JP6425376B2 - Image display apparatus and control method thereof - Google Patents

Description

  The present invention relates to an image display apparatus provided with a temperature sensor and a control method thereof.

  In recent years, in image display devices using various display panels such as liquid crystal panels, plasma display panels, organic EL (electro luminescence) display panels, FED (field emission display) panels, development of image quality improvement technology is in progress .

  It is known that display characteristics as described above change in accordance with the temperature of the display panel. For this reason, in order to obtain a desired display image quality even if the temperature of the display panel changes, it is desirable to perform image quality correction such as gradation correction according to the temperature of the display panel.

  If a temperature sensor is disposed inside the display panel or provided directly on the display panel, it is difficult to directly measure the temperature of the display panel because the temperature sensor may adversely affect the image display. In addition, if it is attempted to realize a configuration in which the temperature of the display panel is directly measured, it is difficult to design, resulting in a significant cost increase, and problems such as an increase in the frame width of the image display device. Therefore, it has been proposed that a temperature sensor be provided at a position away from the display panel inside the housing of the image display apparatus or outside the housing. The temperature of the display panel changes in accordance with the ambient temperature and the heat generation of the image display device itself.

  Even if individual differences occur in display characteristics of individual display panels due to manufacturing variations or the like, an image quality correction step is provided in which image quality correction is individually performed in the manufacturing process of the image display device in order to obtain desired display image quality. However, when the user uses the image display apparatus, the environmental temperature may be different from the image quality correction process described above. In order to obtain a desired display quality even in such a case, it is necessary to perform image quality correction in accordance with the environmental temperature in which the image display apparatus is used.

  Patent Document 1 discloses that the image quality correction of the display panel is performed according to the temperature difference between the detected outside temperature and the inside temperature by detecting each temperature inside and outside the housing of the image display device. ing.

Further, Patent Document 2, comprises two temperature sensors in the housing of the image display device, a correlation between the temperature detected by the two temperature sensors, based on the detected temperature of the two temperature sensors, environmental temperature It is disclosed to guess.

Japanese Patent Application Laid-Open No. 10-253946 JP, 2013-108801, A

In an image display apparatus that performs forced air cooling using a fan, the distribution of air circulating in the housing changes when the driving state of the fan is changed. In addition, each portion in the housing of the image display apparatus has different heat dissipation characteristics due to the difference in shape, material, and the like. Thus, varying the driving state of the fan, the temperature change each part of the housing is a different respective image display apparatus arising.

  Therefore, an object of the present invention is to provide an image display apparatus capable of performing appropriate image quality correction in accordance with the driving state of a fan, and a control method thereof.

In order to solve the problems described above, an image display device according to an embodiment of the present invention is an image display device provided with a temperature sensor, and a display panel for displaying an image, and a device for cooling the image display device. A fan, a light source unit for emitting light from the back side of the display panel, a first temperature sensor provided in the light source unit, a second temperature sensor provided in the image display device, and the first temperature sensor and the detected temperature T _BL by the temperature sensor, the second detection temperature T _K by the temperature sensor, based on the drive value V _f of the fan, and estimating means to estimate the ambient temperature RT, inferred by said estimating means Correction means for correcting the image quality of the display panel on the basis of the detected environmental temperature RT and the detected temperature _T.sub.BL by the first temperature sensor , wherein the estimation means calculates the equation: RT = [T _K - using _{(a × T BL + b)} ] / (1-a), infers ambient temperature RT, a, b are ing to a smaller value the larger the respective _{V f.}

A control method of an image display device according to an embodiment of the present invention includes a temperature sensor, a display panel for displaying an image, a fan for cooling the image display device, and light from a back side of the display panel. A control method of an image display apparatus comprising: a light source unit for irradiating; a first temperature sensor provided in the light source unit; and a second temperature sensor provided in the image display apparatus, and the detected temperature T _BL by 1 temperature sensor, the second detection temperature T _K by the temperature sensor, based on the drive value V _f of the fan, and guessing step to estimate the ambient temperature RT, in the inferred step and inferred ambient temperature RT, based on the detected temperature T _BL by the first temperature sensor has a correction step of performing image correction of the display panel, in the guessing step The environmental temperature RT is estimated using the equation: RT = [T _K − (a × T _BL + b)] / (1−a), and is expressed by the above a = f (V _f ), and the above b = g It is expressed by (V _f ), and a> b, where a and b have smaller values as V _f is larger.

  According to the present invention, it is possible to perform appropriate image quality correction in accordance with the driving state of the fan.

FIG. 1 is a perspective view schematically showing an image display device according to Embodiment 1. FIG. 1 is a cross-sectional view schematically showing an image display device according to Embodiment 1. FIG. 1 is a block diagram showing an example of a functional configuration of an image display device according to Embodiment 1; It is a figure for demonstrating a mode that (gamma) characteristic of a display panel changes according to temperature. Source temperature sensor according to the detected temperature T _BL, it is a graph showing the time course of the detection temperature T _K by environmental temperature sensor. FIG. 16 is a graph showing an example of the relationship between ΔT _BL and ΔT _K in the temperature stable state when the fan driving condition is low speed driving / medium speed driving / high speed driving. It is a graph which shows the example of a relation between drive voltage _{Vf of a} fan, and coefficients a and b. FIG. 7 is a cross-sectional view schematically showing an image display device according to Embodiment 2; FIG. 13 is a block diagram showing an example of a functional configuration of an image display device according to Embodiment 2. The detected temperature T _BL by the light source temperature sensor of the image display _device, the detected temperature T _K by environmental temperature sensor _is a graph showing the time course of the detection temperature T _IC by IC temperature sensor.

  Hereinafter, embodiments of the present invention will be described using the drawings. The technical scope of the present invention is determined by the scope of the claims, and is not limited by the embodiments exemplified below. Moreover, not all combinations of features described in the embodiments are essential to the present invention. The contents described in the specification and the drawings are for illustrative purposes only and should not be considered as limiting the present invention. Various modifications (including organic combinations of the respective embodiments) are possible based on the spirit of the present invention, and they are not excluded from the scope of the present invention. That is, the configuration in which each embodiment and its modification are combined is all included in the present invention.

  The display device shown in each embodiment of the present invention includes a display panel and a light source unit that irradiates the display panel from the back. In addition, although a liquid crystal panel is illustrated as a display panel below and an LED light emitting element is illustrated as a light source of a light source unit, it does not restrict to this. For example, the light source of the light source unit may be an organic EL element or a CCFL (cold cathode tube). The display panel may be a display panel having an element other than a liquid crystal element (an element capable of controlling the transmittance of light from the backlight source). The present invention is also applicable to a liquid crystal projector or the like which projects an image on a screen.

Embodiment 1
FIG. 1 is a perspective view schematically showing an image display apparatus 1 according to the first embodiment. FIG. 2 is a cross-sectional view schematically showing the image display device 1 according to the first embodiment.

  The image display device 1 includes a display panel 2, a light source unit 3, a circuit board 4, a fan 5, a switch board 6, and housings 7 a and 7 b. The light source unit (backlight unit) 3 is disposed on the back side of the display panel 2 and illuminates the display panel 2 from the back side. The light source unit 3 includes a light source substrate 8, an optical sheet 9, and a light source chassis 10 for containing them. In addition, although a direct type | mold, an edge light type etc. are mentioned as a backlight system, the structure of this invention is applicable to any system.

  The circuit board 4 is disposed on the back side of the light source unit 3 and is fixed to the light source chassis 10 via metal fittings (or sheet metal parts) or the like. The circuit board 4 is provided with electronic components such as an IC (Integrated Circuit) 13 and performs drive control of the display panel 2 and the light source unit 3 and supply of power to various components. The fan 5 is disposed on the back side of the light source unit 3 and is fixed to the light source chassis 10 via metal fittings (or sheet metal parts) or the like. The fan 5 is connected to the circuit board 4 via a cable and driven and controlled by the circuit board 4. The fan 5 is used to cool the image display device 1 and exhausts air from the inside of the housing 7 or sucks in air from the outside of the housing 7. The fan 5 may be, for example, an axial fan or a sirocco fan, or may be AC (AC) driven by DC (direct current) driving. Also, there may be a plurality of fans 5.

  The housing 7 includes a housing (front cover) 7a that covers the display panel 2 from the front side, and a housing (rear cover) 7b that covers the display panel 2 and the light source unit 3 from the rear side. The housing 7 accommodates the display panel 2, the light source unit 3, the circuit board 4, the fan 5, the switch board 6 and the like, and functions as an enclosure of the image display device 1. The housing 7 a is provided with an opening for exposing the image display area of the display panel 2. Further, the housing 7 a is provided with an operation switch 21 and a switch board 6 for detecting depression of the operation switch 21 by the user and the like and transmitting the detection to the circuit board 4. The housing 7 b is provided with an intake / exhaust port 7 c for performing air cooling by the fan 5. The housing 7 may be made of any material such as synthetic resin or metal.

  The switch substrate 6 is fixed to the inside of the housing 7a, disposed on the front side of the display panel 2, and connected to the circuit substrate 4 via a cable (not shown). Further, the switch substrate 6 is provided with an environmental temperature sensor 12 for detecting an environmental temperature. Although the switch substrate 6 is not provided with an electronic component that generates a large amount of heat, the switch substrate 6 is affected by the generation of heat due to the driving of the image display device 1 itself, particularly the generation of heat of the light source unit 3. Therefore, the temperature detected by the environmental temperature sensor 12 indicates a value higher than the actual environmental temperature of the room in which the image display device 1 is disposed. The environmental temperature sensor 12 only needs to be provided at a position where the environmental temperature can be suitably detected, and may be provided directly on the housing 7 a or may be provided in a place other than the switch substrate 6.

  The light source substrate 8 is fixed to the front side of the light source chassis 10, and is provided with a light source such as an LED (light emitting diode), a light source temperature sensor 11, and the like. A plurality of light source temperature sensors 11 are provided on the light source substrate 8. However, only one light source temperature sensor 11 may be provided on the light source substrate 8. The temperature detected by the light source temperature sensor 11 has a value close to the actual temperature of the light source substrate 8. The light source temperature sensor 11 may be disposed in the vicinity of the light source unit 3 and may be provided other than the light source substrate 8.

  FIG. 3 is a block diagram showing an example of a functional configuration of the image display device 1 according to the first embodiment. The image display device 1 includes a display panel 2, a light source unit 3, a fan 5, a light source temperature sensor 11, and an environmental temperature sensor 12. Further, the image display device 1 includes a video signal input unit 20, an operation switch 21, a memory 22, a control unit 23, an image quality correction unit 24, a fan control unit 25, a display panel drive unit 26, a light source drive unit 27, and an environmental temperature estimation unit. 28 and a fan drive unit 29.

  A video signal is input to the video signal input unit 20 from an external device such as a PC (personal computer). The video signal input unit 20 outputs a video signal input from an external device to the image quality correction unit 24 in the control unit 23. The video signal from the external device may be input by wire via a cable or may be input by wireless communication. The video signal may be either an analog signal or a digital signal.

  The control unit 23 includes an image quality correction unit 24 and a fan control unit 25. The control unit 23 is, for example, a CPU (Central Processing Unit), and controls the operation of each functional block included in the image display device 1. Specifically, the CPU reads out the program from the ROM (memory 22) and executes it to control the operation of each functional block included in the image display device 1.

  The image quality correction unit 24 corrects the image quality of the display panel 2 based on the input video signal, the detection temperature of the light source temperature sensor 11, and the estimated value of the environmental temperature estimated by the environmental temperature estimation unit 28. At that time, the image quality correction unit 24 refers to the image quality correction table stored in the memory 22, and based on the detected temperature by the light source temperature sensor 11 and the estimated value of the environmental temperature estimated by the environmental temperature estimation unit 28. , Determine the image quality correction amount. However, the image quality correction unit 24 estimates the temperature of the display panel 2 based on the temperature detected by the light source temperature sensor 11 and the estimated value of the environment temperature estimated by the environment temperature estimation unit 28 and the display panel 2 estimated Depending on the temperature of the image quality correction amount may be determined. The image quality correction unit 24 may correct the light emission amount of the light source unit 3 based on the temperature detected by the light source temperature sensor 11 and the estimated value of the environmental temperature estimated by the environmental temperature estimation unit 28.

  FIG. 4 is a diagram for explaining how the γ characteristic (gradation characteristic) of the display panel changes according to the temperature. The γ curve of the solid line shows the γ curve when the temperature of the display panel is normal temperature (for example 15 degrees), and the γ curve of the dotted line shows the γ curve when the temperature of the display panel is high temperature (for example 35 degrees). Thus, the γ characteristic (gradation characteristic) of the display panel changes according to the temperature of the display panel. The memory 22 stores in advance an image quality correction table indicating an image quality correction amount (tone correction amount) according to each temperature of the display panel. Specifically, the image quality correction for correcting the γ characteristic corresponding to each temperature of the display panel (for example, 0 °, 5 °, 10 °, ... 35 °, 40 °) to γ = 2.2 An image quality correction table indicating the amount is stored in advance. The image quality correction amount is calculated in advance by experiment.

  Returning to FIG. 3, the image quality correction unit 24 outputs a panel drive value of the display panel reflecting the determined image quality correction amount to the display panel drive unit 26. Further, the image quality correction unit 24 outputs the light source driving value of the light source unit 3 reflecting the determined image quality correction amount to the light source drive unit 27. Note that the control unit 23 changes the image quality correction amount by the image quality correction unit 24 in accordance with the user's operation content (for example, change of display brightness) input to the image display device 1 via the operation switch 21. Good. The display panel drive unit 26 drives the display panel 2 based on the panel drive value input from the image quality correction unit 24. Further, the light source drive unit 27 drives the light source unit 3 based on the light source drive value input from the image quality correction unit 24.

  The fan control unit 25 determines a fan drive value based on the temperature detected by the light source temperature sensor 11, the temperature detected by the environment temperature sensor 12, and the light source drive value of the light source unit 3 and outputs the fan drive value to the fan drive unit 29. The fan control unit 25 may determine the fan drive value based on at least one of the temperature detected by the light source temperature sensor 11, the temperature detected by the environment temperature sensor 12, and the light source drive value of the light source unit 3. That is, the fan control unit 25 determines the fan drive value based on one or two of the temperature detected by the light source temperature sensor 11, the temperature detected by the environment temperature sensor 12, and the light source drive value of the light source unit 3. May be The fan drive unit 29 drives the fan 5 based on the drive value input from the fan control unit 25.

  The environmental temperature estimation unit 28 calculates the environmental temperature around the image display device 1 based on the temperature detected by the light source temperature sensor 11, the temperature detected by the environment temperature sensor 12, and the fan drive value input from the fan control unit 25. Infer. As a fan drive value, for example, a drive voltage value of the fan 5 is used. However, the rotational speed of the fan 5 may be used as the fan drive value. Further, as the fan drive value, a drive value output from the fan control unit 25 which performs drive control of the fan 5 may be used, or a value obtained by actually measuring the number of rotations or drive voltage value of the fan 5 is used. May be For example, the drive voltage value of the fan 5 may be a DC voltage value, or may be a duty ratio of pulse voltage by PWM (pulse width modulation).

Next, a specific example of the estimation process of the environmental temperature by the environmental temperature estimation unit 28 will be described using FIGS. FIG. 5 is a graph showing an example of the time transition of the detected temperature T _BL by the light source temperature sensor 11 of the image display device 1 and the detected temperature T _K by the environmental temperature sensor 12. In FIG. 5, the horizontal axis indicates the elapsed time (t), and the vertical axis indicates the temperature value (° C.). The temperature difference [Delta] T _BL between the actual ambient temperature RT and the detected temperature _{T BL} by the light source temperature sensor 11, the temperature difference between the actual ambient temperature RT and the detected temperature _{T K} by the environmental temperature sensor 12 and [Delta] T _K. The actual environmental temperature RT indicates the actual environmental temperature of the room in which the image display device 1 is installed, and indicates a value measured by a thermometer provided in the room. Further, as the detected temperature _TBL by the light source temperature sensor 11, an average value of the temperatures detected by the plurality of light source temperature sensors 11 is used. The relationship between ΔT _BL and ΔT _K is expressed by the following equations (1) and (2).
ΔT _BL = T _BL −RT (1)
ΔT _K = T _K −RT (2)

When the image display device 1 is activated, the heat generation of the light source unit 3 and the circuit board 4 causes T _BL and T _K to start to rise. If the light source unit 3 and the fan 5 is driven conditions and ambient temperature RT is constant, such as the image display device 1 becomes a temperature stable state after a certain time, T _BL and T _K is a constant value. That is, in such a temperature stable state, ΔT _BL and ΔT _K also become constant values.

Figure 6 is a graph of the fan drive condition image display device 1 shows an example of the relationship between [Delta] T _BL and [Delta] T _K in temperature stability state when / medium speed driving time / high-speed driving at a low speed driving. In FIG. 6, the horizontal axis indicates ΔT _BL and the vertical axis indicates ΔT _K.

For example, when the fan 5 and low speed driving (fan driving voltage V _{f =} 7V), ΔT _BL is increased or decreased depending on the heating value of increase and decrease of the light source unit 3, the [Delta] T _K is increased or decreased in proportion to the increase or decrease of [Delta] T _BL It can be approximated. This is because, as described above, the switch substrate 6 provided with the environmental temperature sensor 12 has no component that generates a large amount of heat, and the switch substrate is affected by heat transfer from the light source unit 3 which is disposed in the vicinity and has a large amount of generated heat. This is because the temperature of 6 rises. Similarly, when the fan 5 is driven at a medium speed (fan drive voltage V _f = 9.5 V) or at a high speed (fan drive voltage V _f = 12 V), ΔT _K increases or decreases in proportion to increase or decrease of ΔT _BL. It can be approximated. That is, the relation between ΔT _BL and ΔT _K can be expressed by the relation of the following equation (3). Here, the coefficients a and b are coefficients determined according to the driving state of the fan. Further, in FIG. 6, the coefficients a _LOW , a _Mid , a _High and the coefficients b _LOW , b _Mid , b _High respectively indicate the coefficients a, b in the low speed rotation drive, the medium speed rotation drive, and the high speed rotation drive. There is.
ΔT _K = a × ΔT _BL + b (3)

As the driving state of the fan 5 is rotated at a higher speed, the outer peripheral portion of the light source substrate 8 of the light source unit 3 is particularly cooled and the temperature is lowered, and the detected temperature by the environmental temperature sensor 12 is lowered due to the influence. As a result, as the driving state of the fan 5 is rotated at high speed, ΔT _K becomes smaller. A plurality of light source temperature sensors 11 are provided on the light source substrate 8, and the temperature detected by the light source temperature sensor 11 provided on the outer peripheral portion of the light source substrate 8 decreases as the driving state of the fan 5 rotates faster. On the other hand, the temperature detected by the light source temperature sensor 11 provided near the center of the light source substrate 8 does not decrease so much even when the driving state of the fan 5 is rotated at high speed, and the temperature may rise depending on the driving state of the light source unit is there. Therefore, the relationship between ΔT _BL and ΔT _K changes according to the fan drive condition as shown in FIG.

FIG. 7 is a graph showing an example of the relationship between the drive voltage _Vf of the fan and the coefficients a and b. In FIG. 7, the horizontal axis indicates the fan drive voltage _Vf , and the vertical axis indicates the values of the coefficients a and b. The coefficients a and b can be approximated as a function of the fan drive voltage V _{f and} are expressed by the following equations (4) and (5).
a = f (V _f ) (4)
b = g (V _f ) (5)

  Here, the following equation (6) can be obtained by arranging the equations (1) to (5).

The environmental temperature estimation unit 28 performs an estimation process of the environmental temperature using this equation (6). As shown in the equation (6), the ambient temperature RT around the image display device 1 can be estimated from the values of T _BL , T _K , and V _f . That is, even in the case where air cooling using a fan is performed in the image display device 1, the environmental temperature RT can be estimated with high accuracy according to the driving state of the fan.

Even if ΔT _BL and ΔT _K do not have a proportional relationship, similar environmental temperature estimation can be performed using an approximate expression representing the relationship between ΔT _BL and ΔT _K. Also, the coefficients a and b may be selected from the table according to the value of V _f instead of being calculated from the functional equation of V _f as in the equations (4) and (5).

  Therefore, based on the temperature detected by the light source temperature sensor, the temperature detected by the environment temperature sensor, and the fan drive state, the environment temperature estimation unit can estimate the environment temperature around the image display device with high accuracy. . In addition, the image quality correction unit can perform the image quality correction of the display panel with high accuracy based on the temperature detected by the light source temperature sensor and the estimated value of the environment temperature estimated by the environment temperature estimation unit. In other words, the image quality correction of the display panel can be performed with high accuracy based on the temperature detected by the light source temperature sensor, the temperature detected by the environment temperature sensor, and the fan driving state.

  The light source temperature sensor is not essential in the present invention, and instead of providing the light source temperature sensor, the light source temperature may be estimated based on the light source drive value. In this case, the image quality correction of the display panel is performed based on the temperature detected by the environmental temperature sensor and the fan driving state. As described above, it is possible to perform appropriate image quality correction according to the driving state of the fan.

Second Embodiment
The second embodiment will be described below with reference to the drawings. In the second embodiment, the same components as those of the first embodiment are designated by the same reference numerals, and the detailed description thereof will not be repeated.

  FIG. 8 is a cross-sectional view schematically showing an image display device 30 according to the second embodiment. In addition to the IC 13, the circuit substrate 4 is provided with an IC temperature sensor 31 and an environmental temperature sensor 32. The circuit board 4 rises in temperature due to the influence of the heat generation of the light source unit 3 and the heat generation of the IC 13. Therefore, the temperature detected by the environmental temperature sensor 32 indicates a value higher than the actual environmental temperature.

  FIG. 9 is a block diagram showing an example of a functional configuration of the image display device 30 according to the second embodiment. Compared with the image display device 1 of FIG. 3, the image display device 30 of FIG. 9 is different in that the IC temperature sensor 31, the environmental temperature sensor 32, and the environmental temperature estimation unit 33 are provided. Based on the temperature detected by the light source temperature sensor 11, the temperature detected by the environment temperature sensor 32, the IC temperature sensor 31, and the fan drive value input from the fan control unit 25, the environment temperature estimation unit 33 displays the image display device 30. Estimate the ambient temperature around the As a fan drive value, for example, a drive voltage value of a fan is used.

Next, a specific example of estimation processing of the environmental temperature by the environmental temperature estimation unit 33 will be described. FIG. 10 is a graph showing a time transition example of the detection temperature T _BL detected by the light source temperature sensor 11 of the image display device 1, the detection temperature T _K detected by the environment temperature sensor 32, and the detection temperature T _IC detected by the IC temperature sensor 31. In FIG. 10, the horizontal axis indicates the elapsed time (t), and the vertical axis indicates the temperature value (° C.). The temperature difference [Delta] T _BL between the actual ambient temperature RT and the detected temperature _{T BL} by the light source temperature sensor 11, the temperature difference [Delta] T _K between the actual ambient temperature RT and the detected temperature _{T K} by environmental temperature sensor 12, IC temperature sensor 31 The temperature difference between the detected temperature T _IC and the actual environmental temperature RT is defined as ΔT _IC . The actual environmental temperature RT indicates the actual environmental temperature of the room in which the image display device 1 is installed, and indicates a value measured by a thermometer provided in the room. Further, as the detected temperature _TBL by the light source temperature sensor 11, an average value of the temperatures detected by the plurality of light source temperature sensors 11 is used. The relationship between ΔT _BL and ΔT _K is expressed by the following formulas (1), (2) and (3).
ΔT _BL = T _BL −RT (7)
ΔT _K = T _K −RT (8)
ΔT _IC = T _IC −RT (9)

When the image display device 30 is activated, the heat generation of the light source unit 3 and the circuit board 4 causes T _BL , T _K and T _IC to start to rise. Then, the light source unit 3, if the fan 5, IC 13 driving conditions and ambient temperature RT is constant, such as an image display apparatus 30 becomes a temperature stable state after a certain _{time, T BL, T K, T} IC is a fixed value Become. That is, in such a temperature stable state, ΔT _BL , ΔT _K and ΔT _IC also have constant values.

At this time, if the fan is driven at a constant rotational speed, it can be approximated that ΔT _K increases and decreases in proportion to the increase and decrease of ΔT _BL and ΔT _IC . That is, the relationship between ΔT _BL , ΔT _K , and ΔT _IC can be expressed by the following equation (10).
ΔT _K = a × ΔT _BL + b × ΔT _IC + c (10)

Here, the coefficients a, b and c are coefficients determined according to the driving state of the fan. Here, the coefficients a, b and c can be approximated as a function of the fan drive voltage V _{f and} are expressed by the following equations (11) to (13).
a = F (V _f ) ... (11)
b = G (V _f ) ... (12)
c = H (V _f ) (13)

  Here, the following equation (14) can be obtained by arranging the equations (7) to (13).

The environmental temperature estimation unit 33 estimates the environmental temperature using this equation (14). As shown in equation (14), the ambient temperature RT around the image display device 30 can be estimated from the values of T _BL , T _K , T _IC , and V _f . That is, even in the case where air cooling using a fan is performed in the image display device 30, it is possible to estimate the environmental temperature RT with high accuracy according to the driving state of the fan.

Even when ΔT _BL , ΔT _K and ΔT _IC do not have a proportional relationship, similar environmental temperature estimation can be performed using an approximate expression that represents the relationship between ΔT _BL , ΔT _K and ΔT _IC. is there. Also, the coefficients a, b and c may be selected from the table according to the value of V _f instead of being calculated from the functional equation of V _f as in equations (11) to (13). .

  As described above, in the second embodiment, the same effect as the first embodiment can be obtained.

(Other embodiments)
The present invention is also realized by executing the following processing. That is, software (program) for realizing the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media (nonvolatile memories such as ROM and RAM), and the computer (or computer of that system or apparatus). It is a process in which a CPU, an MPU, etc. read and execute a program. Therefore, a computer program for realizing the functions of the above-described embodiment is also one of the present invention.

1, 30 image display device 2 display panel 3 light source unit 5 fan 11 light source sensor 12, 32 environmental temperature sensor 24 image quality correction unit 25 fan control unit 29 fan drive unit 28, 33 environmental temperature estimation unit

Claims (8)

An image display apparatus comprising a temperature sensor,
A display panel that displays an image,
A fan for cooling the image display device;
A light source unit for emitting light from the back side of the display panel;
A first temperature sensor provided in the light source unit;
A second temperature sensor provided in the image display device;
And the detected temperature T _BL by the first temperature sensor, the detection temperature T _K by the second temperature sensor, based on the drive value V _f of the fan, and estimating means to estimate the ambient temperature RT,
A correction unit configured to correct the image quality of the display panel based on the environmental temperature RT estimated by the estimation unit and the detected temperature _TBL detected by the first temperature sensor;
The estimation unit estimates the environmental temperature RT using the equation: RT = [T _K − (a × T _BL + b)] / (1−a),
The a = f (V _f ), the b = g (V _f ), a> b, and a and b have smaller values as V _f is larger. Image display device. The image display apparatus according to claim 1, wherein the second temperature sensor is provided in a housing of the image display apparatus. The drive values of the fan, the rotational speed of the fan, or an image display apparatus according to claim 1 or 2, wherein said a drive voltage of the fan. The image display apparatus according to any one of claims 1 to 3 , wherein the correction unit performs image quality correction related to gradation characteristics of the display panel. A temperature sensor, a display panel for displaying an image, a fan for cooling the image display device, a light source unit for emitting light from the back side of the display panel, and a first temperature provided to the light source unit A control method of an image display apparatus, comprising: a sensor; and a second temperature sensor provided in the image display apparatus,
And the detected temperature T _BL by the first temperature sensor, the detection temperature T _K by the second temperature sensor, based on the drive value V _f of the fan, and guessing step to estimate the ambient temperature RT,
And correcting the image quality of the display panel based on the environmental temperature RT estimated in the estimation step and the detected temperature _TBL detected by the first temperature sensor.
In the inference step, the environmental temperature RT is inferred using the equation: RT = [T _K − (a × T _BL + b)] / (1−a),
The a = f (V _f ), the b = g (V _f ), a> b, and a and b have smaller values as V _f is larger. Control method of the image display device. The control method of an image display device according to claim 5 , wherein the second temperature sensor is provided in a case of the image display device. The control method of the image display apparatus according to claim 5 or 6 , wherein the driving value of the fan is a rotational speed of the fan or a driving voltage value of the fan. The control method of the image display apparatus according to any one of claims 5 to 7 , wherein the image quality correction regarding the gradation characteristic of the display panel is performed in the correction step.

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