JP5865779B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a cooling structure for a liquid crystal display device having a light source array composed of laser light emitting elements and LEDs (Light Emitting Diodes).

  The liquid crystal display element included in the liquid crystal display device does not emit light by itself. For this reason, the liquid crystal display device includes a backlight device on the back surface of the liquid crystal display element as a light source for illuminating the liquid crystal display element. In recent years, with the dramatic improvement in performance of blue light emitting diodes (LEDs), backlight devices using blue LEDs as light sources have been widely adopted in liquid crystal display devices.

  The light source using the blue LED includes a blue LED and a phosphor that absorbs light emitted from the blue LED and emits light that is complementary to blue. The blue complementary color is a color including green and red, yellow or the like. Such an LED is called a white LED.

  White LEDs have high electrical-light conversion efficiency and are effective in reducing power consumption. However, on the other hand, white LEDs have the problem that their wavelength bandwidth is wide and the color reproduction range is narrow. The liquid crystal display device includes a color filter inside the liquid crystal display element. The liquid crystal display device uses this color filter to extract only the red, green, and blue spectral ranges and perform color expression.

  A light source having a continuous spectrum with a wide wavelength bandwidth such as a white LED needs to increase the color purity of the display color of the color filter in order to widen the color reproduction range. That is, the wavelength band that transmits the color filter is set narrow.

  However, if the wavelength band that passes through the color filter is set narrow, the light utilization efficiency decreases. This is because the amount of unnecessary light that is not used for image display by the liquid crystal display element increases. Further, there arises a problem that the brightness of the display surface of the liquid crystal display element is lowered and further the power consumption of the liquid crystal display device is increased.

  As a measure for solving such a problem, a backlight device has been proposed that employs red, green, and blue single color LEDs with higher color purity instead of white LEDs (Patent Document 1). In addition, a backlight device using red, green, and blue lasers having higher color purity than a single-color LED has been proposed (Patent Document 2). High color purity means that the wavelength width is narrow and monochromaticity is excellent. By adopting these light sources in the backlight device of the liquid crystal display device, the color reproduction range of the liquid crystal display device can be expanded.

  However, some light sources composed of three primary color single-color LEDs and lasers have a significant decrease in electro-optical conversion efficiency as the element temperature increases. In particular, when a red laser continues to emit high-power light at a high temperature, the deterioration is accelerated and the lifetime of the element is shortened. Therefore, even when the environmental temperature is high, a forced air cooling system using a cooling blower is generally required to obtain a desired light amount (Patent Document 3).

JP 2009-026635 A JP 2010-101912 A Japanese Patent No. 4910463

  When an air cooling system using a blower is adopted in a home-use liquid crystal display device or the like, a rotating sound or wind noise from the fan of the blower is generated and becomes a problem. Therefore, it is important to control the blower according to the temperature of the light source. Unlike a projection display or the like in which light sources are gathered in one place, in a liquid crystal display device in which light sources are discretely arranged in an array, the temperature of the light source varies depending on the location. Therefore, in the liquid crystal display device, it is necessary to introduce a complicated cooling system in order to appropriately control the temperatures of all the light sources. That is, there is a problem that the configuration becomes complicated in order to cool the light source having the above configuration.

  The present invention has been made to solve such a problem, and an object thereof is to provide a liquid crystal display device capable of efficiently cooling a light source with a simple configuration.

  In order to achieve the above object, a liquid crystal display device according to one embodiment of the present invention is provided with a laser light source array including a plurality of laser light emitting elements arranged along the vertical direction, and arranged along the vertical direction. An LED light source array composed of a plurality of LED (Light Emitting Diode) light sources, an air passage along a vertical direction, and a radiator that radiates heat from the laser light source array and the LED light source array, and a lower portion of the radiator And a temperature measuring unit for measuring temperature, wherein the temperature measuring unit is a laser emitting device arranged at the top of the plurality of laser emitting elements. Arranged in the vicinity of the uppermost light emitting element, which is an element, the blower is obtained by using a forward current amount of the uppermost light emitting element and a measured temperature that is a temperature measured by the temperature measuring unit. Accordance values, controls the air volume.

  According to the present invention, the blower is obtained by using the forward current amount of the uppermost light emitting element arranged at the uppermost part and the temperature measured by the temperature measuring unit arranged in the vicinity of the uppermost light emitting element. The air flow is controlled according to the value to be obtained. Thereby, the air blower can perform more appropriate air blowing.

  The blower is arranged at the lower part of the radiator and blows air to the air path along the vertical direction. Therefore, the air blown into the air passage is directed from the lower part to the upper part of the radiator along the air passage. Thereby, the laser light source array and LED light source array which are light sources can be cooled efficiently. That is, the light source can be cooled with a simple configuration in which the blower blows air to the air path along the vertical direction. Therefore, the light source can be efficiently cooled with a simple configuration.

It is a block diagram which shows the structure of the liquid crystal display device which concerns on Embodiment 1 of this invention. 1 is a rear perspective view of a liquid crystal display device according to Embodiment 1 of the present invention. It is the figure which looked at the internal structure of the liquid crystal display device from the display surface side. It is the figure which looked at the internal structure of the liquid crystal display device from the display surface side. It is sectional drawing of the left end part of a display part. It is a figure which shows an example of the relationship between uppermost element temperature and the rotation speed of the fan of an air blower. It is a figure which shows the other example of the relationship between uppermost element temperature and the rotation speed of the fan of an air blower.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof may be omitted.

  It should be noted that the dimensions, materials, shapes, relative arrangements, and the like of the constituent elements exemplified in the embodiments are appropriately changed depending on the configuration of the apparatus to which the present invention is applied and various conditions. It is not limited to those examples. Moreover, the dimension of each component in each figure may differ from an actual dimension.

<Embodiment 1>
FIG. 1 is a block diagram showing a configuration of a liquid crystal display device 100 according to Embodiment 1 of the present invention. As shown in FIG. 1, the liquid crystal display device 100 includes a laser light source array 6, an LED light source array 8, a radiator 2, a blower 3, a temperature measurement unit 9, and a control unit 50. Note that FIG. 1 does not show components or the like for displaying an image for simplification of the drawing.

  The laser light source array 6 and the LED light source array 8 are composed of a plurality of light sources, as will be described in detail later. Although the details will be described later, the radiator 2 radiates the laser light source array 6 and the LED light source array 8. The radiator 2 is made of a metal that easily transfers heat. The blower 3 has a function of blowing air. The blower 3 is an axial flow blower that blows air by rotating a fan. Note that the blower 3 may be a device that blows air without using a fan.

  The temperature measuring unit 9 is a component for measuring the temperature around the temperature measuring unit 9. The temperature measuring unit 9 is composed of only an element for measuring temperature or a combination of the element and a circuit. Hereinafter, the temperature measured by the temperature measuring unit 9 is also referred to as a measured temperature. The temperature measuring unit 9 transmits the measured temperature to the control unit 50 at any time.

  The control unit 50 controls each unit in the liquid crystal display device 100. The control unit 50 controls, for example, the laser light source array 6, the LED light source array 8, and the blower 3. The control unit 50 is, for example, a CPU (Central Processing Unit), an MPU (microprocessor), or the like.

  The laser light source array 6, the LED light source array 8, the radiator 2, the blower 3, and the temperature measuring unit 9 are arranged symmetrically on the left and right sides of the liquid crystal display device 100. That is, the liquid crystal display device 100 includes a pair of laser light source arrays 6, LED light source arrays 8, a radiator 2, a blower 3, and a temperature measuring unit 9 disposed on the left and right sides of the liquid crystal display device 100.

  In the following, the laser light source array 6, the LED light source array 8, the radiator 2, the blower 3, and the temperature measuring unit 9 arranged on the left side of the liquid crystal display device 100 are respectively referred to as a laser light source array 6 a, an LED light source array 8 a, It also describes with the heat radiator 2a, the air blower 3a, and the temperature measurement part 9a. In the following, the laser light source array 6, the LED light source array 8, the radiator 2, the blower 3, and the temperature measurement unit 9 arranged on the right side of the liquid crystal display device 100 are respectively referred to as a laser light source array 6 b and an LED light source array. 8b, radiator 2b, blower 3b, and temperature measurement unit 9b are also described.

  FIG. 2 is a rear perspective view of the liquid crystal display device 100 according to Embodiment 1 of the present invention. In FIG. 2, only the configuration in the vicinity of the display unit that displays the video is shown in order to make the drawing easier to see.

  In FIG. 2, the X, Y, and Z directions are orthogonal to each other. The X, Y, and Z directions shown in the following figures are also orthogonal to each other. Hereinafter, a direction including the X direction and the direction opposite to the X direction (−X direction) is also referred to as an X-axis direction. In the following, the direction including the Y direction and the direction opposite to the Y direction (−Y direction) is also referred to as a Y-axis direction. In the following, a direction including the Z direction and a direction opposite to the Z direction (−Z direction) is also referred to as a Z-axis direction.

  The liquid crystal display device 100 further includes a plate-like display unit 40. The display unit 40 includes a display surface (not shown) for displaying an image and the back sheet metal 1. The back sheet metal 1 is a sheet metal made of, for example, aluminum formed by pressing.

  The radiators 2a and 2b are disposed at the left end and the right end of the display unit 40, respectively. That is, the radiators 2a and 2b are arranged symmetrically. Further, the radiators 2 a and 2 b are thermally connected to the rear sheet metal 1 of the display unit 40.

  3 and 4 are views of the internal structure of the liquid crystal display device 100 as viewed from the display surface side. In FIGS. 3 and 4, the display surface of the display unit 40 is transparent in order to make the drawings easy to see. FIG. 3 is an enlarged view of the region R1 in FIG. FIG. 4 is an enlarged view of the region R2 in FIG. 3 and 4 show the arrangement state of each light source.

  Referring to FIGS. 2, 3 and 4, each of radiators 2a and 2b has a comb shape. Each of the radiators 2a and 2b is provided with a plurality of air passages 2n along the vertical direction (Y-axis direction). The shapes of the radiators 2a and 2b are not limited to the comb shape, and may be other shapes having a straight air path.

  The air blowers 3a and 3b are disposed below (lower) the radiators 2a and 2b, respectively. Note that each of the blowers 3a and 3b is not limited to the axial flow type blower using a fan, and may be a blower having another configuration such as a multi-blade type.

  Each of the blowers 3a and 3b has a function of making the blown air volume variable under the control of the control unit 50. The control of the control unit 50 is, for example, PWM (Pulse Width Modulation) control, voltage control, or the like. The blowers 3a and 3b take in the amount of outside air corresponding to the number of rotations of the fan, and operate so as to send wind to the radiators 2a and 2b, respectively. In other words, the blowers 3a and 3b send air to the air path 2n of the radiator 2a and the air path 2n of the radiator 2b, respectively.

  Although not shown here, when a comb-type heatsink is used, an enclosure capable of forming a separate air path may be provided around the heatsinks 2a and 2b.

  The liquid crystal display device 100 according to the present embodiment has a configuration having both a wide color reproduction range and low power consumption. Therefore, the liquid crystal display device 100 combines a laser light source array 6 and an LED light source array 8 in which a plurality of LED light sources 7 are arranged in an array.

  The LED light source 7 is composed of a blue LED and a phosphor. Specifically, the LED light source 7 is obtained by filling a package including a blue LED chip that emits blue light with a green phosphor that absorbs the blue light and emits green light. The LED light source array 8 includes a plurality of LED light sources 7 arranged along the vertical direction (Y-axis direction). The plurality of LED light sources 7 are arranged in an array. More specifically, the plurality of LED light sources 7 are surface-mounted on the aluminum substrate 10.

  Some of the plurality of LED light sources 7 constituting the LED light source array 8 are represented as LED light sources 7a to 7w in FIG. 3, and are represented as LED light sources 7A to 7R in FIG. That is, the plurality of LED light sources 7 constituting the LED light source array 8 include the LED light sources 7a to 7w in FIG. 3 and the LED light sources 7A to 7R in FIG.

  The laser light source array 6 is composed of a plurality of laser light emitting elements 5 arranged along the vertical direction (Y-axis direction). The plurality of laser light emitting elements 5 are arranged in an array. The laser light emitting element 5 is a laser that emits red light. The laser light emitting element 5 emits red light when a forward current flows through the laser light emitting element 5 itself. Hereinafter, the forward current flowing through the laser light emitting element 5 is also referred to as a forward current.

  A part of the plurality of laser light emitting elements 5 constituting the laser light source array 6 is denoted as laser light emitting elements 5a1, 5a2, 5b1, 5b2, 5c1, and 5c2 in FIG. Also, some of the plurality of laser light emitting elements 5 constituting the laser light source array 6 are denoted as laser light emitting elements 5d1, 5d2, 5e1, and 5e2 in FIG. That is, the plurality of laser light emitting elements 5 constituting the laser light source array 6 include the laser light emitting elements 5a1, 5a2, 5b1, 5b2, 5c1, and 5c2 in FIG. 3, and the laser light emitting elements 5d1, 5d2, 5e1, and 5e2 in FIG. including.

  Note that an LED light source array 8 and a laser light source array 6 are arranged side by side in a horizontal direction (X-axis direction) perpendicular to the vertical direction on a back metal plate 1 as a metal plate. The laser light source array 6 is disposed inside the back sheet metal 1 with respect to the LED light source array 8. Further, the radiator 2 is disposed only on the back surface of the laser light source array 6 via the back sheet metal 1.

  Here, the LED light source array 8 employs a blue-green LED (LED light source 7) including a blue single-color LED and a phosphor that absorbs blue light and emits green light. This is because monochromatic LEDs and lasers emitting green light are inferior in terms of lower power consumption and higher output than blue-green LEDs in simple and small-sized ones applicable to displays.

  Humans are sensitive to red color differences. Therefore, the difference in wavelength bandwidth in red is felt as a significant difference by human vision. Here, the difference in wavelength bandwidth is the difference in color purity. A white LED used as a light source in a conventional liquid crystal display device has a small amount of energy in the red spectrum particularly in the 600 nm to 700 nm band. In other words, if a color filter having a narrow wavelength bandwidth is used to increase the color purity in a wavelength range of 630 to 640 nm, which is preferable as pure red, the amount of transmitted light is extremely reduced, and the light use efficiency is lowered. Therefore, the conventional liquid crystal display device using a white LED as a light source has a problem that the luminance is remarkably lowered.

  On the other hand, the laser light emitting element has a narrow wavelength bandwidth, and can obtain light with high color purity without losing light. The laser light-emitting element used for the light source is a highly monochromatic laser light-emitting element that emits red light, particularly among the three primary colors, and is highly effective in reducing power consumption and improving color purity. .

  Therefore, in the liquid crystal display device 100 of the first embodiment, the laser light emitting element 5 is employed as a light source that emits red light.

  Further, in the liquid crystal display device using the conventional white LED light source, since the wavelength bandwidth of red light is wide, a part of the red light passes through the green filter adjacent to the spectrum, thereby obtaining a green color purity. Also decreased. However, since the light source of the liquid crystal display device 100 of the first embodiment has an increased red color purity, the amount of red light transmitted through the green filter is reduced, and the green color purity can be improved.

  The red laser light-emitting element 5 having a wavelength of 630 to 640 nm, which is preferable as pure red, has a marked decrease in electro-optical conversion efficiency as the element temperature rises. Further, if the laser light emitting element 5 continues to emit high output light in a high temperature state, the deterioration of the element is accelerated and the life is shortened. Therefore, it is necessary to introduce an efficient cooling system such as forced air cooling.

  On the other hand, the change of the electro-optical conversion efficiency with respect to the temperature of the LED light source 7 is very small as compared with the laser light emitting element 5. However, it is necessary to efficiently dissipate the heat generated by the LED light source 7 so that the heat generated by the LED light source 7 is not transferred to the laser light emitting element 5.

  The light output from the laser light emitting element 5 has high directivity. Therefore, in order to obtain the uniformity of light as the surface light emitting device, the laser light emitting element 5 is required to have a high positioning system.

  A commonly used laser light emitting element is, for example, a cylindrical package having a diameter of about 6 mm, and the method of press-fitting the laser light emitting element to the LD holding member 4 is excellent in terms of heat transfer. The LD holding member 4 is a member for holding the laser light emitting element. In order to manufacture the LD holding member 4 having a complicated shape having a hole for inserting a laser light emitting element at a low cost with high accuracy, it is desirable that the component (laser light emitting element) is small. 3 and 4, the LD holding member 4 is also expressed as LD holding members 4a, 4b, 4c, 4d, and 4e.

  In the present embodiment, as shown in FIGS. 3 and 4, two laser light emitting elements 5 are fixed to one LD holding member 4. That is, two laser light emitting elements 5 are press-fitted (embedded) in one LD holding member 4.

  In addition, the structure which fixes the laser light emitting element 5 is not limited to the said structure. For example, a configuration in which one laser light emitting element 5 is fixed to one LD holding member 4 or a configuration in which three or more laser light emitting elements 5 are fixed may be employed.

  As shown in FIGS. 3 and 4, the LD holding member 4 into which the laser light emitting element 5 is press-fitted is disposed on the center line in the width direction of the radiator 2 a via the back sheet metal 1. The LD holding member 4 is composed of a member having a relatively high thermal conductivity such as aluminum. Thereby, the heat generated by the laser light emitting element 5 is diffused and transferred to the radiator 2. Although not shown, a heat conductive sheet may be attached to the interface between the LD holding member 4 and the radiator 2a or a heat conductive grease may be applied as necessary.

  In addition, the periphery structure of the heat radiator 2b and the heat radiator 2b is the same as the structure demonstrated in FIG. 3 and FIG.

  Next, the configuration of the display unit 40 will be described. FIG. 5 is a cross-sectional view of the left end portion of the display unit 40. In FIG. 5, the blower 3 connected to the radiator 2 is not shown in order to simplify the drawing. Further, the configuration of the right end portion of the display unit 40 is the same as the configuration of FIG. 5 described below.

  As shown in FIG. 5, the display unit 40 includes a back metal plate 1, an LD holding member 4, a temperature measuring unit 9, an LED holding member 11, an auxiliary light guide plate 12, a reflection sheet 13, and a laser light guide plate. 14, LED auxiliary light guide plate 15, diffusion sheets 16 and 17, and liquid crystal display element 18.

  An LED holding member 11 is connected to the inner side of the back sheet metal 1. The LED holding member 11 is made of metal. Moreover, the shape of the LED holding member 11 is L-shaped. As described above, the laser light emitting element 5 is embedded in the LD holding member 4.

  The temperature range in which the LED light source 7 can be used is wider than that of the laser light emitting element 5. Therefore, the LED light source 7 has a margin for cooling as compared with the laser light emitting element 5. Therefore, as shown in FIG. 5, the aluminum substrate 10 on which the plurality of LED light sources 7 are surface-mounted is sufficiently separated (separated) from the laser light source array 6 and the radiator 2 by the LED holding member 11. It is arranged on the back sheet metal 1 at the position. That is, the LED light source array 8 composed of a plurality of LED light sources 7 is disposed at a position sufficiently away from the radiator 2 by a predetermined distance. The predetermined distance is a distance that the back sheet metal 1 can dissipate, for example, 90% or more of the amount of heat transmitted to the radiator 2 by heat generated by the LED light source array 8 (LED light source 7). . With the above configuration, the LED light source array 8 (LED light source 7) is thermally coupled to the back sheet metal 1 via the aluminum substrate 10 and the LED holding member 11.

  By disposing the LED light source array 8 (LED light source 7) at a position sufficiently away from the radiator 2 by a predetermined distance, the heat radiation performance of the LED light source 7 by the radiator 2 is lowered. Therefore, the temperature of the LED light source 7 rises as compared with the case where the LED light source array 8 is arranged to face the radiator 2 via the back metal plate 1. However, part of the heat generated in the LED light source array 8 is radiated from the surface of the back sheet metal 1 in the process of transferring heat to the radiator 2. Therefore, the amount of heat transmitted (inflow) from the LED light source array 8 to the radiator 2 is reduced. As a result, the ratio of the calorific value of the laser light emitting element 5 that can be emitted from the radiator 2 increases. That is, the temperature rise of the laser light emitting element 5 can be minimized.

  3 and 4 again, as described above, the plurality of laser light emitting elements 5 constituting the laser light source array 6 are arranged along the vertical direction (Y-axis direction). Hereinafter, the laser light emitting element 5 arranged at the top of the plurality of laser light emitting elements 5 constituting the laser light source array 6 is also referred to as the top light emitting element. The laser light emitting element 5e2 in FIG. 4 is the uppermost light emitting element.

  In the liquid crystal display device 100 in which each of the LED light source 7 and the laser light emitting element 5 serving as a heat source is arranged in an array in the vertical direction (Y-axis direction), the upper side of the liquid crystal display device 100 follows the flow of cooling air, It gets hotter. The laser light emitting element 5 has a narrower usable temperature range than the LED light source 7. Therefore, the most severe light source of the liquid crystal display device 100 is the laser light emitting element 5e2 arranged at the top of the plurality of laser light emitting elements 5 constituting the laser light source array 6.

  That is, if the temperature of at least the uppermost light emitting element (laser light emitting element 5e2) is measured and managed, other light sources will not break down in temperature. Therefore, in the liquid crystal display device 100 according to the present embodiment, the temperature measuring unit 9 is disposed in the vicinity of the uppermost light emitting element. For example, in FIG. 4, the temperature measurement unit 9a is disposed in the vicinity of the laser light emitting element 5e2 that is the uppermost light emitting element.

  Of course, a configuration in which the temperature measuring unit 9 is attached to the uppermost light emitting element (laser light emitting element 5e2) and the temperature of the uppermost light emitting element is directly measured is most preferable. However, since the size of the laser light emitting element 5 is small, there is no space for attaching the temperature measuring unit 9.

  Therefore, the temperature measuring unit 9 is disposed in the vicinity of the uppermost light emitting element (laser light emitting element 5e2). However, the temperature measuring unit 9 is disposed slightly apart from the uppermost light emitting element (laser light emitting element 5e2). Therefore, in order to accurately estimate the temperature of the uppermost light emitting element, it is necessary to correct the output value (measured temperature) of the temperature measuring unit 9. Hereinafter, the temperature of the uppermost light emitting element is also referred to as the uppermost element temperature.

  The thermal resistance (thermal conductivity) between the uppermost light emitting element (laser light emitting element 5e2) and the temperature measuring unit 9 can be uniquely determined from the structure. The amount of heat generated by the uppermost light emitting element (laser light emitting element 5e2) is approximately proportional to the forward current if the temperature of the laser light emitting element is constant. That is, if the forward current of the laser light emitting element (uppermost light emitting element) is determined, an approximate temperature gradient between the temperature measuring unit 9 and the uppermost light emitting element (laser light emitting element 5e2) can be estimated (calculated). It becomes possible.

  Next, a configuration for calculating (estimating) the uppermost element temperature and controlling the blower 3 using the uppermost element temperature will be described. As shown in FIG. 1, the liquid crystal display device 100 further includes a calculation unit 51. The calculation unit 51 is included in the control unit 50. The calculation unit 51 may not be included in the control unit 50 and may be provided independently of the control unit 50.

  Here, the calculation unit 51 constantly monitors the forward current amount of the uppermost light emitting element (laser light emitting element 5e2) included in the laser light source array 6. Moreover, the calculation part 51 acquires the measurement temperature which the temperature measurement part 9 measured at any time. Hereinafter, the thermal conductivity (thermal resistance) between the uppermost light emitting element and the temperature measuring unit 9 is expressed as thermal conductivity λ1. Further, the distance between the uppermost light emitting element and the temperature measuring unit 9 is expressed as a distance x. A temperature gradient between the temperature measuring unit 9 and the uppermost light emitting element (laser light emitting element 5e2) is referred to as a temperature gradient A.

  In this case, the calculation unit 51 calculates a correction value for obtaining the uppermost element temperature using the forward current amount of the uppermost light emitting element. Specifically, the calculation unit 51 calculates the amount of heat of the uppermost light emitting element corresponding to the forward current based on the fact that the amount of heat of the uppermost light emitting element is proportional to the forward current. And the calculation part 51 calculates the temperature gradient A calculated (estimated) by the formula of thermal resistance Rx (calculated calorie | heat amount) as a correction value using the thermal resistance R calculated beforehand. The thermal resistance R is a value calculated in advance by an equation of distance x / (thermal conductivity λ1 × cross-sectional area). The cross-sectional area is a cross-sectional area of a member that transfers heat existing between the uppermost light emitting element and the temperature measuring unit 9. The temperature gradient A indicates the difference between the uppermost element temperature and the measured temperature measured by the temperature measuring unit 9.

  Then, the calculating unit 51 calculates (estimates) the uppermost element temperature by adding the calculated correction value and the measured temperature obtained from the temperature measuring unit 9. Thereby, temperature correction for correcting the measured temperature is performed.

It should be noted that the temperature gradient is empirically about 1 to 2 K (Kelvin) when the screen luminance is 500 cd / m ² or less. Thus, the temperature gradient may be corrected using discrete values for the forward current value that changes continuously.

  And the control part 50 controls the air blower 3 so that the air blower 3 may perform the following processes. Although details will be described later, the blower 3 controls the amount of blown air according to the uppermost element temperature according to the control of the control unit 50. That is, the blower 3 controls the amount of blown air in accordance with a value (uppermost element temperature) obtained using the forward current amount of the uppermost light emitting element and the measured temperature measured by the temperature measuring unit 9.

  Next, the configuration of the display unit 40 will be further described.

  Referring again to FIG. 5, the light L <b> 5 emitted from the laser light emitting element 5 to the LED light source 7 side passes through the auxiliary light guide plate 12 and enters the laser light guide plate 14. An LED auxiliary light guide plate 15 is disposed on the liquid crystal display element 18 side of the laser light guide plate 14.

  In the LED auxiliary light guide plate 15, the blue-green light L 7 emitted from the LED light source 7 and the red light emitted from the laser light guide plate 14 are combined into white light. That is, the LED auxiliary light guide plate 15 emits white light. The white light is transmitted through the liquid crystal display element 18 constituting the display surface of the display unit 40 via the diffusion sheets 16 and 17. That is, the LED auxiliary light guide plate 15 is used as a light source of the liquid crystal display element 18.

  The temperature measurement unit 9 is disposed outside the region sandwiched between the laser light source array 6 and the LED light source array 8. Specifically, the temperature measuring unit 9 is disposed on the back sheet metal 1 inside the laser light emitting element 5, that is, on the side far from the LED light source 7. This is because the auxiliary light guide plate 12 is provided between the LED light source 7 and the laser light emitting element 5, so that there is little space and it is difficult to arrange the temperature measuring unit 9 in the vicinity of the laser light emitting element 5. Because there is.

  Further, the back sheet metal 1 on the LED light source 7 side is affected by the flow of heat from the LED light source 7 to the radiator 2. Therefore, when estimating the temperature of the laser light emitting element 5 from the measurement result (measurement temperature) of the temperature measuring unit 9, there is a possibility that an error becomes large. Therefore, in the present embodiment, the temperature measuring unit 9 is disposed on the back sheet metal 1 inside the laser light emitting element 5, that is, on the side far from the LED light source 7. Thereby, the error at the time of estimating the temperature of the laser light emitting element 5 from the measurement result of the temperature measurement part 9 can be reduced.

  In the air cooling system using the blower 3, noise such as the noise of the blower 3 and the wind noise in the radiator 2 varies depending on the shape of the radiator 2, the arrangement of obstacles adjacent to the blower 3, and the like. For example, the sound pressure increases as the amount of air blown by the blower 3 (the number of rotations of the fan) increases and the wind speed in the radiator 2 increases. Of course, it is needless to say that the noise is preferably small, but if the amount of air blown by the blower 3 (the number of rotations of the fan) is increased and the wind speed in the radiator 2 is increased, the cooling performance is improved.

  As described above, the red laser light-emitting element 5 having a wavelength of 630 to 640 nm, which is preferable as pure red, has a remarkable decrease in electro-optical conversion efficiency as the element temperature increases. Further, if the laser light emitting element 5 continues to emit high output light in a high temperature state, the deterioration of the element is accelerated and the life is shortened. That is, when the laser light emitting element 5 is used as a light source of a liquid crystal display device, the laser light emitting element 5 has a quality limit temperature necessary for guaranteeing product quality.

  FIG. 6 is a diagram illustrating an example of the relationship between the temperature of the uppermost light emitting element (the uppermost element temperature) and the rotational speed of the fan of the blower 3. The uppermost light emitting element is a laser light emitting element 5e2.

  In FIG. 6, a characteristic line L1 shows an example of control of the blower 3 when the laser light source array 6 is lit. A characteristic line L2 shows a control example of the blower 3 when the laser light source array 6 is turned off for a predetermined time (a certain time). The predetermined time is, for example, the time required for the temperature of the uppermost light emitting element that has been turned off after emitting light to be close to the temperature when the uppermost light emitting element has never emitted light. The case where the laser light source array 6 is turned off is a case where all the laser light emitting elements 5 constituting the laser light source array 6 are not emitting light.

  The control unit 50 controls the blower 3 so that the blower 3 performs the following processing. As described above, according to the control of the control unit 50, the blower 3 controls the amount of blown air according to the uppermost element temperature. That is, the blower 3 controls the amount of blown air in accordance with a value (uppermost element temperature) obtained using the forward current amount of the uppermost light emitting element and the measured temperature measured by the temperature measuring unit 9.

  More specifically, the blower 3 has a constant air flow rate when the uppermost element temperature, which is the temperature of the uppermost light emitting element, is lower than a predetermined threshold T1, and the uppermost element temperature when the uppermost element temperature is equal to or higher than the threshold T1. As the element temperature increases, the air flow rate is increased. That is, when the uppermost element temperature is equal to or higher than the predetermined threshold value T1, the blower 3 increases the air flow rate as the uppermost element temperature is higher. Details will be described below.

  When the temperature of the uppermost light emitting element is lower than the predetermined threshold value T1, the control unit 50 drives the fan of the blower 3 at the minimum necessary number of rotations (hereinafter referred to as the basic number of rotations). The said threshold value T1 is a threshold value (rotation speed change threshold value) of whether the rotation speed of the fan of the air blower 3 is changed. The threshold value T1 is set to a temperature lower than the aforementioned quality limit temperature.

  Further, the basic rotational speed is a rotational speed at which a wind having a wind speed equal to or higher than the rising airflow generated by natural air cooling is obtained. It should be noted that the rotation speed (basic rotation speed) of the fan of the blower 3 can be zero as long as the wind at the required wind speed can be secured in the radiator 2 by optimizing the aperture ratio of the air passage 2n. . Empirically, the rotational speed of the fan of the normal axial blower 3 may be about 30% of the maximum rated rotational speed. In this case, only background noise is generated. The maximum rated speed is the maximum speed of the fan of the blower 3.

  On the other hand, when the temperature of the uppermost light emitting element is equal to or higher than the threshold value T1 and the laser light source array 6 is lit, the rotational speed of the fan of the blower 3 is increased as the temperature of the uppermost light emitting element is increased. To do. When the temperature of the uppermost light emitting element is at least the quality limit temperature, the blower 3 rotates the fan at the maximum rated speed.

  In particular, when feedback control regarding luminance is performed, when the temperature of the uppermost light emitting element rises, the amount of heat generated by the uppermost light emitting element also increases. As a result, a spiral in which the temperature of the uppermost light emitting element further rises is entered. Once the temperature rise spiral is entered, the rate of temperature increase suddenly increases, so that the temperature of the uppermost light emitting element may exceed the quality limit temperature.

  Therefore, in the present embodiment, as the temperature of the uppermost light emitting element rises above the threshold value T1 that is set to a temperature lower than the quality limit temperature, the rotational speed of the blower 3 is increased to positively The laser light source array 6 is cooled. Thereby, in the normal use state, the noise level caused by the blower 3 does not become a problem, and the laser light emitting element 5 can be stably controlled even when the environmental temperature rises.

  When the laser light source array 6 is turned off for a predetermined time or longer, the blower 3 rotates the fan at the basic rotation speed even if the temperature of the uppermost light emitting element is equal to or higher than the threshold value T1.

  The liquid crystal display device 100 provided with the large heat radiator 2 has a large heat capacity. Therefore, even if the laser light-emitting element 5 is not generating heat, the temperature of the laser light-emitting element 5 whose temperature has once increased does not immediately decrease at a natural air cooling level. However, it goes without saying that the temperature of the laser light emitting element 5 should be kept as low as possible in preparation for the next lighting of the laser light emitting element 5.

  However, the acceleration coefficient with respect to the temperature of deterioration of the laser light emitting element 5 when the laser light source array 6 is not lit is much lower than that when the laser light emitting element 5 is lit. Further, since the laser emitting element 5 itself does not generate heat, the rotation speed of the fan of the blower 3 is sufficient to push out the warmed air in the radiator 2.

  Therefore, in this Embodiment, the air blower 3 may be controlled by the control part 50 as follows. Specifically, when the uppermost element temperature is equal to or higher than the threshold value T1 and the laser light source array 6 is turned off for a predetermined time or longer, the blower 3 sets the blower 3 to the maximum blower amount. The upper air temperature is equal to or lower than the predetermined air flow rate when the upper element temperature is lower than the predetermined threshold T1. The predetermined air blowing amount is the air blowing amount when the fan of the blower 3 is rotated at the basic rotation speed.

  That is, even when the temperature of the uppermost light emitting element is equal to or higher than the threshold value T1, if the laser light source array 6 is turned off for a predetermined time or longer, the fan of the blower 3 is rotated at the basic rotational speed or lower. Thereby, even when the laser light source array 6 is turned off for a predetermined time (a predetermined time) or more, noise does not become a problem and the laser light emitting element can be efficiently cooled.

  In the above description, the rotational speed of the fan of the blower 3 is linearly increased as the temperature of the uppermost light emitting element increases. However, the present invention is not limited to this. The rotational speed of the fan of the blower 3 may be increased stepwise (non-linearly) as the temperature of the uppermost light emitting element increases.

  Next, the process for controlling the rotation speed of the fan of the blower 3 in steps will be described.

  FIG. 7 is a diagram illustrating another example of the relationship between the temperature of the uppermost light emitting element (the uppermost element temperature) and the rotational speed of the fan of the blower 3. In FIG. 7, as in FIG. 6, the characteristic line L <b> 1 a indicates a control example of the blower 3 when the laser light source array 6 is lit. The characteristic line L2 is the same as described above.

  7 is different from the driving method of the blower 3 shown in FIG. 6 in that the rotational speed of the fan of the blower 3 is increased stepwise. Specifically, when the laser light source array 6 is lit, when the temperature of the uppermost light emitting element is equal to or higher than the threshold value T1, the rotational speed of the fan of the blower 3 is stepwise according to the temperature of the uppermost light emitting element. It is a point that is fast. That is, when the uppermost element temperature is equal to or higher than the threshold value T1, the blower 3 increases the amount of air blown stepwise as the uppermost element temperature increases.

  When generating the PWM command value of the blower using the control unit 50 (for example, a microcomputer) and controlling the rotational speed of the blower, the configuration for performing the continuous rotational speed control as shown in FIG. 6 is easy. It is possible to make. However, this configuration requires a relatively expensive blower that supports PWM.

  On the other hand, as shown in FIG. 7, when the rotation speed of the fan of the blower 3 is changed stepwise, a simple voltage control circuit constituted by a resistor and a switch may be used. Therefore, the cost of the blower is also lower than that of the PWM compatible product, and as a result, the blower rotation speed control system can be configured at a low cost. In the case of a configuration in which the rotation speed of the fan is changed stepwise, the blower 3 operates without control by the control unit 50.

  As described above, the radiators 2a and 2b are arranged symmetrically in the liquid crystal display device 100 of FIG. However, the laser light emitting element 5 has variations in electro-optical conversion efficiency, and the ambient temperatures of the radiators 2a and 2b are slightly different depending on the structure of the housing in which the liquid crystal display device 100 is incorporated. For this reason, the temperature of the left and right laser light-emitting elements 5 usually varies by about 1 to 2 K (Kelvin).

  However, the temperature difference between the left and right laser light emitting elements 5 is also caused by characteristic variations of the laser light emitting elements 5. For this reason, it is difficult to predict in advance which of the left and right laser light emitting elements 5 will always have a higher temperature.

  In the liquid crystal display device 100 using the laser light source array 6, as long as the temperature of the laser light emitting element having the highest temperature can be managed, other light sources will not break down in temperature. However, as long as the temperature of the left and right laser light emitting elements cannot be predicted, it is necessary to arrange a pair of temperature measuring units 9 symmetrically as described above and measure the temperature of the left and right uppermost light emitting elements. There is.

  Therefore, in the present embodiment, the rotational speeds of the fans of the left and right blowers 3 are determined based on the measurement results of the temperatures of the left and right uppermost light emitting elements (laser light emitting elements 5). Specifically, in the liquid crystal display device 100 according to the present embodiment, the left blower 3a controls the amount of blown air using the measured temperature of the left temperature measurement unit 9a, and the right blower 3b is on the right side. The process of controlling the air flow using the measured temperature of the temperature measuring unit 9b is performed independently.

  The above-described configuration for controlling the rotation speed of the fans of the left and right blowers controls the rotation speed of the fans of the left and right blowers 3a and 3b based on the temperature of the laser light emitting element having the highest temperature in the liquid crystal display device 100. There is a possibility that the number of rotations of the fan of the blower on the lower temperature side can be set lower than that of the configuration to be performed. As a result, it is possible to efficiently cool the laser light emitting element while minimizing the generation of noise.

  As described above, in the liquid crystal display device 100 according to the present embodiment, the blower 3 is measured by the forward current amount of the uppermost light emitting element and the temperature measuring unit 9 disposed in the vicinity of the uppermost light emitting element. The amount of blown air is controlled according to a value (top element temperature) obtained by using the measured temperature. Thereby, the air blower 3 can perform more suitable ventilation.

  Moreover, the air blower 3 is arrange | positioned at the lower part of the heat radiator 2, and ventilates to the air path 2n along a perpendicular direction. Therefore, the air sent to the air path 2n travels from the lower part of the radiator 2 to the upper part along the air path 2n. Thereby, the laser light source array 6 and the LED light source array 8 which are light sources can be cooled efficiently. That is, the light source can be cooled with a simple configuration in which the blower 3 blows air to the air path 2n along the vertical direction. Therefore, the light source can be efficiently cooled with a simple configuration.

  In addition, since the liquid crystal display device 100 according to the present embodiment is configured as described above, the light source is quiet and efficient with a simple (inexpensive) cooling system having a wide color reproduction range. Can be cooled. As a result, the liquid crystal display device 100 can display an image stably.

  In the present invention, the embodiments can be appropriately modified and omitted within the scope of the invention.

  The present invention can be used as a liquid crystal display device capable of efficiently cooling a light source with a simple configuration.

  1 Back plate, 2, 2a, 2b Radiator, 3, 3a, 3b Blower, 4, 4a, 4b, 4c, 4d, 4e LD holding member, 5, 5a1, 5a2, 5b1, 5b2, 5c1, 5c2, 5d1 , 5d2, 5e1, 5e2 Laser light emitting element, 6, 6a, 6b Laser light source array, 7 LED light source, 8, 8a, 8b LED light source array, 9, 9a, 9b Temperature measuring unit, 40 display unit, 50 control unit, 51 Calculation unit, 100 Liquid crystal display device.

Claims (9)

A laser light source array composed of a plurality of laser light emitting elements arranged along the vertical direction;
An LED light source array composed of a plurality of LED (Light Emitting Diode) light sources arranged along the vertical direction;
An air passage along a vertical direction is provided, and a heat radiator that radiates heat from the laser light source array and the LED light source array;
A blower that is disposed at a lower portion of the radiator and blows air to the air passage;
A temperature measuring unit for measuring the temperature,
The temperature measurement unit is disposed in the vicinity of the uppermost light emitting element which is a laser light emitting element disposed at the uppermost part among the plurality of laser light emitting elements,
The air blower controls the air flow rate according to a value obtained by using a forward current amount of the uppermost light emitting element and a measured temperature that is a temperature measured by the temperature measuring unit. The liquid crystal display device further includes:
A calculation unit that calculates a correction value for obtaining the temperature of the uppermost light emitting element using the forward current amount;
The calculation unit further calculates the uppermost element temperature, which is the temperature of the uppermost light emitting element, by adding the correction value and the measured temperature,
The liquid crystal display device according to claim 1, wherein the blower controls the amount of blown air in accordance with the uppermost element temperature. The liquid crystal display device according to claim 1, wherein, when the uppermost element temperature is equal to or higher than a predetermined threshold, the blower increases the amount of airflow as the uppermost element temperature is higher. The liquid crystal display device further includes a sheet metal,
In the sheet metal, the LED light source array and the laser light source array are arranged in a horizontal direction perpendicular to the vertical direction,
The laser light source array is disposed inside the sheet metal than the LED light source array,
The liquid crystal display device according to claim 1, wherein the radiator is disposed only on a back surface of the laser light source array via the sheet metal. The liquid crystal display device according to claim 1, wherein the temperature measurement unit is disposed outside a region sandwiched between the laser light source array and the LED light source array. When the uppermost element temperature, which is the temperature of the uppermost light emitting element, is less than a predetermined threshold value, the blower has a constant air flow rate. The liquid crystal display device according to claim 1, wherein the air flow rate is increased according to. The liquid crystal display device according to claim 6, wherein when the uppermost element temperature is equal to or higher than the threshold value, the blower increases the amount of airflow stepwise as the uppermost element temperature increases. When the uppermost element temperature is equal to or higher than the threshold and the laser light source array is extinguished for a predetermined time or longer, the blower determines the amount of air blown from the blower by the uppermost element temperature. The liquid crystal display device according to any one of claims 1 to 5, wherein the liquid crystal display device is set to be equal to or less than a predetermined air blowing amount in a case of less than a predetermined threshold value. The liquid crystal display device
A pair of the laser light source array, the LED light source array, the radiator, the blower, and the temperature measurement unit, which are respectively disposed on the left side and the right side of the liquid crystal display device;
The liquid crystal display device
The process in which the blower on the left uses the measurement temperature of the temperature measurement unit on the left side to control the air flow rate, and the process in which the blower on the right controls the air flow rate using the measurement temperature of the temperature measurement unit on the right side The liquid crystal display device according to claim 1, wherein the liquid crystal display device is performed independently.

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