Color Intensity Control System

Abstract

Device for effecting polychromatic traces of light, more particularly on the screen of a polychromatic cathode tube, comprising means for regulating the number of repeats of a same trace as a function of its color, in order to regulate the light flux produced by a trace according to its color.

Description

The present invention concerns a device for effecting polychromatic traces of light on a screen, more particularly on the screen of a cathode tube.

It is known practice, in the branch of displaying, and more particularly of polychromatic graphic displaying, to observe, for example, the traffic of various mobile objects in a determined region of space.

Various data relating to mobile objects moving in the region of space in question, and concerning, more particularly their position, their identity, their speed or their altitude, if the mobile objects in question are airborne, are transmitted to a data processing unit forming a part of the observing installation, for example by a radar or other detection or telemeter devices. The vectors which must be traced on the screens of panoramic indicators are intended, for example, to indicate the direction and the speed of the mobile objects. These vectors are sequenced and thus form broken lines or polygonal contours. They have well-defined origins and ends. It is particularly interesting to be able to observe the traffic of these various mobile objects along the traces in different colors, in order to avoid any possible confusion between the paths of the various mobile objects. It is also particularly interesting to be able to observe certain traces, in the form of photographic pictures of the displaying screen, in order, for example, to effect a deep examination of a certain trace, or to keep that trace for archiving operations or for comparison with other traces already affected. It is necessary, for producing these photographic pictures, to have a polychromatic photography device. A conventional photography device provided with a polychromatic photographic film and a shutter having an adjustable opening time, may be arranged facing the screen. This simple means has disadvantages, for on the display screen, the light fluxes of the traces in various colors are different. Thus, for example, in the case of a four-color display system, where the traces may be colored green, yellow, orange or red, the light flux of the traces decreases from green to red, and for a determined exposure time, the photographic film will be too exposed for the green trace, and not exposed enough for the red trace. It is difficult, for a given exposure time, to make the intensity each color vary, in order that, the photograph, the various traces appear to have the same luminosity.

Another known means for such photographing consists in arranging before the screen, an optical filter for each of the colors, and in effecting four exposures for a photograph of the set of traces.

A filter allowing only green to pass, another allowing only yellow to pass, and so on until red. This enables one exposure time to be provided for green, another for yellow, and so on, up to red, the exposure time being greater for red than for green, if the red trace produces the smallest light flux. This device has the disadvantage of requiring expensive optical equipment which is bulky, difficult to handle, needs a fairly long time for adjusting the exposure time, and it is very difficult to intercept the traces which vary too rapidly.

The present invention aims at overcoming these difficulties.

The present invention has for its object a device for effecting polychromatic traces of light, that device comprising:

A display screen; means for making a sequence of sets of traces appear on the said screen; a data processing element controlling the said means for making the said sequence of sets of traces appear, so that the sets be reproduced identically to themselves and correspond to the data contained in the said processing element; means for controlling the colors of the traces, synchronized with the said means for making the sequence of sets of traces appear; an element for selecting the colors of the traces, controlled by the processing element and comprising color selecting outputs; and an element for switching colors, comprising switching inputs connected up to the said selecting outputs, one output of that switching element being connected to the said means for controlling the colors of the traces, the said selecting outputs sending color switching signals so that one and the same color corresponds to an output.

This device being characterized in that each said selecting output is connected respectively to each said switching input through a switch controlled by adjustable counting means, so that the number of the said sets which comprise the traces of each of the said colors be a predetermined number, depending on that color.

Purely by way of illustration, an example of an embodiment of a device for effecting polychromatic traces of light on a screen will be described with reference to the single figure which is a block diagram of an example of the present invention.

In the figure a display screen 1, which, in the case of the embodiment chosen, is the potentials, of a cathode ray tube 2. Means 3 is connected to the cathode ray tube 2 for making a sequence of sets of traces 4 appear on the screen 1. These means are constituted here by a generator for controlling the deflecting system for the electronic beam produced in the tube. In the example of the embodiment chosen, this deflecting system is of the electrostatic type; it is constituted by horizontal deflecting plates 5 and 6 and vertical deflecting plates 7 and 8. The means 3 sending to their outputs 9 and 10 to the plates 6 and 7 binary signals corresponding, for example to the directing parameters Xo, X and Yo, the Y of a displayed vector. These directing parameters are, for example, for X and Y, the lengths of the projections of the vector in question on each of the coordinates axes of a Cartesian system; for Xo and Yo, the coordinates of the origin of the vector in the Cartesian system in question. The plates 5 and 8 are, themselves, brought to fixed reference otentials, produces by sources 11 and 12. It is quite evident that in the example of the embodiment chosen, the deviation of the cathode ray beam is electrostatic, but magnetic deflecting would be perfectly suitable.

The device also comprises a data processing element 13, which receives, at inputs 14, data relating to the traces to be effected. This data is processed by that element, and its outputs 15, 16, 17 and 18 send out, respectively, to the means 3, signals relating to Xo, X, Yo, Y, characteristic of the sequence of vectors which, by succession, form one of the traces of the set of traces appearing on the screen. The means 3 is controlled by a processing element, so that the sets of traces can be reproduced identically to themselves and correspond to the data contained in the processing element.

Means for controlling the color of the traces is synchronized with the means 3. These control means are constituted here by the control electrode 19 of the cathode ray tube 2 connected to the output of a voltage switching element 20, so that each high voltage corresponds to a color on the screen. It is supposed that the cathode 21 of the cathode ray tube 2 is brought to a fixed reference potential.

An element 22 is provided for selecting the colors of the traces, controlled by the processing element 13 and comprising color selecting outputs 23, 24, 25 and 26. These outputs are connected to the switching inputs 27, 28, 29 and 30, of the switching element 20. The outputs of that selecting element send to the switching element the color switching signals, so that one and the same color correspond to an output during the sequence of sets of traces. Each switching input is connected to a selecting output through a switch, controlled by adjustable counting means. Thus, there is one switch per selecting output. The set comprising these switches is constituted here by "AND" gates 31, 32, 33 and 34, each of the "AND" gates having an input connected to a selecting output, and another input connected to the adjustable counting means 35, 36, 37 and 38. These counting means enable the number of successive sets which comprise traces of each color to be adjusted, so that this number be predetermined according to the color. These counting means, for each of the "AND" gates, are constituted by a reverse counting counter which receives, at an input, pulses synchronized with the succession of sets of traces. These pulses are supplied to the reverse counting counters by the output 39 of the processing element 13, across a switch 40. The adjusting of the counting means is effected by a display element 41, whose outputs are respectively connected to an adjustment input of each reverse counting counter. This display element enables the adjusting of the number of successive sets of traces to be effected in each color, since the pulses which reach the reverse counting counters are synchronized with the renewal of these assemblies. One output of each reverse counting counter is connected to the input of a flip-flop which forms a part of a flip-flop assembly shown here at 42, 43, 44 and 45. The outputs of these flip-flops are connected respectively to another input of the "AND" gates 31, 32, 33 and 34. The flip-flop supplies to the "AND" gate corresponding to it a signal whose duration is that of the reverse counting, and corresponds to the number of pulses displayed on the element 41. The "AND" gate which receives that signal is then open throughout that duration and thus enables the passing of the color switching signal coming from the selecting element 22. Thus, in the example of the embodiment chosen, the number of "AND" gates, fulfilling the function of a switch, is equal to four. Each of these gates receives, respectively, from the outputs 23, 24, 25 and 26 of the selecting element 22, a signal corresponding, for example, to the controlling of the green, yellow, orange and red traces, for a four-color polychromatic device. It is quite evident that the number of colors of the traces, chosen as four, in the example of the embodiment, may be different.

This device enables, for example, in the case of a photograph of the traces appearing on the screen the light flux produced for each trace to be made to vary, as a function of its color. Indeed, this is made necessary by the fact that the polychromatic photographic film may have a different sensitivity for each of the colors, or, if that film is also sensitive to each of the colors, traces of different colors may produce light fluxes of different values. Thus, the invention enables the adjusting of the light flux produced by one or several traces, as a function of their color. As the traces are renewed according to the successive sets comprising each of the colors, which are four in number in the example chosen, it is possible, due to the adjustable counting means, to effect, for example:

1. Two sets of traces comprising all the colors, that is, green, yellow, orange and red, no trace being canceled;

2. A third set of traces, comprising the yellow, orange and red traces, the green trace being canceled;

3. From the third to the fifth set of traces, only the orange and red traces remain; the yellow and green traces being canceled;

4. From the fifth to the ninth set of traces, only the red trace remains; the green, yellow and orange traces being canceled.

These numbers are chosen, in the example, in the case where the light-intensity decreases from green to red. Thus the green trace, which is the brightest will have been effected twice, the yellow three times, the orange five times and the red nine times. This is due to the reverse counting counters, each of them allowing the opening of the "AND" gate corresponding to it only during the time corresponding to the number of sequences chosen for the renewal of one or several traces of a given color.

In the example of the embodiment chosen, the reverse counting counters 35, 36, 37 and 38 are adjusted respectively at 2, 3, 5 and 9; these counters receive synchronizing pulses from the processing element when the switch 40 is closed, and they control, by means of the flip-flops 42, 43, 44 and 45, the gates 31, 32, 33 and 34 corresponding respectively to the colors green, yellow, orange, red.

At the outset, after the adjusting of the counters and closing of the switch 40, all the gates will be opened during two sets of traces of all the colors, then, for the third set of traces, the counter 35 being at zero, the green trace will not be effected; only the yellow, orange and red traces will remain, the gates 32, 33 and 34 being open. After the third set of traces, the counter 36 will be at zero and the fourth and fifth sets of traces will comprise only the orange and red traces, the gates 33 and 34 being open. Lastly beyond and up to the ninth set of traces, only the red trace will be renewed, the gate 34 being open. The green will have been traced twice, the yellow three times, the orange five times and the red nine times.

This may enable polychromatic photographing of the traces effected on the screen 1, for example, by means of the photographic apparatus 46, whose lens is facing the screen; if the light intensity of the traces decreases from green to red, the light flux produced by these traces will thus be made substantially equal for the different colors of traces.

The output of the flip-flop 45, which controls the opening of the gate 34, corresponding to the last intense color, may also control the opening circuit of the shutter in the photographic apparatus 46.

The device may also be provided, at the output of each of the flip-flops 42, 43, 44 and 45, with two-position switches 47, 48, 49 and 50. These switches placed in the positions 51, 52, 53 and 54, enable the implementing of the device, after adjusting of the counters according to the value of the light flux chosen as a function of the color, and after closing of the switch 40.

These switches placed in the positions 55, 56, 57 and 58 enable one of the inputs of each "AND" gate to be brought to a fixed potential 59 ensuring the constant opening of each of these gates each time a color switching signal reaches its other input. In other words, the switches 47, 48, 49 and 50 being in that position, and if the processing element controls the renewal of identical sets of traces, a trace of one color is then effected the same number of times as the trace of a different color and the display device is then in "normal" operation, allowing an observation adapted to direct vision. It is quite evident that the switches 47, 48, 49 and 50 have been mentioned here to show the possibility of operation of the device according to two different modes:

1. A first mode, known as "normal" operation, enabling direct vision on the screen;

2. A second mode of operation known as "photographing."

It is quite evident that the number of reverse counting counters, flip-flops, gates, trace colors, which has been chosen as four in the example of embodiment, may be different. It is also quite evident that the means used could be replaced by different means, ensuring the same technical results, without going beyond the scope of the invention.

Claims

What is claimed is:

1. A system for producing polychromatic traces of light with controlled intensity on a display screen, comprising display generating means for producing a sequence of sets of traces on a display screen, data processing means for controlling said display generating means to repetitively display identical sets of traces in a sequence of a given number, color selection means responsive to said data processing means for generating color designation signals indicating the colors of the respective traces, switching means responsive to said color selection means for controlling said display generating means to control the color of each trace on said display screen and color intensity control means for controlling said switching means to enable generation of traces of different colors in each set of traces a different number of times in each display sequence.

2. A system according to claim 1 wherein said color intensity control means includes a plurality of adjustable counters each providing an output for controlling a respective color, means for setting said counters at the beginning of each sequence to different values, means responsive to said data processing means for simultaneously driving said counters, and gating means for gating the outputs of said counters with respective outputs of said color selection means to control said switching means.

3. A system according to claim 2 wherein said adjustable counters are reverse counting counters connected by a switch to receive drive pulses from said data processing means during each sequence.

4. A system according to claim 3 wherein said gating means includes a plurality of flip-flops each connected to be set by the output of a respective counter and a plurality of AND gates each receiving a respective color designation signal at one input and the output of a respective flip-flop at the other input, so that a trace of a given color is produced for that number of sets of the sequence corresponding to the preset count of the corresponding counter.

5. A system according to claim 4, further including a photographic apparatus for filming the display on said display screen, the output of the flip-flop connected to the counter having the highest preset count being connected to actuate said photographic apparatus.

6. A system according to claim 4 wherein said display generating means includes a cathode ray tube capable of producing color displays, said switching means being responsive to the outputs of said AND gates for controlling said cathode ray tube to select the colors of the traces which are displayed.