EP4383240A1 - Method and device for diagnosing a display unit, in particular with regard to a freeze state - Google Patents

Abstract

The invention relates to a method for diagnosing a display unit (20) with regard to at least one fault state, in particular a freezing state, namely a pixel-based display unit (20) with a pixel matrix display (22, 22', 22") comprising a pixel matrix, in particular an active pixel matrix with row drivers and column drivers or with gate drivers and source drivers for controlling individual pixels of the pixel matrix. According to the invention, in at least one method step, at least one time behavior of a total operating current, which comprises at least the operating current of the pixel matrix of the pixel matrix display (22, 22', 22"), is recorded, in particular at at least one supply connection of the display unit (20). In addition, in at least one method step, the at least one recorded time behavior of the total operating current is evaluated computationally for the purpose of checking for a fault state, in particular a freezing state.

Description

STATE OF THE ART

The invention relates generally to displays in applications for which safety in the sense of hazard or operational safety is crucial, such as displays in the driver's cab of a rail vehicle or in the control panel of an industrial plant. The invention relates to a method for diagnosing a display unit with regard to at least one fault condition, in particular a freezing condition, in particular according to the preamble of claim 1, and a display device with a diagnostic function with regard to such a fault condition, in particular according to the preamble of claim 10, and a corresponding display system and a multifunctional terminal with such a device or such a system.

The representation of information as computer graphics is prone to errors. For example, errors can occur in every single component of the computer generating the graphics, e.g. due to a defective microprocessor, in the graphics processor, in the individual memory modules, in the power supply, but in particular also due to software errors in the operating system, in libraries used in software production and in particular in the application software, or other software components.

When displaying security-relevant information, data content must be displayed correctly and in a timely manner. Essentially, this means that the processing of the information on the platform generating the visualization of the security-relevant information must be monitored and potential deviations must be revealed. A significant improvement in this regard is offered by the technology available under the brand name IconTrust ^® for displaying security-relevant information in accordance with the principle of WO 2011/003872 A1 or the patent EP 2 353 089 B1 of the applicant. This solution ensures that the content is presented correctly.

In order to ensure that certain information is displayed on the screen in a way that is safe in terms of hazard or operational safety, measures must be taken to ensure that the information to be displayed is not only correct in terms of content, but also actually up-to-date, i.e., correctly displayed on the screen at the right time. In addition to the potential errors mentioned above, a major source of error is the freezing of the information shown on the screen. The danger is that a display, particularly a TFT or LCD display, continues to display information that is no longer up-to-date "frozen" and the viewer (e.g. the driver) does not notice the frozen state. A potentially dangerous error could therefore occur if the viewer does not recognize the slow change in the screen display within the time until the error is revealed, e.g. due to illegibility, and the display still appears consistent and correct to the viewer, but the information content to be displayed has changed in a safety-relevant way within this time period.

In EN 10 2004 039 498 A1 To solve the latter problem, the applicant had proposed displaying a specific time-varying bit pattern in a defined area of the screen in addition to the actual information, which is then read back again via a light sensor. This solution has proven itself in practice but is disadvantageous in two respects. Firstly, part of the usable display area is covered by the bit pattern to be covered and is therefore not usable for the actual information display for the user. Secondly, attaching additional light sensors is structurally complex. Furthermore, practice has shown rare but annoying cases in which the light sensors are disturbed by ambient light and thus trigger an incorrect freeze detection.

From the article " AXMANN, Benjamin, et al. Advanced methods for safe visualization on automotive displays. Journal of the Society for Information Display, 2020, 28th vol., no. 6, pp. 483-498 - see https://doi.org/10.1002/jsid.909 " is a technique in which an optical diagnosis is carried out using pixel sensors in combination with a measured value internally in the LCD display unit. Line activation current is evaluated to check for proper function. This solution is also structurally complex due to the optical diagnosis using pixel sensors and requires an application-specific design of the driver IC for the display unit for driver-specific current measurement. This disadvantage arises from the fact that the line activation current is tapped independently of other currents on the line driver. The individual line drivers are integrated in the driver IC, which is typically an electrical component built internally into an LC display. This solution could theoretically also detect freezing, but cannot be implemented with conventional driver ICs or commercially available COTS TFT or LCD displays.

Another solution for diagnosing a display taking into account the current consumption was EP 2 220 640 B1 proposed. In this case, a characteristic value is measured for the graphics, which characterizes the power consumption or the change in the power consumption of the screen or display device, and compared with a corresponding value predetermined for the desired image. In particular, it is proposed to divide the display into sub-images, which are selected in such a way that their power consumption differs from a previously displayed image (which is to be overwritten), so that two different pieces of information which would result in identical power consumption cannot be distinguished. This solution could theoretically also detect freezing, but is not intended for this purpose and is also very complex to implement in software, since it has to be adapted to the format of the desired display in each case.

TASK

A first object of the invention, based on the above-mentioned prior art, is therefore to provide a solution for an increased security standard in the presentation of information with a display that can be used on commercially available existing display designs, in particular without changes to the actual display unit, such as a TFT or LCD display. A further object of the invention is to provide a device that is as simple to implement as possible and that can be used as an extension for diagnosis with regard to at least one A fault condition, in particular a freeze condition, can be combined with a commercially available existing display design, in particular without changes to the actual display unit or the driver IC. The solution should be able to be implemented with relatively little hardware effort and still enable reliable diagnosis.

GENERAL DESCRIPTION AND ADVANTAGES OF THE INVENTION Procedural aspects

The invention is based on a method for detecting at least one specific error state or fault state, in particular the state of "frozen image content", referred to here as the freezing state, on a pixel matrix display, in particular a conventional TFT display with an active matrix. In principle, the method of measuring or monitoring the operating current is used.

The invention is based on the knowledge that an error state or fault state, in particular a freeze state, must be at least indirectly recognizable in the temporal behavior of the operating current of commercially available pixel matrix displays, due to the typical design with row drivers and column drivers or with gate drivers and source drivers for controlling individual pixels of the pixel matrix. A specific change in current is indicative of correct or incorrect operating behavior of a display. The invention is therefore also based on the knowledge that - assuming a constant supply voltage - the energy consumption can be indirectly recorded. Since energy is retained or "cannot simply disappear", the energetic behavior is indicative of a certain technical behavior of the display.

The proposed method can preferably be carried out at least partially as a computer-implemented method on a suitable computing unit, such as a microprocessor, a DSP, an FPGA or the like. It is proposed that in at least one method step the at least one fault condition is detected from at least one total operating current of the pixel display unit, namely from at least one time behavior of the total operating current under consideration, the time behavior being based on a selected, representative time interval, e.g. it can only be limited to a partial interval of the image transmission or frame refresh periods, i.e. the total duration does not have to include an image refresh period.

The total operating current can preferably represent the total power consumption of the display, so that it can be easily recorded from the outside at at least one supply connection of the display unit without any structural changes. However, the total operating current is also understood to mean a current which includes at least the operating current of the pixel matrix itself of the pixel matrix display, and can thus be recorded, for example, as the total power consumption of the driver IC, e.g. without the power consumption of the backlight and other electronics. This also enables a considerable structural simplification.

According to the invention, it is further proposed for the method that, in at least one method step, the at least one recorded time behavior of the total operating current is evaluated computationally for the purpose of checking for a fault condition, in particular a freeze condition.

The computational evaluation can in particular include a frequency analysis of the operating current recorded or observed. This makes it possible to identify, using comparatively simple computational technology, those frequency components in the operating current that are characteristic of correct functioning, i.e. actual operation of row drivers and/or column drivers or gate drivers and/or source drivers. The invention is based in particular on the surprisingly simple finding that these frequency components can be reliably identified in the total operating current of the display, in particular using comparatively simple circuit and computational technology. In conventional pixel matrix displays, there is a characteristic frequency component that is necessarily determined from the refresh rate and the resolution or number of drivers. The current consumption for this characteristic frequency component is therefore indicative of correct functioning.

It is not necessary to determine the time behavior of the total operating current during the complete image build-up or for all To capture row drivers and/or column drivers, it is sufficient to capture a sufficient duration with respect to some representative drivers, since a partial freeze caused by only some drivers is probabilistically extremely unlikely and would probably reveal an error through noticeably incorrect representation.

• erstes Zeitverhalten des Gesamtbetriebsstroms, insbesondere der Displayeinheit, zumindest teilweise während einer Bildübertragungs- bzw. Bilderneuerungsperiode der Displayeinheit erfasst wird; und/oder
• ein zweites Zeitverhalten des Gesamtbetriebsstroms, insbesondere der Displayeinheit, zumindest teilweise zwischen zwei Bildübertragungs- bzw. Bilderneuerungsperioden, insbesondere während einer Austastlücke zwischen zwei Bildübertragungen bzw. Bilderneuerungen, ermittelt wird.

In one embodiment of the method it is preferably provided that

• first time behavior of the total operating current, in particular of the display unit, is detected at least partially during an image transmission or image refresh period of the display unit; and/or
• a second time behavior of the total operating current, in particular of the display unit, is determined at least partially between two image transmission or image refresh periods, in particular during a blanking interval between two image transmissions or image refreshes.

• in zumindest einem Verfahrensschritt ein Zeitverhalten bzw. eine zeitliche Varianz des zumindest einen Gesamtbetriebsstroms rechentechnisch ermittelt wird; und/oder
• in zumindest einem Verfahrensschritt ein Zeitverhalten bzw. eine zeitliche Varianz des zumindest einen Gesamtbetriebsstroms einer Frequenzanalyse unterzogen wird. Insbesondere hierbei ist es vorteilhaft, wenn in zumindest einem Verfahrensschritt auf Grundlage zumindest einer Frequenzanalyse des zumindest einen Gesamtbetriebsstroms, insbesondere ein Einfrierzustand, eine rechentechnische Auswertung dahingehend erfolgt, ob ein Störzustand erkannt wird.

In a particularly preferred embodiment of the method, it is preferably provided that

• in at least one method step, a time behavior or a temporal variance of the at least one total operating current is determined by calculation; and/or
• in at least one method step, a time behavior or a temporal variance of the at least one total operating current is subjected to a frequency analysis. In particular, it is advantageous here if, in at least one method step, a computational evaluation is carried out on the basis of at least one frequency analysis of the at least one total operating current, in particular a freezing state, to determine whether a fault state is detected.

Preferably, the computational evaluation is based on a comparison of at least two frequency analyses of at least two time profiles of the total operating current recorded at different time intervals.

The evaluation can be based in particular on a comparison of the frequency analyses of a first time behavior of the total operating current during an image transmission period and a second Time behavior of the total operating current during a blanking interval of an image transmission.

In this case, the comparison can preferably be based on whether in a certain frequency range, in particular approximately at a line frequency and/or at a column frequency, a higher current consumption occurs during an image transmission or image refresh period than during a blanking interval. This enables a particularly reliable or robust discrimination of a freeze state.

• die Frequenzanalyse zumindest eine Analog-Digitalwandung, insbesondere mit einer Abtastrate größer als der zweieinhalbfachen charakteristischen Betriebsfrequenz, eines vorzugsweise tiefpassgefilterten Gesamtstromsignals zur Erzeugung eines zeitdiskreten Signals, umfasst; und/oder
• die Frequenzanalyse zumindest eine Fourier-Transformation, insbesondere eine diskrete Fourier-Transformation (DFT) eines bzw. des zeitdiskreten Signals umfasst, wobei die DFT vorzugweise als Goertzel-Algorithmus zur Erkennung zumindest eines Spektralanteils, insbesondere bei der charakteristischen Betriebsfrequenz bzw. Zeilenfrequenz, ausgeführt ist. Eine DFT, insbesondere der Goertzel-Algorithmus, ist rechentechnisch mit besonders wenig Ressourcen auch bei hochauflösenden Displays realisierbar.

The pixel matrix typically has at least one characteristic operating frequency, in particular a line frequency characteristic for the operation of line drivers. Based on this, a preferred embodiment of the method provides that

• the frequency analysis comprises at least one analog-digital conversion, in particular with a sampling rate greater than two and a half times the characteristic operating frequency, of a preferably low-pass filtered total current signal for generating a time-discrete signal; and/or
• the frequency analysis comprises at least one Fourier transformation, in particular a discrete Fourier transformation (DFT) of a or the time-discrete signal, wherein the DFT is preferably designed as a Goertzel algorithm for detecting at least one spectral component, in particular at the characteristic operating frequency or line frequency. A DFT, in particular the Goertzel algorithm, can be implemented computationally with particularly few resources even in high-resolution displays.

Preferably, in at least one method step, at least one safety-related reaction is triggered when a fault condition is detected, wherein in particular the display unit is at least partially switched off and/or restarted and/or an alarm signal is forwarded or output.

In terms of the procedure, a diagnosis or a test is carried out with regard to a fault condition such as a freezing condition in the sense of a good case test.

The approval test can be carried out in particular by conducting a frequency analysis at one or more of the It is checked at the operating frequency characteristic of the pixel matrix whether a sufficiently different current consumption is detected in two different operating states for at least a partial area of the pixel matrix, in particular a higher current consumption during an image refresh period than during a blanking interval or a synchronization interval between two image refreshes.

This approach to the good case test alone enables the detection of further potential faults that do not necessarily lead to "freezing". Any state that does not correspond to the nominal or intended correct operating state of the pixel matrix with sufficient power consumption, e.g. greater than a predetermined threshold value at the characteristic operating frequency, in particular line frequency, during image formation can be assumed to be a potential fault or faulty state.

Device or system aspects

What is generally proposed is a display device with a diagnostic function with regard to a fault state, in particular with regard to a freeze state, wherein the display device is a pixel-based display unit with a pixel matrix display, in particular comprising a pixel matrix, such as an active pixel matrix with row drivers and column drivers or with gate drivers and source drivers for controlling individual pixels of the pixel matrix.

• eine Erfassungsschaltung, welche dazu ausgebildet ist, zumindest einen Gesamtbetriebsstrom zu erfassen insbesondere an zumindest einem Versorgungsanschluss der Displayeinheit, und
• eine Recheneinheit welche mit der Erfassungsschaltung verbunden ist und dazu eingerichtet ist, ein erfasstes Zeitverhalten des Gesamtbetriebsstroms rechentechnisch auszuwerten zwecks Prüfung hinsichtlich eines Störzustands, insbesondere eines Einfrierzustands.

According to the invention, the display device comprises in particular

• a detection circuit which is designed to detect at least one total operating current, in particular at at least one supply connection of the display unit, and
• a computing unit which is connected to the detection circuit and is configured to computationally evaluate a detected time behavior of the total operating current for the purpose of checking for a fault condition, in particular a freeze condition.

The computing unit, e.g. a microprocessor, DSP, FPGA or the like, is particularly preferably designed to determine a time behavior or a temporal variance of the at least one total operating current. determine, in particular to carry out a frequency analysis. On the basis of the frequency analysis, the computing unit can check for a fault condition, in particular a freezing condition - in particular also in the sense of a good case test for its absence or non-existence. The computing unit can be designed to trigger a safety-related reaction if the result of the test is negative, such as at least partially switching off the display unit and/or restarting it and/or generating an alarm signal.

A practically simple and reliable detection circuit comprises a current measuring shunt resistor, in particular in series with the supply connection of the display unit, and a current measuring amplifier, in particular a discrete current measuring amplifier, for measuring a voltage drop across the current measuring shunt resistor, wherein the output of the current measuring amplifier is connected to the computing unit, preferably via a low-pass filter. The low-pass filter can in particular be selected with a cut-off frequency corresponding to a sampling frequency of the computing unit in order to act as an anti-aliasing filter and to suppress unwanted higher-frequency components.

According to a further aspect, a display system with a display unit and a display computer is proposed, which has a modular monitoring unit for monitoring the content of the image data. The modular monitoring unit can be used with regard to the content monitoring or testing, for example in the sense of the disclosure from WO 2011/003872 A1 or the patent EP 2 353 089 B1 of the applicant or in the sense of the doctrine of the patent EP 3 712 770 B1 of the applicant, whose teaching is incorporated herein by reference for the sake of brevity.

According to one aspect of the invention, the detection circuit and the proposed computing unit or a computing unit for carrying out the above-mentioned method steps can be integrated into the modular monitoring unit as a detection circuit.

According to one aspect of the invention, the monitoring unit thus comprises a detection circuit which is designed to to detect at least one total operating current, in particular at at least one supply connection of the display unit, and furthermore at least one computing unit which is connected to the detection circuit and is set up to computationally evaluate a detected time behavior of the total operating current for the purpose of checking for a fault condition, in particular a freeze condition.

The proposed display device or the proposed display system is particularly suitable for use or installation in a multifunctional terminal for a safety-relevant application, in particular for the driver's cab of a rail vehicle.

Further aspects

The pixel display unit comprises in particular at least one pixel matrix display, which is preferably designed as a TFT display and which preferably has at least one display housing. The at least one pixel matrix display can be designed at least partially as an active matrix, a passive matrix, an OLED, an AMOLED and/or an IPS display. The display housing preferably at least substantially completely encloses all electrical components of the at least one pixel matrix display that are designed separately from the display housing. In particular, the pixel matrix display has at least one electrical operating interface, which is arranged in particular on the display housing. The at least one electrical operating interface is preferably designed to connect the pixel matrix display, in particular all electrical components of the pixel matrix display, to an electrical power supply line for operating the pixel matrix display. The pixel matrix display preferably has at least one electrical data interface, which is arranged in particular on the display housing. The at least one data interface is preferably designed to transmit display data to the pixel matrix display. Preferably, the pixel matrix display is designed to display the display data, in particular in the form of images. The data interface can be arranged adjacent to the operating interface on the display housing, in particular on a same outer side of the display housing, particularly preferably in relation to six different Sides of a smallest imaginary cuboid, which just completely surrounds the display housing. Preferably, the pixel display unit, in particular the at least one pixel matrix display, has a plurality of pixel cells, which form a pixel matrix and are arranged in particular in pixel rows and pixel columns.

The at least one total operating current of the pixel display unit is preferably an electrical supply current for operating at least one entire pixel matrix display, in particular all electrical components of at least one pixel matrix display. Preferably, the at least one total operating current of the pixel display unit is sufficient to put the at least one pixel matrix display completely into an operating state, in particular to keep it in the operating state at any time during the operating state of the at least one pixel matrix display. Preferably, the at least one pixel matrix display has at least one electrical power supply component. Preferably, the at least one pixel matrix display has at least one electrical backlight component. Preferably, the at least one pixel matrix display has at least one electrical control component, which in particular has at least one row driver and at least one column driver. Preferably, the power supply component, the backlight component and the control component are each supplied with sufficient electrical current from the total operating current in the operating state of the pixel matrix display to operate the pixel matrix display. The total operating current is in particular a sum, which can be measured in particular from the outside of the display housing, of all the activation currents required internally, in particular in the display housing, for all electrical components of the pixel matrix display. The total operating current can be measured, for example, at a power source of the at least one pixel matrix display. In particular, the at least one total operating current differs from an activation current of the control component, in particular individual pixel cells, of the pixel display unit, such as pixel rows or pixel columns of the pixel display unit, in particular at any time in an operating state of the pixel matrix display, at least by a superposition of the activation current of the control component, in particular individual pixel cells, of the pixel display unit, such as for example pixel rows or pixel columns of the pixel display unit, with further currents which are necessary for operating the other components of the pixel matrix display. In particular, the at least one total operating current is greater at any time in an operating state of the pixel matrix display than an activation current of the control component of the pixel display unit and/or of pixel cells of the pixel display unit. Preferably, the at least one total operating current is designed as a current intensity and is determined in particular in amperes. Preferably, the at least one total operating current can be measured from the outside of the pixel display unit, in particular outside the display housing and/or at an interface, such as preferably the operating interface, on the display housing. In particular, no pixel matrix displays are known which have only one electrical control component, which in turn has only one row driver or only one column driver.

Preferably, the at least one total operating current is measured outside the display housing, in particular via a voltage measurement. Preferably, the at least one total operating current, in particular of the pixel display unit, is measured externally at the operating interface. Preferably, the at least one total operating current is determined continuously in every operating state of the pixel display unit, in particular with a measuring frequency of at least 10 Hz, preferably of at least 100 Hz.

Preferably, in at least one method step, the at least one fault state of the pixel display unit, in particular the freezing state of the pixel display unit, is determined, in particular recognized, from the at least one total operating current. Preferably, in at least one method step, the pixel display unit is permanently monitored, in particular continuously, in particular at a frequency of at least 10 Hz, preferably at least 100 Hz, with regard to the at least one fault state, preferably the freezing state, via the at least one total operating current.

The inventive design of the method makes it possible to achieve an advantageously cost-effective detection of fault conditions, in particular freezing conditions, on pixel display units. In particular, fault conditions, in particular freezing conditions, on Pixel display units can be detected without existing designs of pixel display units having to be changed. In particular, a method can be achieved which can detect fault conditions on any pixel display units, in particular without having to intervene in the electronics of the pixel display units.

It is further proposed that in at least one method step the at least one total operating current is detected at at least one supply connection of the pixel display unit. Preferably the at least one supply connection of the pixel display unit is designed as the at least one electrical operating interface. Preferably the at least one total operating current is detected in at least one method step from the outside at the at least one supply connection, in particular at the at least one electrical operating interface, of the pixel display unit. An advantageously uncomplicated measurement of the at least one total operating current can be achieved.

It is further proposed that in at least one method step the at least one total operating current is determined at least partially in an image transmission period of the pixel display unit. Preferably, in at least one method step the at least one total operating current is recorded in temporal measurement windows. Preferably, in at least one method step the at least one total operating current is recorded in an active state of the at least one control component. Preferably, in at least one method step the at least one total operating current is recorded in a passive state of the at least one control component. Preferably the at least one control component consumes electrical energy depending on an image refresh rate, in particular display frequency, such as 60 Hz, 75 Hz, 100 Hz, 120 Hz, 144 Hz or 240 Hz, and in particular depending on the pixel rows and/or pixel columns of the pixel matrix display. For example, the at least one control component consumes electrical energy to control 768 pixel rows at 60 Hz, partially at a frequency of 46.08 kHz plus an optional blanking interval. Between the display of two images of the 60 frames per second at a display frequency of 60 Hz, the control component can form a blanking interval in which the control component has a reduced electrical energy consumption because no pixel rows are newly controlled, in particular written to. Preferably, the at least one total operating current is determined in a first measurement window in an image transmission period of the pixel display unit, wherein at least one, preferably at least two, particularly preferably at least three and/or, for example, all, pixel row(s) is/are completely written in the first measurement window. Preferably, all pixel rows are completely written once in an image transmission period to display exactly one image. The at least one first measurement window is arranged in an image transmission, in particular during writing of at least one pixel row and/or pixel column. An advantageous measurement of the at least one total operating current can be achieved in a fully, in particular maximally, active operating state of the control component.

It is further proposed that in at least one method step the at least one total operating current is determined at least partially between two image transmission periods, in particular a blanking interval of an image transmission, of the pixel display unit. Preferably, the at least one total operating current is recorded at least once in at least one method step in a temporal measurement window, in particular at least one further measurement window, which is arranged entirely in a blanking interval. Preferably, the at least one total operating current is recorded repeatedly in at least one method step in temporal measurement windows, in particular further measurement windows, which are each arranged entirely in one blanking interval(s), preferably in mutually different blanking intervals. Preferably, the at least one total operating current is recorded in at least one method step between the writing of a last pixel row of an image and a first pixel row of a further image. Preferably, a time interval, in particular a blanking interval, is provided between the display of two images, in which no pixel row and/or pixel column is written. Preferably, a temporal measurement window has a length of at most one total, preferably approximately 90%, duration of a blanking interval. The at least one further measurement window is in a blanking interval without Image transmission, in particular without writing a pixel row and/or pixel column. An advantageous measurement of the at least one total operating current in a slightly, in particular minimally, active operating state of the control component can be achieved. In particular, the total operating current can advantageously be recorded in different strongly active states of the control component. Preferably, first temporal measurement windows have the same length as further temporal measurement windows.

It is further proposed that a temporal variance of the at least one total operating current is determined in at least one method step. Preferably, in at least one method step, a temporal variance, in particular a time derivative, of the at least one total operating current is determined, preferably calculated, from at least one, preferably all, temporal measurement window(s) of the at least one total operating current. Preferably, in at least one method step, a temporal variance, in particular a time derivative, of the at least one total operating current is determined, preferably calculated, for each measurement of the at least one total operating current. A rate of change of the at least one total operating current can advantageously be determined, preferably made visible, in at least one measurement window.

It is further proposed that in at least one method step, a temporal variance of the at least one total operating current is subjected to a frequency analysis. Preferably, in at least one method step, a temporal variance of each measurement of the at least one total operating current is subjected to a frequency analysis, in particular a mathematical one, to determine an energy consumption of the pixel display unit at least in a frequency band around a line frequency and/or column frequency, for example at 46-50 kHz, of the control component. Preferably, in at least one method step, a frequency analysis is determined for each determined temporal variance of each measurement of the at least one total operating current. Preferably, a frequency analysis is carried out for at least two first measurement windows, in particular for each transmitted image. Preferably, a frequency analysis is carried out for at least two further measurement windows, in particular for each transmitted image. A parameter that changes as a function of a disturbance state can advantageously be isolated from the at least one total operating current. In particular, a change, preferably an energy consumption, of the at least one total operating current during writing to pixel rows in the range of the row frequency and/or the column frequency is greater than during a blanking interval or in a freeze state of the pixel display unit in which the pixel rows are no longer rewritten. A mathematical frequency analysis can be, for example, a Fourier analysis, in particular a Fourier transformation, or a Laplace transformation. An advantageously clear, fast and uncomplicated method for detecting at least one disturbance state of a pixel display unit, in particular a freeze state of the pixel display unit, can be achieved.

It is further proposed that in at least one method step the at least one disturbance state is detected from at least one frequency analysis of a temporal variance of the at least one total operating current. In particular, in at least one method step the at least one disturbance state is detected from a peak amplitude and/or peak area at the row frequency and/or column frequency of the at least one frequency analysis of at least one temporal variance of the at least one total operating current, in particular by comparing it with at least one defined threshold value, with a previous peak amplitude and/or previous peak area in a first measurement window and/or with a further peak amplitude and/or peak area measured in particular in a further measurement window. A detection of the at least one disturbance state that is advantageously robust with respect to measurement errors can be achieved.

It is further proposed that in at least one method step, the at least one disturbance state is detected from a comparison of at least two frequency analyses of temporal variances of at least two total operating currents, in particular at a row frequency and/or a column frequency. Preferably, in at least one method step, the difference between a peak amplitude and/or peak area at a Line frequency and/or a column frequency in at least one first measurement window, preferably averaged over at least two first measurement windows, and a peak amplitude and/or peak area at a line frequency and/or a column frequency in at least one further measurement window, preferably averaged over at least two further measurement windows, the at least one threshold value is determined, and in particular the at least one fault condition is detected. Preferably, in at least one method step, the at least one threshold value is determined from a peak amplitude and/or peak area at a line frequency and/or a column frequency in at least one further measurement window, preferably averaged over at least two further measurement windows. Preferably, a peak amplitude and/or peak area at a line frequency and/or a column frequency in at least one first measurement window, preferably averaged over at least two first measurement windows, is larger, in particular by at least a factor of two, preferably by at least a factor of four, particularly preferably by at least a factor of five, and most preferably by at least a factor of ten, than a peak amplitude and/or peak area at a line frequency and/or a column frequency in at least one further measurement window, preferably averaged over at least two further measurement windows. Preferably, in at least one method step, if the at least one threshold value is not reached by a peak amplitude and/or peak area at a line frequency and/or a column frequency in at least one first measurement window, preferably averaged over at least two first measurement windows, the at least one disturbance state, in particular the freezing state, is detected. Preferably, in at least one method step, from a comparison, for example of a peak amplitude and/or peak area, in particular at a line frequency and/or a column frequency, of at least one frequency analysis of temporal variances of at least one total operating current from at least one first measurement window, preferably averaged over at least two first measurement windows, with at least one frequency analysis of temporal variances of at least one total operating current from at least one further measurement window, preferably averaged over at least two further measurement windows, the at least one disturbance state is detected. For example, in at least one method step, from a comparison of at least one temporal change in a frequency analysis, in particular a peak amplitude and/or peak area, preferably at a line frequency and/or a column frequency, of temporal variances of at least one total operating current from at least one first measuring window, preferably averaged over at least two first measuring windows, with at least one temporal change in a frequency analysis, in particular a peak amplitude and/or peak area, preferably at a line frequency and/or a column frequency, of temporal variances of at least one total operating current from at least one further measuring window, preferably averaged over at least two further measuring windows, the at least one disturbance state can be detected. For example, in at least one method step, the at least one disturbance state can be detected from a temporal change in a frequency analysis, in particular a peak amplitude and/or peak area, preferably at a line frequency and/or a column frequency, of temporal variances of at least one total operating current from at least one first measuring window, preferably averaged over at least two first measuring windows, and/or from at least one further measuring window, preferably averaged over at least two further measuring windows. For example, in at least one method step, the at least one fault condition can be detected by comparing at least one temporal change in a frequency analysis, in particular a peak amplitude and/or peak area, preferably at a line frequency and/or a column frequency, of temporal variances of at least one total operating current from at least one first measurement window, preferably averaged over at least two first measurement windows, with at least one temporal change in a frequency analysis, in particular a peak amplitude and/or peak area, preferably at a line frequency and/or a column frequency, of temporal variances of at least one total operating current from at least one further measurement window, preferably averaged over at least two further measurement windows. An advantageously fast, error-free and/or cost-effective method for detecting the freezing condition can be achieved. In particular, the threshold value can be dynamic, preferably determined, for example determined anew for each image, determined anew for every second image, determined anew for every tenth image. or the like. In particular, the threshold value can be static, for example determined exactly once.

In particular, the method detects whether a display content is continuously updated. In particular, the method at least detects whether, in particular, individual selected pixel rows or pixel columns are continuously written to. Pixel rows are written to in particular at the line frequency. Pixel columns are written to in particular at a column frequency. In particular, the at least one total operating current of the pixel display unit is a sum of all currents of the electrical components, in particular consumers, of the at least one pixel matrix display. The at least one total operating current of the at least one pixel matrix display has in particular a complex temporal profile because in particular individual electrical components of the at least one pixel matrix display operate with different and/or non-synchronized cycle times, in particular consume electrical energy. By means of a frequency analysis of the at least one total operating current, in particular a temporal profile of the at least one total operating current, in particular the temporal variance of the at least one total operating current, characteristic frequency bands of an energy distribution of the pixel display unit can be determined. By using defined test images, the method can be used to detect faults in the color display and/or a video interface of the pixel display unit. Using monochrome color test images, in particular only red, only green or only blue, for example, the switching of the pixel cells to display the corresponding color can be checked using a peak amplitude and/or peak area, preferably at a line frequency and/or a column frequency, from a frequency analysis of temporal variances of the at least one total operating current. The term pixel matrix display should be understood in particular as a synonym for pixel matrix display. The resulting energy share in a frequency analysis around the line frequency is proportional to the number of switched pixel cells in a pixel row. For monochrome color displays, a characteristic energy share of approx. 1/3 of the energy for white display results. This makes it possible to detect failures in the color representation or the video interface to the pixel matrix display.

It is further proposed that in at least one method step, at least one alarm signal is output when a fault condition is detected. The at least one alarm signal can be designed as an optical, acoustic and/or haptic alarm signal. Preferably, in at least one method step, when a fault condition is detected, at least one optical alarm signal is output via the pixel display unit and/or an acoustic alarm signal is output via a reaction module of a computing unit. An advantageously high safety standard can be achieved.

It is further proposed that in at least one method step, when a fault condition is detected, the pixel display unit is at least partially switched off and/or restarted. Preferably, in at least one method step, at least one, preferably affected, pixel matrix display is switched off, in particular for at least 5 seconds. Preferably, in at least one method step, at least one, preferably affected, pixel matrix display is restarted, in particular switched off and switched on again before 5 seconds have elapsed. An advantageous reaction to fault conditions of the pixel display unit can be achieved.

In addition, a computing unit is proposed which is preferably designed to carry out a method according to the invention, in particular in an automated manner. In particular, the computing unit is designed to be coupled to the pixel display unit. A "computing unit" is to be understood in particular as a unit with an information input, an information processing unit and an information output. The computing unit advantageously has at least one processor and/or a processor unit, a memory and/or a storage unit, input and output means, further electrical components, an operating program, control routines, control routines and/or calculation routines. In particular, the computing unit comprises an operating, control and/or calculation program stored in the memory and/or in the storage unit. The computing unit is preferably coupled to the pixel display unit. coupled.

It is proposed that the computing unit has a detection module which is designed to detect at least one, in particular the at least one already mentioned, total operating current of the pixel display unit. The detection circuit is preferably designed as a subassembly of the computing unit, for example as an integrated circuit, as a microcontroller, a CPU, a chip and/or as an ASIC, in particular an application-specific integrated circuit. The at least one detection module is preferably designed to detect the at least one total operating current, in particular exclusively, at the at least one supply connection of the pixel display unit. The at least one detection module is preferably designed to determine the at least one total operating current at least partially, in particular temporarily, in particular continuously in first measurement windows separated from one another in an image transmission period of the pixel display unit. The at least one detection module is preferably designed to determine the at least one total operating current at least partially, in particular temporarily, in particular continuously in further measurement windows separated from one another in time between two image transmission periods, in particular a blanking interval of an image transmission, of the pixel display unit. An advantageous computer implementation of the method can be achieved.

It is further proposed that the computing unit has an evaluation module which is designed to determine a temporal variance of the at least one total operating current, to carry out a frequency analysis of the temporal variance and to determine a fault condition from the frequency analysis. Preferably, the evaluation module is designed to determine a temporal variance of the at least one total operating current, in particular for each measurement window. Preferably, the evaluation module is designed to carry out a frequency analysis on at least one temporal variance of the at least one total operating current, in particular for each measurement window. Preferably, the evaluation module is designed to determine the at least one temporal variance of the at least one total operating current from at least one frequency analysis of a temporal variance of the at least one total operating current. The evaluation module is preferably designed as a subassembly of the computing unit, for example as an integrated circuit, as a microcontroller, a CPU, a chip and/or as an ASIC, in particular an application-specific integrated circuit. The evaluation module can be designed as one part with the acquisition module. The computing unit can be designed as an advantageous additional module to existing pixel display units.

It is further proposed that the computing unit has a reaction module which is designed to at least partially switch off and/or restart the pixel display unit when a fault condition is detected by the evaluation module. The reaction module is preferably designed as a subassembly of the computing unit, for example as an integrated circuit, as a microcontroller, a CPU, a chip and/or as an ASIC, in particular an application-specific integrated circuit. The reaction module can be designed as a part with the detection module and/or the evaluation module. The reaction module is preferably designed to output at least one alarm signal when a fault condition is detected. The reaction module can have an acoustic output sub-module for outputting an acoustic alarm signal. A computing unit with an advantageously high security standard can be achieved.

Furthermore, a pixel display system is proposed with at least one pixel display unit, which comprises at least one pixel matrix display, and with at least one computing unit according to the invention.

It is proposed that the pixel display system has at least one DR platform module for generating a visualization of information on the at least one pixel matrix display. Preferably, the at least one DR platform module is coupled to the computing unit and in particular mechanically connected. Preferably, the at least one DR platform module is coupled to the pixel display unit, in particular at least connected to the at least one pixel matrix display. Preferably, the DR platform module is designed as a computer or the like. In particular, the DR platform module can be designed as a computing unit. In particular, the computing unit can be designed to be coupled to the DR platform module to form a safety DR platform module unit from the computing unit and the DR platform module. An advantageous combination of pixel display unit with the computing unit and/or the DR platform module can be achieved. In particular, the computing unit can advantageously be attached to the DR platform module.

Furthermore, a multifunctional terminal is proposed with at least one terminal housing unit and with at least one pixel display system according to the invention. The pixel display system is preferably arranged in the terminal housing unit, with at least one pixel matrix display of the pixel display unit forming an outer side of the terminal housing unit. An advantageously protected pixel display system can be achieved, which can be designed in particular for special applications, such as as a control panel or the like.

In addition, a vehicle module is proposed with at least one vehicle unit, preferably a rail vehicle unit, and with at least one multifunctional terminal according to the invention. The at least one vehicle unit is preferably designed as a railcar of a rail vehicle. Advantageously safe rail traffic can be achieved.

The method according to the invention, the computing unit according to the invention, the pixel display system according to the invention, the multifunctional terminal according to the invention and/or the vehicle module according to the invention should not be limited to the application and embodiment described above. In particular, the method according to the invention, the computing unit according to the invention, the pixel display system according to the invention, the multifunctional terminal according to the invention and/or the vehicle module according to the invention can have a number of individual elements, components, units and/or method steps that differs from the number stated herein in order to fulfill a function described herein. In addition, in the value ranges specified in this disclosure, values within the stated limits should also be considered disclosed and can be used as desired.

BRIEF DESCRIPTION OF THE DRAWINGS Further advantages arise from the following

Description of the drawings. At least one embodiment of the invention is shown in the drawings. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will also expediently consider the features individually as relevant to the invention and, if necessary, combine them to form further useful combinations.

• FIG. 1 eine erfindungsgemäßes Fahrzeugmodul mit einem erfindungsgemäßen Multifunktionsterminal, welches ein erfindungsgemäßes LCD-Displaysystem aufweist, das wiederum eine erfindungsgemäße Recheneinheit aufweist, in einer schematischen Darstellung,
• FIG. 2 eine erfindungsgemäße Recheneinheit an einer LCD-Displayeinheit in einer schematischen Darstellung,
• FIG. 3 ein erfindungsgemäßes Verfahren in einer schematischen Darstellung,
• FIG. 4 eine Frequenzanalyse eines Gesamtbetriebsstroms aus zumindest einem ersten Messfenster und eine Frequenzanalyse eines Gesamtbetriebsstroms aus zumindest einem weiteren Messfenster in einer schematischen Darstellung;
• FIG.5ein weiteres Ausführungsbeispiel der Erfindung als Ergänzung der Prüf- bzw. Überwachungseinheit aus EP 2 353 089 B1 ; und
• FIG.6eine bevorzugte Erfassungsschaltung zur breitbandigen Strommessung des Gesamtbetriebsstroms eines TFT-Displays wie in FIG.1 bzw. FIG.5.

Show it:

• FIG. 1 a vehicle module according to the invention with a multifunctional terminal according to the invention, which has an LCD display system according to the invention, which in turn has a computing unit according to the invention, in a schematic representation,
• FIG. 2 a computing unit according to the invention on an LCD display unit in a schematic representation,
• FIG. 3 a method according to the invention in a schematic representation,
• FIG. 4 a frequency analysis of a total operating current from at least one first measuring window and a frequency analysis of a total operating current from at least one further measuring window in a schematic representation;
• FIG.5 a further embodiment of the invention as a supplement to the testing or monitoring unit from EP 2 353 089 B1 ; and
• FIG.6 a preferred detection circuit for broadband current measurement of the total operating current of a TFT display as in FIG.1 or. FIG.5 .

DESCRIPTION OF EXAMPLES OF IMPLEMENTATION

FIG.1 shows a vehicle module 10 in a vehicle 12, here eg a rail vehicle. The vehicle 12 is in particular a rail vehicle railcar. The vehicle module 10 comprises a multifunctional terminal 14. The multifunctional terminal 14 is installed in the driver's cab for the rail vehicle railcar. The Multifunctional terminal 14 has a terminal housing unit 16 and an LCD display 18. The LCD display 18 comprises a display unit 20. The LCD display unit 20 has one or more pixel matrix displays, here for example three TFT displays 22, 22', 22". The TFT displays 22, 22', 22" are each arranged on the front of the terminal housing unit 16.

The LCD display system 18 comprises a computing unit 24 and a DR platform module 26 with a display computer (DR), which is designed in particular to generate a visualization of information in the form of images on the three TFT displays 22, 22', 22". The DR platform module 26 is designed as a computer platform, e.g. with PC or computer architecture, which in particular has one or more DR boards. The computing unit 24 has its own modular board. All components of the computing unit 24 are arranged entirely on the separate computing board. The computing board is designed separately from the DR board(s). The computing board is designed to be connected to the DR board(s). The computing unit 24 is designed in particular as a modular supplementary or retrofit component for the LCD display system 18 or the DR platform module 26. The computing unit 24 is designed to be coupled to the DR platform module 26. forming a Safety-DR platform module unit from the computing unit 24 and the DR platform module 26.

The computing unit 24 and the DR platform module 26 are in particular each a unit with an information input, an information processing unit and an information output. The computing unit 24 and the DR platform module 26 each have a processor, a memory, input and output means, further electrical components, an operating program, control routines, control routines and/or calculation routines.

The DR platform module 26 is connected to the LCD display unit 20, in particular to each of the three TFT displays 22, 22', 22" for data transfer, in particular for switching pixel cells of the displays 22, 22', 22" for displaying images on the displays 22, 22', 22" (cf. Fig.2 ). The computing unit 24 is connected to an electrical supply connection 23 of the LCD display unit 20. The computing unit 24 is connected to each of the three electrical The computing unit 24 is connected to each data line between the DR platform module 26 and the three TFT displays 22, 22', 22". The three electrical supply connections 23 of the three TFT displays 22, 22', 22" are connected to an electrical energy source.

The computing unit 24 is connected to a detection circuit 28. This detection circuit 28 is designed to detect three total operating currents of the LCD display unit 20, in particular total operating currents to each TFT display 22, 22', 22". The detection circuit 28 can be designed as a discrete circuit or subassembly on the circuit board of the computing unit 24. The detection circuit 28 is designed to detect the three total operating currents, in particular exclusively, at the three supply connections 23 of the LCD display unit 20, in particular of the three TFT displays 22, 22', 22".

The detection circuit 28 is designed to detect the three total operating currents continuously in first measurement windows separated from one another in time during image transmission periods of the LCD display unit 20. The detection circuit 28 is designed to detect the three total operating currents continuously in further measurement windows separated from one another in time between two image transmission periods, in particular during a blanking interval of an image transmission, of the LCD display unit 20.

The computing unit 24 has an evaluation module 30, which can be implemented as a logical unit, i.e. in software. The evaluation module 30 is designed to determine a temporal variance of the total operating currents, to carry out a frequency analysis of the temporal variance and to determine a fault state of the LCD display unit 20, in particular at least one of the three TFT displays 22, 22', 22", from the frequency analysis.

The evaluation module 30 is designed to determine a temporal variance of the at least one total operating current for each temporal measurement window. The evaluation module 30 is designed to perform a frequency analysis on at least one temporal variance of the total operating currents, in particular for each measurement window. The evaluation module 30 is designed to detect at least one fault condition from at least one frequency analysis of a temporal variance of the total operating currents. The evaluation module 30 is designed as a subassembly of the computing unit 24.

The computing unit 24 has a reaction module 32, which can be implemented as a logical unit, i.e. in software. The reaction module 32 is designed to at least partially switch off and/or restart the LCD display unit 20, in particular the at least one affected display 22, 22', 22", when a fault condition is detected by the evaluation module 30.

The reaction module 32 is designed to output at least one alarm signal when a fault condition is detected. The reaction module 32 comprises an acoustic output sub-module 34 for outputting an acoustic alarm signal. The computing unit 24 is designed to carry out a method described below for detecting at least one fault condition of the LCD display unit 20, in particular a freezing condition of the LCD display unit 20. The computing unit 24 is designed in particular to run the method for detecting a freezing condition of at least one TFT display 22, 22', 22" in a computer-implemented manner.

The LCD display unit 20 comprises, for example, three TFT displays 22, 22', 22", each of which has a display housing 36, 36', 36". The display housing 36, 36', 36" completely encloses all electrical components of the respective TFT display 22, 22', 22", which are formed separately from the display housing.

In particular, each TFT display 22, 22', 22" has an electrical operating interface 38, which is arranged in particular on the display housing 36, 36', 36". The electrical operating interfaces 38 are designed to connect the TFT displays 22, 22', 22", in particular all electrical components of the TFT displays 22, 22', 22", to an electrical power supply line for operating the TFT displays 22, 22', 22''.

The TFT displays 22, 22', 22" each have an electrical data interface 40, for example an LVDS interface, which is arranged in particular on the respective display housing 36, 36', 36". In particular, the respective data interface 40 is designed to transmit display data to the corresponding TFT display 22, 22', 22". In particular, each TFT display 22, 22', 22" is designed to display the display data, in particular in the form of images. The data interfaces 40 are arranged adjacent to the operating interfaces 38 on the respective display housing 36, 36', 36", in particular on a same outer side of the display housing 36, 36', 36".

The TFT displays 22, 22', 22" of the LCD display unit 20 each have a plurality of pixel cells which form a pixel matrix and are arranged in particular in pixel rows and pixel columns.

In particular, the TFT displays 22, 22', 22" each have an electrical power supply component, for example a DC/DC converter. In particular, the TFT displays 22, 22', 22" each have an electrical backlight component. In particular, the TFT displays 22, 22', 22" each have an electrical control component, which is designed in particular as a main controller, which in particular comprises a row driver, in particular for controlling pixel rows to take over voltages for the targeted switching of the pixel cells of the pixel rows, and a column driver, in particular for converting pixel brightness values of a pixel row into analog voltages. The tasks of the row drivers and column drivers can be interchanged.

In particular, in the operating state of a TFT display 22, 22', 22", the power supply component, the backlight component and the control component are each supplied with sufficient electrical current from the total operating current of the TFT display 22, 22', 22" to operate the TFT display 22, 22 ', 22".

The total operating current of a TFT display 22, 22', 22" of the LCD display unit 20 is in particular an electrical supply current for operating a TFT display 22, 22', 22", in particular all electrical components of at least one TFT display 22, 22', 22". In particular, the total operating current of the LCD display unit 20 is sufficient to fully put a TFT display 22, 22', 22" into an operating state.

The total operating current here is, for example, a sum, in particular measurable from the outside on the display housing 36, 36', 36", of all activation currents required internally, in particular in a display housing 36, 36', 36', for all electrical components of the corresponding TFT display 22, 22', 22''. In particular, the total operating current differs from an activation current of individual pixel cells of the LCD display unit 20, such as pixel rows or pixel columns of the corresponding TFT display 22, 22', 22" of the LCD display unit 20, in particular at any time of an operating state of the TFT display 22, 22', 22", by a superposition of the activation current of individual pixel cells of the LCD display unit 20, such as pixel rows or pixel columns of the TFT display 22, 22', 22" of the LCD display unit 20, with further currents which are required to operate the further Components of the TFT display 22, 22', 22" are required.

In particular, the total operating currents at any time of an operating state of the TFT displays 22, 22', 22" are greater than an activation current of the control component of the individual TFT displays 22, 22', 22" of the LCD display unit 20 and/or of pixel cells of the LCD display unit 20. In particular, the total operating currents are designed as a current intensity and are determined in particular in amperes. In particular, the total operating currents can be measured from the outside of the LCD display unit 20, in particular outside the display housings 36, 36', 36" and/or at an interface, such as in particular the operating interface 38, on the display housings 36, 36', 36".

FIG.3 shows in particular the schematic method for detecting at least one fault state of an LCD display unit 20, in particular a freeze state of the LCD display unit 20. The individual method steps are described in an exemplary order. However, each method step in this method is continuously repeated in order to monitor the states of the TFT displays 22, 22', 22" and to detect fault states.

The total operating currents are measured in a method step, in particular in a detection step 50, outside the display housings 36, 36', 36", in particular via a voltage measurement. The total operating currents, in particular of the LCD display unit 20, are measured in a method step, in particular in the detection step 50, from the outside at the operating interface 38. The total operating currents are determined in a method step, in particular in the detection step 50, in each operating state of the LCD display unit 20 continuously, in particular with a measuring frequency of at least 10 Hz. The detection step 50 runs in particular repeatedly with a frequency of at least 30 Hz. In particular, the total operating currents are measured in a method step, in particular in the detection step 50, for each TFT display 22, 22', 22" at least twice per second, in particular in two different time measurement windows, in particular of at least 70 µs.

The total operating currents are recorded in one method step, in particular in the recording step 50, at at least one supply connection 23, in particular the operating interfaces 38, of the LCD display unit 20. The supply connections 23 of the LCD display unit 20 are designed as the electrical operating interfaces 38. The total operating currents are recorded in one method step, in particular in the recording step 50, from the outside at the supply connections 23, in particular at the electrical operating interfaces 38, of the TFT displays 22, 22', 22" of the LCD display unit 20.

A TFT display 22, 22', 22" can have two different electrical operating interfaces 38, one of which is designed, among other things, to supply a control component of the TFT display 22, 22', 22" and one of which is designed, among other things, to supply a backlight component of the TFT display 22, 22', 22". In such a case, the total operating current is measured at the electrical operating interface 38, which is designed to supply a control component of the TFT display 22, 22', 22".

The total operating currents are, in a method step, in particular in the detection step 50, at least partially in a Image transmission period of the LCD display unit 20 is determined, in particular recorded. The total operating currents are recorded in a method step, in particular in the recording step 50, in each case in temporal measurement windows. The total operating currents are recorded in a method step, in particular in the recording step 50, in an active state of the respective control component.

The total operating currents are detected in a method step, in particular in the detection step 50, in a passive state of the respective control component.

The control component consumes electrical energy depending on an image refresh rate, in particular display frequency, such as 60 Hz and in particular depending on the pixel rows and/or pixel columns of the TFT display 22, 22', 22''. For example, the at least one control component consumes electrical energy to control 768 pixel rows at 60 Hz, partly at a frequency of 46.08 kHz, plus an optional blanking interval. Between the display of two images of the 60 images per second at a display frequency of 60 Hz, the control component forms a blanking interval in which the control component has a reduced electrical energy consumption because no pixel rows are newly controlled, in particular written to.

The total operating currents are recorded in a method step, in particular in the recording step 50, in first measuring windows in an image transmission period of the respective TFT display 22, 22', 22" of the LCD display unit 20, wherein at least three pixel rows are completely written in first measuring windows. In an image transmission period, all pixel rows are completely written once to display exactly one image. The first measuring windows are arranged in an image transmission, in particular during writing of at least three pixel rows and/or pixel columns.

The total operating currents are recorded in a method step, in particular in the recording step 50, at least partially between two image transmission periods, in particular a blanking interval of an image transmission, of each TFT display 22, 22', 22" of the LCD display unit 20. The total operating currents are recorded in a Method step, in particular in the detection step 50, repeatedly detects in temporal measurement windows, in particular further measurement windows, which is arranged completely in a blanking interval of the image transmission.

The total operating currents are recorded in a method step, in particular in the recording step 50, in temporal measurement windows, in particular further measurement windows, which are each arranged completely in one blanking interval, in particular in mutually different blanking intervals. The total operating currents are recorded in a method step, in particular in the recording step 50, temporally between the writing of a last pixel row of an image and a first pixel row of a further image, in particular in further measurement windows, which are arranged temporally between the writing of a last pixel row of an image and a first pixel row of a further image.

Between the display of two images by a TFT display 22, 22', 22", a time interval, in particular a blanking interval, is provided in which no pixel row and/or pixel column is written.

The first temporal measurement windows and/or the further measurement windows have a maximum length of a total, in particular of approximately 90% of a, duration of a blanking interval. The further measurement windows are each arranged in different blanking intervals without image transmission, in particular without writing a pixel row and/or pixel column.

In a method step, in particular in a determination step 52, a temporal variance of the total operating currents is determined. In a method step, in particular in the determination step 52, a temporal variance, in particular a time derivative, of the total operating currents is determined, in particular formed, approximated and/or calculated from all recorded temporal measurement windows of the total operating currents. In a method step, in particular in the determination step 52, at least one temporal variance, in particular a time derivative, of the total operating currents is determined, in particular formed, approximated and/or calculated for each measurement of the total operating currents.

In a method step, in particular in the determination step 52, each measurement of the total operating currents is used at least once to determine, in particular to form, approximate and/or calculate at least one temporal variance, in particular a time derivative, of the total operating currents. In a method step, in particular in the determination step 52, each measurement of the total operating currents is used at least once to determine, in particular to form, approximate and/or calculate at least one temporal profile of the total operating currents in first measurement windows. In a method step, in particular in the determination step 52, each measurement of the total operating currents is used at least once to determine, in particular to form, approximate and/or calculate at least one temporal profile of the total operating currents in further measurement windows.

In a method step, in particular in an analysis step 54, a temporal variance of the total operating currents is subjected to a frequency analysis. In a method step, in particular in the analysis step 54, a frequency analysis is formed for each determined temporal variance of the total operating currents in order to determine an energy consumption of the LCD display unit 20 at least in one frequency band, around at least one row frequency and/or column frequency, for example at 46-50 kHz, of the control component of at least one of the TFT displays 22, 22', 22".

In one method step, in particular in an analysis step 54, a frequency analysis is determined for each determined temporal variance of each measurement of the total operating currents. In one method step, in particular in the analysis step 54, a frequency analysis is carried out for at least two first measurement windows, in particular for each transmitted image. In one method step, in particular in the analysis step 54, a frequency analysis is carried out for at least two further measurement windows, in particular for each transmitted image.

In a method step, in particular in a detection step 56, the at least one fault condition is detected from at least one frequency analysis of a temporal variance of the at least one total operating current. In a method step, in particular in the In detection step 56, the at least one fault condition is detected from a peak amplitude at the line frequency in a frequency spectrum of the frequency analysis of the total operating currents, in particular by comparison with a defined threshold value and with a peak amplitude measured in a further measurement window.

In FIG.4 an exemplary graph of a frequency analysis is shown. A frequency, in particular in kHz, is plotted on an abscissa 42, in particular the x-axis. An amplitude, in particular in arbitrary units (au), is plotted on an ordinate 43, in particular the y-axis. In FIG.4 Two frequency analyses, which were determined from two measurements, in particular from at least one first measurement window and from at least one further measurement window, of a total operating current, are shown schematically.

A first frequency analysis curve 44, which was determined from at least a first measurement window of the total operating current, is shown in dashed form. The first frequency analysis curve 44 corresponds approximately to an image writing level of the power consumption of one of the TFT displays 22, 22', 22", in particular to a power consumption of one of the TFT displays 22, 22', 22" during writing of rows of the pixel matrix of the TFT display 22, 22', 22''.

A further frequency analysis curve 46, which was determined from at least one further measurement window of the total operating current, is shown in dotted form. The further frequency analysis curve 46 corresponds approximately to a noise level of the power consumption of one of the TFT displays 22, 22', 22", in particular to a power consumption of one of the TFT displays 22, 22', 22" between displaying two images, in particular in a blanking interval between writing lines of the pixel matrix of the TFT display 22, 22', 22" for displaying two images at the display frequency of, for example, 60 Hz.

The further frequency analysis curve 46 differs greatly from the first frequency analysis curve 44 in areas 47, 47` of the line frequency and the double line frequency, here for example about 48 kHz and 96 kHz, of one of the corresponding TFT displays 22, 22', 22". From a comparison of the first frequency analysis curve 44 with the further frequency analysis curve 46, which were recorded in particular close to each other, at least in areas 47, 47` the line frequency and the double line frequency, it can be determined whether the corresponding TFT display 22, 22', 22" is displaying an image that is currently to be shown or whether the corresponding TFT display 22, 22', 22" in particular is consuming too little energy in the range 47, 47` of the line frequency and whether the corresponding TFT display 22, 22', 22" is in a faulty state, in particular a freeze state. In a freeze state, the peaks 48, 48` of the first frequency analysis curve 44 in the ranges 47, 47` of the line frequency and the double line frequency are significantly reduced, if in particular they are recognizable at all.

In a method step, in particular in the detection step 56, the at least one disturbance state is detected from a comparison of at least two frequency analyses of temporal variances of at least two total operating currents at a line frequency. In a method step, in particular in the detection step 56, the at least one threshold value is determined from a difference between a peak amplitude at a line frequency of a frequency analysis averaged over at least two first measurement windows and a peak amplitude at a line frequency of a frequency analysis averaged over at least two further measurement windows and the at least one disturbance state is detected.

In a method step, in particular in the detection step 56, the at least one threshold value is determined from a peak amplitude at a line frequency averaged over at least two further measurement windows.

In a method step, in particular in the detection step 56, if the at least one threshold value is not reached by a peak amplitude at a line frequency of a frequency analysis averaged over at least two first measurement windows, the at least one disturbance state, in particular the freezing state, is detected.

In a method step, in particular in the detection step 56, a comparison at a line frequency of at least one frequency analysis of temporal variances of at least one total operating current averaged over at least two first measurement windows with at least one frequency analysis of temporal variances of at least one total operating current averaged over at least two further measuring windows in which at least one fault condition is detected.

In a method step, in particular in the detection step 56, the at least one fault state is detected from the total operating currents of the TFT displays 22, 22', 22" of the LCD display unit 20.

In one method step, in particular in the detection step 56, the at least one fault state of the LCD display unit 20, in particular the freezing state of the LCD display unit 20, is determined, in particular recognized, from the total operating currents. In several method steps, in particular in the detection step 50, the determination step 52, the analysis step 54 and the detection step 56, the LCD display unit 20 is permanently monitored, in particular continuously, in particular at a frequency of at least 100 Hz, with regard to the at least one fault state, in particular the freezing state, via the at least one total operating current.

In a method step, in particular in an alarm step 58, at least one alarm signal is output when a fault condition is detected. In a method step, in particular in the alarm step 58, at least one optical alarm signal is output via the LCD display unit 20 and/or an acoustic alarm signal is output via the reaction module 32 of the computing unit 24 when a fault condition is detected.

In a method step, in particular in a reaction step 60, the LCD display unit 20 is at least partially switched off and/or restarted when a fault condition is detected. In a method step, in particular in the reaction step 60, at least one, in particular affected, TFT display 22, 22', 22" is switched off, in particular for at least 5 seconds. In a method step, in particular in the reaction step 60, at least one, in particular affected, TFT display 22, 22', 22" is restarted, in particular switched off and switched on again before 5 seconds have elapsed.

The power supply component, the backlight component and the control component of all TFT displays 22, 22', 22" can alternatively be supplied with sufficient electrical power from the total operating current in the operating state of the LCD display unit 20 to operate all TFT displays 22, 22', 22", wherein the method for detecting a fault state of one of the TFT displays 22, 22', 22" can be carried out and individual TFT displays 22, 22', 22" can be detected on the basis of characteristic line frequencies and/or column frequencies, in particular analogously to the described method.

The detection step 50, the determination step 52 and/or the analysis step 54 are carried out repeatedly at a frequency of at least 30 Hz.

FIG.1 shows the basic structure of a security unit 102 according to EP2353089 known principle for checking the content or monitoring the image data. This has a display computer (DR) 104 and a TFT display 106 as a display device, whereby DR 104 and TFT 106 are connected via an image data line, e.g. an LVDS line. The safety unit 102 comprises a test unit designed as an FPGA 110. The DR 104 displays safety-relevant information on a delimited sub-area 116 of the TFT display 106.

The high-frequency input signal of the TFT display 106 fed in via the image data line is read out or read back by the FPGA 110 via the read-back line 120. The FPGA 110 creates a check code for the area 116 during the security check, e.g. a CRC checksum in a check code generator 112. In this case, each bitmap generated by the DR or PC 104 is uniquely assigned a pre-calculated CRC checksum as a comparison code in a lookup table 118 of the FPGA 110, and a possible value of the input variable 14 is provided for each of these comparison codes.

The FPGA 110 first compares the test code calculated by the test code generator 112 with the comparison codes in the table 118. If the test code matches a comparison code, the possible value of the input variable determined from the table 118 is then compared in a comparison unit 120 with the value of the input variable stored in a memory 124. If impermissible deviations are determined, a safety-related reaction is carried out, e.g. by interrupting the power supply line 108 of the TFT display 106. The shutdown function effected by the FPGA 110 preferably works according to the "quiescent current principle" (equivalent to safety-relevant relay circuits). so that an active output is required to maintain the regular operating state by the test unit, and in the event of failure of the test unit / shutdown function ("passivation") a safety-related failure reaction takes place.

According to the invention, the security unit 102 is extended by a detection circuit 130, which is designed to detect the operating current of the TFT 106 on its supply line 108. In the security unit 102, e.g. in the FPGA 110, or as a separate microcontroller, the computing unit, see reference numeral 24 in FIG.1-2 , implemented to which the detection circuit 130 is connected.

As in the example from FIG.5 shown, the detection circuit 130 preferably has a shunt resistor 132 which is connected in series with the supply connection or in the supply line 108 of the TFT 106. A suitable broadband and high-precision current measuring amplifier 134, e.g. a current measuring amplifier of the type INA290 from Texas Instruments, is connected to the shunt resistor 132 to measure a voltage drop. The output of the current measuring amplifier 134 is connected via a low-pass filter 136 to an output 138 which is connected to the computing unit 24 of the security unit, preferably to an input of an A/D converter of a microcontroller (not shown in FIG.5 ), as in EP 3 712 770 B1 - whose teaching is included here in this respect.

The operation of the detection circuit 130 and the computing unit 24 can be similar to that described above with respect to FIG.3 described procedures.

The shutdown function by means of the current diagnosis by means of the detection circuit 130 and the computing unit 24 preferably works according to the "quiescent current principle", so that an active output is required by the test unit to maintain the regular operating state, and if there is no good result, determined on the basis of the frequency analysis of the operating current on the supply line 108 which is looped through the safety unit 102, a safety-related reaction takes place, here for example by switching off the TFT 106.

List of reference symbols

10

Vehicle module

12

Vehicle unit

14

Multifunctional terminal

16

Terminal housing unit

18

LCD display system

20

LCD display unit

22

TFT display

24

Computing unit

26

DR platform module

28

Detection circuit

30

Evaluation module

32

Reaction module

34

Output submodule

36

Display housing

38

Operational interface

40

Data interface

42

abscissa

43

ordinate

44

Frequency analysis curve

46

Frequency analysis curve

47

Area

48

Peak

50

Capture step

52

Determination step

54

Analysis step

56

Recognition step

58

Alarm step

60

Reaction step

102

Security unit

104

PC / DR

106

TFT display

108

Supply line

110

FPGA

112

Verification code generator

116

Image area / monitoring area

118

LUT

120

Comparison unit

122

Readback line

124

Storage

126

Input line

130

Detection circuit

132

Shunt resistance

134

Current measuring amplifier

136

Low-pass filter

138

Circuit output

Claims (15)

Method for diagnosing a display unit (20) with respect to at least one fault condition, in particular a freeze condition, namely a pixel-based display unit (20) with a pixel matrix display (22, 22', 22") comprising a pixel matrix, in particular an active pixel matrix with row drivers and column drivers or with gate drivers and source drivers for controlling individual pixels of the pixel matrix, characterized in that - in at least one method step, at least one time response of a total operating current, which comprises at least the operating current of the pixel matrix of the pixel matrix display (22, 22', 22"), is detected, in particular at at least one supply connection of the display unit (20); and - in at least one method step, the at least one recorded time behavior of the total operating current is evaluated computationally for the purpose of checking for a fault condition, in particular a freeze condition. Method according to claim 1, characterized in that a first time behavior of the total operating current, in particular of the display unit (20), is detected at least partially during an image transmission or image refresh period of the display unit (20); and/or
a second time behavior of the total operating current, in particular of the display unit (20), is determined at least partially between two image transmission or image refresh periods, in particular during a blanking interval between two image transmissions or image refreshes. Method according to claim 1 or 2, characterized in that in at least one method step a time behavior or a temporal variance of the at least one total operating current is determined by calculation; and/or
in at least one method step, a time behavior or a temporal variance of the at least one total operating current is subjected to a frequency analysis. Method according to one of the preceding claims, in particular according to claim 3, characterized in that in at least one method step, on the basis of at least one frequency analysis of the at least one total operating current, in particular a freezing state, a computational evaluation is carried out as to whether a fault state is detected. Method according to one of the preceding claims, in particular according to claim 4, characterized in that the evaluation is based on a comparison of at least two frequency analyses of at least two time profiles of the total operating current recorded at different time intervals, in particular on a comparison of the frequency analyses of a first time behavior of the total operating current during an image transmission period and a second time behavior of the total operating current during a blanking interval of an image transmission. Method according to claim 5, characterized in that the comparison is based on whether in a certain frequency range, in particular approximately at a line frequency, a higher current consumption occurs during an image transmission period than during a blanking interval. Method according to one of claims 3 to 6, wherein the pixel matrix has a characteristic operating frequency, in particular a line frequency characteristic for the operation of line drivers, characterized in that - the frequency analysis comprises at least one analog-digital conversion, in particular with a sampling rate greater than two and a half times the characteristic operating frequency, of a preferably low-pass filtered total current signal for generating a time-discrete signal; and/or - the frequency analysis comprises at least one Fourier transformation, in particular a discrete Fourier transformation (DFT) of a or the time-discrete signal, wherein the DFT is preferably designed as a Goertzel algorithm for detecting at least one spectral component, in particular at the characteristic operating frequency or line frequency. Method according to one of the preceding claims, characterized in that in at least one method step, when a fault condition is detected, at least one safety-related reaction is triggered, wherein in particular the display unit (20) is at least partially switched off and/or restarted and/or an alarm signal is forwarded or output. Method according to one of the preceding claims, characterized in that in at least one method step a check is carried out with regard to a fault condition in the sense of a good case test, in particular in that on the basis of a frequency analysis at an operating frequency or the operating frequency characteristic of the pixel matrix it is checked whether a sufficiently different current consumption in two different operating states is detected for at least a partial area of the pixel matrix. Display device with diagnostic function with regard to a fault condition, in particular with regard to a freezing condition, comprising - a pixel-based display unit (20) with a pixel matrix display (22, 22', 22") comprising a pixel matrix, in particular an active pixel matrix with row drivers and column drivers or with gate drivers and source drivers for controlling individual pixels of the pixel matrix, characterized by - a detection circuit (28) which is designed to detect at least one total operating current, in particular at at least one supply connection of the display unit (20), wherein the total operating current comprises at least the operating current of the pixel matrix of the pixel matrix display (22, 22', 22"), and - a computing unit (24) which is connected to the detection circuit (28) and is designed to computationally evaluate a detected time behavior of the total operating current for the purpose of checking for a fault condition, in particular a freeze condition. Display device according to claim 10, characterized in that the computing unit (24) is designed to determine a time behavior or a temporal variance of the at least one total operating current, in particular to carry out a frequency analysis in order to check for a fault state, in particular a freezing state, on the basis of the frequency analysis. Display device according to claim 10 or 11, characterized in that the detection circuit (28) comprises a current measuring shunt resistor, in particular in series with the supply connection of the display unit (20), and a current measuring amplifier, in particular a discrete current measuring amplifier, for measuring a voltage drop across the current measuring shunt resistor, wherein the output of the current measuring amplifier is connected to the computing unit (24), preferably via a low-pass filter. Display device according to one of claims 10, 11 or 12, characterized in that the computing unit (24) is designed to trigger a safety-related reaction in the event of a negative result of the test, in particular to at least partially switch off and/or restart the display unit (20) and/or to generate an alarm signal. Display system comprising a display computer and a pixel-based display unit (20) with a pixel matrix display (22, 22', 22") comprising a pixel matrix, wherein the display computer is connected to the display unit (20) via an image data line, in particular an LVDS interface, an HDMI interface or the like, for transmitting computer-generated image data,
characterized in that that a modular monitoring unit is provided for monitoring the image data, which is connected on the input side to the display computer and on the output side to the display unit (20), and that the modular monitoring unit comprises a detection circuit (28) which is designed to detect at least one total operating current, in particular at at least one supply connection of the display unit (20), and the modular monitoring unit comprises a computing unit (24) which is connected to the detection circuit (28) and is designed to computationally evaluate a detected time behavior of the total operating current for the purpose of checking for a fault condition, in particular a freeze condition. Multifunctional terminal for a safety-relevant application, in particular for the driver's cab of a rail vehicle, comprising a display device according to one of claims 10 to 13, in particular comprising a display system according to claim 14.

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