JP4423666B2 - Discharge tube lighting device and display device - Google Patents

Description

  The present invention relates to a discharge tube lighting device and a display device, and more particularly to a discharge tube lighting device and a display device capable of suppressing infrared rays emitted from the discharge tube.

  2. Description of the Related Art A discharge tube filled with mercury and a discharge gas containing argon, such as a cold cathode fluorescent tube (CCFL Cold Cathode Fluorescent Lamp), has been widely used as a light source for a backlight of a display device such as a liquid crystal television. A cold cathode fluorescent tube comprises a glass tube filled with rare gas such as neon gas, argon gas and xenon gas and mercury, a pair of electrodes disposed therein, and a fluorescent film coated on the inner wall of the glass tube. I have. One end of an introduction line is connected to the pair of electrodes of the discharge tube, and the other end of the introduction line is led out from both ends of the glass tube. When a voltage is applied between the pair of electrodes, electrons are emitted from one electrode, and the electrons collide with mercury atoms in the glass tube to generate ultraviolet rays. This ultraviolet light is wavelength-converted into visible light by a fluorescent film formed on the inner wall of the glass tube.

  FIG. 13 shows a liquid crystal television display (1) as an example of a display device including a cold cathode fluorescent tube as a light source for backlight. The display (1) includes a cold cathode fluorescent tube as a backlight light source and a discharge tube lighting device (30) in the main body. In recent years, this type of display (1) includes an infrared receiver (6) in the display body, and is configured to be able to control channel switching and the like by an infrared signal (21) from a remote controller (8). .

  However, this type of conventional display (1) has a problem that it cannot be controlled well by the remote controller (8) during the initial period when the screen is displayed on the display (1). When the discharge tube is turned on, light (22) emitted from the discharge tube is emitted to the outside from the display screen of the display (1), and part of the light is reflected by the ground and reaches the infrared receiver (6). The light (22) emitted from the discharge tube includes infrared rays having a wavelength of about 910 nm emitted from a discharge gas (argon gas) filled in the discharge tube. Due to this infrared ray, the infrared receiving device (6) cannot distinguish and recognize the infrared signal (21) of the remote controller (8), and the display (1) cannot be controlled. As a countermeasure, for example, as shown in Patent Document 1 below, it has been considered to provide an additional part such as an infrared cut sheet that blocks infrared rays adjacent to the backlight.

JP 2002-323860 A

  However, there is a problem that the cost of the display device is increased due to additional components such as an infrared cut sheet. Further, additional parts such as an infrared cut film (multilayer film) that does not attenuate visible light are very expensive and are not practical from this point.

  Therefore, an object of the present invention is to provide a discharge tube lighting device and a display device that can suppress infrared emission of the discharge tube by circuit control of the discharge tube lighting device without using an additional part such as an infrared cut sheet. . It is another object of the present invention to provide a discharge tube lighting device and a display device that can solve the problem that control by a remote controller cannot be performed in an initial period after the screen is displayed on the display.

  The discharge tube lighting device of the present invention includes a power generation device (4) for supplying power to the discharge tube (2) and a power control device (3) for controlling the output power of the power generation device (4). The power control device (3) includes a first power control means for controlling the output power of the power generation device (4) in the first period at the start of power supply to the first power, and a second following the first period. A second power control means for controlling the output power of the power generation device (4) in the period of time to a second power smaller than the first power, and a power generation device (4 in the third period following the second period) And a third power control means for controlling the output power to a third power that is larger than the second power and smaller than the first power. If a relatively large amount of power is supplied to the discharge tube (2) in the first period at the start of power supply, the tube temperature of the discharge tube (2) rises in a short time. For this reason, even if a relatively small amount of power is supplied to the discharge tube (2) during the second period following the first period, the tube temperature of the discharge tube (2) is maintained at a relatively high temperature. Therefore, the mercury vapor pressure in the pipe can be kept high. In such a state, that is, in a state where the tube temperature is high and the supply tube power is low, infrared radiation to the outside from the discharge tube (2) can be effectively suppressed. This is because the infrared rays generated in the tube collide with the mercury vapor in the tube and are absorbed, and the higher the mercury vapor pressure in the tube, the higher the probability of absorption, which is presumed to suppress infrared emission. .

  As a result, since the emission of infrared rays can be suppressed from the second period, malfunctions caused by infrared rays (infrared rays radiated from the discharge tubes) of the devices and peripheral devices provided with the lighting device in periods other than the first period. Can be prevented.

Since infrared emission from the discharge tube after the first period (second and third periods) can be suppressed, the power generator supplies the discharge tube without using additional parts such as an infrared cut sheet. Infrared emission from the discharge tube can be suppressed only by controlling the electric power.
In the case of a display device incorporating this lighting device, an infrared signal is transmitted from the remote controller to the display device from the second period, and control such as channel switching becomes possible.

  Hereinafter, an embodiment of a discharge tube lighting device and a display device according to the present invention will be described with reference to FIGS.

  For example, as shown in FIG. 1, a display device such as a liquid crystal television includes a display (1) composed of a known device such as a liquid crystal panel, a discharge tube (2) that functions as a light source of the display (1), and a discharge tube ( 2) a discharge tube lighting device (10) for lighting in accordance with the present invention, and a switch for controlling on / off of power supplied from a DC power source (5) to a device constituting the display device such as the discharge tube lighting device (10) (7) and an infrared receiver (6) that receives the infrared signal (21) from the remote controller (8) and turns the switch (7) on and off. The display (1), the discharge tube (2), the discharge tube lighting device (10), the switch (7) and the infrared receiving device (6) are integrally incorporated in the main body of the display device.

  The discharge tube (2) is a cold cathode fluorescent tube in which the discharge tube (2) is filled with argon gas and mercury as a discharge gas. For this reason, infrared light having a wavelength of about 910 nm is inevitably emitted by argon gas at the beginning of lighting of the discharge tube (2). The DC power source (5) rectifies commercial AC and outputs DC power, and supplies predetermined DC power to the discharge tube (2) and the display (1). The infrared receiving device (6) is composed of a light receiving element such as a phototransistor, and is configured to sense infrared rays having a wavelength near 910 nm. For this reason, the receiving operation of the infrared receiver (6) is affected by the infrared rays emitted from the discharge tube (2).

  The discharge tube lighting device (10) includes an inverter (4) that converts DC power from a DC power source (5) into AC power, and output power of the inverter (4), that is, power applied to the discharge tube (2). And a power control device (3) for controlling according to the present invention. The power control device (3) is configured by a program-controllable one-chip microcomputer or a discrete circuit, and supplies power supplied to the discharge tube (2) in a first period following the turn-on of the switch (7). First power control means for controlling the power, and second power for controlling the power supplied to the discharge tube (2) in the second period following the first period to a second power smaller than the first power The control means and a third power that is supplied to the discharge tube (2) in the third period (rated power supply period) after the second period is larger than the second power amount and smaller than the first power amount. And third power control means for controlling the power (rated power).

  In the present embodiment, the first period and the initial period of the second period are included in the non-display period of the screen of the display (1). The first period is an initial period in which the switch (7) is turned on and AC power is applied to the discharge tube (2) through the inverter (4). The first period starts at the first time point when the switch (7) is turned on. , Indicates the period when the display (1) is set up and displayed on the screen or at the second time before the screen display. Accordingly, the first period includes at least an initial period of a period during which no screen is displayed on the display (1) (non-display period). The first period is set to about 10 seconds, for example. The second period starts from the end of the first period, that is, the second time point, and includes the initial period of the display (display period) after the setup of the display (1) is completed. It shows the display period from when the display (1) is displayed on the screen after the period until it shifts to the predetermined rated power. When the second time point is before the setup of the display (1) is completed, the second period includes a non-display period and a subsequent display period. The second period is set to about 10 seconds, for example. The third period starts at the third time point, and predetermined rated power is supplied to the discharge tube (2). The rated power is not necessarily constant, and can be controlled according to conditions such as the brightness of room lighting, for example. The rated power control technique according to the conditions is a well-known technique and will not be described.

  The present invention is not a technique for controlling the rated power, but is characterized by controlling the power supplied to the discharge tube (2) in the period before the rated power supply period (third period). In the conventional display device, the same rated power as that in the third period is supplied to the discharge tube in the first period and the second period. That is, from the time when the switch (7) of the display device is turned on to the time when the switch is turned off, the display device is connected to the discharge tube (2) for each display device without distinguishing the first period, the second period, and the third period. The rated power set forth in 1 was being supplied. For this reason, a relatively large amount of infrared rays due to the discharge gas is emitted from the discharge tube at the beginning of the non-display period and the display period, and the screen is displayed on the display (1), but the predetermined immediately after the screen display. During the period, inconvenience that could not be controlled by the remote controller (8) occurred. In the discharge tube lighting device (10) according to the present invention, the amount of power supplied to the discharge tube (2) in the first period and the second period is the first power larger than the rated power and the first power smaller than the rated power. The infrared rays emitted from the discharge tube (2) can be controlled by controlling the power to 2 respectively.

  The graph of FIG. 2 shows changes in the tube temperature (tube wall temperature) of the discharge tube (2) in the first period, the second period, and the third period. In the conventional discharge tube lighting device (30) that supplies a constant rated power to the discharge tube (2), the tube temperature gradually increases as the energization time of the discharge tube (2) elapses. On the other hand, in the discharge tube lighting device (10) of the present invention, since the power larger than the rated power is supplied in the first period, the tube temperature of the discharge tube (2) rises to a high temperature in a short time. However, a large amount of mercury vapor is dispersed in the discharge tube (2). In the second period following the first period, relatively small power is supplied to the discharge tube (2), but the tube temperature of the discharge tube (2) is already maintained at a high temperature in the first period. Therefore, the mercury vapor pressure in the discharge tube (2) is kept high. In such a state, that is, in a state where the tube temperature is high and the supply tube power is low, infrared radiation to the outside from the discharge tube (2) can be effectively suppressed. This is because the infrared rays generated in the tube collide with the mercury vapor in the tube and are absorbed, and the higher the mercury vapor pressure in the tube, the higher the probability of absorption, which is presumed to suppress infrared emission. . In addition, in the second period, the supply power is small and the amount of infrared radiation generated by the discharge gas itself can be reduced. Therefore, coupled with the infrared suppression effect of mercury vapor, the infrared radiation to the outside of the display (1) Release can be well controlled. As a result, immediately after the screen is displayed on the display (1), operations such as screen switching by the remote controller (8) can be performed.

  Next, the operation of the discharge tube lighting device and the display device of the present invention will be described according to the operation procedure shown in the flowchart of FIG. First, when the switch (7) of the display device is turned on in step 50, power is supplied to the display (1), and the setup operation of the display (1) starts (step 51). However, the setup operation of the display (1) is not completed immediately, and a certain delay time (delay) is provided until the display (1) is displayed on the screen. During this time, the discharge tube lighting device (10) supplies the discharge tube (2) with the first power larger than the rated power (step 52). When the switch (7) of the display device is turned on, the first signal is input from the power control device (3) to the inverter (4), and the operation of the inverter (4) is started. The output power of the inverter (4) is controlled by a signal from the power control device (3) and is larger than the rated power in the discharge tube (2) in the first period until the display (1) is displayed on the screen. A first power is applied.

  When a certain delay time has elapsed, the setup operation of the display (1) is completed (step 53), and a screen is displayed on the display (1) (step 55). The power control device (3) supplies the second signal to the inverter (4) simultaneously with or slightly before the screen display of the display (1) in step 55. As a result, the output power of the inverter (4) becomes a second power smaller than the first power (step 54). After a predetermined time has elapsed since the screen was displayed on the display (1), the power control device (3) gives a third signal to the inverter (4). As a result, the output power of the inverter (4) becomes the third power (step 56). At the beginning of lighting of the discharge tube (2), the tube current and the tube voltage are likely to change due to the influence of the impedance of the discharge gas and the like. Accordingly, the first power, the second power, and the third power indicate average power in each period. The power control device (3) controls the output power of the inverter (4) to the third power until the display device is turned off in step 57.

  Next, referring to FIG. 4 as the first embodiment, the amplitude (crest value) of the output current (output voltage) of the inverter (4) is changed to change the power in the first period and the second period. The discharge tube lighting device to be controlled will be described. As shown in FIG. 4, the inverter (4) includes an output transformer (9) and an oscillation circuit (18). The output transformer (9) includes a primary winding (11) with a center tap, a secondary winding. (12) and a feedback winding (13). A discharge tube (2) is connected in parallel to both ends of the secondary winding (12) via a varactor capacitor (17). The varactor capacitor (17) has a function of limiting an overcurrent flowing through the discharge tube (2) by a high voltage applied at the beginning of lighting. The oscillation circuit (18) is configured as a positive feedback amplifier circuit including a primary winding (11), a feedback winding (13), transistors (14, 15), and a capacitor (16). That is, a pair of transistors (14, 15) and a capacitor (16) are connected in parallel to both ends of the primary winding (11), and the base of one transistor (14) and the base of the other transistor (15) are Each is connected to one end and the other end of the feedback winding (13).

  The power control device (3) includes a transistor (19) having a collector connected to the positive output terminal of the DC power supply (5) and an emitter connected to the positive output terminal of the inverter (4), and this transistor ( And an amplifier circuit (26) having an output terminal connected to the base of 19). The base of one transistor (14) and the base of the other transistor (15) are connected to the emitter of the transistor (19) via resistors (24, 25), respectively. When the input voltage of the amplifier circuit (26) is increased, the output voltage of the power control device (3) increases, and as a result, the output current of the inverter (4) increases. On the other hand, when the input voltage of the amplifier circuit (26) is lowered, the output voltage of the power control device (3) is lowered, and as a result, the output current of the inverter (4) is reduced. Therefore, the power in the first period is set to the first power, the power in the second period following the first period is set to the second power smaller than the first power, and the third period following the second period. In order to control the power of the second power to a third power that is larger than the second power and smaller than the first power, a relatively high voltage is applied to the input terminal of the amplifier circuit (26) during the first period, A voltage lower than the voltage of the first period may be applied to the second period, and a voltage lower than the voltage of the first period and higher than the voltage of the second period may be applied to the third period. FIG. 5B shows the transition of the power supplied to the discharge tube (2) in the first period, the second period, and the third period. By controlling the input voltage of the amplifier circuit (26), that is, the output current of the inverter (4) as shown in FIG. 5 (a), the power control shown in FIG. 5 (b) becomes possible.

  In the embodiment of the present invention, the same circuit is caused to function as the first power control means, the second power control means, and the third power control means by program control, but the first power control means, the second power control means, The power control means and the third power control means may be constructed by separate circuits in the power control device (3).

  Next, with reference to FIG. 6 as a second embodiment, a discharge tube lighting device for controlling the power in the first period and the second period by providing a pause period in the output of the inverter (4) will be described. . The inverter (4) is an output transformer having a primary winding (11) with a center tap, a secondary winding (12), and a feedback winding (13), as in the discharge tube lighting device of the first embodiment. (9) and an oscillation circuit (18) configured as a positive feedback amplifier circuit including a primary winding (11), a feedback winding (13), transistors (14, 15), and a capacitor (16). . In the inverter (4), a transistor (23) constituting a switch is connected to a connection point between the emitter of one transistor (14) constituting the oscillation circuit (18) and the emitter of the other transistor (15). The base of one transistor (14) and the base of the other transistor (15) are connected to the positive terminal of the DC power supply (5) via resistors (24, 25), respectively. The connection point between the emitter of one transistor (14) and the emitter of the other transistor (15) is connected to the collector of the transistor (23) and is grounded via the transistor (23). The output signal of the power control device (3) is applied to the base of the transistor (23). When the transistor (23) is turned off based on the output signal from the power control device (3), the primary winding (11), the feedback winding (13), the transistors (14, 15), and the capacitor (16) are configured. Oscillation of the oscillation circuit (18) stops.

  The power control device (duty ratio control means) (3) controls the output power of the inverter (4), that is, the AC power supplied to the discharge tube (2). Specifically, when an ON signal is input from the power control device (3) to the base of the transistor (23), the transistor (23) is turned on, the oscillation circuit (18) oscillates, and the discharge tube (2 ) Is supplied with AC power. On the other hand, when an off signal is input from the power control device (3) to the base of the transistor (23) and the transistor (23) is turned off, the oscillation of the oscillation circuit (18) stops and the discharge to the discharge tube (2) The supply of AC power stops (rest period). Therefore, changing the duty ratio [AC power output period / (AC power output period + pause period)] during the AC power output period by the power control device (3), that is, the period during which AC power is output from the inverter (4). Thus, the magnitude of the AC power applied to the discharge tube (2) can be controlled. In contrast to the amount of output power of the inverter (4) shown in FIG. 7 (a), the power control device (3) of FIG. 4 uses the amplitude of the output current of the inverter (4) as shown in FIG. 7 (b). 6 is controlled, the power control device (3) in FIG. 6 controls the power amount by changing the duty ratio as shown in FIG. 7C. The AC power output period in which AC power is output from the inverter (4) is controlled at a predetermined interval by the power control device (3) through the pause period, and the AC power output period and the pause period are alternately provided.

  Increasing the duty ratio in the AC power output period, in other words, decreasing the duty ratio in the pause period, increases the AC power (average power) applied to the discharge tube (2). As shown in FIG. 8, the power in the first period is set to the first power, the power in the second period following the first period is set to the second power smaller than the first power, and the power is supplied in the second period. In order to control the power in the subsequent third period to a third power that is greater than the second power and smaller than the first power, the duty ratio of the AC power output period in the first period is relatively The duty ratio of the AC power output period in the second period is relatively decreased, and the duty ratio of the AC power output period in the third period is set to be equal to the duty ratio of the AC power output period in the first period. It is set between the duty ratio of the AC power output period in period 2. FIG. 8B shows the transition of the power supplied to the discharge tube (2) in the first period, the second period, and the third period in the discharge tube lighting device of the second embodiment. By controlling the duty ratio of the output of the inverter (4) in the first period, the second period, and the third period as shown in FIG. 8A, the power control shown in FIG. 8B is possible. It becomes. The duty ratio in each period can be set by a control means such as a timer circuit built in the power control device (3), for example.

  In the first and second embodiments described above, the first period is a period during which mercury vapor sufficient to raise the tube temperature of the discharge tube (2) and suppress infrared emission in the tube is generated. Thus, the optimum value for the first period can be confirmed experimentally. For example, the greater the input power in the first period, the greater the infrared suppression effect in the second period. However, if too much power is applied, the lamp life is affected, so it is necessary to set the power appropriately. Similarly, the optimum value for the second period can also be confirmed experimentally. Therefore, the timing of switching from the first period to the second period can be set in advance, but may be switched by a detection means (not shown) that detects when the setup operation of the display (1) is completed. In the embodiment, a self-excited oscillation circuit is used, but a separately excited oscillation circuit can also be used. Therefore, the means for stopping the oscillation of the oscillation circuit (18) is not limited to the example shown in FIG. In the power control device (3) of FIG. 4, in order to control the power by changing the amplitude of the output current (output voltage) of the inverter (4), a discharge tube (2) as in the power control device (3) of FIG. It is not necessary to change the duty ratio of the AC power supplied to) in each period. For example, the duty ratio during the AC power output period may be fixed to 100%.

  11 and 12 are experimental data showing the infrared radiation intensity and luminance change of the present invention as Example 1 and Example 2. FIG. In the experiment, a 22-inch liquid crystal display (adopting a direct backlight using a cold cathode tube) was used. The first period (non-display period) was set to 10 seconds, and the second period after display (display period) (display period) was set to 10 seconds.

  As a conventional technique, the output current of the inverter (4) is set to be constant at 5.0 mA and the duty ratio is 100%. When control is performed with a constant output current in this way, the vapor pressure in the tube rises as the tube temperature rises, and the amount of infrared emission gradually attenuates. At this time, the luminance gradually increases as the ambient temperature (tube temperature of the discharge tube) increases. In Example 1, as shown in FIG. 9, the output current (tube current) of the inverter (4) is 9.0 mA for the first period, 3.0 mA for the first 5 seconds of the second period, The remaining period of 5 seconds was set to 4.0 mA for the third period, 5.0 mA for the third period, and the duty ratio was set constant at 100%. As for the power supplied to the discharge tube in FIG. 9 (c), the supply power is constant if the output current is constant for convenience of explanation, but the tube voltage actually increases slightly as the tube temperature rises even if the output current is the same. The tube power is reduced. In the second embodiment, as shown in FIG. 10, the output current of the inverter (4) is set to 9.0 mA for the first period, the duty ratio is set to 100%, and to 5.0 mA for the third period. The ratio is set to 100%, and in the second period, the output current value is gradually attenuated from 9.0 mA to 5.0 mA and the duty ratio is gradually increased from 50% to 100%. The electric power supplied to the discharge tube was set to gradually increase. Furthermore, in the comparative example, the output current of the inverter is set to 9.0 mA for the first period, 5.0 mA for the second period and the third period, and the duty ratio is set to the first, second and third periods. The period was set at a constant 100%.

  FIG. 11 is a graph showing the radiation intensity of infrared rays emitted from the liquid crystal surface with respect to the elapsed time after the switch (7) is turned on. In the display device such as the liquid crystal television of this embodiment, if the relative radiant intensity of infrared rays emitted from the display (1) is lower than 60 a.u., the infrared receiving device (6) is emitted from the discharge tube. Does not cause malfunction due to infrared rays. As shown in FIG. 11, in contrast to the prior art and the comparative example, the first and second embodiments of the present invention are 1 to 2 from the completion of the setup of the display (1) after 10 seconds after the switch (7) is turned on. In about 2 seconds, the infrared radiation intensity is greatly reduced to 60 a.u. or less and sufficiently suppressed. In the comparative example, although the infrared radiation intensity can be greatly reduced as compared with the prior art, the malfunction is caused by infrared rays for about 5 seconds after the switch (7) is turned on, so that the effect is insufficient.

  As a result, in the discharge tube lighting device (10) according to the first and second embodiments, the remote controller (10) immediately after the display (1) is displayed on the screen by controlling the power supplied to the discharge tube (2). It can be seen that control such as channel switching can be performed by transmitting the infrared signal of 8) to the display device. Moreover, the amount of infrared rays emitted after the display (1) is displayed on the screen can be sufficiently suppressed by switching from the first period to the second period substantially simultaneously with the completion of the setup of the display (1). The switching from the first period to the second period may be performed before the setup of the display (1) is completed. In the past, the display device such as a liquid crystal television could not be switched and controlled by the remote controller (8) for about 10 seconds in the initial state after the screen display on the display, and when the temperature was low, the period more than doubled. We were able to solve the problem.

  FIG. 12 is a graph showing the light emission intensity as the luminance on the liquid crystal surface with respect to the elapsed time after the switch (7) is turned on. As shown in FIG. 12, in the first and second embodiments of the present invention, when the second period starts, the power supplied to the discharge tube (2) is once reduced and the power is gradually increased. At the beginning of this period, the luminance once decreases, but the luminance increases as the power increases. By increasing the power in the second period, the luminance can be increased in a short time. In the comparative example, since a large current is supplied during the first period, the tube temperature rises quickly and the luminance can be increased in a short time, but there is a problem that the infrared radiation period is long. Therefore, in Example 1 and Example 2, it turns out that the infrared rays emitted from the discharge tube (2) can be effectively suppressed and the luminance rise time can be shortened.

  The present invention is not limited to the embodiment shown in FIGS. 1 to 12, and can be implemented in other forms and includes all modifications that fall within the scope of the claims. In the embodiment, the basic operation of the power control device (3) is that the switching from the first period to the second period is performed at the time of switching between the non-display period and the display period of the display device. Switching from the first period to the second period may be performed within the non-display period of the display device or within the display period after the non-display period although the effect of suppressing the emission of infrared rays from the discharge tube (2) is reduced. . The output power of the inverter (4) is not limited to either the amplitude control of the output current of the inverter (4) or the duty ratio control, and both may be performed during the same period. Further, the output power of the inverter (4) may be increased stepwise or continuously. Further, the power in the first period may be set higher than 9.0 mA shown in the first and second embodiments in order to raise the tube temperature of the discharge tube (2) in a shorter time. Although there is a problem such as a decrease in the life of the discharge tube (2), the amount of power in the first period may be set as high as about 15.0 mA, for example, and the numerical range of the output current or duty ratio of the inverter (4) Is not intended to limit the invention. Furthermore, the delay time provided in the setup of the display (1) may be set as appropriate together with the first period, the second period, and the third period. Further, the control period of the output power of the inverter (4) is not limited to the first period, the second period, or the third period, and other periods such as a fourth period may be provided. The present invention is not limited to a liquid crystal television, and can be applied to a display device such as a personal computer, a navigation display, a video monitor, or an amusement display.

  Furthermore, in the present invention, reception stop means (not shown) for stopping the infrared reception operation of the infrared receiver (6) during the non-display period of the screen of the display (1) may be provided. For example, the reception stopping means receives infrared signals (21) from the remote controller (8) and infrared rays emitted from the discharge tube (2) into the light receiving element of the infrared receiving device (6) for a certain period of time according to the non-display period. It is a control device that prevents light from being emitted. During the non-display period of the screen of the display (1), the infrared receiver (6) stops the infrared reception operation, and the infrared receiver radiates during the non-display period by the infrared rays emitted by the large current supply of this embodiment. It is possible to prevent malfunction.

  The present invention can be applied to a display device such as a liquid crystal television using a discharge tube that generates infrared rays in a backlight.

Electrical circuit diagram showing an embodiment of a discharge tube lighting device and a display device according to the present invention Graph showing change in tube temperature with time to discharge tube The flowchart which shows operation | movement of the discharge tube lighting device by this invention, and a display apparatus. Electrical circuit diagram showing the inverter of the first embodiment The graph which shows transition of the electric power supplied to the discharge tube by 1st Embodiment Electric circuit diagram showing an inverter of a second embodiment Waveform diagram showing changes in output current and duty ratio with respect to inverter output power The graph which shows transition of the electric power supplied to the discharge tube by 2nd Embodiment The graph which shows control of the output current with respect to the output power of the inverter of Example 1, and a duty ratio The graph which shows control of the output current with respect to the output power of the inverter of Example 2, and a duty ratio The graph which shows the infrared rays suppression effect of Example 1 and Example 2 The graph which shows the brightness | luminance rise characteristic of Example 1 and Example 2 A perspective view showing a conventional liquid crystal television and a remote controller for switching and controlling the liquid crystal television

Explanation of symbols

  (1) ・ ・ Display, (2) ・ ・ Discharge tube, (3) ・ ・ Power control device, (4) ・ ・ Power generator (inverter), (6) ・ ・ Infrared receiver, (18) ・ ・Oscillation circuit,

Claims (10)

A discharge tube filled with a discharge gas containing mercury and mercury, a power generation device for supplying power to the discharge tube, and a power control device for controlling the output power of the power generation device,
The power control device
First power control means for controlling the output power of the power generation device in the first period at the start of power supply to the first power;
Second power control means for controlling the output power of the power generation device in a second period following the first period to a second power smaller than the first power;
Third power control means for controlling the output power of the power generation device in a third period following the second period to a third power that is larger than the second power and smaller than the first power. A discharge tube lighting device comprising: The discharge tube is a light source of a display;
The discharge tube lighting device according to claim 1, wherein the first period is included in a non-display period of the screen of the display.   The discharge tube lighting device according to claim 1 or 2, wherein an initial period of the second period is included in a non-display period of the display screen.   The said power control apparatus is provided with the switching element which stops the output of the said power generation device, and controls the output electric power of the said power generation device with the duty ratio of ON / OFF of the said switching element. The discharge tube lighting device according to item. The power generation device includes an oscillation circuit,
5. The discharge tube lighting device according to claim 1, wherein the power control device controls output power of the power generation device based on a duty ratio between an oscillation period and an oscillation pause period of the oscillation circuit.   The discharge lamp lighting device according to any one of claims 1 to 5, wherein the power control device controls output power of the power generation device by changing an output amplitude of the power generation device.   The discharge tube lighting device according to any one of claims 1 to 6, wherein an infrared ray emission amount from the discharge tube in the second period is smaller than an infrared ray emission amount from the discharge tube in the first period. .   The discharge tube lighting device according to any one of claims 1 to 7, wherein the discharge tube is heated in the first period to disperse mercury vapor in the discharge tube. A display comprising a discharge tube containing argon and a discharge tube filled with mercury and an infrared receiver for receiving a control signal of a remote controller, a power generator for supplying power to the discharge tube, and a power generator for the power generator A power control device for controlling the output power,
The power control device
First power control means for controlling the output power of the power generation device in the first period at the start of power supply to the first power;
Second power control means for controlling the output power of the power generation device in a second period following the first period to a second power smaller than the first power;
Third power control means for controlling the output power of the power generation device in a third period following the second period to a third power that is larger than the second power and smaller than the first power. And
The display device according to claim 1, wherein the first period is included in a non-display period of the display screen.   The display device according to claim 9, further comprising a reception stop unit that stops an infrared reception operation of the infrared reception device during a non-display period of the screen of the display.

Images