DE4141318A1 - METHOD AND DEVICE FOR CONTROLLING POINT CONTROL - Google Patents

Abstract

For the purposes of blocking point control, brightness signals are to be taken via a shared line and an achromatic image is to be shown during this time. According to the invention, at least individual brightness signals are to be taken to a measuring device via switching means in succession and/or simultaneously. Those not conveyed are taken to a device generating electric voltages. The invention is preferably used in a television receiver with a cathode ray tube.

Description

The present invention relates to a method according to the Preamble of claim 1 and one for carrying out the device according to the invention suitable device according to General term of the first property claim.

Three are usually used to display a color image monochromatic single images of the colors red (r), green (g), Blue (b) overlaid.

For a flawless overall picture reproduction with a picture like dergabgerät, such as a television, it is necessary that the brightness level of the individual images specified correspond to the above values. This is the case if at abge switched color channel at all occurring levels of the light density signal as the screen achromatic, d. H. white, gray or black, appears. Is the image display device with a Provided picture tube, the beam currents are then in one certain fixed relationship to each other.

Because of tolerances in the circuit and the picture tube this requirement is usually not a priori fulfilled, but must first be achieved through suitable comparisons be opened. There are two adjustment tasks to be carried out for this, with which the characteristics of the three beam systems with regard the luminance signal drive voltage at two points each to be covered:

A blocking point adjustment in dark current and a white balance with relatively large jet currents.

It has been shown that white balance is usually not must be tracked and regulated. A unique setting  Production is usually sufficient. The Dark current, however, must be readjusted continuously.

It is known, for example from technical informatics on TI 850719 from Valvo for the video combination TDA 4580 that such a checkpoint adjustment automatically and can be provided dynamically for a keyed control, which is called the blocking point control for short.

Usually not required in one for image display th time interval, the cathode current is periodically every Picture tube system (this is usually almost identical with the beam current) at a certain picture tube signal pe gel (e.g. the nominal black level) and measured with compared to an internal setpoint that corresponds to the desired Dun kelstrom corresponds. From the deviations between target and Actual value is derived from a manipulated variable that acts as an offset signal the cathode current and thus also the Controls the beam current operating point so that the target / actual value softening disappears except for very small control errors. The The manipulated variable is saved, for example in an analogue manner Capacitor or digital in a register so that they too is effective outside the measuring time and the level shift the output stage control signal also during the image display tion is maintained.

In the technical information mentioned there is a blocking point measurement and control described in different, norma lines that are not visible, one after the other Playback systems for the red, green and blue Check single image.

However, it has been shown that these are not normally visible lines under certain circumstances for a viewer become visible. This is especially true if a Image is transferred in 16: 9 format and on a screen should be reproduced in 4: 3 format. In one  Case will be three measurement lines with different for the viewer visible colors.

The TA 8751 AN integrated circuit is also known, the measurements and adjustments for all three color systems carried out in a single measurement line. To do this integrated circuits via three separate inputs the same Dark current measurement signals supplied to the control electronics tronics can be taken from a color picture tube.

This eliminates the three measuring lines with different ones Hues, but there are a total of three connection pins to one Integrated circuit for supplying the jet currents necessary dig.

It is an object of the present invention, a system, best based on a method and a suitable device, to introduce that produces achromatic measuring lines and also with only one connection for supplying brightness signals, such as for example, signals derived from beam currents is coming.

This object is achieved by a method according to the main claim and a device according to the first claim.

According to the invention, it is proposed that a display emitted and trained as streams of different values brightness signals, the values of which are a measure of the Brightness of the corresponding individual images, in a given one Way via a measuring device or via a voltage or To conduct power source. The measuring device can also as Control device, for example as a blocking point control device be trained.

For example, a picture tube can serve as the display unit and the brightness signals substantially correspond to those Jet currents of the individual jet systems or are thereof  derived. Something similar is also the case when the picture is repeated Giving device as a projection device and the display device as a plurality of picture tubes is formed.

However, it is also conceivable that the display unit with Liquid crystal panels are provided by one or more lamps and their individually modulated ones monochromatic images result in an overall color picture. As For example, current values relevant to brightness can be found here the individual current values of the lamps used, output si signals from suitable sensors, signals derived therefrom or the like serve.

The brightness signals can also be used with cathode ray tubes are generated by sensors, their output signals or signals derived therefrom each represent values for the Brightness of the red, green and blue single images of.

The brightness signals to be conducted via the measuring device are used for further processing, such as Implementation of regulation processes, a common lei device or a common connector pin.

The brightness signals are successively individually and / or in suitable combinations together via the mentioned An final line sent. The corresponding selection happens by means of switching means, for example as a diode switch can be trained.

Further features, advantages and details of the invention are in the following embodiments with reference to Drawing explained. Show:

Figure 1 shows the block diagram of a preferred embodiment example.

FIG. 2 shows time diagrams of different control signals according to the embodiment of FIG. 2.

Before proceeding to the description of the exemplary embodiments is received, it should be noted that the in the Figures individually shown blocks only for the better Understand the invention. Usually are single or several of these blocks combined into units. These can be integrated or hybrid technology or as a program controlled microcomputer or as part of one for its control suitable program.

The elements contained in the individual stages can each but can also be carried out separately.

In the following, means and waveforms are the same Meanings in the figures each with the same reference time Chen provided and on it, once described were included in the further description only to this extent conditions as is necessary for the understanding of the present invention necessary is.

Fig. 1 shows a blocking point control device 10 , which is Darge in this embodiment in a boxed block. This symbolically drawn block is to be realized in example as a circuit board, as an integrated circuit, as a hybrid circuit, or the like and have various connecting pins.

Via video connecting pins 11 r, 11 g, 11 b, the blocking point control device 10 video signals of the colors red (R), green (G) and blue (B) are supplied. The video signals arrive at first inputs of a switching device 12 , the second inputs of which are connected to one another and to which a reference signal Sd is supplied by an electronic control unit 13 (electronic control unit, ECU).

The outputs of the switching device 12 lead to first inputs of adder stages 14 r, 14 g, 14 b, the second inputs of which are connected to a correction storage means 15 which provides corresponding correction values for each of the three color signals. The switching device 12 is controlled by a control signal S1 output by the electronic control unit 13 .

In the simplest case, the correction storage means 15 can be formed by three capacitors, each of which stores one of the correction values as a DC voltage value. However, it is also conceivable that respective correction values are predetermined by the electronic control unit 13 , which are fed into the adder stages 14 directly or via the correction storage means 15 via suitable means (not shown), such as, for example, digital / analog converters, adder stages and the like. Such an alternative is indicated in Fig. 1 by the dashed connection between rule's 13 and the storage means 15 .

This means that there may be no need for storage capacitors tet, or their size can be reduced in this way that an integration as part of an integrated scarf device, for example in BICMOS technology, is possible.

The outputs of the adder stages 14 r, 14 g, 14 b lead to amplifier stages 16 r, 16 g and 16 b, respectively. The outputs of the amplifier stages 16 are connected via connection pins to the inputs of video end amplifiers 17 r, 17 g and 17 b. The outputs of these video output amplifiers 17 each lead to a base connection of measuring transistors 18 r, 18 g and 18 b formed as pnp transistors, the emitters of which are connected to a beam cathode 19 r for the red frame, a beam cathode 19 g for the green frame or a beam cathode 19 b for the blue single image. The beam cathodes are part of a picture tube 50 , which together with the measuring transistors 18 is part of a display unit 51 .

The collector of the red measuring transistor 18 r leads to a Meßan circuit 20 of the blocking point control device 10 . The collector of the green measuring transistor 18 g leads on the one hand to the anode of a green measuring diode 21 , the cathode of which leads to the measuring connection 20 , and on the other hand to the anode of a green overlay diode 22 , the cathode of which leads to a first connection 23 of a voltage supply Device 24 leads.

The collector of the blue measuring transistor 18 b leads on the one hand to the anode of a blue measuring diode 25 , the cathode of which leads to the measuring input 20 , and on the other hand to the anode of a blue superimposed diode 26 , the cathode of which leads to a second terminal 27 Voltage supply device 25 leads.

The voltage supply device 25 is designed in this exemplary embodiment such that a first positive voltage U1 at the first terminal 23 and a second positive voltage U2 at the second terminal 27 is provided. In this exemplary embodiment, the voltage value of U1 is below that of voltage U2.

The measurement terminal 20 leads internally, ie within the blocking point control device 10 , further to a first connection of a resistor 28 , the second connection of which is applied to a positive voltage, such as a supply voltage + U.

Furthermore, three measuring current sources 29 r, 29 g, 29 b and the three compensation current sources 30 r, 30 g, 30 b and the first input (-) of a differential amplifier 31 are connected to the measuring connection 20 . The current sources 29 , 30 are switched to ground and values of the currents they emit are determined by control processes described later. The second input (+) of the differential amplifier 32 leads to the control unit 13 , which outputs a measurement voltage Vx of different values via the control output in question.

The output of the differential amplifier 31 is connected on the one hand to a switching input of leakage current storage switches 32 r, 32 g and 32 b and on the other hand to an input of control switches 33 r, 33 g and 33 g. The switching outputs of the switch 32 lead to a leakage current correction storage means 34 and the outputs of the control switch 33 each Weil to the second input of the adders 14 r, 14 g and 14 b. The leakage current storage switch 32 are controlled by control signals Lr, Lg and Lb and the control switches 33 are controlled by control signals Sr, Sg, Sb of the electronic control unit 13 .

The leakage current storage means 34 , which can be at least partially replaced by memory within the control unit 13 , similar to the correction storage means 15 , has three outputs, each with the switching input of a leakage current correction switch 35 r, 35 g and 35 b are connected. The switching outputs of the correction switches 35 r, 35 g, 35 b each lead to a control input of the compensation current sources 30 r, 30 g and 30 b. The correction switch 35 are each weils driven by the control unit 13 by means of a control signal Kr, Kg and Kb.

The method which is carried out by the device according to the exemplary embodiment according to FIG. 1 is described below with the aid of FIG. 2. The following illustration assumes that a visible image can only be displayed from the twenty-fourth line or a later line of a video image.

During the vertical retraction, for example during the image blanking signal Ba indicated in the first line, the electron beam of the picture tube 50 , the compensation currents Ior, Iog, Iob emitted by the compensation current sources 30 are compared and in lines 21 , 22 , 23 are measured - Current sources 29 measuring currents Ixr, Ixg, Ixb impressed.

At the beginning of the method, the Umschaltvorrich device 12 is first switched by the signal S1 such that the adder stages 14 are no longer connected to the video connection pins 11 , but that the reference signal Sd is supplied to them, which is implemented here as a DC voltage with different values is. Thus, the beam cathodes 19 are driven with predetermined values for the monochromatic frames via the amplifier stages 16 , the video power amplifier 17 and the measuring transistors 18 .

The beam current value caused by this control essentially corresponds to the values of the currents flowing through the collector connections of the measuring transistors 18 .

At the beginning (t0) of the adjustment of the leakage current Io, the value of the signal Sd is set to a low value, for example "super black", and the voltage Vx is set to a value which is both above the value U1 of the first terminal 23 applied voltage, as well as above the higher value U2 of the second voltage from terminal 27 .

This causes the differential amplifier 31 to use only the collector current of the transistor 18 r. Thus, only the cathode current for the red single image can be amplified and passed on.

At time t0, the switch 32 r is further closed by means of the control signal Lr, as a result of which the output of the amplifier 31 is connected to the corresponding input of the leakage current memory by means of 34 .

In addition, the switch 35 r is closed by the control signal Kr, so that the compensation current source 29 r is driven via the corresponding output of the storage means 34 and this then outputs a red compensation current with the value Ior. This value Ior is entered in such a way that leakage currents are compensated for.

The selection of the red brightness signals is based on the following principle. Closed loop (31-34 - 30 r) causes the differential amplifier 31 that at its two inputs the same voltage potentials, ie the entspre sponding value of Vx, abut. As long as Vx has the value Vx1, there is a voltage at the minus input with a value both above U1 and U2. This means that both the green measuring diode 21 and the blue measuring diode 25 are in the blocking direction and the superimposed diodes 22 , 26 are in the through direction.

From time t1, a leakage current correction for the Representation of the blue single image determined.

For this purpose, the voltage Vx is reduced to a value Vx2 which lies between the value U1 and the value U2. Since U2 is larger than Vx2, the blue measuring diode 25 lies after switching the corresponding control circuit in the forward direction and the blue superimposed diode 26 in the reverse direction. Both the collector currents of the red and the blue display part can thus be evaluated by the amplifier 31 .

To switch the control circuit, on the one hand the switch 32 r is opened by means of the control signal Lr and on the other hand the switch 32 b is closed by means of the signal Lb and the switch ter 35 b is closed by means of the signal Kb. Since the switch 35 r remains closed, a current is impressed by the compensation current sources 30 r, 30 b together, which corresponds to the leakage currents of the red and blue display parts. Zvi rule the time t1 and the time t2, however, regulated only the current Iob, because ter of the leakage current memory scarf is 32, only the Red switch r closed 32nd

Between times t2 and t3, the voltage Vx assumes a value Vx3 which is below both U2 and U1. Thus, the two measuring diodes 21 , 25 are in the transmission direction and the superposition diodes 22, 26 in the blocking direction.

Corresponding control signals open switch 32 b and switches 32 g and 35 g are closed. Thus, compensation current sources 29 r, 29 g, 29 b jointly impress a current that compensates for the leakage currents of all three display branches. However, only the value of the green compensation measuring current Iog is regulated, since in the period under consideration the switches 35 r, 35 b remain closed and thus the leakage currents of the red and blue display branches by corresponding values Io, the associated control signals of which are read out from the memory 34 , be compensated.

After the compensation currents Io have been determined, the switches 32 g, 35 g, 35 b are opened and the value of the reference signal Sd is increased so that the actual dark current adjustment can be carried out.

In line 21 , ie between times t3 and t4, the voltage Vx is increased again to the value Vx1. The switches 32 , 35 g, 35 b are opened. Since the switch 35 r is still closed, the drive signal is passed from the leakage current correction memory 34 to the compensation current source 30 r and the red compensation current Ior is impressed with a value matching the value of the reference signal Sd.

Furthermore, the red control switch 33 r is closed by means of the control signal Sr so that the output of the differential amplifier 31 is connected to the second input of the adder 14 r and the corresponding input of the correction memory means 15 .

This closes the control loop and a correction can be made value with simultaneous compensation of leakage currents be true.  

In this embodiment, the switch 33 r is opened before the end of the line and the reference signal Sd is set to “su black” so that activation of the red beam cathode 19 r is avoided during the line return.

In line 22, the determination is made of a blue correction value by addition to the red-measuring current Ixr a belonging to the reference signal Sd Blue Ixb measuring current as well as the Kompensati onsströme Ior, Iob embossed and the switch 33 b is CLOSED sen. Since the previously determined red correction value is read out from the memory 15 , although the sum of the collector currents of the transistors 18 r, 18 b is supplied to the differential amplifier 31 , the value of the blue correction value can be adjusted. During line 22 , the switches 35 r, 35 b are closed.

Analogously, the green correction value is determined with additional impressing of the measuring current Ixg and the compensation current Iog in line 23 .

In a second exemplary embodiment, the values of the voltage Vx are not varied in order to switch on the brightness measurement signals with the aid of the diodes 21 , 22 , 25 , 26 , but rather the voltages emitted by the voltage supply device 24 . This voltage variation can be controlled, for example, by the electronic control unit 13 , by a timing element (not shown) or by line trigger pulses. It can also be achieved that the anode connections of the measuring diodes 21 , 25 or the superposition diodes 22, 26 are above or below the voltages emitted by the device 24 .

As a result, the collector currents of the measuring transistors 18 can be directed via the measuring connection 20 .

It is also conceivable that the network formed by the diodes 21 , 22 , 25 , 26 is replaced by switching means. A variable voltage (Vx) or variable values U1, U2 can then be dispensed with and a single voltage output by the device 24 would also suffice.

In addition, it should be mentioned that the order of the measurements, here red-blue-green, can be interchanged as desired.

It should also be mentioned that the specified periods, such as. B. the lines 21 , 22 , 23 , are only exemplary. It is also possible that the control process for one of the values Io or one of the color correction values can take place in a shorter or in a longer period of time or at another time.

In one version of the exemplary embodiments, the values of the currents Io or of the color correction values can be passed to the electronic control unit 13 . By forwarding to suitable service connections, this is a clear advantage, especially for service purposes.

As a further design option, in addition to the matching processes within lines 21 , 22 , 23 , which are normally above an image to be displayed and appear gray (achromatic) during the comparison, further lines below the image to be displayed can be grayed out. As a result, the image to be displayed appears framed by a spectator achromatic (gray).

Claims (9)

1. A method for blocking point control, correction signals determined during a supply of a reference signal (Sd) due to brightness signals which are a measure of brightness values of individual display branches and fed to the input branches of a display unit, characterized in that the brightness signals are switched in such a way that that at least some of them are timed via a measuring device and that those that are not routed through the measuring device at a given time are connected to an electrical voltage. 2. The method according to claim 1, characterized in that for the display of a video signal during a first line duration the brightness signal of a first Display branch during a second line duration Brightness signals of the first and an additional two th display branch and for a third line duration essentially the brightness signals of three display branches passed over the measuring device will. 3. The method according to claim 1 or 2, characterized net that the values of the supplied to the measuring device Brightness signals essentially through their current values are determined that a measuring current corresponds to a value according to the number of brightness signals and the value of the reference signal, the brightness signals is superimposed and that in each case a correction value such it is determined that the measuring current is the brightness signals compensated. 4. The method according to any one of claims 1 to 3, characterized characterized in that the reference signal Sd first  has a value corresponding to a dark signal that determined by regulation values of a compensation current be based on the number of to the measuring device dependent brightness signals depend, and that the leak currents of the individual display branches during the blocking point regulation are essentially compensated. 5. Device for reverse current control which, when a reference signal (Sd) with a predetermined value is present, brightness signals which are a measure of the brightness values of individual display branches ( 17 r, 18 r, 19 r; 17 g, 18 g, 19 g; or 17 b, 18 b, 19 b) are supplied and the correction signals are determined, stored and passed on via correction means ( 14 ) to input branches of a display unit ( 51 ), characterized in that switching means ( 21 , 22 , 25 , 26 , 13 ) are provided, which switch the Brightness signals such that at least some of them are passed through a measuring device ( 10 ) and that those which are not passed through the measuring device ( 10 ) at a given time, with the output of a voltage-emitting device connected. 6. The device according to claim 5, characterized in that the switching means ( 21 , 22 , 25 , 26 , 13 ) are controlled such that during the duration of a first line (line 21 ) of a video signal, the brightness signal of a first display branch (r), during the duration of a second line (line 22 ), the brightness signals of the first (r) and in addition a second (b) display branch and for the duration of a third line (line 23 ), the brightness signals of three display branches (r, g , b) passed over the measuring device ( 10 ). 7. The device according to claim 5 or 6, characterized in that the values of the measuring device ( 10 ) th brightness signals are essentially determined by their current values that current-releasing means ( 29 ) are provided, which are controlled by control means ( 13 ) Are controlled that they overlap a measuring current (Ix) with a value corresponding to the number of Hel brightness signals supplied and the value of the reference signal (Sd) the brightness signals and that correction values are determined by a control circuit ( 31 , 14 , 18 , 19 ) that the measuring current (Ix) essentially compensates for the brightness values. 8. Device according to one of claims 5 to 7, characterized in that the switching means are formed from a network of diodes ( 21 , 22 , 25 , 26 ) and a variable voltage source ( 13 or 24 ). 9. Device according to one of claims 5 to 8, characterized in that the control means ( 13 ) set the reference signal (Sd) to a value corresponding to a dark value, that a second control loop ( 31 , 30 ) is provided by the values a compensation current (Io) are determined, which depend on the number of brightness signals passed to the measuring device ( 10 ), and in that the control means ( 13 ) connect a leakage current correction storage means ( 34 ) to compensation current sources ( 30 ) via correction switches ( 35 ) and these are controlled by such that the leakage currents of the individual display branches are compensated for during the blocking point control.