JP2013131244A - Memory malfunction detecting device for image processing, image display device using the same, and memory malfunction detecting method for image processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a memory malfunction detecting device for image processing which correctly detects an abnormal operation without monitoring an image signal when a memory for the image processing abnormally operates, and to provide an image display device using the memory malfunction detecting device, and a memory malfunction detecting method for the image processing.SOLUTION: A memory malfunction detecting device for image processing comprises: a temperature difference measuring part 17A for measuring temperature difference of ambient temperature of a DRAM 5 which is a memory for image processing; a memory 9 which is a temperature difference range holding part for holding a predetermined range of the temperature difference in the DRAM 5 which is the memory for the image processing; and a fault determining part 8 which is a determining part for comparing measured power source current with a current range (IthL-IthH) held in the memory 9, and determining whether the measured temperature difference is out of the range of the temperature difference or not.

Description

  The present invention relates to an image processing memory malfunction detection device, an image display device using the image processing memory malfunction detection method, and an image processing memory malfunction detection method.

  In image processing, rearrangement of signals for each pixel and signal correction for gradation display need to be processed in accordance with the frame rate, and therefore data exchange with the image processing memory is indispensable. However, in the exchange of data, if an error occurs in the exchanged data, the memory may malfunction. Therefore, for example, in the field of data communication between the CPU and the memory, a parity signal is added to the image data to be written in the memory, and the data error is detected by reading the parity at the time of reading from the memory. Alternatively, a DRAM access control device that adds a parity bit to an address signal applied to a memory and checks the parity bit added on the memory side has been proposed (see, for example, Patent Document 1).

JP-A 64-13657 (2nd page, Fig. 1)

  As described above, when a malfunction is detected using a parity signal, for example, when malfunction becomes impossible due to a cause other than a data error such as an abnormality of the device itself, the detection is difficult. In addition, when image reading / writing is repeated at high speed as in an image processing memory, the above monitoring is often not possible due to memory access time limitations. In particular, in the case of an image processing memory, it may be pre-installed in another device, and there may be a case where a monitoring circuit as described above cannot be added. In such a case, even if the operation of the memory becomes abnormal, there is a problem that the memory cannot be detected on the system side and the display of the image remains stopped.

  The present invention has been made to solve the above-described problems, and for image processing that can detect abnormal operation correctly without monitoring an image signal when the image processing memory becomes abnormal operation. An object of the present invention is to obtain a memory malfunction detection device, an image display device using the same, and a memory malfunction detection method for image processing.

  An image processing memory malfunction detection device according to the present invention is a device that detects a malfunction of an image processing memory that writes / reads image signals, and that measures a temperature difference between the image processing memory and ambient temperature. Measurement is performed by comparing the measured temperature difference and the temperature difference range with the difference measurement unit, the temperature difference range holding unit that holds a predetermined temperature difference range as the temperature range during normal operation of the image processing memory And a failure determination unit that is a determination unit that determines whether the temperature difference is out of the temperature difference range.

  An image display apparatus according to the present invention includes a light modulation element that converts light incident from a light source into video light, an image signal processing unit that outputs an image signal for controlling the light modulation element, and the image signal. The image processing memory malfunction detecting device that detects malfunction of the image processing memory for writing / reading the image signal in the processing unit.

  The image processing memory malfunction detection method according to the present invention is a method for detecting malfunction of an image processing memory for writing / reading an image signal, and measuring a temperature difference between the image processing memory and the ambient temperature. A temperature difference measurement step, a temperature difference range holding step for holding a temperature difference range determined in advance as a temperature range during normal operation of the image processing memory, and a comparison between the measured temperature difference and the temperature difference range. And a failure determination step which is a determination unit for determining whether or not the measured temperature difference is out of the temperature difference range.

According to the present invention, since the failure of the image processing memory is detected by measuring the temperature difference between the image processing memory and the surroundings, the image signal is monitored when the image processing memory malfunctions. An image processing memory malfunction detection device, an image display device using the image processing memory malfunction detection method, and an image processing memory malfunction detection method can be obtained.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of an image display apparatus according to Embodiment 1 of the present invention. The image display apparatus 100 is a projection display apparatus that uses a DMD element 30 (Digital Micro Mirror Device) as a light modulation element (light valve) that converts light incident from a light source into image light, and controls the DMD element 30. An image processing unit 20 for outputting an image signal for image processing, and an image processing memory malfunction detecting device 10 for detecting malfunction of the DRAM 5 which is an image signal processing memory for writing / reading the image signal in the image processing unit 20 And. Further, although not shown, a light source, a projection lens system for enlarging and projecting image light emitted from the light modulation element, and a screen for displaying the enlarged image light are also provided. Details will be described below.

  In the figure, a DMD element 30 which is a light modulation element is a planar arrangement of a large number (for example, several hundred thousand) of minute mirrors corresponding to each pixel of image light to be projected. By operating each mirror, the image light is emitted based on the light incident from the light source.

  The image processing unit 20 includes an input terminal 1 to which a video signal is input, a video signal processing circuit 2 that performs image processing such as frame rate frequency conversion and pixel conversion on the video signal input from the input terminal, and a DMD element In order to generate an image signal for driving 30, PWM (Pulse Width Modulation) processing for signal rearrangement and gradation display is performed based on the video signal converted by the video signal processing circuit 2. The DMD control circuit 3, the DRAM 5 that is an image processing memory for writing / reading the image signal in the process of generating the image signal by the DMD control circuit 3, and a clock signal for the entire operation including the DRAM 5 are generated. A clock generation circuit 4 and a power supply 6 for supplying a drive current for driving the DRAM 5 are provided.

  In the PWM processing for gradation display described above, it is necessary to calculate the on-duty of the micro mirror corresponding to each pixel for each frame of the video signal, write it to the DRAM 5, read it in accordance with the frame frequency, and output it as an image signal. is there. For example, in a high-definition video image having horizontal 1920 pixels, vertical 1080 lines, and a frame frequency of 60 Hz, writing / reading of data in 100 million units is performed per second. Therefore, by using a high-speed memory with a very high operation clock for the DRAM 5, high-speed data writing / reading that can be applied to image processing is possible. Therefore, it is difficult to monitor the data during high-speed writing / reading as described above, and the image processing unit for the DMD element itself is often customized, and the data being written / read-out is sampled. To do so has become virtually difficult.

  On the other hand, power is supplied from the power source 6 to the DRAM 5 as a matter of course, but the measurement of the power source current can be easily performed for the customized image processing unit. Therefore, in the present embodiment, a shunt resistor (not shown) is connected in series between the power source 6 and the DRAM 5 and the power source current of the DRAM 5 is measured by measuring the voltage of the shunt resistor. Thereby, the current detection circuit 7 can always monitor the power supply current of the DRAM 5 which is an image processing memory. Note that the current measurement need not be limited to the method of connecting in series between the power source 6 and the DRAM 5, and may be performed by measuring the magnetic lines of force of the wiring.

  The image processing memory malfunction detection device 10 is preliminarily determined as a current detection circuit 7 that is a power supply current measuring unit that measures the power supply current of the DRAM 5 that is the above-described image processing memory, and a power supply current range during normal operation of the DRAM 5. The memory 9 that is a normal current range holding unit that holds the range of the supplied power current is compared with the measured power supply current and the normal current range held by the memory 9 so that the measured power supply current is within the normal current range. And a failure determination unit 8 which is a determination unit for determining whether or not it is detached.

Next, the operation will be described.
FIG. 2 is a diagram showing the operation of the image signal processing memory malfunction detection device 10 and the image signal processing memory malfunction detection method in the image display device 100. The power source of the DRAM 5 when the image display device 100 displays an image. The time change of the electric current and the comparison output in the failure determination part 8 is shown. In the figure, the vertical axis in the upper part indicates the power supply current of the DRAM 5, the vertical axis in the lower part indicates the comparison output L in the circuit of the failure determination unit 8, and the horizontal axis indicates time in common in the upper and lower parts. As shown in FIG. 2, the power supply current of the DRAM 5 changes with time due to changes in video signals and the like. In the present embodiment, for the comparison output L in the circuit of the lower-stage failure determination unit 8, the malfunction state is set to high level and the normal state is set to low level. In FIG. 2, for simplification, an unstable portion immediately after the apparatus is started is omitted, and a change in the power supply current from a state where the operation is stable is shown. In FIG. 2, Iopmax indicates the maximum power supply current of the DRAM 5 including temperature characteristics (dependence on the temperature condition of operation), and Iopmin indicates the minimum power supply current of the DRAM 5 including temperature characteristics. Normally, when a fine image or an all-white signal is input as a video signal, the power supply current of the DRAM 5 is close to the maximum, and thus a value close to Iopmax is displayed. Show.

  In the normal operation state, the power supply current of the DRAM 5 changes between Iopmin and Iopmax. For example, when the signal of the clock generation circuit 4 is temporarily interrupted or an error occurs in the control command of the DRAM 5, the DRAM 5 is in the standby state. Alternatively, the power saving mode may be entered, and a value Imin lower than the normal operating current consumption may be indicated. Even when this malfunction occurs, the DMD control circuit 3 cannot recognize the malfunction unless there is a signal from the image signal processing memory malfunction detection device 10.

  In the first embodiment of the present invention, in order to detect this malfunction, a threshold value IthL is set in advance between the minimum value Iopmin of the normal operation current of the DRAM 5 and the Imin in the malfunction state, and the power supply current during the normal operation of the DRAM 5 is set. Is stored in the memory 9 as a lower limit value. The failure determination unit 8 which is a determination unit compares the output signal of the current detection circuit 7 with the lower limit value IthL held in the memory 9, determines whether the power supply current of the DRAM 5 is smaller than the lower limit value IthL, Based on the result, it is determined whether the DRAM 5 is in a malfunctioning state or a normal operation state. That is, the image processing memory malfunction detection device 10 determines that the DRAM 5 has failed when the power supply current of the DRAM 5 deviates from the predetermined normal current range. In FIG. 2, at the timing TaL when the value of the power supply current of the DRAM 5 falls below IthL, the failure determination unit 8 detects that the DRAM 5 malfunctions because the comparison output L in the circuit changes to the high level.

  When the comparison output L in the circuit changes to a high level, the failure determination unit 8 instructs the DMD control circuit 3 to reset by means of serial communication such as I2C. In response to this instruction, the DMD control circuit 3 executes initialization processing of the DRAM 5 and shifts the DRAM 5 which is a malfunctioning image processing memory to a normal operation state.

  Also, depending on the type of memory, when a malfunction occurs, the power supply current may become larger than the normal state. FIG. 3 is also a diagram showing the operation of the image signal processing memory malfunction detection device 10 and the image signal processing memory malfunction detection method in the image display apparatus 100 as in FIG. 2, and displaying an image by the image display apparatus 100. 6 shows the time variation of the power supply current of the DRAM 5 and the comparison output H in the failure determination unit 8 at that time. In the figure, Imax indicates a current at the time of malfunction. In this case, in order to determine a malfunction, the threshold current IthH may be set between the maximum value Iopmax of the normal consumption current and the current Imax at the time of malfunction and held in the memory 9. The level of the malfunction state may be set in the arithmetic circuit 7. In this embodiment, the malfunction state is the high level and the normal state is the low level. The return sequence after malfunction detection (TaH) is the same as in the case of TaL that has become high level by IthL.

  Note that, when the power supply current is lower than IthL and when it is higher than IthH, when the countermeasure for returning the DRAM 5 is different, the subsequent processing may be changed depending on which one detects the failure.

  2 and 3 separately show changes in the power supply current of the DRAM 5, and changes in the in-circuit comparison output H and in-circuit comparison output L, it goes without saying that both may be monitored simultaneously. In that case, when the power supply current of the DRAM 5 is out of the normal current range defined by the lower limit value IthL and the upper limit value IthH, the failure determination unit 8 changes the in-circuit comparison output L or the in-circuit comparison output H to a high level. It can be determined that the DRAM 5 that is the processing memory has failed.

  As described above, according to the image processing memory malfunction detection device 10 according to the first embodiment of the present invention, the power supply current measuring unit 7 that measures the power supply current of the DRAM 5 that is the image processing memory, and the image processing memory. A memory 9 that is a current range holding unit that holds a predetermined power supply current range (IthL to IthH) as a power supply current during normal operation of the DRAM 5, and the measured power supply current and the current held in the memory 9 A failure determination unit 8 that is a determination unit that compares the range (IthL to IthH) and determines whether or not the measured power supply current is out of the normal current range (IthL to IthH). Therefore, even if the data being written / read by the DRAM 5 is monitored or the DMD control circuit 3 itself cannot determine the malfunction, It is possible to detect the operation. Then, by performing processing based on the detection result, the image processing apparatus 20 can be restarted and image display can be performed appropriately.

  In addition, according to the image processing memory malfunction detection method 10 according to the first embodiment of the present invention, the power source current measuring step for measuring the power source current of the DRAM 5 that is the image processing memory, and the DRAM 5 that is the image processing memory. A current range holding step for holding a predetermined power supply current range (IthL to IthH) as a power supply current during normal operation, and a measured power supply current and a current range (IthL to IthH) held in the memory 9 In comparison, the determination step for determining whether or not the measured power supply current is out of the current range (IthL to IthH) is provided, so that the data on which the DRAM 5 is performing the write / read process is monitored. Even if the DMD control circuit 3 itself cannot determine the malfunction, the malfunction of the DRAM 5 can be reliably detected.Then, by performing processing based on the detection result, the image processing apparatus 20 can be restarted and image display can be performed appropriately.

  In particular, the image processing memory malfunction detection device 10 uses a DMD element 30 as a light modulation element, which requires PWM control for gradation display, requires high-speed image data reading / writing, and is difficult to monitor image data. Since the present invention is applied to the image display device 100, the malfunction of the DRAM 5 can be reliably detected even if the data written / read in the DRAM 5 is not monitored or the DMD control circuit 3 itself cannot determine the malfunction.

  Therefore, even if the DRAM 5 is incorporated in the image processing unit 20 in advance and sampling of the image data is difficult, if the power supply current of the DRAM 5 is measured, the image processing memory malfunction detection device 10 reliably detects the malfunction of the DRAM 5. can do.

  In the first embodiment, the case where the power supply current threshold value IthL or IthH is stored in advance in the memory 9 has been described. However, the power supply current of the DRAM 5 may vary depending on the environmental temperature or the variation of the DRAM 5 itself. . Therefore, there is a case where it is desired to correct the threshold according to the environmental temperature and individual variations. In this case, for the lower limit value IthL, the power supply current Iopmin in the all black state is measured, and a value slightly lower than Iopmin may be set as IthL depending on the accuracy of the current detection circuit, or may be set individually. . For the upper limit value IthH, the power supply current Iopmax at the time of high-frequency data such as all white state or gathers is measured, and a value slightly higher than Iopmax is set as IthH according to the accuracy of the current detection circuit, or individually May be set.

  Furthermore, it is assumed that the operating current of the DRAM 5 changes due to secular change or the like. In this case, the control may be performed so that the power supply currents Iopmin and Iopmax in the all black state and the all white state are periodically measured to update the threshold values IthL and IthH.

  The communication between the failure determination unit 8 and the DMD control circuit 3 is serial communication such as I2C. However, the communication method is not limited to this, and a method according to the method of the DMD control circuit 3 such as a parallel method is used. Should be taken.

  In the first embodiment, the example in which the image processing memory malfunction detection device 10 is used for the DRAM 5 for writing / reading the image signal for controlling the DMD element 30 as the light modulation element has been described. The present invention can be applied even when liquid crystal is used as the light modulation element. Even if no light modulation element is used, an image processing memory that is required to write / read image signals at high speed can be effective even when the light modulation element is not used. Not too long. The image processing memory may be a memory other than DRAM.

Embodiment 2. FIG.
In the second embodiment, the power supply current of the DRAM 5 that is the image processing memory is measured by measuring the temperature difference from the ambient temperature of the DRAM 5 that varies with the power supply current. This is because the DRAM 5 itself generates heat due to the power supply current supplied to the DRAM 5, thereby causing a temperature difference with respect to the ambient temperature (environment temperature), and the temperature difference increases in proportion to the power supply current flowing through the DRAM 5. This is because the power supply current is measured instead of directly measuring the power supply current by measuring the temperature difference. Details will be described below.

  FIG. 4 is a block diagram of an image display apparatus according to the second embodiment of the present invention. In the figure, the same reference numerals as those in the first embodiment are the same as those in the first embodiment. In the second embodiment, instead of the current detection unit 7 in the first embodiment, a temperature difference detection unit 17 that detects a temperature difference from the ambient temperature of the DRAM 5 is provided, and the failure determination unit 18 includes a memory 9 The failure difference of the DRAM 5 is detected by comparing the temperature difference range held by the temperature difference of the DRAM 5 detected by the temperature difference output unit 17. The temperature difference detection unit 17 includes a memory temperature measurement unit 17A that measures the temperature of the DRAM 5 and an ambient temperature measurement unit 17B that measures the ambient temperature. The failure determination unit 18 outputs the DRAM 5 output from the memory temperature measurement unit 17A. The temperature difference between the ambient temperature of the DRAM 5 is detected from the signal indicating the ambient temperature and the signal indicating the ambient temperature output from the ambient temperature measuring unit 17B. Therefore, part of the failure determination unit 8 also functions as a temperature difference detection unit.

  In the figure, the memory temperature measuring unit 17A is arranged close to or in contact with the DRAM 5, and detects a change in the operating temperature of the DRAM 5 due to the power supply current flowing through the DRAM 5. Further, the ambient temperature measurement unit 17B measures the temperature in the casing of the image processing unit 20 or the ambient temperature as the ambient temperature Ta. This is used to correct the operating temperature when the ambient temperature Ta changes even if the power supply current flowing through the DRAM 5 does not change, because the operating temperature also changes accordingly. By subtracting the output of the ambient temperature measurement unit 17B from the output of the normal memory temperature measurement unit 17A, it is possible to detect the temperature difference ΔT due to the temperature rise of the DRAM 5. These calculations are performed in the failure determination unit 18 as described above. The range of the temperature difference from the ambient temperature Ta of the DRAM 5 when the DRAM 5 is operating normally (during normal operation) is ΔTopmin to ΔTopmax, and the ambient temperature Ta of the DRAM 5 when a malfunction (low current side) occurs in the DRAM 5 Is set to ΔTmin (corresponding to Imin), a threshold value ΔTthL serving as a lower limit value of the temperature difference at the time of malfunction is set in the memory 9 between ΔTmin and ΔTopmin. Further, if the temperature difference from the ambient temperature Ta of the DRAM 5 when a malfunction (high current side) occurs in the DRAM 5 is ΔTmax (corresponding to Imax), an upper limit value of the temperature difference at the time of malfunction between ΔTmax and ΔTopmax Is set in the memory 9.

  FIG. 5 is a diagram showing the operation of the image signal processing memory malfunction detection device 210 and the image signal processing memory malfunction detection method in the image display device 200. The periphery of the DRAM 5 when the image display device 200 displays an image. The temperature difference ΔT with respect to the temperature and the time change of the comparison output in the failure determination unit 18 are shown. In the figure, the vertical axis of the upper stage indicates a temperature difference ΔT with respect to the ambient temperature Ta of the DRAM 5, the vertical axis of the lower stage indicates a comparison output L in the circuit of the failure determination unit 18, and the horizontal axis indicates time common to the upper and lower sides. ing. As shown in FIG. 5, the temperature difference ΔT (the difference between the operating temperature of the DRAM 5 measured by the memory temperature measuring unit 17A and the ambient temperature) from the ambient temperature Ta (measured by the ambient temperature measuring unit 17B) of the DRAM 5 is a video signal or the like. Changes with time due to changes in. Also in the present embodiment, as for the comparison output L in the circuit of the failure determination unit 18 in the lower stage, the malfunction state is set to high level and the normal state is set to low level. In FIG. 5, the operating temperature and the ambient temperature Ta are both stable by omitting a portion where the temperature of the DRAM 5 itself and the temperature of the housing of the image processing unit 20 that becomes the ambient temperature Ta change immediately after the image display device 200 is started. A change in the temperature difference ΔT from a state where the temperature difference ΔT is constant is shown.

  The failure determination unit 18 compares the temperature difference ΔT calculated from the output signals of the memory temperature measurement unit 17A and the ambient temperature measurement unit 17B with the lower limit value ΔTthL held in the memory 9, and the temperature difference ΔT from the ambient temperature of the DRAM 5 Is smaller than the lower limit ΔTthL, it is determined whether the DRAM 5 is in a malfunctioning state or a normal operation state. That is, if the temperature difference ΔT of the DRAM 5 deviates from the normal temperature difference range, it is determined that the DRAM 5 has failed. In FIG. 5, at the timing TaL when the value of the temperature difference ΔT with respect to the ambient temperature of the DRAM 5 falls below ΔTthL, the failure determination unit 18 detects that the comparison output L in the circuit changes to a high level and the DRAM 5 malfunctions. To do.

  As described above, by measuring the temperature difference instead of the current, if the temperature difference ΔT with respect to the ambient temperature Ta of the DRAM 5 falls below the lower limit value ΔTthL set in the memory 9, it can be detected as a malfunction of the DRAM 5. is there. When a malfunction is detected, as in the first embodiment, the DMD control circuit 3 is instructed to reset the DMD control circuit 3 by means of serial communication such as I2C. In response to this command, the DMD control circuit 3 executes initialization processing of the DRAM 5 which is an image processing memory, and shifts the malfunctioning DRAM 5 to a normal operation state.

  However, since a change in temperature difference causes a time difference from a change in power supply current due to a heat transfer path between the heat generation part and the temperature measurement part in the DRAM 5, a dead period is set in the failure determination unit 18, for example, for a few seconds after startup. Does not determine that there is a failure even if the temperature difference ΔT is zero.

  FIG. 5 shows an example in which it is determined whether or not the DRAM 5 has failed depending on whether or not the temperature difference ΔT is lower than the lower limit value ΔTthL. However, as in the first embodiment, the upper limit value ΔTthH of the temperature difference ΔT is Needless to say, it can be determined whether or not the DRAM 5 is out of order based on whether or not it exceeds the threshold. That is, the failure determination unit 18 determines that the DRAM 5 is defective when the temperature difference ΔT with respect to the ambient temperature of the DRAM 5 is out of the normal temperature difference range. However, although the difference between the temperature of the DRAM 5 and the ambient temperature is used in the second embodiment, there is a temperature variation when the difference from the ambient temperature is observed because there is a local temperature rise when the device is started up. There is sex. In this case, a dead period during which failure determination is not performed may be provided for a certain period after the device is started up.

  As described above, according to the image processing memory malfunction detection device 210 according to the second embodiment, the temperature difference measuring unit 17 that measures the temperature difference ΔT with respect to the ambient temperature Ta of the DRAM 5 that is the image processing memory, A memory 9 that is a temperature difference range holding unit that holds a predetermined temperature difference ΔT range (ΔTthL to ΔTthH) as a temperature range during normal operation of the DRAM 5, and the measured temperature difference ΔT and temperature difference range (ΔTthL to ΔTthH) ) And a failure determination unit 18 that is a determination unit that determines whether or not the measured temperature difference ΔT is out of the temperature difference range (ΔTthL to ΔTthH). A malfunction of the DRAM 5 can be detected without monitoring the data that is being written / read. Then, by performing processing based on the detection result, the image processing apparatus 20 can be restarted and image display can be performed appropriately.

  Further, according to the image processing memory malfunction detection method according to the second embodiment, the temperature difference measuring step for measuring the temperature difference ΔT with respect to the ambient temperature Ta of the DRAM 5 as the image processing memory, and the normal operation of the DRAM 5 A temperature difference range holding step for holding a predetermined temperature difference ΔT range (ΔTthL to ΔTthH) as a temperature range was compared with the measured temperature difference ΔT and the temperature difference range (ΔTthL to ΔTthH). A determination step for determining whether or not the temperature difference ΔT is out of the temperature difference range (ΔTthL to ΔTthH), so that the DRAM 5 does not have to monitor the data that is being written / read. Thus, malfunction of the DRAM 5 can be detected. Then, by performing processing based on the detection result, the image processing apparatus 20 can be restarted and image display can be performed appropriately.

  That is, since the malfunction of the DRAM 5 is detected by measuring the temperature difference Δ with the ambient temperature Ta accompanying the change in the power supply current, the DMD control circuit 3 itself cannot recognize the malfunction as in the first embodiment. Even in such a case, malfunction can be detected, and even when the power supply current of the DRAM 5 cannot be measured, malfunction of the DRAM 5 can be detected and restarted.

  Also in the second embodiment, the temperature difference threshold values ΔTthL and ΔTthH are stored in the memory 9 in advance. However, the threshold values may be corrected in consideration of variations in characteristics of the DRAM 5 and changes over time. For example, for ΔTthL which is the lower limit value, the temperature difference ΔTopmin in the all black state is measured, and a value slightly lower than ΔTopmin is set as ΔTthL according to the accuracy of the temperature difference detection unit 17 or may be set individually. Good. For ΔTthH, which is the upper limit value, the power supply current ΔTopmax at the time of high-frequency data such as an all white state or gathers is measured, and a value slightly higher than ΔTopmax is set as ΔTthH according to the accuracy of the temperature difference detection unit 17, or , May be set individually.

  The communication between the failure determination unit 18 and the DMD control circuit 3 is serial communication such as I2C. However, the communication method is not limited to this, and a method according to the DMD control circuit method such as a parallel method is used. Take it.

It is a block diagram which shows the structure of the image display apparatus concerning Embodiment 1 of this invention. It is a figure which shows the operation | movement of the image signal processing memory malfunction detection apparatus and the image signal processing memory malfunction detection method in the image display apparatus concerning Embodiment 1 of this invention. It is a figure which shows the operation | movement of the image signal processing memory malfunction detection apparatus and the image signal processing memory malfunction detection method in the image display apparatus concerning Embodiment 1 of this invention. It is a block diagram which shows the structure of the image display apparatus concerning Embodiment 2 of this invention. It is a figure which shows the operation | movement of the memory malfunction detection apparatus for image signal processing in the image display apparatus concerning Embodiment 2 of this invention, and the memory malfunction detection method for image signal processing.

DESCRIPTION OF SYMBOLS 1 Video input terminal, 2 Video signal processing circuit, 3 DMD control circuit, 4 Clock generation circuit, 5 DRAM (memory for image processing), 6 Power supply, 7 Current detection part (power supply current measurement part), 8,18 Failure determination part (Determination unit), 9 memory (current range holding unit, temperature difference range holding unit), 10,210 image signal processing memory malfunction detection device, 17 temperature difference measuring unit, 17A memory temperature measuring unit, 17B ambient temperature measuring unit,
20 image processing unit, 30 DMD element (light modulation element), 100,200 image display device

Claims (6)

An apparatus for detecting a malfunction of an image processing memory for writing / reading an image signal,
A temperature difference measuring unit for measuring a temperature difference with an ambient temperature of the image processing memory;
A temperature difference range holding unit for holding a predetermined temperature difference range of the image processing memory;
A determination unit that compares the measured temperature difference with the temperature difference range and determines whether the measured temperature difference is out of the temperature difference range; and
An image processing memory malfunction detection device comprising: 2. The image processing memory malfunction according to claim 1, wherein the lower limit value of the temperature difference range is corrected based on a temperature difference when an image signal indicating an all-black state is input to the image processing memory. Detection device. 2. The image processing memory malfunction according to claim 1, wherein the upper limit value of the temperature difference range is corrected based on a temperature difference when an image signal indicating an all white state is input to the image processing memory. Detection device. A light modulation element that converts light incident from a light source into image light;
An image signal processing unit for outputting an image signal for controlling the light modulation element;
The image processing memory malfunction detection device according to any one of claims 1 to 3, wherein a malfunction of an image processing memory for writing / reading the image signal is detected in the image signal processing unit,
An image display device comprising: The image display device according to claim 4, wherein the light modulation element includes a DMD element. A method of detecting a malfunction of an image processing memory for writing / reading an image signal,
A temperature difference measuring step for measuring a temperature difference with an ambient temperature of the image processing memory;
A temperature difference range holding step for holding a predetermined temperature difference range of the image processing memory;
A determination step of comparing the measured temperature difference with the temperature difference range to determine whether the measured temperature difference is out of the temperature difference range;
An image processing memory malfunction detection method comprising:

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