DE102019204124A1 - Temperature-dependent operation of a screen - Google Patents

Abstract

The invention relates to a method for temperature-dependent operation of a screen (100), comprising the display of several contents on a screen in a normal mode, recording of the respective temperature (150) of at least two display areas (111, 112), which cover at least part of a screen area take in; and if the temperature in at least one display area exceeds a first predetermined limit value (T1), activating a heat protection mode which comprises: hiding content with a low display priority (270, 280), first selecting one or more of the at least two display areas (111, 112) ) to obtain first selected display areas; and displaying content with higher display priority (210, 220, 230, 260) in the first selected display areas.

Description

The present invention relates to a method for temperature-dependent operation of a screen as well as a computing unit and a computer program for its implementation.

State of the art

Many screen elements such as liquid crystal screens (LCD displays) or OLED displays (Organic Light Emitting Diode, organic light emitting diodes), which are used today in a wide variety of applications, have a certain temperature sensitivity. The self-heating of the screen during operation can also play an important role, especially at higher temperatures, which is usually more pronounced in light and high-contrast elements than in dark areas. The luminous efficacy of screens only corresponds to a fraction of the power consumed; the heat development also increases disproportionately with the brightness achieved. In order to prevent irreparable damage to the screen, an emergency shutdown can therefore be used, which is used when the screen temperature is too high.

In areas in which the screen elements are also used for safety-related functions, i.e. constant operation of the display should be guaranteed, malfunctions, failures or shutdowns caused by heat are undesirable. For example, one or more screens are increasingly being used in vehicles to serve as a display for a number of different functions. Many elements that were previously provided in the form of analog display elements and individual lamps on the dashboard of a vehicle, such as speedometers and warning lights, can now also be displayed on electronic screens. A wide variety of functions can be combined on a single screen; Starting with vehicle-specific information such as fuel level, parking aids and warning displays for component functions, to driving-relevant displays such as navigation instructions and road conditions, to entertainment elements that are less relevant to safety such as music control, weather reports or time. More and more complex systems are also being used in vehicles, such as camera support for the vehicle environment, lane assistants or even fully autonomous driving functions such as autopilot systems, the use and status of which the driver should be constantly informed of for safety reasons.

To avoid an emergency shutdown, a reduction in the screen brightness can therefore be used, for example, in order to reduce self-heating. However, this inevitably leads to poorer illumination and therefore also harbors the risk that safety-relevant display elements (e.g. a camera image or a warning display) can no longer be reliably recognized on such a dimmed screen.

Disclosure of the invention

According to the invention, a method for temperature-dependent operation of a screen as well as a computing unit and a computer program for its implementation are proposed with the features of the independent claims. Advantageous configurations are the subject of the subclaims and the description below.

According to the invention it is proposed to display several contents on a screen in a normal mode and to detect the temperature of several display areas, the areas taking up at least part of the screen area; and if the temperature in at least one display area exceeds a first predetermined limit value, a heat protection mode is activated, which comprises hiding content with lower display priority and selecting display areas for displaying content with higher display priority.

In this way, a screen can be protected from emergency shutdowns and damage in the event of self-heating by limiting the content and thus also the heating to certain display areas, and yet it can be ensured that all absolutely necessary content is displayed on the screen with sufficient brightness at all times can.

According to a preferred embodiment, the contents are displayed for a predetermined period of time in the selected display areas, and after the period has expired or after a limit temperature has been exceeded before the period of time has elapsed, new display areas are selected on which the contents are displayed with higher priority. As a result, some of the display areas can temporarily cool down again or at least the heating can be limited while they are not being used, and the temperature rise can be effectively limited for each screen area by the time-dependent change to new display areas.

According to one embodiment, the first selected display areas and the second, newly selected display areas are at least partially identical. This means that some of the areas For example, areas that have already been overheated can be completely switched off, while the selected display areas are used, for example, in a cyclical change to display the content, so that at least part of the content is displayed alternately on different of the selected display areas. The display areas can be changed according to a predetermined sequence.

In all exemplary embodiments, the selection of the display areas can be carried out on the basis of their current temperature, so that for example only the currently coolest area or all areas below a certain temperature are used for display.

The selection of the display areas for each content is preferably carried out on the basis of stored parameters of the display areas and / or the content, wherein the parameters stored for the content can include, for example, the following: brightness of the display of the content; Area of content; Display priority of content; User preferences; Position of the content in normal mode.

In a further embodiment it is possible to divide the contents with a higher display priority into at least two subsets, a subset of the contents with a higher display priority also being hidden if the temperature exceeds a third predetermined limit value. In this way, a two-stage or multi-stage heat protection process is obtained with different display priorities, which allow a finer adjustment of the hidden content.

The normal mode can preferably be reactivated and all contents, regardless of their display priority, can be displayed in their original position if the temperature in all display areas falls below a fourth limit temperature or at least for a predetermined time. This means that the full functionality of the screen is available to the user again as soon as it is ensured that the screen does not enter critical temperature ranges.

A computing unit according to the invention, e.g. a control unit of a motor vehicle is set up, in particular in terms of programming, to carry out a method according to the invention.

The implementation of a method according to the invention in the form of a computer program or computer program product with program code for performing all method steps is advantageous, since this causes particularly low costs, in particular if an executing control device is also used for other tasks and is therefore available anyway. Suitable data carriers for providing the computer program are, in particular, magnetic, optical and electrical memories, e.g. Hard disks, flash memories, EEPROMs, DVDs, etc. A program can also be downloaded via computer networks (Internet, intranet, etc.).

Further advantages and configurations of the invention emerge from the description and the accompanying drawing.

The invention is illustrated schematically in the drawing using exemplary embodiments and is described below with reference to the drawing.

Figure list

• 1a shows a diagram with the temperature profile over time of an overheating screen not according to the invention;
• 1b shows a diagram with the temperature profile over time of a dimmed display not according to the invention;
• 1c shows a diagram with the temperature profile over time according to an exemplary embodiment of the invention with two display areas used;
• 2a to 2c show various possibilities for dividing an exemplary display according to the invention,
• 3a shows example content items on a screen while 3b shows the division of such a screen into display areas; and
• 4a to 4c show screen elements in the course of an exemplary heat protection mode according to the invention.

Embodiment (s) of the invention

1 shows different temperature profiles over time in a typical screen element. Starting from a relatively cool screen element, the temperature T (curve 10 ) of the screen element in 1a with progressive time t increases until it exceeds an upper critical limit temperature T _k , which can lead to a malfunction or destruction of the screen without further intervention. The line that continues to rise shows 12 the course without intervention (further rising temperature), while the sharply falling line 14th corresponds to an emergency shutdown when the critical temperature T _k is reached. This represents the course on a conventional screen, where no further precautions have to be taken Temperature limit have been met. Various factors contribute to warming; For example, environmental conditions, such as the general ambient temperature and solar radiation on or near the screen, can play a role as well as heating from components of the screen itself or other elements with waste heat that are in the immediate vicinity of the screen (e.g. power supply, wireless Transceivers, microprocessors and others). In addition to these external factors, there is then the heating caused by the operation of the screen itself, whereby it can approximately be assumed that with increasing brightness of the display, the temperature in the respective screen area increases correspondingly more. An area that is constantly brightly lit is likely to heat up more than an area of the screen on which nothing is displayed for a long period of time or is very dark.

1b shows the possibility of limiting the heating by dimming or reducing the brightness of the display and thus staying below the critical temperature T _k as far as possible, at which damage or shutdowns can occur. For this purpose, a temperature T ₀ below the critical temperature T _{k is} defined as the threshold value, which is dimensioned such that a corresponding reduction in brightness by a certain amount when this temperature is reached ensures that the critical temperature is not reached. As soon as the brightness is reduced at time t _dim , the self-heating of the screen is also reduced, so that the temperature now rises more slowly (section 20th ). As already described, the disadvantage remains that a darkened screen could lead to reduced perception of security-relevant content, even if shutdowns and damage can be avoided.

Therefore, according to an exemplary embodiment of the invention, several areas are defined on a screen, so that in the event of an impending overheating, the areas are controlled differently in terms of time and location as a function of temperature. For example, a part of the display can be temporarily switched off, and then display elements can be displayed in another area after a certain time has elapsed, so that the previous area has the opportunity to at least partially cool down. A subdivision of the display content into relevant or necessary and unnecessary elements can serve to determine the proportion of the screen area that must continue to be operated, while less relevant content does not have to be displayed temporarily in this heat protection mode. In this way it can be ensured that necessary and security-relevant elements can be displayed at any time with sufficient brightness and visible contrast without the risk of overheating. The aforementioned screen areas are usually not separated from one another on the hardware side; rather, it can be a purely virtual definition of screen areas. In principle, however, the formation of separate screen elements, which together result in a screen, is also conceivable, or screen elements can partially be physically separated by subdivisions.

1c shows the temperature profile over time in an exemplary simple embodiment of the invention, in which the screen area of a screen is divided into only two separate display areas and one display area is switched off periodically while the necessary content continues to be displayed alternately in the other display area. It is therefore assumed that part of the content to be displayed is not always necessary and can therefore be temporarily hidden in a heat protection mode to avoid damage to the screen. Other content that is constantly required, for example because it relates to security-related information, is then displayed in the remaining part of the screen. When a predetermined threshold temperature or limit temperature T _{1 is reached} below the critical temperature T _k , the heat protection mode is activated at time t ₀ , so that only part of the screen is illuminated, recognizable by the now separate temperature curves 30th and 40 . This part of the screen continues to heat up (Section 30th ), while the temperature of the second, switched off area can now drop temporarily (section 40 ). In good time before the first part reaches too high a temperature, the necessary content is now displayed in the second instead of the first part of the screen. The temperature of the first screen area can now drop again, while the temperature in the second area currently in use increases accordingly. When the critical temperature T _k is reached or shortly before it is reached, the display areas can be changed again, so that a periodic curve results and the temperature over the entire screen surface always remains below the critical temperature T _k . Alternatively, as shown in the figure, a cycle with the length t _{c can be} specified for changing the display areas, whereby it should be ensured that the critical temperature is nevertheless not exceeded.

It is noted that the limit temperature T ₁ in 1c for the beginning use of the changing display areas does not have to correspond to the threshold T ₀ , which in 1b was used for the brightness reduction. The respective temperatures can be set the same for all methods, or can, for example, depend on the number of areas used, depending on the required illuminated screen area in heat protection mode, or depending on other parameters. For example, different limit temperatures can be set and called up during operation for the respective process used.

If, for example, it can be determined on the basis of the display content used in the vehicle that a proportion of 30% of the content (based on the screen area) is safety-relevant and has to be displayed constantly, while 70% can be temporarily switched off in heat protection mode, then another, Preferably, a higher limit temperature should be selected than when there is content, of which 60% (again based on the area) must be constantly active and cannot be switched off or hidden. The more content that has to be displayed constantly, the stronger and faster the expected warming and the earlier a heat protection mode should preferably be activated in order to protect the screen elements. Instead of the screen area used, the cumulative brightness over the screen area can also be improved. Since the existing and necessary screen contents can also change during continuous operation, for example depending on whether a navigation display is currently required or not, the limit temperatures can also change as a function of this during operation. A controller can determine which limit temperature is currently applicable. A heat protection mode is preferably activated as soon as the limit temperature is exceeded in at least one of the defined display areas. Depending on the definition of the temperature, it can also be determined that a heat protection mode is only activated when a limit temperature is exceeded in two areas or in several areas. It is also possible to initially dim less important displays and only activate the full heat protection mode with switched off and / or changing screen areas when the temperature rises further.

In order to be able to use a method according to the invention, the screen element must be able to be controlled at least partially selectively, i. E. it must be possible to control at least the brightness or the lighting of an area locally. In the exemplary case of an OLED display, this is the case since each pixel or subpixel of the display can be selectively controlled in the usual way (passively or actively). If, for example, a backlit LCD display (LED backlight) is used, selective control of the background LEDs can be implemented (local dimming). Depending on the type of screen, either the background lighting and / or the display pixels themselves can be partially switched off or reduced. The screens can also be a touch-sensitive screen or touchscreen.

It must also be possible to determine the necessary temperatures. For this purpose, for example, each (or at least a part) of the display areas can be provided with a temperature sensor which is able to output a temperature that is representative of this area. The position of the temperature sensors can be adjusted so that they monitor an area with the most homogeneous temperature distribution possible, or, for example, so that they are located where the maximum temperature of the area is expected. If, for example, it is known that a certain screen area is strongly heated by a nearby external component, it can be assumed that a temperature maximum will also be present there during operation, so that a measurement at this location is preferred in order to avoid damage . The position and number of temperature sensors should preferably correspond to the position and number of display areas that are defined for the screen. However, it is also possible, for example, to provide a screen with a larger number of temperature sensors than are defined for display areas. In this case it is possible to specify the temperature of the area as the maximum of the temperature values in the area or as an average value of the temperature values of several sensors, or to define one of several sensors in the area as the relevant sensor whose temperature is used for carrying out the method .

Instead of or in addition to temperature sensors, other methods known in the art are also possible in principle to determine the temperature of the display areas. For example, different signals can be monitored and the current temperatures of a display area can be estimated based on stored data. It is also possible to use a model that estimates the expected self-heating of the screen during operation, for example on the basis of evaluated test images and the respective brightness of the display content. Such estimated values can, however, deviate significantly from the actual temperatures of the screen areas. In principle, such estimated temperature values can also flow into the method together with measured temperatures, for example from sensors. In this way, it is possible, for example, to model how long it is likely to take when displaying a certain content with a specified brightness / lighting power before the temperature of the area will rise above the limit temperature or the critical temperature.

As above in connection with 1c described, the screen surface can be divided into only two display areas in a simple embodiment of the invention. Such a division is exemplified in 2a shown; the dash-dotted lines show the two virtually defined display areas 111 and 112 on. The definition of the display areas is preferably in one with the screen 100 connected controller stored and retrievable. The lighting elements 110 can be optoelectronic elements of the screen, for example background LEDs or OLED elements or any other lighting elements that can be selectively controlled and are arranged, for example, in the form of a matrix. Not every single element 110 , but at least the defined areas 111 , 112 can be controlled separately. It goes without saying that the lighting elements 110 are only shown schematically here and are much smaller in conventional screens, and that, for example, three different-colored OLED elements are present per image pixel, that is usually a very large number of lighting elements on a screen surface.

As already described, when the heat protection mode is activated, part of the content can then be hidden, while the part of the content that must continue to be displayed to the user, for example alternately in the areas 111 and 112 is shown. There is a temperature sensor in each of the display areas 150 shown, which can also be attached to another location of the respective area.

In general, however, a division into a large number of display areas is possible, with the areas being able to have different geometric shapes and / or sizes. 2 B shows a division into four display areas 121 , 122 , 123 , 124 with associated temperature sensors 150 in each area, again taking the entire screen area 100 is covered by the display areas. However, this is also not absolutely necessary.

Areas can also be disregarded when defining the areas. Such a division is in 2c shown. As can be seen there, the display areas can also assume any shape, for example homogeneous or inhomogeneous polygons 131 , 132 , 133 , 134 different shape and size to cover suitable screen areas. For areas not covered by defined display areas 140 For example, it can then be stipulated that when a heat protection mode is activated they are always switched off and not used, so that they are not taken into account for the shifting and changing display of content.

In general, to define the display areas (see Areas 111 , 112 , 121 , 122 , 123 , 124 , 131 , 132 , 133 , 134 ) different sizes and shapes are taken into account. For example, the size can be selected so that there is sufficient space for the content to be displayed. The size and shape of a display area can be selected depending on the expected temperature distribution, so that each area has as homogeneous a temperature distribution as possible. The number of display areas results partly from the size of the areas. The areas preferably have at least similar dimensions. In certain embodiments it is also possible to temporarily combine several previously individually defined display areas into a larger area, for example if only correspondingly large content elements are currently to be displayed or it is sufficient to group several content elements together. In this way, the control of the heat protection mode can then be simplified. As soon as - for example, by changing the driving mode - further content elements are to be displayed that are smaller, the areas can be separated again into smaller display areas. For example, the in 2 B areas shown are summarized in this way (areas 121 and 124 , or areas 122 and 123 ) that instead of four display areas, only two display areas are taken into account, as in 2a shown.

A parameter can be assigned to the display areas, which determines the preference with which the respective area should be used in a heat protection mode. For example, the center of a screen typically heats up faster than the edges, so display areas (like 134 ) a value can be assigned in the middle that prevents or limits their use in heat protection mode. The same applies to display areas that are constantly exposed to increased heating due to their proximity to other components, for example. On the other hand, marginal areas (e.g. areas 131 , 133 ) of a screen are often cooler or heat up more slowly because the heat can be better dissipated towards the housing. Correspondingly, a suitable thermal parameter can then be assigned to these areas, which can later be used for the content display. If content elements are then alternately displayed on several display areas, areas with a high thermal parameter (eg areas that overheat more quickly) can be used less often than areas with a lower thermal parameter (ie cooler areas). In a further optional embodiment, the system may be able to change and improve these parameters, for example by monitoring how much and how often the respective display areas heat up. To this In actual operation, the control can learn which areas are better suited for display.

Optionally, the display areas can also be assigned a parameter that evaluates their suitability for safety-critical elements. In this way, it can be prevented that very important elements are arranged in poorly visible corners or outside of the driver's central field of vision. Depending on the design, such a parameter can also be confirmed or changed by user inputs, since the visibility has to be assessed differently for each user. This parameter can also be combined with the previously mentioned priority parameter.

Using the example of a screen 100 in a motor vehicle are in 3a various content items are shown that can be viewed in normal mode. The screen can be arranged, for example, on a dashboard or a center console of the vehicle. Which content is available and displayed depends both on the specific vehicle and on the current situation or, for example, on the driving mode selected by the driver. The content elements shown are only given by way of example in order to clarify the basic functioning of embodiments according to the invention. In this example, the content items include a speed display, for example 210 , various warning displays or indicator lights 220 such as tank warning light, oil pressure warning and engine warning light, a tachometer 230 , a navigation area 240 , a weather and temperature display 250 , the real-time image 260 an outside camera (e.g. to display the blind spot area on the vehicle), a clock 270 , a media ad 280 as well as any other content element 290 . Further or alternative content elements are also possible. If it is a matter of a display in a different area of application than in vehicles, other content elements are of course provided accordingly.

3b shows the display 3a overlaid with possible display areas, similar to in 2c . It can be seen that some contents can also be larger than a display area and that certain areas of the screen are not assigned to a display area. In normal mode these areas are used as usual as a display area, in heat protection mode they can then be switched off.

In order to be able to decide for a heat protection mode which content must be displayed and which can be temporarily switched off or hidden, a corresponding display priority should preferably be assigned to each content to be displayed. In a simple embodiment, this can be a simple status indicator which, for example, assigns the values 0 and 1 (correspondingly unimportant / important) to the content. As soon as a heat protection mode is activated, all content with priority 0 is then preferentially hidden and only the content with priority 1 is displayed in the selected areas. As already described, the content can also be displayed alternately in different areas.

In a further embodiment, the display priority can assume a series of values, so that graded evaluations and display modes are made possible. This version is in 4a and is described in more detail in connection with the different variants of the heat protection modes. This makes it possible to display a large part of the content in a first stage of the heat protection mode and to hide only unimportant elements, while with further heating towards critical temperatures T _k, further content elements are then hidden in a second stage of the heat protection mode and only absolutely critical elements remain displayed. For example, some of the content could be such as necessary warning lights 220 , Speed indicator 210 , Tachometer 230 and a camera screen 260 , which are assigned display priority 2 (indispensable), a navigation display 240 and one more element 290 could be assigned display priority 1, and weather display 250 , Clock 270 and music control 280 can be assigned the display priority 0 (unimportant). Correspondingly, two different limit temperatures T ₁ and T ₂ can then be defined, from which the first or second stage of the heat protection mode takes effect. Finer gradations and other versions than an indicator value as suggested here can also be used.

The contents can also be provided with further parameters that are taken into account in the heat protection mode according to exemplary embodiments of the invention. The size can be stored for each content to be displayed, with a size range optionally being specified which allows the respective content to be enlarged or reduced, if necessary, up to a certain value or percentage of the actual size. This can be useful, for example, if, in the event of a partial shutdown of the display, there is less space than the content elements that must be displayed would take up in their original size. The shape of the required display area can also be saved or a specific shape (for example rectangular or adapted to the shape of the Display areas) to simplify the arrangement.

Furthermore, a heat parameter can be assigned to each content, which indicates how much the display of this content is likely to heat the screen area. This parameter can be pre-stored and derived from a model calculation based on the area and brightness values, or it can be known and stored, for example, from previous temperature measurements. A bright, large content area such as a camera image, for example, will bring more heat into the respective area than an area on which the time is only shown with narrow elements and the other areas remain dark all around. In simplified terms, such a heat parameter can therefore also correspond to a cumulative brightness value of a content area. The parameter can specify a specific value for each content or be divided into only a few levels in order to differentiate between content with low and high self-heating.

It is optionally also possible to forbid changing to different display areas for important content or to make it dependent on a higher level of the heat protection mode. For this purpose, a further status indicator can be assigned to the content. Such an indicator can prevent a user from being confused by a constant change of position in the case of very important content and thus possibly no longer being able to correctly assign the safety-critical display. Alternatively or in addition, content can also be assigned a value in this way that indicates how far the position of the content may be removed from the original display location on the screen, and / or whether a certain content element is fixed together with a or several other content is to be grouped in order to offer the user a continuous appearance.

All these parameters and indicators can be stored in a central database or table of the control for each content element and each defined display area of the screen, or they can also be transmitted by the respective software elements of the control.

It is not absolutely necessary that all parameters are specified for each content element even when using several evaluation parameters and indicators. Processes can only use some of the parameters or provide rules that apply to content elements for which a certain parameter (e.g. expected heat input) is not saved.

The values and indicators for each content to be displayed are preferably already permanently stored in the displaying software or control and are called up from there. If no value is specified for a content element to be displayed, it can optionally be specified that the controller first defines the highest possible content indicator for such content in order not to inadvertently hide security-relevant content (e.g. when retrofitting systems). This means that a content element is always displayed without predefined values, for example. Additionally or alternatively, possibilities can be provided with which a user can define or change these values. It should preferably be prevented that users subsequently rate security-relevant content lower, but it should optionally be possible, for example, to assign a higher status indicator to a content and thus guarantee a continuous display of this content, provided that the function of the screen is not endangered. Another possibility is for a controller to be supplied with updated values and indicators for the content currently available via an update, which can be imported into the system, for example, via a telecommunications connection or an external interface.

In order to indicate to the user that the heat protection mode has been activated and part of the otherwise usual content is temporarily no longer displayed, a visual notice such as a warning text or symbol can be used to indicate the heat protection mode. Alternatively or additionally, an audio signal can be output during activation. Overall, the driver should be as aware as possible that the heat protection mode has been activated to ensure the functionality of the screen, and he should be able to continue to intuitively understand the content elements still displayed based on their position and arrangement.

As soon as the heat protection mode is initiated as described by exceeding a certain temperature T _1, the content to be displayed is selected by the controller depending on its display priority and the appropriate display areas. Again, different strategies can be used for this. 4a to 4c show different exemplary variants of the display 3a in a heat protection mode.

4a shows as an example the application of a two-stage heat protection mode, in which two limit temperatures T ₁ and T _{2 are} defined as already described above. When a first limit temperature T ₁ is exceeded, content with a low display priority, such as a clock, is used 270 who have favourited Media Player Ad 280 and the temperature display 250 hidden. The remaining content will be partially displayed in their original position, such as the warning lights 220 and the speedometer 210 , and partially moved to a thermally more favorable position, such as the navigation display shifted downwards 240 . This means that areas that are more heated can already be protected. If a further, higher limit temperature T _{2 is} also exceeded, then further contents with a medium display priority that are not absolutely necessary, in this case the navigation display, are hidden 240 and another content element 290 . For both levels, in addition to hiding content, the remaining content can also be switched between different display areas, which is described in more detail below.

If, for example, only a few areas are possible for display, because the other areas, for example, exceed the corresponding limit temperature, the necessary content can be divided into these areas and initially displayed there continuously. Alternatively, one or more areas, for example the area with the currently coldest temperature, can be selected and the defined contents can be displayed in this area for a predetermined time tc. After the specified time period t _{c has} elapsed, the display of the necessary content changes to a further area, for example either to the coolest area at this time or according to a defined sequence, such that the content always “wanders” one area further. It is also possible for the area parameters and content parameters described above to be used in order to determine the sequence and / or display duration of the areas. Depending on the size of the areas and contents, one content element can also take up several display areas.

If a display area that is currently used for displaying content comes into the range of the critical temperature T _k or exceeds an upper limit temperature before the specified period of time has elapsed, the change of the content to the next area is initiated prematurely. The respective content is thus displayed in the selected display areas either for a predefined period of time t _c or until the point in time before this period expires at which a further temperature is already exceeded in one of the areas. If, with such changes, the time until the critical temperature is reached is below a predefined minimum dwell time, the affected display area or the entire screen can be switched off so as not to confuse the user with jumping content.

In order to keep the arrangement of contents on the screen as constant as possible, it is also possible, depending on a low limit temperature, to initially include only some of the areas in the method and to leave the remaining display areas unchanged.

It is also possible to display certain content in the same position without changing in heat protection mode, or to specify only a limited subset of the display areas in which a certain content may be displayed in order to prevent confusing changes in critical content elements. This can be useful, for example, for a warning display that is only displayed with a small or low brightness level and which will therefore only contribute little to warming. At the same time, other content can switch between different display areas according to the method already described.

4b shows such a variant as an example, in which part of the content with a low display priority is already hidden in a heat protection mode. While a group of warning lights 220 continues to be displayed at the same position without changing the display area, the other necessary content with higher priority is moved to another display area. In the example shown, two of the content items 210 , 230 slightly changed in size to allow a display of all elements in the temperature-dependent selected and available display areas. Whether such a size change is permissible and to what extent can be specified for each content in an additional parameter. This prevents important content from being displayed too small.

In order to change the display as little as possible - also for security reasons - in addition to fixed content positions, it can be specified how far a content display may be from the normal display position. For example, it could be stipulated that important warning indicators must always be displayed at the top of the screen. Additionally or alternatively, the content can be shifted or changed in such a way that the distance between the display areas used in the heat protection mode is as small as possible compared to the normal display position in normal mode. To this end, the control can perform an optimization of the selected display areas for the content on the basis of normal positions stored with the content, which results in a minimal shift for all or for certain content. In particular, it can be stipulated that content with a low display priority (less important or less safety-relevant) may change to more distant positions, while content with a very high display priority may not change its location. In this way, a multi-level priority value for the display priority, as already described above, can be used not only for the decision about hiding or displaying, but also for the targeted selection of the display areas used.

4c shows a further exemplary embodiment of the invention in which various steps according to the invention are combined. First of all, some of the content is hidden again, depending on the specified display priorities of the respective content. The remaining content is alternately moved to selected display areas. First the camera image 260 as a light, two-dimensional content element with an expected high heat input moved from right to left into a new display area while the ads 210 , 220 and 230 cannot be moved in the upper half of the screen with lower heat input. The display area at the bottom right can now be temporarily switched off and allowed to cool down to an acceptable value. Then the camera image 260 moved to the upper area while the two displays 210 and 230 from the upper half can be moved together and in fixed relation to one another into the lower half. In a next step, for example, the camera image 260 in the upper half can be moved to the right, while the two displays for speed 210 and speed 230 remain in the lower area before the display changes back to the first variant in a fourth step. As described above, the transition between the steps can be dependent on the expiry of a predetermined time t _c and / or on the temperature profile of the areas. The cycle to change between the display areas can be repeated until the heat protection mode is ended.

The warning lights 220 are in this example again arranged in the same display position in all steps and are not moved. Alternatively, this content could also be shifted cyclically like the other content elements.

Switching a content display between two areas can take place in different ways. On the one hand, there can be a hard changeover in which the screen areas are briefly black and then display the new content. As an alternative, short-term, i.e. A double display can be provided over a few image frames. It is also possible, however, for the content to be moved dynamically to the new position, i.e. to slide from the old to the new display area in a way that is visible to the user, or to move from one position to the new position with several intermediate images. This has the advantage that the content elements are shifted in a clear and comprehensible manner for the user. However, more energy is consumed and thus more heat is produced again if the content is displayed between two areas and the appropriate lighting is necessary in both areas.

Similar to the limit temperature T ₁ , which was described above for the activation of the heat protection mode, the same or a different limit temperature T ₄ can also be set, if the temperature falls below this limit, the display switches back to normal mode and all content elements are constantly displayed at their usual location . It can also be stipulated that the temperature T _{4 must} first remain below the corresponding temperature T ₄ for a predetermined time in order to avoid a constant change between normal mode and heat protection mode.

The above invention has been described with reference to screens in vehicles and can be used there optimally; however, the invention can also be used with any screen element in which a local temperature-dependent control of the screen surface is possible, in particular if critical content elements are to be displayed reliably and the self-heating of the screen element plays a role. The use of the invention is therefore also conceivable, for example, in machine controls, generally in screens in industry and manufacturing and other areas. For example, in a machine control system, it might be necessary to constantly display critical machine parameters for monitoring purposes, while other content such as statistical data and setting options do not have to be displayed at all times, even if it makes sense and is convenient in normal operation. If the temperature rises above the limit temperature, as described above, the critical content can then be displayed dynamically changing and temperature-dependent in the predetermined screen areas, while the other areas are optionally switched off.

Claims (15)

A method for temperature-dependent operation of a screen (100), comprising: displaying multiple contents on a screen in a normal mode, detecting the respective temperature (150) of at least two display areas (111, 112) which occupy at least part of a screen area; if the temperature in at least one display area exceeds a first predetermined limit value (T ₁ ), activating a heat protection mode, which comprises: hiding content with a low display priority (270, 280), first selecting one or more of the at least two display areas (111, 112) to obtain first selected display areas; and - displaying content with higher display priority (210, 220, 230, 260) in the first selected display areas. Procedure according to Claim 1 , wherein the heat protection mode further comprises: - displaying the contents with higher display priority (210, 220, 230, 260) in the first selected display areas for a predetermined period of time (t _c ), and - further selecting one or more display areas from the at least two Display areas for obtaining further selected display areas; - Display of the contents with higher priority (210, 220, 230, 260) in the further selected display areas if the predetermined time period (t _c ) has expired or if the temperature in at least one of the first selected display areas has passed a second before the predetermined time period has expired exceeds a predetermined limit. Procedure according to Claim 2 wherein the first selected display areas and the second selected display areas are at least partially identical. Method according to one of the preceding claims, wherein at least part of the content is displayed alternately on different ones of the selected display areas. Procedure according to Claim 4 wherein the contents are alternately displayed on the selected display areas according to a predetermined order. Method according to one of the preceding claims, wherein the selection of the display areas is carried out on the basis of their current temperature. Method according to one of the preceding claims, wherein the selection of the display areas for each content is carried out on the basis of stored parameters of the display areas and / or the contents. Procedure according to Claim 7 wherein the parameters stored for the content include at least one of the following: brightness of the display of the content; Area of content; Display priority of content; User preferences; Position of the content in normal mode. Method according to one of the preceding claims, wherein the contents with a higher display priority are divided into at least two subsets, and wherein a subset of the contents with a higher display priority is also masked out if the temperature exceeds a third predetermined limit value (T ₂ ). Method according to one of the preceding claims, wherein the normal mode is reactivated and all contents are displayed in their original position regardless of their display priority if the temperature in all display areas falls below a fourth limit temperature (T ₄ ) or at least for a predetermined time. Computing unit which is set up to carry out all method steps of a method according to one of the preceding claims. Computer program that causes a computing unit to perform all process steps of a process according to one of the Claims 1 to 10 to be performed when it is executed on the computing unit. Machine-readable storage medium with a computer program stored thereon Claim 12 . Device comprising a screen (100) which can be selectively activated in at least two defined display areas (111, 112), and a detection device (150) which is set up to detect the respective temperature of the defined display areas, further comprising a computing unit according to Claim 11 . Device according to Claim 14 wherein the screen (100) is a screen in a motor vehicle, in an aircraft, in a rail vehicle or in a machine control.

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