JP2012242419A - Multi-screen display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-screen display capable of keeping uniformity of brightness, chromaticity and white balance, while suppressing excessive rise in temperature of light sources.SOLUTION: Each of multiple unit displays 101 forming a multi-screen display 100 includes: temperature sensors 13 for measuring temperature of respective LEDs 12 of light source parts 1R, 1G, 1B; current control circuits 11 for controlling current made flow to the respective LEDs 12 on the basis of a common setting value shared by the multiple unit displays 101; and a color conversion circuit 7a for performing color adjustment by matrix arithmetic using a matrix set according to the common setting value. A control processing part of the multi-screen display 100 monitors the temperature of the respective LEDs 12 measured by the temperature sensors 13 and adjusts the common setting value so that the temperature does not exceed the highest allowable temperature.

Description

  The present invention relates to a multi-screen display device including a plurality of image display devices, and more particularly to temperature control of a light source.

  Various multi-screen display devices that realize a large screen by arranging the screens of a plurality of image display devices side by side have been proposed. Hereinafter, each of the plurality of image display devices constituting the multi-screen display device is referred to as a “unit display device”, and the entire screen of the multi-screen display device including the screens of the plurality of unit display devices is referred to as “multi-large screen”. Call it.

  In a multi-screen display device using a projection type unit display device, in recent years, a light source of a light emitting diode (Light Emitting Diode: hereinafter referred to as “LED”) is being used instead of a conventional lamp light source. In general, LEDs have a longer lifetime than lamps, but it has been found that the lifetime of LEDs is greatly affected by temperature. Since the temperature of the LED depends on the current flowing through the LED, the cooling conditions, etc. in addition to the temperature of the use environment, the actual life may be significantly different from the nominal life (expected value of the life under a predetermined condition). For this reason, in a display device using an LED light source, it is important to appropriately manage the temperature of the LED light source.

  Therefore, in a projection display device using an LED light source, a technique for controlling the light emission amount of the LED light source based on the temperature of the LED light source is proposed so that the temperature of the LED light source does not exceed a predetermined value (for example, the following). Patent Document 1). In Patent Document 1, the light emission amount and the heat generation amount of the LED light source are controlled by changing the duty ratio of the drive pulse of the LED light source in accordance with the temperature of the LED light source. Patent Document 2 discloses a technique for performing color correction of an image by performing color conversion by an operation using a 3 × 3 matrix (3 × 3 matrix operation) on an input video signal. Yes.

JP 2005-274484 A JP 2002-116750 A

  When a multi-screen display device is configured using a unit display device in which the light emission amount of the LED light source varies according to temperature as in Patent Document 1, the light emission amount of the LED light source is individually controlled in each unit display device. There is a possibility that the brightness of the screen varies for each display device, and the brightness of the multi-large screen may not be uniform. Further, in each unit display device, for example, when the light emission amounts of the red (R), green (G), and blue (B) LED light sources are individually controlled, the white balance also varies from unit display device to unit display device. . Also, the LED light source varies in luminance and chromaticity due to variations in device manufacturing and current flowing. Therefore, the uniformity of the brightness, chromaticity and white balance of the multi-large screen is not maintained, causing a problem that the display quality is deteriorated.

  The present invention has been made to solve the above-described problems, and is capable of maintaining the uniformity of luminance, chromaticity, and white balance while suppressing an excessive increase in the temperature of the light source. An object is to provide an apparatus.

  The multi-screen display device according to the present invention is a multi-screen display device including a plurality of unit display devices that display an image based on a video signal using a light source, and each of the plurality of unit display devices includes the light source. Using a temperature sensor that measures temperature, a current control circuit that controls a current that flows to the light source based on a common setting value shared by the plurality of unit display devices, and a matrix that is determined based on the common setting value A color conversion circuit that performs color conversion of the video signal by matrix calculation, and the multi-screen display device monitors the temperature of the light source measured by the temperature sensor of the plurality of unit display devices, A control processing unit configured to adjust the common setting value so that a temperature of the light source does not exceed a predetermined first threshold, and the common setting value is selected by selecting one of a plurality of predetermined values; Merare, the matrix is in each value of the common setting value, the brightness of a plurality of unit display devices, in which the chromaticity and white balance is set to be the same.

  According to the present invention, since the temperature of the light source is controlled so as not to exceed a predetermined value, the life of the light source is prevented from being shortened. Further, since the current of the light source of each unit display device is adjusted using a common setting value shared by the plurality of unit display devices, it is possible to prevent the current of the light source from being individually adjusted in each unit display device. Further, in each of the unit display devices, a matrix used for matrix calculation performed by the color conversion circuit is also determined based on the common setting value, and the matrix has the same brightness, chromaticity, and white balance of the plurality of unit display devices. Is set to be Therefore, in the multi-screen display device of the present invention, the brightness, chromaticity, and white balance of each unit display device change in the same manner while the plateau temperature control is performed. ) Uniformity of brightness, chromaticity and white balance.

It is a figure which shows an example of a structure of the multi-screen display apparatus which concerns on this invention. It is a schematic block diagram of the unit display apparatus which concerns on this invention. It is a schematic block diagram of the light source part of the unit display apparatus which concerns on this invention. It is a flowchart which shows operation | movement of the multi-screen display apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the multi-screen display apparatus which concerns on Embodiment 2 of this invention.

<Embodiment 1>
FIG. 1 is a diagram illustrating a configuration example of a multi-screen display device 100 according to Embodiment 1 of the present invention. Since the screen (multi-large screen) of the multi-screen display device 100 is configured by arranging the screens of the plurality of unit display devices 101, a larger display can be obtained.

  For example, the multi-screen display device 100 illustrated in FIG. 1 includes first to fourth unit display devices 101 [1] to 101 [4]. Here, the first unit display device 101 [1] is a master unit display device that controls the entire operation of the multi-screen display device 100, and the second to fourth unit display devices 101 [2] to 101 [ 4] is a slave image display device controlled by a master unit display device.

  The unit display devices 101 are connected via a communication cable 102. FIG. 1 shows an example in which first to fourth unit display devices 101 [1] to 101 [4] are connected in cascade. The connection configuration of the first to fourth unit display devices 101 [1] to 101 [4] is not limited to the cascade connection. For example, the second to fourth unit display devices 101 [1] (master) are connected to each other. The unit display devices 101 [2] to 101 [4] (slave) may be connected in a star connection, or the first unit display device 101 [1] and the fourth unit display device may be added to the configuration of FIG. A ring connection may be provided in which a communication cable 102 is connected to 101 [4].

  In general, the plurality of unit display devices 101 constituting the multi-screen display device 100 have the same configuration. FIG. 2 is a diagram illustrating a configuration example of the unit display device 101. For example, the first to fourth unit display devices 101 [1] to 101 [4] in FIG. 1 can all have the same configuration as in FIG.

  2 includes a red light source unit 1R, a green light source unit 1G, a blue light source unit 1B, a dichroic mirror unit 2, a DMD (Digital Micromirror Device) 3, a projection lens 4, a screen 5, an image signal input unit 6, An image signal processing unit 7, a control processing unit 8, and a communication unit 9 are provided.

  The dichroic mirror unit 2 includes two dichroic mirrors, and reflects or transmits light output from the red light source unit 1R, the green light source unit 1G, and the blue light source unit 1B, and supplies the light to the DMD 3. Specifically, the red light (R light) output from the red light source unit 1R is reflected by one dichroic mirror and enters the DMD 3, and the blue light (B light) output from the blue light source unit 1B is the other dichroic. The green light (G light) reflected by the mirror and incident on the DMD 3 and output from the green light source unit 1G passes through both dichroic mirrors and enters the DMD 3.

  The image signal input unit 6 supplies a video signal input from the outside to the image signal processing unit 7. The image signal processing unit 7 performs signal processing such as image enlargement / reduction and chromaticity conversion (color conversion) on the input video signal, and performs color conversion processing by 3 × 3 matrix calculation. A color conversion circuit 7a is included. The image signal input unit 6 converts the video signal subjected to the signal processing into a drive signal for driving the DMD 3 and inputs the drive signal to the DMD 3.

  The color conversion circuit 7a of the image signal processing unit 7 performs color conversion by the 3 × 3 matrix operation shown in the following equation (1) on the input video signals Ri, Gi, Bi of each color, and after color conversion Signals Ro, Go, Bo are output.

  Note that the color conversion itself by the 3 × 3 matrix calculation is a technique disclosed in Patent Document 2 described above. The image signal processing unit 7 can also perform the 3 × 3 matrix operation on the video signal such as a test pattern for chromaticity adjustment generated by itself.

  Based on the drive signal from the image signal processing unit 7, the DMD 3 modulates the intensity of light (R light, G light, B light) input via the dichroic mirror unit 2 and outputs it to the projection lens 4. The projection lens 4 projects the light onto the image signal processing unit 7, and as a result, an image is displayed on the screen (screen) 5.

  When the first to fourth unit display devices 101 [1] to 101 [4] in FIG. 1 have the configuration shown in FIG. 2, the screens 5 are arranged side by side as shown in FIG. Composed.

  The control processing unit 8 controls the color conversion processing performed by the color conversion circuit 7a of the image signal processing unit 7, and also controls the operations of the red light source unit 1R, the green light source unit 1G, and the blue light source unit 1B, so that the screen 5 Adjust the brightness, chromaticity and white balance of the image displayed on the screen. The communication unit 9 transmits / receives information to / from another unit display device 101 through the communication cable 102. The control processing unit 8 of the master unit display device 101 (first unit display device 101 [1] in FIG. 1) uses the communication unit 9 to display the slave unit display device 101 (second to fourth in FIG. 1). The control processing unit 8 of the unit display devices 101 [2] to 101 [4]) can be controlled.

  3A to 3C are configuration diagrams of the red light source unit 1R, the green light source unit 1G, and the blue light source unit 1B, respectively. The red light source unit 1R, the green light source unit 1G, and the blue light source unit 1B are similarly configured, and include a current control circuit 11, an LED 12, and a temperature sensor 13, respectively. As a matter of course, the LED 12 of the red light source unit 1R is a “red LED” that generates R light, the LED 12 of the green light source unit 1G is a “green LED” that generates G light, and the LED 12 of the blue light source unit 1B is It is a “blue LED” that generates B light.

In each of the red light source unit 1R, the green light source unit 1G, and the blue light source unit 1B, the current control circuit 11 receives a control signal (current control signal) from the control processing unit 8, and supplies a current having a magnitude corresponding to the control signal to the LED 12. Shed. The control processing unit 8 controls the intensity of light output from each of the red light source unit 1R, the green light source unit 1G, and the blue light source unit 1B by utilizing the fact that the light emission amount of each LED 12 changes according to the current flowing therethrough. Thus, the brightness and white balance of the image displayed on the screen 5 can be adjusted. That is, the control processing unit 8 can increase the luminance by increasing the currents I _R , I _G , and I _B that flow through the LEDs 12 of the red light source unit 1R, the green light source unit 1G, and the blue light source unit 1B, and the currents I _R , I _G , it can be lowered brightness by reducing the I _B.

The temperature sensor 13 measures the temperature of the LED 12 (or the temperature around the LED 12), and transmits a signal indicating the measurement result (measured temperature signal) to the control processing unit 8. The control processing unit 8 uses the currents I _R , I _G , and I _B based on the measured temperature values T _R , T _G , and T _B of the LEDs 12 of the red light source unit 1R, the green light source unit 1G, and the blue light source unit 1B. Thus, the amount of heat generated by each LED 12 can be adjusted. Since the heat generation amount of the LED 12 changes according to the current flowing therethrough, the temperature rise can be suppressed by reducing the currents I _R , I _G , and I _B.

  The temperature sensor 13 may be built in the LED 12 or may be disposed in the vicinity of the LED 12. When the temperature sensor 13 is disposed in the vicinity of the LED 12, it is desirable that the LED 12 and the temperature sensor 13 be coupled with a material having low thermal resistance.

  The luminance, chromaticity, and white balance of the screen 5 of the unit display device 101 (that is, the white image color-converted by the color conversion circuit 7a is displayed with the respective light emission amounts of the red light source unit 1R, the green light source unit 1G, and the blue light source unit 1B Can be individually adjusted. In the multi-screen display device 100 of the present embodiment, a plurality of large-screen brightness, chromaticity, and white balance uniformity are maintained. The unit display device 101 unifies the adjustments. For example, in the example of FIG. 1, the control processing unit 8 of the master first unit display device 101 [1] has the luminance, chromaticity and the first to fourth unit display devices 101 [1] to 101 [4]. Supervises white balance control.

  In the multi-screen display device 100 of the present embodiment, a plurality of unit display devices 101 share a plurality of setting values m related to luminance, chromaticity, and white balance. That is, the setting value m takes a common value in the plurality of unit display devices 101. Hereinafter, this set value m is referred to as a “common set value”. In the present embodiment, M values are prepared as the common setting value m, and one of integers 1 to M can be selected. Further, it is defined that the larger the common set value m, the higher the luminance. That is, the lowest luminance is obtained when m = 1, and the highest luminance is obtained when m = M.

  The user may select the common setting value m, but may automatically set the common setting value m according to the surrounding environment and display video. For example, when the multi-screen display device 100 has an optical sensor and the common setting value m is automatically set according to the ambient brightness, visibility is increased by increasing m by increasing m in a bright environment. In a dark environment, an operation that suppresses power consumption by decreasing m and decreasing luminance is possible. Alternatively, the common setting value m may be automatically changed according to the change of the content displayed on the screen, and the color temperature may be switched according to the content.

Further, in the multi-screen display device 100, the set values i _R , I _R , I _G , and I _B of the red light source unit 1R, the green light source unit 1G, and the blue light source unit 1B of the plurality of unit display devices 101 that are passed through the LEDs 12 are set. i _G, i _B, and the setting value k ₁ to k ₉ of coefficients K ₁ ~K ₉ 9 amino is an element of the 3 × 3 matrix of the formula (1) of the color conversion circuit 7a is used for color conversion, common It is predetermined for each set value m. These preset values i _R , i _G , i _B , and k _{1 to} k ₉ are referred to as “preset values”. The preset values i _R , i _G , i _B , and k _{1 to} k ₉ are set at the time of initial adjustment after the multi-screen display device 100 is installed, for example.

When the multi-screen display device 100 is composed of N unit display devices 101 and M levels of brightness (common setting value m) can be set, preset values i _R [n, m], i _G [n, m] , I _B [n, m], k ₁ [n, m], k ₂ [n, m], k ₃ [n, m], k ₄ [n, m], k ₅ [n, m], k ₆ [n, m], k ₇ [n, m], k ₈ [n, m], k ₉ [n, m] will be determined (n = 1, 2,..., N, m = 1). , 2, ..., M). i _R [n, m], i _G [n, m], i _B [n, m], k ₁ [n, m], k ₂ [n, m], k ₃ [n, m], k ₄ [N, m], k ₅ [n, m], k ₆ [n, m], k ₇ [n, m], k ₈ [n, m], k ₉ [n, m] are unit display devices The preset values i _R , i _G , i _B , k _{1 to} k ₉ corresponding to the common set value m in 101 [n] are represented. That is, in the multi-screen display device 100, M × N × 12 preset values are defined.

Preset values i _R [n, m], i _G [n, m], i _B [n, m], k ₁ [n, m], k ₂ [n, m], k ₃ [n, m], k ₄ [n, m], k ₅ [n, m], k ₆ [n, m], k ₇ [n, m], k ₈ [n, m], k ₉ [n, m] The screen display device 100 itself may hold it, or it may be held in an external storage device (for example, a hard disk of a computer connected to the multi-screen display device 100).

The preset values i _R [n, m], i _G [n, m], i _B [n, m], k ₁ [n, m], k ₂ [n, m], k ₃ [N, m], k ₄ [n, m], k ₅ [n, m], k ₆ [n, m], k ₇ [n, m], k ₈ [n, m], k ₉ [n , M], the master unit display device 101 may have holding means (such as a memory) that collectively holds preset values of all unit display devices 101, or individual unit display devices 101. May have its own preset value holding means (for example, the holding means of the first unit display device 101 [1] has preset values i _R [1, m], i _G [1, m], i _B [1, m], k ₁ [1, m], k ₂ [1, m], k ₃ [1, m], k ₄ [1, m], k ₅ [1, m], k ₆ [ _{1, m], k 7 [} 1, m], k 8 _{1, m], k 9 [} 1, m] only is held).

In the multi-screen display device 100 of FIG. 1, for example, preset values i _R [n, m], i _G [n] are stored in the memory (holding means) of the control processing unit 8 of the first unit display device 101 [1] (master). , M], i _B [n, m], k ₁ [n, m], k ₂ [n, m], k ₃ [n, m], k ₄ [n, m], k ₅ [n, m ], K ₆ [n, m], k ₇ [n, m], k ₈ [n, m], k ₉ [n, m] (n = 1, 2,..., N, m = 1, 2, .., M) is held, the first unit display device 101 [1] is connected to the second to fourth unit display devices 101 [2] to 101 through the communication unit 9 and the communication cable 102. [4] To each of the slaves, the required preset values i _R [n, m], i _G [n, m], i _B [n, m], k ₁ [n, m], k ₂ [N, m], k ₃ [n, m], k ₄ [n, m], k ₅ [n, m], k ₆ [n, m], k ₇ [n, m], k ₈ [n, m], k ₉ [n, m] are transmitted.

Further, for example, preset values i _R [n, m], i _G [n, m], i _B [n, m], k ₁ [n, m], k ₂ [n] of the multi-screen display device 100 of FIG. , M], k ₃ [n, m], k ₄ [n, m], k ₅ [n, m], k ₆ [n, m], k ₇ [n, m], k ₈ [n, m ], K ₉ [n, m] are stored in an external storage device (not shown), each of the first to fourth unit display devices 101 [1] to 101 [4] uses the communication unit 9. Necessary preset values i _R [n, m], i _G [n, m], i _B [n, m], k ₁ [n, m], k ₂ [n, m], k ₃ from the storage device. [N, m], k ₄ [n, m], k ₅ [n, m], k ₆ [n, m], k ₇ [n, m], k ₈ [n, m], k ₉ [n , M] may be received, and the first unit display device 101 [1] (master) is typically described. Preset values i _R from the device _{[n, m], i G} [n, m], i B [n, m], k 1 [n, m], k 2 [n, m], k 3 [n, m ], K ₄ [n, m], k ₅ [n, m], k ₆ [n, m], k ₇ [n, m], k ₈ [n, m], k ₉ [n, m] It may be received and transferred to the unit display devices 101 [2] to 101 [4] (slave).

The control processing unit 8 of the unit display device 101 [n] controls the current control circuit 11 of each of the red light source unit 1R, the green light source unit 1G, and the blue light source unit 1B, and the LED 12 of the red light source unit 1R (hereinafter “red LED”). ") the current value I _R [n] of the current value of the green light source unit 1G LED 12 (hereinafter" current I _G of the green LED ") [n], the blue light source unit 1B LED 12 (hereinafter" blue LED ") I _B [n] is set to preset values i _R [n, m], i _G [n, m], i _B [n, m] corresponding to the common set value m, respectively. The control processing unit 8 of the unit display device 101 [n] further controls the image signal processing unit 7 and nine coefficients K ₁ used for 3 × 3 matrix calculation (Equation (1)) performed by the color conversion circuit 7a. [N], K ₂ [n], K ₃ [n], K ₄ [n], K ₅ [n], K ₆ [n], K ₇ [n], K ₈ [n], K ₉ [n ] Are preset values k ₁ [n, m], k ₂ [n, m], k ₃ [n, m], k ₄ [n, m], k ₅ [n, m], k ₆ [n, m], k ₇ [n, m], k ₈ [n, m], k ₉ [n, m].

Preset values i _R [n, m], i _G [n, m], i _B [n, m], k ₁ [n, m], k ₂ [n, m], k ₃ [n, m], k ₄ [n, m], k ₅ [n, m], k ₆ [n, m], k ₇ [n, m], k ₈ [n, m], k ₉ [n, m] is m Are set in advance so that the same luminance, chromaticity and white balance can be obtained in all the unit display devices 101. Since the common setting value m is shared by all the unit display devices 101, the luminance, chromaticity, and white balance are adjusted by individually adjusting the light source current and the nine coefficients of the 3 × 3 matrix calculation in each unit display device 101. It is possible to prevent variation.

  That is, in the multi-screen display device 100 of the present embodiment, when the value of the common setting value m is changed, the luminance, chromaticity, and white balance are similarly changed in all the unit display devices 101. Therefore, by adjusting the common setting value m, it is possible to instantaneously switch the brightness, chromaticity and white balance while maintaining uniform brightness, chromaticity and white balance of the entire multi-large screen.

  Furthermore, the multi-screen display device 100 of this embodiment has a function of monitoring the temperature of the light source (LED) of each unit display device 101 and preventing the temperature from rising excessively. Hereinafter, temperature control of the multi-screen display device 100 of the present embodiment will be described.

As described above, the temperature of the LED depends on the temperature of the use environment, the current of the LED, the cooling conditions, and the like, and is not directly related to the chromaticity or white balance of an image displayed using the LED. That is, the nine coefficients K _{1 to} K ₉ of the 3 × 3 matrix calculation hardly affect the temperature of the LED. Therefore, the description regarding the coefficients K _{1 to} K ₉ is omitted here. However, while this temperature control is performed, the color conversion circuit 7a of the unit display devices 101 [1] to 101 [n] has the common set value m and the preset values k ₁ [n, m] to k ₉ [n, The coefficients K ₁ [n] to K ₉ [n] are set in parallel using m]. As long as the coefficients K ₁ [n] to K ₉ [n] are set based on the common setting value m, the above-described effect that the brightness, chromaticity, and white balance of the entire multi-large screen can be maintained uniformly continues. can get.

  FIG. 4 is a flowchart showing the temperature control operation in the multi-screen display device 100. The operation of the multi-screen display device 100 is centrally controlled by the control processing unit 8 of the master unit display device 101 among the plurality of unit display devices 101.

As a premise, the multi-screen display device 100 is composed of N unit display devices 101 [1] to 101 [N], and the common setting value m can be set in M stages. Further, the preset value i _R [n, m], i _G [n, m], i _B [n, m] (n = 1, n) is already stored in the multi-screen display device 100 (or the external storage device). 2,..., N, m = 1, 2,. Further, it is defined that the luminance of the multi-screen display device 100 increases as the common setting value m increases. That is, the current flowing through each LED increases as the value of m increases. For the sake of simplicity, it is assumed that the unit display device 101 [1] is a master and the other unit display devices 101 [2] to 101 [N] are slaves.

After the power is turned on, the common set value m is set to a predetermined initial value M _SEL (M _SEL is an integer of 1 ≦ M _SEL ≦ M) (S1). The value of M _SEL may be arbitrary, but here is assumed to be a value arbitrarily selected by the user (user set value). The value of the common setting value m is notified to all of the unit display devices 101 [1] to 101 [N] constituting the multi-screen display device 100 (S2).

Based on the latest common set value m, the control processing unit 8 of each unit display device 101 [n] has a red LED current value I _R [n], a green LED current value I _G [n], and a blue LED current value. The current value I _B [n] is set (updated) to preset values i _R [n, m], i _G [n, m], i _B [n, m], respectively (S3).

The control processing unit 8 of the master unit display device 101 [1] waits for a time long enough for the temperature of each LED to stabilize (S4), and then each of the unit display devices 101 [1] to 101 [N]. The temperature measurement value T _R [n] of the red LED, the temperature measurement value T _G [n] of the green LED, and the temperature measurement value T _B [n] of the blue LED are acquired (S5).

Subsequently, the control processing unit 8 of the master unit display device 101 [1] _performs the maximum value T _{R_MAX} of the temperature measurement value T _R [n] of the red LED and the maximum value T of the temperature measurement value T _G [n] of the green LED. _{G_MAX} , the maximum value T _{B_MAX} of the temperature measurement value T _B [n] of the blue LED is _obtained (S6). And either T _{R_MAX} does not exceed the threshold T1 _R is the maximum allowable temperature of the red LED, a or T _{G_MAX} does not exceed the threshold T1 _G is the maximum allowable temperature of the green LED, the maximum allowable temperature of T _{b_max} blue LED It is determined whether or not the threshold value T1 _B is exceeded (S7).

If any one of T _{R_MAX} , T _{G_MAX} , and T _{B_MAX} exceeds the maximum allowable temperature (first threshold) (“Yes” in step S7), the common set value m is set to 1 (S8), Return to step S2.

If T _{R_MAX} , T _{G_MAX} , and T _{B_MAX} are all equal to or lower than the maximum allowable temperature (“No” in step S7), then the control processing unit 8 of the master unit display device 101 [1] has the common set value m user setting value M _SEL (initial value) is smaller than, and T _{R_MAX,} T _{G_MAX,} T _{b_MAX} determines or lower than respective predetermined threshold _{T2 R, T2 G, T2 B} . The threshold values T2 _R , T2 _G , T2 _B (second threshold values) are temperatures (steady state return temperatures) lower than the above T1 _R , T1 _G , T1 _B (T2 _R <T1 _R , T2 _G < T1 _G , T2 _B <T1 _B ).

As a result, if m is smaller than M _SEL and T _{R_MAX} , T _{G_MAX} , and T _{B_MAX} are lower than the steady state return temperatures (T2 _R , T2 _G , T2 _B ) (“Yes” in step S9), the common setting is made. The value m is incremented by 1 (S10), and the process returns to step S2. In other cases, that is, if m is equal to M _SEL , or if any of T _{R_MAX} , T _{G_MAX} , T _{B_MAX exceeds} the steady state return temperature (T2 _R , T2 _G , T2 _B ) (in step S9 “ No "), without doing anything, return to step S2. Thereafter, the operations of steps S2 to S10 are repeatedly executed.

According to the above operation, the temperature of any of the LEDs (red LED, green LED, and blue LED) of the plurality of unit display devices 101 constituting the multi-screen display device 100 is the maximum allowable temperature (T1 _R , T1 _G , T1 _{If B} ) is exceeded, the common set value m is set to 1. Thereby, the current flowing through each LED becomes the smallest, and the state where the temperature of the LED exceeds the maximum allowable temperature is prevented from continuing. Thereafter, until the temperature of any one of the LEDs reaches the steady state return temperature (T2 _R , T2 _G , T2 _B ), or until the common set value m reaches the user set value M _SEL (that is, the brightness is the user). The common set value m is gradually increased (by 1) until the level set by (1) is reached.

As a result, if the maximum temperature of the LED is commonly set value m in the range of less than the maximum allowable temperature is set to the user set value M _SEL, or, LED in the range of common setting value m does not exceed the user setting value M _SEL The maximum temperature is between the steady state return temperature and the maximum allowable temperature. Therefore, the temperature of the LED is prevented from rising excessively.

While the temperature control is being performed, the color conversion circuits 7a of the unit display devices 101 [1] to 101 [n] have presets corresponding to the common set value m determined by the temperature control operation. The value k ₁ [n, m] to k ₉ [n, m] is automatically set as the coefficients K ₁ [n] to K ₉ [n], and then the color conversion process is performed. Therefore, the above-described effect that the brightness, chromaticity and white balance of the entire multi-large screen can be maintained uniformly can be continuously obtained.

More steady state restoration temperature _{(T2 R, T2 G, T2} B) is close to the maximum allowable temperature _{(T1 R, T1 G, T1} B), it can be a common set value m to a value close to the user set value M _SEL, higher Brightness can be obtained. However, if the steady-state return temperature is too close to the maximum allowable temperature, when the LED temperature exceeds the maximum allowable temperature and the common set value m is set to 1 (S8) and increases by 1 (S10), the LED is again turned on. The operation in which the temperature exceeds the maximum allowable temperature and the common set value m is set to 1 (S8) is repeated, and the luminance may become unstable. In order to prevent this, the difference between the steady-state return temperature and the maximum allowable temperature needs to be secured to some extent and is larger than the LED temperature change amount when the common set value m is changed by 1. It is preferable.

In the present embodiment, the red LED temperature measurement value T _R [n], the green LED temperature measurement value T _G [n], and the blue LED temperature measurement of each of the unit display devices 101 [1] to 101 [N]. Although all the values T _B [n] are detected and the common set value m is adjusted based on the detected value T _B [n], the common set value m is simply calculated based on the temperature measurement value of one of the LEDs. It is good also as a system to adjust.

Further, in the present embodiment, the initial value M _SEL of the common setting value m is set by the user in advance, but when it is not set, for example, M _SEL = M may be set. In this case, the brightness of the multi-screen display device 100 is adjusted to the maximum value in a range where the maximum LED temperature does not exceed the maximum allowable temperature.

  Although FIG. 1 shows an example in which the multi-screen display device 100 includes four unit display devices 101, the present invention can be widely applied to the multi-screen display device 100 configured with two or more unit display devices 101. It is.

  Further, FIG. 2 shows an example in which DMD is used as a device for intensity modulation of light as a configuration of unit display device 101. However, for example, other light valve devices such as a transmissive liquid crystal element and a reflective liquid crystal element may be used. Good. The application of the present invention is not limited to a multi-screen display device using three-color (R, G, B) light sources, and can be applied to a multi-screen display device using one or more light sources. Needless to say, in the case of a multi-screen display device in which only one color light source is used, it is not necessary to consider white balance adjustment.

  The present invention can be applied to a multi-screen display device using a semiconductor light source such as an LED, and is not limited to a semiconductor light source. A multi-screen using a light source whose lifetime and electrical characteristics are affected by temperature. Widely applicable to display devices.

<Embodiment 2>
FIG. 5 is a flowchart for explaining the operation of the multi-screen display device according to the second embodiment. The configurations of the multi-screen display device 100 and the plurality of unit display devices 101 constituting the same are the same as those in the first embodiment.

Also in the present embodiment, it is assumed that the multi-screen display device 100 includes N unit display devices 101 [1] to 101 [N], and the common setting value m corresponding to the luminance can be adjusted in M stages. To do. Further, preset values i _R [n, m], i _G [n, m], i _B [n, m] of the currents flowing to the LEDs of the unit display devices 101 are performed by the color conversion circuit 7 a of the image signal processing unit 7. Preset values of _nine coefficients K _{1 to} K ₉ which are elements of a determinant of 3 × 3 matrix operation, k ₁ [n, m], k ₂ [n, m], k ₃ [n, m], k ₄ [n, m], k ₅ [n, m], k ₆ [n, m], k ₇ [n, m], k ₈ [n, m], k ₉ [n, m], The maximum allowable temperature (T1 _R , T1 _G , T1 _B ), the steady-state return temperature (T2 _R , T2 _G , T2 _B ), etc. are also set in advance as in the first embodiment, and a predetermined location (unit display) Device 101 or an external storage device).

Also in this embodiment, the preset values i _R [n, m], i _G [n, m], i _B [n, m] of the LED current are the smallest when the common set value m is 1, and m It is specified to increase as the value increases. That is, the luminance of the multi-screen display device 100 is lowest when the common setting value m is 1, and is highest when m is M.

The multi-screen display device 100 of the present embodiment is different from the first embodiment in the method of controlling the temperature of the LED, and the other operations are the same. Therefore, the description regarding the setting of the coefficients K _{1 to} K ₉ is omitted here. Similarly to the first embodiment, during the LED temperature control, the color conversion circuit 7a of the unit display devices 101 [1] to 101 [n] uses the common setting value m and the preset value k ₁ [n, The coefficients K ₁ [n] to K ₉ [n] using m] to k ₉ [n, m] are set in parallel. As long as the coefficients K ₁ [n] to K ₉ [n] are set based on the common setting value m, the effect that the brightness, chromaticity, and white balance of the entire multi-large screen can be maintained uniformly can be continuously obtained. .

The operation of the multi-screen display device 100 shown in FIG. 5 is different from the first embodiment (FIG. 4) in that any one of the maximum temperature values (T _{R_MAX} , T _{G_MAX} , T _{B_MAX} ) of each LED is the maximum allowable temperature (T1). The operation in the case (“Yes” in step S7) exceeding _R 1, T1 _G , T1 _B ) is different. That is, in the second embodiment, when any of T _{R_MAX} , T _{G_MAX} , and T _{B_MAX} exceeds the maximum allowable temperature, it is determined whether the common set value m is greater than 1 (S11). (S12), the process returns to step S2.

In the first embodiment, when any of T _{R_MAX} , T _{G_MAX} , and T _{B_MAX} exceeds the maximum allowable temperature, the common setting value m is set to the minimum value 1, so that the luminance drop at that time is large and the display quality is reduced. There is concern about damaging it. In the present embodiment, since the common set value m is decreased by one step, the luminance is prevented from greatly decreasing at a time.

  In the flow of FIG. 5, if step S12 is continuously executed at short intervals, there is a possibility that the decrease in luminance may be conspicuous. However, when m is changed by 1 by increasing the number M of steps of the common set value m. If the amount of change in luminance is reduced or the waiting time in step S4 is increased, the change in luminance becomes gradual, and a steep decrease in luminance can be prevented.

In the multi-screen display device 100 according to the present embodiment, the temperature of any of the LEDs (red LED, green LED, and blue LED) of the plurality of unit display devices 101 is the maximum allowable temperature (T1 _R , T1 _G , T1 _B ). If they exceed the common setting value m, the common setting value m is decreased by one until they become lower than the maximum allowable temperature or until the common setting value m reaches 1. As a result, the current flowing through each LED gradually decreases, preventing the LED temperature from exceeding the maximum allowable temperature.

As a result of the current of each LED being reduced, when the temperature of all LEDs is equal to or lower than the steady state return temperature (T2 _R , T2 _G , T2 _B ), the common set value m is gradually increased (by 1) ( Step S10 in FIG. Thereby, the common set value m is set to a value closer to the initial value M _SEL , and higher luminance can be obtained.

While the temperature control is being performed, the color conversion circuits 7a of the unit display devices 101 [1] to 101 [n] have presets corresponding to the common set value m determined by the temperature control operation. The value k ₁ [n, m] to k ₉ [n, m] is automatically set as the coefficients K ₁ [n] to K ₉ [n], and then the color conversion process is performed. Therefore, the above-described effect that the brightness, chromaticity and white balance of the entire multi-large screen can be maintained uniformly can be continuously obtained.

Accordingly, in the second embodiment, as in the first embodiment, the common set value m is set to the user set value M _SEL within the range where the maximum LED temperature is equal to or lower than the maximum allowable temperature, or the common set value m The maximum temperature of the LED is between the steady state return temperature and the maximum allowable temperature in a range that does not exceed the user set value _MSEL . Therefore, the temperature of the LED is prevented from rising excessively.

  100 multi-screen display device, 101 unit display device, 1R red light source unit, 1G green light source unit, 1B blue light source unit, 2 dichroic mirror unit, 3 DMD, 4 projection lens, 5 screen, 6 image signal input unit, 7 image signal Processing part, 7a Color conversion circuit, 8 Control processing part, 9 Communication part, 11 Current control circuit, 12 LED, 13 Temperature sensor.

Claims (4)

A multi-screen display device comprising a plurality of unit display devices for displaying an image based on a video signal using a light source,
Each of the plurality of unit display devices is
A temperature sensor for measuring the temperature of the light source;
A current control circuit for controlling a current flowing through the light source based on a common setting value shared by the plurality of unit display devices;
A color conversion circuit that performs color conversion of the video signal by matrix calculation using a matrix determined based on the common setting value;
The multi-screen display device
A control processing unit that monitors the temperature of the light source measured by the temperature sensors of the plurality of unit display devices and adjusts the common setting value so that the temperature of each light source does not exceed a predetermined first threshold;
The common setting value is determined by selecting one of a plurality of predetermined values,
The multi-screen display device, wherein the matrix is set so that brightness, chromaticity, and white balance of the plurality of unit display devices are the same for each value of the common setting value. The multi-screen display device according to claim 1,
The multi-screen display device further comprising holding means for holding the current of the light source corresponding to each value of the common setting value and a preset value of each element of the matrix. The multi-screen display device according to claim 1 or 2,
The control processing unit
When the temperature of any light source exceeds the first threshold, the common setting value is adjusted so that the current of the light source is minimized, and then the common setting value reaches a specific value or any light source The multi-screen display device is characterized in that the common setting value is adjusted so that the current of the light source gradually increases until the temperature reaches a second threshold value that is lower than the first threshold value. The multi-screen display device according to claim 1 or 2,
The control processing unit
When the temperature of any light source exceeds the first threshold, the current of the light source gradually decreases until the temperature of the light source becomes lower than the first threshold or the common setting value reaches a specific value. The common light source current is gradually adjusted until the common light set value reaches a specific value or the temperature of any light source reaches a second threshold value lower than the first threshold value. A multi-screen display device, wherein the common setting value is adjusted so as to increase.

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