GB2076617A - Method and Apparatus for Tracing a Temperature Profile Associated with the Surface of an Object - Google Patents

Abstract

A method of an apparatus for tracing a surface temperature profile on the screen of a CRT using an infrared scanning camera system. Horizontal and vertical CRT beam deflection signals are derived from the appropriate scanning elements of the camera and horizontal and vertical beam control signals are produced by superimposing on the horizontal deflection signal and on the sensor signal respectively, a fraction, preferably different fractions, of the vertical deflection signal to produce an apparently three-dimensional display of the temperature profile. <IMAGE>

Description

SPECIFICATION Method and Apparatus for Tracing a Temperature Profile Associated with the Surface of an Object This invention relates to a method of and apparatus for tracing a temperature profile associated with the surface of an object, on the screen of an electron beam tube. It is known to map the surface of the object (dot-and-line fashion) on a sensor signal corresponding to the intensity of radiation of the surface point displayed being obtained, and linearly traced on the screen, using suitable horizontal and vertical electron beam deflection signals obtained from the movement of the horizontal and vertical scanning elements of the camera.

Conventionally, an infrared camera system is used to map the surface of the object dot-and-line fashion on a sensor that emits a signal corresponding to the intensity of radiation of the dot mapped. A first instrument transformer device determines the movement of the camera elements provided for horizontal electron beam deflection signals suitable for the linear tracing of the sensor signal on the screen. Movement of the camera elements provided for vertical scanning is determined by a second instrument transformer device which transforms the values determined into vertical electron beam deflection signals suitable for the linear.tracing of the sensor signal on the screen, which may be the screen of a commercially available oscilloscope.

One such system including an infrared camera system and monitor AGA 750 is available from Messrs. A.G.A. and is described in their trade publications. In that system, horizontal and vertical timing signals of a frequency proportional to the scanning rate are derived from the horizontal and vertical scanning movements of the camera, and the timing signals are then processed in the monitor to form horizontal and vertical deflection signals. The system operates on a quadruple interline process principle, a full image of the surface of the object tested being scanned successively in the form of four quarterframes of a hundred quarter-lines each, and the frames being successively interlaced on the screen of the monitor electron beam tube.For this purpose the infrared camera system has an electro-mechanically driven rotary prism system scanning the surface of the object (in a dot-andline), during an image, each point of the object being mapped once only on an infrared sensor.

The rotary prism system essentially consists of a vertical and a horizontal octahedral prism rotated via speed-governed DC motors. Each rotary prism is coupled with a timing signal disc, the discs providing horizontal and vertical timing signals which are used for speed control of the two rotary prisms of the electro-mechanically driven rotary prism system. The timing signal pulses essentially are square pulses processed in the monitor to form horizontal and vertical saw-tooth deflection signals and then serve, in that form, for the control or deflection of the electron beam on the screeen of the monitor. The horizontal-to-vertical prism speed ratio is 401:1, since this system operates on the quadruple interline process principle.Using the infrared sensor, the IR light intensity captured from each point of the object surface with the aid of transmission optics (essentially consisting of a front lens system and the rotary prisms) is transformed into electrical sensor signals the amplitude of which is a measure of the surface temperature of the scanned point on the surface of the object. The geometrical dimensions of the sensor and the path of rays permit a resolution of about 100 points per line. On the screen of the monitor the sensor signals produce a black-and-white, lightand-shade image on which temperature differences on the surface of the object are made apparent by varying shades of grey. The higher the temperature of a point on the surface of the object, the brighter the corresponding point of the image.The system additionally permits points of equal brilliance -- or of equal temperature -- to be connected on the screen with a line. The isothermal marking device permits, via a calibration curve and a reference beam generator in the surface of the object, a quantitative analysis to be made of any one temperature level whereas simultaneous assessment of absolute temperature differences is prevented, because points of the object not contained in this isotherm, can only be assessed qualitatively.

Another disadvantage is that representation of the surface temperature profile by differences in brilliance is handicapped by limited resolution.

This applies equally to geometrical resolution and to the sensitivity of the temperature measurement proper.

This invention aims to enable all points on the surface of the object to be made susceptible of rapid quantitative thermal evaluation.

According to one aspect of this invention we propose a method of tracing a temperature profile associated with the surface of an object on the screen of an electron tube, by mapping the surface of the object on a sensor using an infrared camera system, to obtain a sensor signal corresponding to the intensity of radiation of the surface point displayed and comprising deriving from the movement of the horizontal and vertical scanning elements of the camera suitable horizontal and vertical electron beam deflection signals for tracing the sensor signal on the screen superimposing on the horizontal deflection signal a fraction of the vertical deflection signal to produce a horizontal control signal for the electron beam, and superimposing on the sensor signal a fraction of the vertical deflection signal to produce a vertical control signal for the electron beam.

According to another aspect of this invention we propose apparatus for tracing a temperature profile associated with the surface of an object on the screen of an electron beam tube, having an infrared camera system which maps the surface of the object dot-and-line fashion on a sensor that emits a sensor signal corresponding to the intensity of radiation of the surface dot displayed, a first instrument transformer for sensing the movement of the camera elements provided for horizontal scanning and for transforming the values sensed into horizontal electron beam deflection signals suitable for the linear tracing of the sensor signal on the screen, and a second instrument transformer for sensing the movement of the camera elements provided for vertical scanning and for transforming the values sensed into vertical electron beam deflection signals suitable for the linear tracing of the sensor signal on the screen, and comprising a signal divider circuit receiving -the signal output of the second instrument transformer device and having a first and a second output, a first summer circuit the input of which is connected to the output of the first instrument transformer and to the first output of the signal divider circuit, and the output of which is connected to the output of the sensor and to the second output of the signal divider circuit, and the output of which is connected to the vertical control input (Y) of the el.ectron beam tube.

One advantage of this invention resides in the fact that the amplitude of the sensor signal, which amplitude is a measure of the temperature of the corresponding point on the surface of the object under test, can be displayed with the aid of the vertical and horizontal deflection signals by linear scanning, i.e. in individual lines on a conventional electron beam tube in an apparently threedimensional form. The sensor signal is traced on each line as an ordinate value, the line being taken as the abscissa. Also, it is possible to use the known infrared camera system AGA 750 and monitor to generate the timing and deflection signals, or a conventional electron beam tube.

The addition of a fraction of the vertical deflection signal to the horizontal deflection signal, and the use of the recalling signal as a horizontal control signal for the electron beam produces, for each frame, a line offset which increases continuously from the left upper rim of the picture to the right lower rim, where the line offset is the same between two immediately successive lines. This applies equally to the full image. Superimposition of a fraction of the vertical deflection signal upon the sensor signal, and use of the resulting signal as a vertical electron beam control signal produces coordinate transformation in the sense of rotation or inclination of the abscissa. Both effects taken together produce the apparently threedimensional display of the surface profile in the form of a perspective view of temperature massif.

Such a display provides a readily assimilated visual representation, which can easily be quantified, of the temperature profile of the surface of the object under test.

The abovementioned Camera system AGA 680 is supplied with a profile adapter used to map the temperature profile of a test surface line by line in apparently three-dimensional form on an oscilloscope. The sensor signal amplitude is traced in each line as an ordinate over the horizontal local co-ordinate, where a small amount of line offset is provided between individual horizontal lines. In this manner, all temperature values can simultaneously be mapped and recorded photographically with a high degree of resolution. For quantitative evaluation the sensor signal amplitudes on any one line can, if necessary, be made visible singly, and can be scaled into absolute temperature values using a calibration curve. This differs from the conventional approach wherein the known adapter cannot be connected to the infrared camera system AGA 750.

In a preferred embodiment the signal divider ratio of the signal divider circuit is separately adjustable for each output so that various fractions of the vertical deflection signal can be superimposed on the horizontal signal and/or the sensor signal. This makes the perspective of the apparently three-dimensional display of the temperature profile variable and, thus, adaptable to various service conditions or requirements.

The infrared camera system and the first and the second instrument transformer devices for scanning and tracing the surface of the object under test are preferably designed in accordance with the quadruple interline process. This makes it possible to utilize the known advantages afforded by the interline process, especially by the quaduple interline process.

The magnitude of the sensor signals (the vertical deflection signals and/or the horizontal deflection signals) may each be compared with given threshold values, and the horizontal and/or vertical control signals may then be suppressed when the magnitude of the sensor signals and/or of the deflection signals is below the given threshold values. For this purpose, each of the sensor, the first and/or second instrument transformer device is preferably associate with a threshold circuit the outputs of which are connected to the control input of an analogue switch interconnected between the second summer circuit and the vertical control input of the electron beam tube, so permits the suppression of insignificant image portions, i.e. of relatively weak sensor signals, of the upper rim of the picture and/or of the beginnings of the lines.

In order to display the temperature profile in inverted and non-inverted, apparently threedimensional form, the analogue switch is preferably designed for change-over between an inverting terminal and a non-inverting terminal.

The inverted display ensures that preselected portions of the picture are blanked on the screen.

For more accurate evaluation of the temperature profile each line of an image may be displayed singly or blanked from the total field of lines, i.e. may be displayed in inverted form. Such tracing makes it possible, especially by inverted display of a single line or perhaps frame, to determine its location within the surface of the object and then display it separately with the electron beam, i.e. to trace it in non-inverted form.

To achieve this, the first instrument transformer preferably has - in a manner known from the camera system AGA 750 - a first measuring device directly connected to the camera elements provided for horizontal scanning to generate horizontal timing signals at a frequency proportional to the scanning rate and a transformer device, at the output end, to transform the horizontal timing signals into horizontal deflection signals, and in accordance with the present invention, the first measuring device is followed by a counter programmed to count preselected timing signals, the counter output being connected to the control input of the analogue switch. The counter output is preferably connected, directly or alternatively through a negation stage, to the control input of the analogue switch.In this arrangement the temperature profiles corresponding to the selected lines are traced when there is a direct connection between the counter output and the control input of the analogue switch, and they are suppressed when the connection is via the negation stage.

For ease of selecting the respective line to be displayed or suppressed, the counter preferably includes a divider to divide the incoming horizontal timing signals by the number of horizontal timing signals provided for each line, and it also includes a comparator connected to a BCD coded line preselector switch. The counter may be reset to its original condition by means of a control pulse, where the reset control pulse is preferably derived from the second instrument transformer device.

In order to select between frame display and full image display and to ensure that the frame displayed is invariably the same, the second instrument transformer preferably includes a second measuring device directly connected to the camera elements provided for vertical scanning, to generate a synchronizing pulse at the beginning of each complete scan of the surface of the object and to generate vertical timing signals at a frequency proportional to the scanning rate, and, at the output end, a transformer device to transform the vertical timing signals into vertical deflection signals. While this arrangement is generally known from the camera system AGA 750, it is known - as far as the synchronizing pulse is concerned -- only to the extent that the pulse is supplied before every other full image only.In accordance with the present invention, however, the second measuring device is immediately followed by a divider which divides the incoming signals received between the respective synchronizing pulse and the start of the last frame. The reset input of the divider is connected to the synchronizing pulse line, and its output is connected to the control input of the analogue switch. By changing over an image selector switch between the output of the divider and a branch line bypassing the divider, selection can be made of either a full image or frame display. Different frames, i.e. the first, second, third or fourth quarter-frame can be selected by (e.g.) connecting the reset input of the divider to a time delay stage, preferably a monostable trigger circuit the time delay constant of which can be varied in steps corresponding to the duration of a frame scan.

Rather than deriving the vertical timing signals from the second measuring device, these can be derived also from the first measuring device provided the scanning movements between the horizontal and vertical scanning camera elements respectively follow a fixed ratio. The synchronizing pulse is nevertheless taken from the second measuring device.

For displaying only the respective selected portions of the image, lines or frames, the outputs of the counter and of the divider are preferably interlocked via a first AND module ahead of the control input of the analogue switch, the outputs of the threshold value circuits associated with the sensor signal and the horizontal and vertical deflection signals are interconnected through an OR module ahead of the control input of the analogue switch, and the outputs of the OR module and of the first AND module are interlocked through a second AND module behind said logic elements and ahead of the control input of the analogue switch. Use can be made of twoor-more-stage logic elements such that, e.g., the first and the second AND modules are combined to form a single, three-stage AND module.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 illustrates the line pattern used in the quadruple interline process; Fig. 2 illustrates an infrared camera system followed by instrument transformer devices; and Fig. 3 illustrates a signal processing circuit arranged between the instrument transformer devices and an electron beam tube.

The embodiment of the present invention illustrated on the accompanying drawings is a device for tracing a temperature profile associated with the surface of an object on the screen of an electron beam tube using the quadruple interline process, where the full image of the object surface is scanned and traced successively in the form of four quarter-frames of a hundred quarterlines each. The quarter-frames are interlaced lineby-line. This will become apparent from Fig. 1. As shown in this Fig. the electron beam first traces the first quarter-frame A, beginning with line 1 which is here shown as a continuous line. Having completed the one hundred quarter-lines of the first quarter-frame A, the electron beam jumps back to the first line and starts tracing the frame B, which in Fig. 1 is shown in dash-dotted line.

When this frame has been traced, frame C, and thereafter frame D, will be traced. The tracing process will then start again. Owing to the inertia of the screen of an electron beam tube and of the interline process employed the traced picture will appear as a full stationary image. The general quadruple interline process is known, as perhaps .from the infrared camera and tracing system 750 from Messrs. AGA., or from the publications having appeared on the product.

Figs. 2 and 3 illustrate the infrared camera system 10 and associated electron beam control electronics used for scanning and tracing the temperature profile associated with the object surface by quadruple interline process. The infrared camera system 10 essentially consists of a front lens system 12 which serves to focus the heat rays emitted by the object surface on to a vertical octahedral prism 14. The vertical octahedral prism 14 is arranged as a rotary prism such that it vertically scans the object surface. For the purpose, it had two sets of octahedral surfaces, which are the octahedral surfaces A, B, C, D and A', B', C', D', respectively, where each octahedral surface A or A', B or B', C or C', and D or D' exactly corresponds to one of the frames A to D.A horizontal octahedral prism 1 6 taking the form of a rotary prism is additionally provided and arranged such that it scans the object surface horizontally. For the purpose, the axis of rotation 1 7 of the horizontal octahedral prism 1 6 is arranged at right angles to the axis of rotation 1 5 of the vertical octahedral prism 14.The front lens system 12, the vertical octahedral prism 14 and the horizontal octahedral prism 1 6 are arranged and attuned one to the other such that the object surface is traced in the form of dots on an infrared sensor 1 8. The sensor signal emanating from the sensor 1 8 is amplified in its passage through a preamplifier 20 and is then processed, in the circuitry illustrated in Fig. 3, to form a control signal for the vertical movement of the electron beam.

Under these circumstances, where use is made of an electro-mechanically driven rotary prism system of two octahedral prisms for scanning and tracing the object surface in the form of four frames interlaced by interline process and having a hundred quarter-lines each, the speed ratio of the horizontal to the vertical octahedral prism is necessarily 401:1 or 100-1/4:1. Additionally, the deflection of the electron beam surface is scanned by means of the electromechanical rotary prism system. For the purpose, a first timing disc 24 and a second timing disc 34 are attached to, respectively, the rotary axes 1 5 and 1 7 of the vertical octahedral prism 14 and the horizontal octahedral prism 1 6. The first timing disc forms, together with a first opto-electrical converter 26, a first measuring device 22.The second timing disc 34 forms, together with a second optoelectrical converter 36, a second measuring device 32. The vertical octahedral prism 14 and the horizontal octahedral prism 1 6 are rotated by means of DC motors 28 and 38, respectively.

When the timing discs 24 or 34 are revolving, the opto-electrical converters 26 and 36 respond to suitable marks on the timing discs. This permits horizontal timing signals to be picked off the optoelectrical converter 26, and vertical timing signals off the opto-electrical converter 36. The horizontal and vertical timing signals are conventionally related one to the other by phase interlock circuitry such that the proper speed ratio is invariably ensured by suitable control of the motors 28 and 38. Reference is here made, e.g., to the infrared camera system 750 by Messrs.

A.G.A. or the publications having appeared on the product. The horizontal and vertical timing signals are then processed, using succeeding transforming devices 30 and 40, respectively, to form horizontal and vertical deflection signals that are generally suitable for deflecting the electron beam to enable tracing by the quadruple interline process. Said processing of the timing signals to form deflection signals can be achieved, e.g., in a monitor, such as it is frequently being used in conjunction with the camera system, or in some other circuitry capable of generating suitable sawtooth pulses. In the embodiment illustrated the first converter 30 behind the first measuring device 22 is designed such that both the horizontal deflection signals and the unchanged horizontal timing signals can be picked off the transformer 30.This applies equally to the second transformer 40 behind the second measuring device 32.

In accordance with the present invention, now, the horizontal and vertical deflection signals emanating from the first and second transformers 30 and 40 are not directly routed to the horizontal and vertical control inputs end of the electron beam tube but are processed in a signal processor circuit (Fig. 3) interconnected between the infrared camera system 10 plus associated instrument transformers 22, 30 and 32, 40 and the electron beam tube such that a selectable fraction of the vertical deflection signal is superimposed on the horizontal deflection signal and that the signal obtained by such superimposition is routed as a horizontal control signal to the horizontal control input for the electron beam and that simultaneously, a selectable fraction of the vertical deflection signal is superimposed on the sensor signal and that the signal obtained by such superimposition is routed as a vertical control signal to the vertical control input for the electron beam. The signal processor circuit preferably exhibits additional circuit groups enabling selection to be made of given frames, i.e.

for the display of, e.g., the first, second, third or fourth frame, plus circuit groups for displaying certain lines. The circuitry is preferably designed such that it enables the vertical component, or the vertical control signal, to be displayed in noninverted or in inverted form.

Fig. 3 Illustrates an embodiment of the processor circuitry arranged in accordance with the present invention.

The horizontal and vertical deflection signals are picked off at the output ends of the transformers 30 and 40, respectively. When use is made of an infrared camera system AGA 750, these signals are picked off the monitor output at terminals P8 and P9 (connector PJ 3) through impedance compensators 46 and 48. The impedance compensators 46 and 48 serve to match the circuits joined together via impedance compensators 46 and 48, especially in order to maintain the forms of signal. The video or sensor signal is picked off the preamplifier 20 -- and where an infrared camera system AGA 750 is used, off the terminal P2 (PJ 3) - and is routed, through a buffer 50, to the video buffer output and to a second amplifier stage 52 with background suppression provisions.For background suppression, the second amplifier stage 52 is connected to a variable potentiometer 54 which permits adjustment to be made of the voltage corresponding to the background.

Background suppression is basically achieved by means of a subtraction circuit in which the output voltage from the potentiometer 54 is subtracted from the sensor signal. In order to adapt to considerable differences in temperature on the surface of the object under test, the second amplifier stage 52 is followed by an infinitely variable third amplifier stage 56. The third amplifier stage 56 is used, via a change-over switch 58, to choose between variable amplification and fixed amplification X1.

The change-over switch 58 is followed by second summer circuit 60, in which a fraction of the vertical deflection signali s added to the amplified video signal provided by the sensor 1 8.

The signal so conditioned in the second summer circuit 60 will hereafter be termed the vertical control signal. This vertical control system is routed to the vertical control input end of the electron beam tube through an analogue switch 62 (invester stage 64) and an output amplifier 66.

The horizontal and vertical deflection signals are picked directly off the first and second transformers 30 and 40. If use is made of an infrared camera system AGA 750, the horizontal and vertical deflection signals can be picked, at high-resistance values, directly off the monitor output at terminals P8 and P9 (connector PJ 3) via the impedance compensators 46 and 48. In order to suppress the sensor signal over about 25% of the length of line, counting from the start of line, the horizontal deflection signal is compared, in a horizontal threshold value circuit 68, with an adjustable threshold value.

In order to suppress the sensor signal in the first, or upper 25 lines, the vertical deflection signal is compared, in a vertical threshold value circuit 70, with an adjustable threshold value. The outputs of the two threshold value circuits 68 and 70 are interconnected through and OR module 72. The output of the OR module 72 and the output of a comparator 76 are interconnected through another OR module 74. The comparator 76, basically, is another threshold value circuit and serves to suppress insignificant portions of the picture. For the purpose, the sensor signal emanating from the change-over switch 58 is compared in the comparator 76 with the output voltage of a potentiometer 78.The output of the OR module 74 is interlocked, via an AND module 80, with the output of an image and line selector logic circuit, a more detailed description of which will be offered elsewhere herein. The output signal from the AND module 80 is connected to the control input 81 of the analogue switch 62.

The analogue switch is designed such that it can be changed over from one terminal to another, where the one terminal is connected to the output amplifier 66 through an inverter stage 64. The output signal of the AND module 80 is used to activate or deactivate the analogue switch 62.

Whenever the sensor signal, the vertical deflection signal and/or the horizontal deflection signal fail to achieve a given threshold value, therefore, the analogue switch is cut out, and the picture portions corresponding to these signals will not be traced.

The vertical deflection signal fraction to be added to the sensor signal is picked off a potentiometer 82. Added to the horizontal deflection signal in a first summer 86 is also a fraction of the vertical deflection signal. This fraction of the vertical deflection signal is picked off the potentiometer 84. The output of the first summer circuit 86 is connected to the horizontal control input of the electron beam tube through an output amplifier 88. The circuitry as described so far achieves an apparently three-dimensional display of the temperature profile associated with the surface to be tested, for the addition of a fraction of the vertical deflection signal to the horizontal deflection signal produces the line offset that grows increasingly with the rise in vertical deflection signal voltage.Line offset, therefore grows continuously from the start to the end of the image, with the line offset from one line to the next nevertheless remaining constant.

Addition of a selectable fraction of the vertical deflection signal to the sensor signal produces a variable inclination accompanied by a change in the spacing of the lines or abscissae over which the respective ordinate values governed by the sensor signal are plotted. The inclination of the lines of abscissae in conjunction with their relative offset produces an apparently threedimensional display of the temperature profile.

This displays the temperature profile of the surface under test in an easily visualised manner as a three-dimensional temperature massif, where the inverter stage 64 achieves inverted display, especially the blanking as described above of individual lines from a frame or image.

The perspective of the apparently threedimensional temperature profile can be varied by shifting the pickoffs (outputs) 83 and 85 at the potentiometers 82 and 84.

The picture portions suppressed by means of the horizontal and/or vertical threshold value circuit 68 or 70 are displayed in the electron beam tube into the non-visible portion of the screen using a vertical and/or horizontal position potentiometer omitted on the drawing.

What immediately follows is a description of the image selector logic circuit.

Inasmuch as the vertical deflection signal picked off the terminal P9 together with the vertical timing signal picked off the terminal 11, the horizontal deflection signal picked off the terminal P8 together with the horizontal timing signal picked off the terminal 10, and the length of sensor signal pulse are synchronous, the image selector control can be derived directly from said digital timing signals.

In the embodiment illustrated it was assumed that each image was composed of four frames, .and that each frame was composed of a hundred horizontal quarter-lines. With this embodiment, also, the lines are traced at a frequency of 2500 cps. 40 ms, therefore, will be required for tracing a quarter-frame. The time between vertical timing signals, therefore, is 40 ms for the embodiment here illustrated, considering that a vertical timing signal is generated for every frame. Now in order to display a frame only, the vertical timing signals from the second transformer 40 are routed to a divider 90, which divides incoming timing signals by four. In order to invariably display the same frame, the reset input 92 of the divider 90 is fed, for every full image, a synchronizing pulse F No. 1, which is derived from the second timing disc 34.

-With the infrared camera system AGA 750 this synchronizing pulse is the field No. 1 pulse, which is picked directly off the trigger disc of the vertical prism, which appears for every second full image, and which normally serves to control the quadruple interline process. -The pulse-to interval ratio of the vertical timing signal at the output of the divider 90, therefore is 1:3.

Using a time delay circuit 94 ahead of the reset input 92, as perhaps a monostable trigger circuit, any one of the four quarter-frames can be selected for display. For the purpose, it will be necessary only to vary the time constant of the time delay circuit 94 in stages that correspond to the time required for displaying a frame (i.e. 40 ms).

For displaying the full image, a picture selector switch 96 is provided which can be changed over between the output end of the divider 90 and the terminal of a branch line 98 bypassing the divider 90.

For displaying a frame, the outputs of the divider 90 and of the first transformer 30 for the horizontal timing signals (terminal P10) are interlocked using an AND module 100. The output of the AND module 100 is interlocked with the output of the OR module 74 via the AND module 80, which in turn controls the analogue switch 62. For directly interlocking the output P 10 (for the horizontal timing signals) of the first transformer 30 with the output of the divider 90, use is made of a change-over switch 104 and a branch line 102.

With the embodiment illustrated, a pulse is available at the output of the divider 90 for a duration of 40 ms, during which time 100 timing pulses (equal to 100 lines) are transmitted. At the output of the AND module 100, therefore, a pulse package of a total length of 40 ms, a single pulse length of 400 us and a duration of 120 ms is available between two pulse packages.

For a duration of 40 ms (equivalent to a quarter-frame), therefore, the analogue switch 62 allows passage of the vertical control signals, and it blocks off the vertical control signals after the quarter-frame for a duration of 1 20 ms (equivalent to three quarter-frames).

For line selection, the change-over switch 104 is switched over to a counter 106 which is programmed to count given timing signals. For the purpose, a divider 108 ahead of the counter 106 serves to divide the incoming horizontal timing signals by the number of timing signals per 1 line. Inasmuch as in this case, there are 100 horizontal timing signals per 1 line, the divider 108 divides by 100. The reset input 110 of the counter 106 is connected to the output of the picture selector switch 96.

Now in order to select a certain line, a BCDcoded line preselector switch 112 is provided the output of which is routed to a comparator (omitted on the drawing) provided in the counter 106, said comparator also receiving the count pulses of the counter 106. Then when the count agrees with the value selected by the line preselector switch 112, the comparator in the counter 106 emits a pulse to the AND module 100. As this pulse corresponds to the length of a line, the signal emanating from the picture selector switch 96 is interlocked, for said duration, with the horizontal timing signal via the AND module 100. For the duration of a line, therefore, the analogue switch 62 will conduct and trace the vertical control signal emanating from the second summer circuit 60 on the screen of the electron beam tube.In order to choose between inverted and non-inverted display, the output of the counter is connected, directly through a line selector switch 114 or through a negation circuit 11 6, to the input of the AND module 100. With said line selector logic circuitry, therefore, randomly selected single lines can be blanked from a frame or full image, and can thus be located and subsequently be traced singly.

The embodiment illustrated on the drawing is especially suitable for direct connection to the infrared camera system 750 supplied by Messrs.

A.G.A. The circuitry shown makes it possible to provide an apparently three-dimensional, readily visualised display of the temperature profile associated with the surface of the object under test, a display of a temperature profile associated with a frame only, and a display of a temperature profile associated with a single line only, where the temperature is plotted over the relevant line as an ordinate value.

Claims (23)

Claims

1. A method of tracing a temperature profile associated with the surface of an object on the screen of an electron tube, by mapping the surface of the object on a sensor using an infrared camera system, to obtain a sensor signal 'corresponding to the intensity of radiation of the surface point displayed and comprising deriving from the movement of the horizontal and vertical scanning elements of the camera suitable horizontal and vertical electron beam deflection signals for tracing the sensor signal on the screen superimposing on the horizontal deflection signal a fraction of the vertical deflection signal to produce a horizontal control signal for the electron beam, and superimposing on the sensor signal a fraction of the vertical deflection signal to produce a vertical control signal for the electron beam.

2. A method according to Claim 1, wherein the fraction of the vertical deflection signal superimposed on the horizontal deflection signal is different from that superimposed on the sensor signal.

3. A method according to Claim 1 or Claim 2, wherein the surface of the object is scanned and traced by the interline process.

4. A method according to Claim 3, wherein scanning and tracing is achieved by the quadruple interline process.

5. A method according to any one of the preceding ciaims, wherein the magnitude of the sensor signal, of the vertical deflection signal and/or of the horizontal deflection signal are each compared with given threshold values, and the horizontal and/or vertical control signals are suppressed when the magnitude of the sensor signal and/or of the deflection signals is below the given threshold values.

6. A method according to any one of the preceding ciaims, wherein horizontal timing signals of a frequency proportional to the scanning rate are derived from the horizontal scanning movement of the camera, these timing signals are processed to form horizontal deflection signals, and wherein the horizontal timing signals are counted and the horizontal and/or vertical control signals are suppressed only for the duration of the count of the horizontal timing signals associated with a given line or wherein both control signals are used for control of the electron beam.

7. A method according to any of the Claims 3 to 6, wherein vertical timing signals of a frequency proportional to the scanning rate are derived from the vertical scanning movement of the camera and these timings signals are processed to form vertical deflection signals, wherein the vertical timing signals are suppressed for the duration of the count of the timing signals associated with one or several frames or wherein both control signals are used for control of the electron beam.

8. Apparatus for tracing a temperature profile associated with the surface of an object on the screen of an electron beam tube, having an infrared camera system which maps the surface of the object dot-and-line fashion on a sensor that emits a sensor signal corresponding to the intensity of radiation of the surface dot displayed, a first instrument transformer for sensing the movement of the camera elements provided for horizontal scanning and for transforming the values sensed into horizontal electron beam deflection signals suitable for the linear tracing of the sensor signal on the screen, and a second instrument transformer for sensing the movement of the camera elements provided for vertical scanning and for transforming the values sensed into vertical electron beam deflection signals suitable for the linear tracing of the sensor signal on the screen and comprising a signal divider circuit receiving the signal output of the second instrument transformer device and having a first and a second output, a first summer circuit the input of which is connected to the output of the first instrument transformer and to the first output of the signal divider circuit, the output of which is connected to the horizontal control input (X) of the electron beam tube, and a second summer circuit the input of which is connected to the output of the sensor and to the second output of the signal divider circuit, and the output of which is connected to the vertical control input (Y) of the electron beam tube.

9. Apparatus according to Claim 8, wherein the signal divider ratio of the signal divider circuit is separately adjustable for each output.

10. Apparatus according to Claim 8 or 9, wherein the infrared camera system and the first and the second instrument transformer -- are operable to scan and trace the surface of the object by the interline process.

11. Apparatus according to Claim 10, wherein the infrared camera system and the first and the second instrument transformer -- are operable to scan and trace the surface of the object by the quadruple interline process.

12. Apparatus according to any one of the Claims 8 to 11, wherein the sensor, the firs and/or second instrument transformer are each connected to a threshold value circuit the outputs of the threshold value circuit being connected to the control input of an analogue switch arranged between the second summer circuit and the vertical control input (Y) of the electron tube.

1 3. Apparatus according to Claim 12, wherein the analogue switch is designed for changing over between an inverting and a non-inverting terminal.

14. Apparatus according to any one of the Claims 8 to 13, wherein the first instrument transformer includes a first measuring device directly connected to the horizontal scanning elements of the camera to generate horizontal timing signals of a frequency proportional to the scanning rate, and a transformer device immediately following the first measuring device for transforming the horizontal timing signals into horizontal deflection signals the first measuring device being immediately followed by a counter programmed to count preselected horizontal timing signals and the counter output being connected to the control input of the analogue switch.

1 5. Apparatus according to Claim 14, wherein the output of the counter is connectable to the control input of the analogue switch via a negation stage.

1 6. Apparatus according to Claim 14 or 15, wherein the counter includes a divider for dividing the incoming horizontal timing signals by the number of horizontal timing signals selected for each line, and a comparator connected to a BCD coded line preselector switch and wherein the counter can be reset to its original condition by means of a control pulse.

1 7. Apparaus according to one of the Claims 10 to 1 6, wherein the second instrument transformer includes a second measuring device directly connected to the vertical scanning elements of the camera for generating a synchronizing pulse at the beginning of every full scan of the surface of the object and for generating vertical timing signals of a frequency proportional to the scanning rate, and at its output a device for transforming the vertical timing signals into vertical deflection signals, wherein the second measuring device in immediately followed by a divider which divides the incoming vertical timing signals by the number of vertical timing signals received between the respective synchronizing pulse and the start of the last frame, and wherein the reset input of the divider is connected to the synchronizing pulse line and its output to the control input of the analogue switch.

18. Apparatus according to Claim 17, wherein the reset input of the divider is preceded by a monostable trigger circuit the delay time constant of which is variable in steps corresponding to the duration of a frame scan.

1 9. Apparatus according to any one of the Claims 8 to 18, wherein the outputs of the counter and of the divider are interlocked via a first AND module preceding the control input of the analogue switch.

20. Apparatus according to any one of the Claims 8 to 1 9, wherein the outputs of the threshold value circuits associated with the sensor signal and the deflection signals are interconnected via an OR module preceding the control input of the analogue switch.

21. Apparatus according to Claim 20 or Claim 21, wherein the outputs of the first AND module and the OR module are interlocked through an AND module preceding the control input of the analogue switch.

22. A method of tracing the temperature profile associated with the surface of an object, on the screen of an electron tube, which method is substantially as hereinbefore described.

23. Apparatus for tracing the temperature profile associated with the surface of an object on the screen of an electron tube, which apparatus is constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.