clock selector, and the information input of the first comparator is connected to the input of the delay unit per frame and connected to the output of the television signal sensor, whose photo target is optically connected to the optical frame of the lens.

Comparative analysis with the prototype shows that the claimed camera is characterized by the presence of new units, including: a block delay unit, a second comparator, an OR element, and an element, as well as the presence of new connections between the new and other blocks.

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

In the proposed solution, a multiplex video signal is generated at the output of the photodetector, adjacent frames in which are generated at two different durations of CCD array accumulation, which are optimal or close to optimal values, respectively, for light and dark fragments of the scene. Subsequent demultiplexing of this image signal provides a synthesis of the output video signal of a television camera with an extended dynamic range of transmitted images, regardless of the spatial distribution in the field of view of objects and details of the observed scene with a sharp difference in illumination or brightness.

According to the technical result and methods for its achievement, the claimed solution meets the requirement of inventive step.

Figure 1 shows a structural diagram of the inventive camera, figure 2 shows an example of the electrical circuit of the switch, figure 3 presents a timing diagram explaining the operation of the camera, figure 4 shows one possible embodiment of the electrical circuit of the switch-mixer; figure 5 presents a timing chart explaining the operation of the counter-divider.

The inventive camera (see Fig. 1) contains sequentially located and optically coupled lens 1 and a photo target of a television signal sensor 2, as well as an RS trigger 3, a clock selector 4, a counter divider 5, a switch 6, a first comparator 7, a delay unit 8 per frame, consisting of a series-connected ADC 8-1, RAM 8-2 and DAC 8-3, a second comparator 9, element OR 10, element 11 and switch-mixer 12, and the video output of sensor 2 is connected to the input of the selector 4 clock pulses, the output of which is connected to the clock input of the RS-trigger 3 and ootvetstvenno to the input series connected counter-divider 5 and the switch 6, the control input of which is connected to the direct output RS-flip-flop 3, and is connected to a first control input of the transmitter 2 and with strobe inputs of comparators 7 and 9, the reference inputs are connected to the threshold voltage U _n, an information input of the comparator 7 is connected with an input unit 8 and the frame delay, respectively, with the first information input of the mixer switch 10, connected to the output "Video" sensor 2, a second control input cat it is connected to the output of the switch 6, while the second information input of the switch-mixer 10 is connected to the output of the delay unit 8 per frame, the first control input of the switch-mixer 12 is connected to the output of the element And 11, the first and second inputs of which are connected respectively to the direct output RS -trigger 3 and the output of the counter-divider 5, the second control input of the switch-mixer 10 - to the output of the OR element 10, the first and second inputs of which are connected respectively to the outputs of the comparators 9 and 7, the input "S" of the RS-trigger 3 is the input "Start ", Input" R "RS -trigger 3-input "Stop", and the output of the switch-mixer 12 - the output of the "Video" camera.

As sensor 2, the open-frame camera VSI-746 [2], proposed by the Russian company “EVS” (St. Petersburg), can be used, which is made on the basis of a CCD matrix with 582 × 752 elements and a размером inch diagonal target size.

A feature of the sensor 2 in the claimed solution is the presence of the first and second control inputs.

For the VSI-746, the first control input is pin 20 of the CXD2463R. If you need to enable automatic adjustment of accumulation time (ARVN), you need to send a logical "0" to this output, to switch to manual control of the accumulation time - logical "1" in the TTL levels.

The second control input of the VSI-746 device is formed by the terminals 11, 12, 13 of the CXD2463R chip. To work in ARVN mode, these conclusions must be “hanging in the air”, because using high-resistance resistive dividers, they are supplied with the corresponding potentials in the range 1.3-3.5 V. If it is necessary to switch eight values of fixed exposures in the range from 10 μs to 10 ms, then code combinations of zeros should be applied to them ("0 ") And units (" 1 ") indicated in the table below.

Table 1 Pin number Time: exposure (accumulation) of the photodetector, μs 10.0 100.0 200,0 500,0 1000,0 2000.0 4000,0 10,000.0 Code combination eleven 0 one 0 one 0 one 0 one 13 0 0 one one 0 0 one one 12 0 0 0 0 one one one one

In this solution, two code combinations are used: “000”, which corresponds to the minimum accumulation time of the photodetector, equal to 10 μs, and “111” - to the maximum time of 10,000 μs. Preset of these codes is provided in the switch 6.

A possible electrical circuit of this unit (see figure 2) contains the first element And 6-1, the second element And 6-2, the third element And 6-3, as well as the first switch 6-4, the second switch 6-5 and the third switch 6-6, while the first inputs of the elements And are interconnected and connected to the output of the counter-divider 5, the second inputs of the elements And - to the direct output of the RS-trigger 3, and the outputs of the elements And - respectively, to the control inputs of the first 6-4, second 6-5 and the third 6-6 switch, the resolution enable inputs of the switches are interconnected and connected to the direct output of the RS-trigger ra 3, and switches the outputs are output unit 6.

When applying a high logical signal level to the resolution inputs of the switches 6-4, 6-5, 6-6 and a high logical signal level to the first inputs of the elements And 6-1, 6-2, 6-3 at the output of block 6, a logical combination “ 111. "

When the logical “0” is supplied to the first inputs of the elements And 6-1, 6-2, 6-3, the logical combination “000” will be established at the output of block 6.

If a low logic level is applied to the permission inputs of the switches 6-4, 6-5, 6-6, then, regardless of the state of the inputs of the elements And 6-1, 6-2, 6-3, the outputs of the switches will be isolated from the inputs.

The RS-trigger 3 is an RS-type tactile trigger device with a high active level at the control inputs. The OR element 10 and the AND element 11 are logical elements with an unambiguous idea of the functions they perform.

The clock selector 4 is designed to extract from the composite video signal at the input of the receiver synchronization signal (MSS) with the subsequent formation of a frame synchronizing pulse (CSI) at the output.

Counter-divider 5 is intended for dividing the frequency of pulses of CSI into two (from 50 Hz to 25 Hz) during progressive scanning and, accordingly, into four (from 50 Hz to 12.5 Hz) during interlaced scanning of the video signal in the camera.

Features of comparators 7 and 9 is the use of a gate input in each of them. KM597CA1 microcircuits can be used as an element base for performing the necessary comparators [3, p. 366]. When a logic “1” is applied to the gate input of the comparator, the signal under study is compared with the reference voltage. If a logical “0” is set at the gate input of the comparators, then the comparison process is excluded, and a zero level is formed at the output of the comparator.

Block 8 is designed to delay the input video signal for a duration of one frame. If a progressive scan with a frame rate of 50 Hz is used in the camera, then the delay time is 20 ms. When organizing a standard interlaced scan in the camera, the duration of the required delay will be two half frames, i.e. 40 ms The technical implementation of block 8 can be carried out by serial connection of an analog-to-digital converter (ADC) 8-1, random access memory (RAM) 8-2, digital-to-analog device (DAC) 8-3.

The switch-mixer 12 is designed to synthesize the output video signal of the camera. The electrical circuit of block 12 can be made on the basis of one of two four-channel analog switches of the KR590KN3 microcircuit [3, p. 450-451], as proposed in Fig. 4. Depending on the levels of logic signals supplied to the first and second control inputs, in accordance with Table 2, one of the channels opens, namely: 1A or 2A, or 3A, or 4A.

table 2 Levels on control inputs Open channel number # 2 #one E 0 0 one 1A one 0 one 2A 0 one one 3A one one one 4A

The camera (see figure 1) works as follows.

In the field of view of the camera, there can simultaneously be strongly and dimly lit objects and / or objects with a sharp difference in brightness. Suppose the camera is in progressive scan mode.

Automatic adjustment of the accumulation time (ARVN) of the photodetector in the sensor 2 of the television signal will set the value of the current exposure from a strongly lit or bright scene. For dark and low-lit scene details transmitted in the same television field, this exposure time will lead to a real loss of sensitivity and distortion of the corresponding image fragments due to the lower dynamic range of the camera. The clock selector 4 selects the output frame sync pulses with a period of T _p (see figa), and the counter-divider 5 - divides the input frequency by two, forming the square wave with a period of T _d1 = 2T _p (see fig.3b )

Let a positive polarity pulse be applied to the “Start” input. At the moment of coincidence at the “S” input of the RS flip-flop 3 of the high level of this pulse with a high level of frame sync pulses at its clock input, the state of the trigger changes. On the direct output of trigger 3, a logic signal “1” is set. The latter is fed to the control input of block 6, to the first control input of sensor 2 and to the gate inputs of comparators 7 and 9. Therefore, the ARVN circuit in sensor 2 is turned off, and its second control input is connected to the output of block 6. At the same time, comparators 7 and 9 are prepared to work.

Note that, regardless of this switching, the clock selector 4 continues to select frame sync pulses at the output, and pulses with a period T _d are generated at the output of the counter-divider 5.

When connecting the second control input of sensor 2 to the output of block 6 at this input for the duration of the low level of the meander of pulses from the output of block 5, the logical combination “000” is set, which ensures the duration of the frame accumulation of charges in the photodetector equal to 10 μs (see Table 1) . When, from the output of block 5, a high level of the meander of pulses is given, then at this time the logical combination “111” will be established at the second control input of the sensor 2, which guarantees the accumulation time of the CCD matrix of 10,000 μs (see Table 1). The sensor 2 generates a multiplex image signal (see Fig. 3d), adjacent frames of which are "long" and "short" video signals in accordance with the mode of accumulation of charges in the photodetector.

This multiplexed image signal is simultaneously fed to the first information input of the switch-mixer 12, the input of the first comparator 7 and to the input of the delay unit 8 per frame. The comparator 7 compares the video signal at the input with a threshold voltage U _reference , forming at the output the pulses shown in Fig.3d. In block 8, a delay per frame of the input multiplexed image signal is performed, as shown in FIG. This delayed multiplex video signal is simultaneously supplied to the second information input of block 12 and to the second comparator 9. Comparator 9 compares the video signal at the input with a threshold voltage U _reference , forming the pulses shown in Fig. 3e at the output.

The output pulses of the comparators are logically summed on the element OR 10, providing the formation of the necessary signal at the second control input of the switch-mixer 12 (see figv). At the first control input of block 12, there are pulses from the output of the counter-divider 5, as shown in Fig.3b, which are the result of logical multiplication by the element And 11 of this signal and logical "1" from the direct output of the RS-trigger 3.

The synthesis of the output image signal is carried out in the switch-mixer 12 using four-channel switching of the components of the video signals (see figure 4 and table 2).

When logical “0” is present at the first and second control inputs of block 12, then channel 1A opens at this time, and the video signal from the first information input is transmitted to the output. If during the action at the first control input a logical “0”, at the second control input a logical “1” is set, then channel 2A opens at this time, and the video signal from the second information input is transmitted to the output.

When logical “1” is set at the first and second control inputs, then channel 3A opens at this time, and the video signal from the second information input is transmitted to the output. If during the action the logical “1” is also present at the first control input of the logic 1, the logical 1 is also present at the second control input, then channel 4A opens and the video signal from the first information input is transmitted to the output.

The synthesized video signal (see fig.3z) has an extended dynamic range, because Compared with the prototype, the signal-to-noise ratio for dimly lit and dark areas of the observed scene is increased due to the accumulation time optimally selected for them on the photographic target.

Suppose the camera is in interlaced mode. Then, pulses with a half-frame period T _p are formed at the output of the selector 4 clock pulses. Counter divider 5 performs the division of the input frequency into four, i.e. the period of the output pulses will be: T _d2 = 4T _p (see figv). During the action of the high level of this meander in the sensor 2, not one, but two exposure cycles with a “long” charge accumulation of 100,000 μs for each will be performed. Similarly, during the low-level action of the new meander in the sensor 2, not one, but two exposure cycles with a “short” charge accumulation of 10 μs each will take place. Block 8 delays the input video signal by two half frames, i.e. the duration of two T _p . The rest of the work of the camera does not differ from its functioning in progressive scan mode.

If necessary, return the camera to the prototype mode of operation should apply a pulse of positive polarity to the input "Stop". At the moment of coincidence at the “R” input of the RS flip-flop 3 of a high level of this pulse with a high level of clock pulses (CSI), the state of the trigger changes. At the direct output of the RS-flip-flop 3, the logic signal “0” will be set, and in the sensor 2 the operation of the ARVN circuit will be restored. At the same time, the operation of the comparators 7 and 9 will be suspended due to the supply of a logical “0” signal to their gate inputs. At the first and second control inputs of the switch-mixer 12, a logical combination “00” will be established, due to which a typical television signal of the sensor 2 will be transmitted to the output of the block from the first information input.

Currently, all blocks of the proposed solution have been mastered or can be mastered by domestic industry, therefore, the proposed invention should be considered as meeting the requirement for industrial applicability.

INFORMATION SOURCES

1. Patent No. 2305376 of the Russian Federation. MPK H04N 5/225, G08B 13/196. A television camera for observation in difficult lighting conditions and / or complex brightness of objects / V.M.Smelkov // BI - 2007. - No. 24.

2. Television cameras of the EVS company, catalog, 2005

3. Digital and analog integrated circuits: Reference / S.V. Yakubovsky, L.I. Nisselson, V.I. Kuleshova and others. - M .: Radio and communications, 1990.

Claims (2)

1. A television camera for observation in conditions of complex illumination and / or complex brightness of objects, comprising a lens, a television signal sensor, a sync pulse selector, a divider counter and a switch, as well as an RS trigger, a first comparator, the reference input of which is connected to a threshold voltage, and a switch-mixer, wherein the first control input of the television signal sensor is connected to the control input of the switch and connected to the direct output of the RS-trigger, the second control input of the body sensor Evision signal - to the output of the switch, the information input of which is connected to the output of the counter-divider, and the video output of the television signal sensor - to the first information input of the switch-mixer, the S-input of the RS-trigger is the input of the “Start” camera, R-input RS-flip-flop - with the input “Stop” of the television camera, and the output of the switch-mixer - with the output “Video” of the television camera, characterized in that the element “I” is inserted into it and the delay unit per frame is connected in series, consisting of an analog-to-digital converter connected in series device (ADC), random access memory (RAM) and digital-to-analog converter (DAC), a second comparator and an OR element, while the output of the delay unit per frame is connected to the second information input of the switch-mixer, the first control input of the switch-mixer is connected to the output of the “AND” element, the first and second inputs of which are connected respectively to the direct output of the RS-trigger and the output of the counter-divider, the second control input of the switch-mixer is connected to the output of the “OR” element, the second input of which is connected to the output of the first comparator, the gate inputs of the first and second comparators are combined and connected to the direct output of the RS trigger, the clock input of which is connected to the output of the clock selector, and the information input of the first comparator is connected to the input of the delay unit per frame and connected to the output of the television signal sensor, photo target which is optically coupled to the optical frame of the lens. 2. The television camera according to claim 1, characterized in that in progressive scanning of the image signal, the counter-divider is a divider of the input frequency by two, and in interlaced scanning, it is a divider by four, while the delay unit per frame in progressive scan mode is a delay unit two halves in interlaced mode.

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