JP2008034221A - Lamp driving control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lamp driving control device that allows to set a user-setting light-amount to a light amount with respect to 100% of an initial light-amount value, at the time when a lamp is brand-new while maximally maintaining a maximum light amount at 100% in the same manner as a brand-new lamp. <P>SOLUTION: When a power supply is turned on, inverter-control is executed corresponding to the initial light-amount value so as to drive a fluorescent tube. When the user-setting light-amount is set; a target light-amount detection value is calculated on the basis of the initial light-amount value, a light-amount detection value, and the user-setting light-amount value. When determined that the target light-amount detection value does not exceed a limit value, an inverter setting value making the light-amount detection value become the target light-amount detection value is calculated so as to inverter-control and drive the fluorescent tube corresponding to the inverter setting value. When determined that driving power supplied to the fluorescent tube exceeds a prescribed value, a warning showing replacement time of the fluorescent tube is issued since the fluorescent tube is broken if it is left as it is. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lamp drive control device that drives a lamp used as a backlight of a display device such as a liquid crystal display device or a rear projection device and controls the light amount of the lamp.

In recent years, liquid crystal display devices are increasingly used as display devices in personal computers and television receivers. The liquid crystal display device is provided with a backlight on the back surface, and the brightness of the display surface is secured by the light from the backlight. As a lamp used as the backlight, a fluorescent tube (fluorescent lamp) is generally employed. The fluorescent tube has a lifetime when the amount of light gradually decreases with long-term use and the amount of light becomes, for example, 50% or less of the initial value. That is, since the amount of light of the fluorescent tube gradually decreases with the use time, the amount of light decreases to 50% at the time of life in the catalog specification. Since it is generally difficult for the user to determine the lifetime, the conventional lamp drive control device detects the lamp lifetime and informs the user, for example, by an alarm.
Japanese Patent Laid-Open No. 10-222129 JP-A-7-281155

  However, in the conventional lamp drive control device, even if the light amount of the fluorescent tube gradually decreases with time, the user does not notice the decrease in the light amount and is used until the light amount becomes 50%. Therefore, there is a problem that it is possible to emit as much light as possible as long as the fluorescent tube can be produced, and it is impossible to cope with a request to use the display device for a long time with the brightness set by the user.

  The prior art disclosed in Patent Document 1 is configured to cancel the influence of variations in the luminance of the backlight and variations in the sensitivity of the sensor itself, so that an accurate decrease in luminance can be grasped. However, there is a problem that it is not possible to cope with a desire to use the display device for a long time as with a new product while maintaining the luminance set by the user.

  In the prior art of Patent Document 2, the lamp's light quantity is always kept constant under optimum conditions, and the center value of the light quantity is automatically shifted to extend the lamp life. If you use it, the lamp will deteriorate, so there is a limit to how much the light quantity of the lamp can be kept constant. There is a problem that it is impossible to cope with the desire to use.

  The present invention has been made to solve the above-described problems, and can maintain the maximum light intensity as much as possible as 100% as much as possible, so that the user-set light intensity is initially 100% at the time of the new article. An object of the present invention is to provide a lamp drive control device capable of setting a light amount with respect to a light amount value.

  In order to achieve the above object, a first aspect of the present invention is a lamp drive control device that drives a lamp used as a backlight of a display device and controls the amount of light of the lamp. Initial light quantity value reading means for reading the initial light quantity value stored in the memory, light quantity detection means for detecting the light quantity of the lamp, lamp driving means for driving the lamp by inverter control, and the initial light quantity value according to the initial light quantity value. A light amount detection value reading means for reading a light amount detection value detected by the light amount detection means for the lamp driven by a lamp driving means, and a user setting light amount value reading for reading a user set light amount value which is a light amount value set by a user. Means for detecting the target light quantity based on the initial light quantity value, the light quantity detection value, and the user-set light quantity value. A target light amount detection value calculating means for calculating a target light amount detection value by calculating a target light amount detection value = initial light amount value−light amount detection value + user setting light amount value conceptually; The limit target light amount detection value until the applied voltage to the lamp exceeds the rated voltage or / and the applied current exceeds the rated current is set as a limit value, and the target light amount detection value exceeds the limit value. Target light amount detection value determination means for determining whether or not, and limit value application means for applying the limit value to inverter control of the lamp driving means when it is determined that the target light amount detection value exceeds the limit value When the target light quantity detection value is determined not to exceed the limit value, an inverter setting value is calculated such that the light quantity detection value becomes the target light quantity detection value. Inverter setting value calculating means, inverter setting value applying means for applying the calculated inverter setting value to inverter control, driving power determining means for determining whether or not the driving power of the lamp exceeds a predetermined value, When it is determined that the driving power of the lamp exceeds a predetermined value, warning signal output means for outputting a warning signal for generating a warning indicating the replacement time of the lamp, and a warning in response to the warning signal And a warning means for generating the lamp drive control device.

  In this configuration, when the power is turned on, the initial light quantity value reading means reads the initial light quantity value from the nonvolatile memory. Next, the lamp driving means drives the lamp by performing inverter control according to the initial light quantity value. When the lamp is used for the first time, the lamp emits 100% light, and the light quantity detection value reading means reads the light quantity detection value (original light quantity) for the 100% light quantity. Also, as the lamp is used, the amount of light decreases, and therefore the lamp cannot emit 100% of the amount of light regardless of how much the lamp driving means performs inverter control according to the initial light amount value. Therefore, the light amount detection value reading means reads a light amount detection value (current light amount) lower than the light amount detection value (original light amount) for 100% light amount.

  Here, processing when the light amount detection value reading unit detects a current light amount detection value lower than the initial light amount value will be described below. When the user-specified light quantity is set in order for the user to set the liquid crystal display device to his / her preferred brightness, the user-set light quantity value reading means reads the user-set light quantity value. This user-set light amount value is a value representing what percentage of the user wants to use the liquid crystal display device with respect to the initial light amount value.

  Next, the target light amount detection value calculation means calculates the target light amount detection value based on the initial light amount value, the light amount detection value, and the user set light amount value. That is, if the initial light amount value is 100%, the light amount detection value is 90%, and the user set light value is, for example, 80%, the user set light value is 80%. Even if the light quantity value is set, the light quantity corresponding to the difference light quantity (10%) obtained by subtracting the light quantity detection value (90%) from the initial light quantity value (100%) is attenuated due to deterioration due to lamp usage time. Actually, the liquid crystal display device is not displayed with the light amount of 80% desired by the user.

  Therefore, the target light amount detection value calculation means conceptually calculates a 90% target light amount detection value corrected by adding a 10% difference light amount to the 80% user setting light amount value. That is, although the lamp deteriorates and the light quantity is reduced by 10%, the lamp driving means performs inverter control of the lamp so that the target light quantity detection value becomes 90%, so even if the light quantity is reduced by 10%, the user Is set to a user-set light amount value of 80%, it is possible to achieve 80% of the light amount at the time of a new article. The corrected target light amount detection value is stored in the non-volatile memory, and is read from the non-volatile memory when the power is turned on next time, and used as the initial light amount value.

  Next, the target light amount detection value determination means determines whether or not the target light amount detection value exceeds a predetermined limit value. For example, assuming that the current light amount is reduced by 10% compared to the light amount when the lamp is new, and the user sets the light amount to 80% and the user-set light amount value is 80%. The lamp driving means increases the voltage and current applied to the lamp so that the light quantity becomes 10% and as a result 90% light quantity (90% light quantity when the lamp is deteriorated) is obtained. In other words, the output power is increased, but if the rated voltage or / and the rated current of the lamp are exceeded, the lamp is damaged, and a limit value is provided to prevent this.

  To achieve the target light intensity detection value, if the applied voltage of the lamp exceeds the rated voltage and / or if the applied current exceeds the rated current, the lamp will be damaged. A limit target light amount detection value is set until the voltage is exceeded or / and the applied current exceeds the rated current.

  Therefore, when it is determined that the target light quantity detection value exceeds the limit value, the limit value application unit applies the limit value to inverter control of the lamp driving unit in order to prevent the lamp from being damaged. For example, the target light amount detection value is 98% target light amount detection value corrected by adding 10% difference light amount to 88% user set light amount value, and the limit value (limit target light amount detection value) is 95%. Assuming that, the limit value of 95% is applied to the inverter control of the lamp driving circuit. Thereby, the lamp drive circuit 3 drives the lamp by applying a voltage and a current corresponding to the 95% limit value to the lamp. As a result, the voltage and current applied to the lamp are suppressed within the rating, and the lamp can be prevented from being damaged.

  On the other hand, when it is determined that the target light amount detection value does not exceed the limit value, the inverter set value calculation means calculates an inverter set value such that the light amount detection value becomes the target light amount detection value. For example, the 90% target light amount detection value corrected by adding the 10% difference light amount to the 80% user set light amount value is equal to or less than the 95% limit value, so the target light amount detection value does not exceed the limit value. And the inverter set value calculation means calculates the inverter set values (voltage and current) of the lamp drive means so that the light quantity detection value becomes the target light quantity detection value of 90%.

  Then, the inverter set value applying means applies the calculated inverter set value to inverter control, whereby the lamp driving means drives the lamp by inverter control according to the inverter set value. In this way, the lamp is driven and used as a backlight of the display device. When the power of the apparatus is turned off, the present process ends. When the power is not turned off, the process proceeds to the process described below.

  Incidentally, in order to determine whether or not it is time to replace the lamp, the driving power determination means determines whether or not the driving power supplied to the lamp exceeds a predetermined value. In order to achieve the target light quantity detection value, the lamp is damaged when the applied voltage of the lamp exceeds the rated voltage and / or the applied current exceeds the rated current. Therefore, the predetermined value is within a range where the lamp is not damaged. It will indicate the maximum allowable power.

  If it is determined that the driving power supplied to the lamp does not exceed the predetermined value, the process returns to the above processing, and the same processing is performed thereafter, but the driving power supplied to the lamp exceeds the predetermined value. If it is determined, the lamp will be damaged as it is, so that the warning signal output means outputs a warning signal for generating a warning indicating the lamp replacement timing, thereby warning the lamp replacement timing. It becomes possible to do.

  According to this configuration, even when the lamp is used and the light quantity decreases, the light quantity can be corrected so that it is the light quantity at the time of the new article. The brightness of the display device can be adjusted with high accuracy. In addition, in order to enable the user-set light amount to be set to a light amount with respect to the initial light amount value of 100% at the time of a new product, the driving power to the lamp is increased. However, when the driving power exceeds a predetermined value, Since a warning indicating the replacement time is generated, it is convenient for the user to know the lamp life and the replacement time, and when the lamp is replaced, the lamp is always in a new light level. You can watch the video.

  According to a second aspect of the present invention, in a lamp drive control device that drives a lamp used as a backlight of a display device and controls the light amount of the lamp, an initial light amount value stored in a nonvolatile memory when the power is turned on. Initial light quantity value reading means, light quantity detection means for detecting the light quantity of the lamp, lamp driving means for driving the lamp by inverter control, and the lamp driven by the lamp driving means according to the initial light quantity value On the other hand, a light quantity detection value reading means for reading a light quantity detection value detected by the light quantity detection means, a user setting light quantity value reading means for reading a user set light quantity value which is a light quantity value set by a user, the initial light quantity value, and the Target light amount detection value for calculating a target light amount detection value based on the light amount detection value and the user-set light amount value Output means, target light amount detection value determination means for determining whether or not the target light amount detection value exceeds a predetermined limit value, and when it is determined that the target light amount detection value exceeds the limit value Limit value applying means for applying the limit value to inverter control of the lamp driving means, and when it is determined that the target light quantity detection value does not exceed the limit value, the light quantity detection value is the target light quantity detection value. An inverter set value calculating means for calculating an inverter set value such that the inverter set value applying means for applying the calculated inverter set value to inverter control, and whether or not the driving power of the lamp exceeds a predetermined value Driving power determining means for determining the lamp, and when it is determined that the driving power of the lamp exceeds a predetermined value, a warning indicating the replacement time of the lamp is generated. And alarm signal output means for outputting a warning signal for, to provide a lamp drive control device, characterized in that it and a warning means for generating an alarm in response to said warning signal.

  In this configuration, when the power is turned on, the initial light quantity value reading means reads the initial light quantity value from the nonvolatile memory. Next, the lamp driving means drives the lamp by performing inverter control according to the initial light quantity value. When the lamp is used for the first time, the lamp emits 100% light, and the light quantity detection value reading means reads the light quantity detection value (original light quantity) for the 100% light quantity. Also, as the lamp is used, the amount of light decreases, and therefore the lamp cannot emit 100% of the amount of light regardless of how much the lamp driving means performs inverter control according to the initial light amount value. Therefore, the light amount detection value reading means reads a light amount detection value (current light amount) lower than the light amount detection value (original light amount) for 100% light amount.

  Here, processing when the light amount detection value reading unit detects a current light amount detection value lower than the initial light amount value will be described below. When the user-specified light quantity is set in order for the user to set the liquid crystal display device to his / her preferred brightness, the user-set light quantity value reading means reads the user-set light quantity value. This user-set light amount value is a value representing what percentage of the user wants to use the liquid crystal display device with respect to the initial light amount value.

  Next, the target light quantity detection value calculation means calculates a target light quantity detection value based on the initial light quantity value, the light quantity detection value, and the user-set light quantity value, and the target light quantity detection value determination means determines that the target light quantity detection value is obtained in advance. It is determined whether or not the specified limit value is exceeded. For example, assuming that the current light amount is reduced by 10% compared to the light amount when the lamp is new, and the user sets the light amount to 80% and the user-set light amount value is 80%. The lamp driving means increases the voltage and current to the lamp, that is, the output so that the light quantity becomes 10% and as a result 90% light quantity (90% light quantity when the lamp is deteriorated) is obtained. Although the electric power is increased, if the rated voltage or rated current of the lamp is exceeded, the lamp is damaged. Therefore, a limit value is provided to prevent this.

  To achieve the target light intensity detection value, if the applied voltage of the lamp exceeds the rated voltage and / or if the applied current exceeds the rated current, the lamp will be damaged. A limit target light amount detection value is set until the voltage is exceeded or / and the applied current exceeds the rated current.

  Therefore, when it is determined that the target light quantity detection value exceeds the limit value, the limit value application unit applies the limit value to inverter control of the lamp driving unit in order to prevent the lamp from being damaged. For example, the target light amount detection value is 98% target light amount detection value corrected by adding 10% difference light amount to 88% user set light amount value, and the limit value (limit target light amount detection value) is 95%. Assuming that, the limit value of 95% is applied to the inverter control of the lamp driving circuit. Thereby, the lamp driving means applies a voltage and a current according to the limit value of 95% to the lamp to drive the lamp. As a result, the voltage and current applied to the lamp are suppressed within the rating, and the lamp can be prevented from being damaged.

  On the other hand, when it is determined that the target light amount detection value does not exceed the limit value, the inverter set value calculation means calculates an inverter set value such that the light amount detection value becomes the target light amount detection value. For example, the 90% target light amount detection value corrected by adding the 10% difference light amount to the 80% user set light amount value is equal to or less than the 95% limit value, so the target light amount detection value does not exceed the limit value. And the inverter set value calculation means calculates the inverter set values (voltage and current) of the lamp drive means so that the light quantity detection value becomes the target light quantity detection value of 90%.

  Then, the inverter set value applying means applies the calculated inverter set value to inverter control, whereby the lamp driving means drives the lamp by inverter control according to the inverter set value. In this way, the lamp is driven and used as a backlight of the display device. When the power of the apparatus is turned off, the present process ends. When the power is not turned off, the process proceeds to the process described below.

  Incidentally, in order to determine whether or not it is time to replace the lamp, the driving power determination means determines whether or not the driving power supplied to the lamp exceeds a predetermined value. In order to achieve the target light quantity detection value, the lamp is damaged when the applied voltage of the lamp exceeds the rated voltage and / or the applied current exceeds the rated current. Therefore, the predetermined value is within a range where the lamp is not damaged. It will indicate the maximum allowable power.

  If it is determined that the driving power supplied to the lamp does not exceed the predetermined value, the process returns to the above processing, and the same processing is performed thereafter, but the driving power supplied to the lamp exceeds the predetermined value. If it is determined, the lamp will be damaged as it is, so that the warning signal output means outputs a warning signal for generating a warning indicating the lamp replacement timing, thereby warning the lamp replacement timing. I do.

  According to this configuration, even when the lamp is used and the light quantity decreases, the light quantity can be corrected so that it is the light quantity at the time of the new article. The brightness of the display device can be adjusted with high accuracy. In addition, in order to enable the user-set light amount to be set to a light amount with respect to the initial light amount value of 100% at the time of a new product, the driving power to the lamp is increased. However, when the driving power exceeds a predetermined value, Since a warning indicating the replacement time is generated, it is convenient for the user to know the lamp life and the replacement time, and when the lamp is replaced, the lamp is always in a new light level. You can watch the video.

  According to a third aspect of the present invention, in the second aspect of the invention, the target light amount detection value calculating means conceptually performs a calculation of target light amount detection value = initial light amount value−light amount detection value + user set light amount value. Since the target light amount detection value is calculated, even if the light amount of the lamp decreases as the usage time elapses, it can be corrected to the light amount of a new lamp.

  According to a fourth aspect of the present invention, in the second aspect of the invention, the target light amount detection value determining means is configured to limit the target light amount until the applied voltage to the lamp exceeds the rated voltage or / and the applied current exceeds the rated current. Since the detection value is set as the limit value and it is determined whether or not the target light amount detection value exceeds the limit value, it is possible to keep the voltage and current applied to the lamp within the ratings.

  As described above, according to the present invention, in a lamp drive control device that drives a lamp used as a backlight of a display device and controls the light amount of the lamp, when the power is turned on, the lamp is stored in a nonvolatile memory. An initial light quantity reading means for reading the initial light quantity value, a light quantity detecting means for detecting the light quantity of the lamp, a lamp driving means for driving the lamp by inverter control, and driving by the lamp driving means in accordance with the initial light quantity value A light quantity detection value reading means for reading a light quantity detection value detected by the light quantity detection means for the lamp, a user setting light quantity value reading means for reading a user set light quantity value which is a light quantity value set by a user, and the initial stage A target light amount detection value is calculated based on the light amount value, the light amount detection value, and the user set light amount value. Conceptually, a target light amount detection value = initial light amount value−light amount detection value + a user-set light amount value is calculated to calculate a target light amount detection value calculating means for calculating a target light amount detection value; The limit target light intensity detection value until the applied voltage exceeds the rated voltage and / or the applied current exceeds the rated current is set as a limit value, and it is determined whether the target light intensity detection value exceeds the limit value. Target light quantity detection value determination means; limit value application means for applying the limit value to inverter control of the lamp driving means when it is determined that the target light quantity detection value exceeds the limit value; and the target light quantity When it is determined that the detected value does not exceed the limit value, the inverter setting value is calculated so that the detected light amount value becomes the target detected light amount value. Value calculating means, inverter setting value applying means for applying the calculated inverter setting value to inverter control, driving power determining means for determining whether or not the driving power of the lamp exceeds a predetermined value, and Warning signal output means for outputting a warning signal for generating a warning indicating the lamp replacement time when it is determined that the driving power exceeds a predetermined value, and a warning for generating a warning in response to the warning signal Therefore, even when the lamp is used and the light quantity decreases, the light quantity can be corrected so that it is the light quantity at the time of the new article, so that the user set light quantity is 100% of the initial light quantity value at the time of the new article. The brightness of the display device can be adjusted with high accuracy. In addition, in order to enable the user-set light amount to be set to a light amount with respect to the initial light amount value of 100% at the time of a new product, the driving power to the lamp is increased. However, when the driving power exceeds a predetermined value, Since a warning indicating the replacement time is generated, it is convenient for the user to know the lamp life and the replacement time, and when the lamp is replaced, the lamp is always in a new light level. You can watch the video.

  According to the present invention, in the lamp drive control device that drives the lamp used as the backlight of the display device and controls the light quantity of the lamp, when the power is turned on, the initial value stored in the nonvolatile memory is stored. An initial light amount reading means for reading a light amount value; a light amount detecting means for detecting the light amount of the lamp; a lamp driving means for driving the lamp by inverter control; and the lamp driving means driven according to the initial light amount value. A light quantity detection value reading means for reading a light quantity detection value detected by the light quantity detection means for the lamp; a user setting light quantity value reading means for reading a user set light quantity value which is a light quantity value set by a user; and the initial light quantity value. And a target light amount for calculating a target light amount detection value based on the light amount detection value and the user-set light amount value It is determined that an output value calculating unit, a target light amount detection value determining unit for determining whether or not the target light amount detection value exceeds a predetermined limit value, and the target light amount detection value exceeds a limit value When the limit value applying means for applying the limit value to inverter control of the lamp driving means and the target light quantity detection value is determined not to exceed the limit value, the light quantity detection value is converted to the target light quantity. Inverter set value calculating means for calculating an inverter set value that becomes a detected value, inverter set value applying means for applying the calculated inverter set value to inverter control, and whether the driving power of the lamp exceeds a predetermined value Driving power determining means for determining whether or not a lamp indicating a lamp replacement time is issued when it is determined that the driving power of the lamp exceeds a predetermined value. A warning signal output means for outputting a warning signal for generating a warning signal and a warning means for generating a warning in response to the warning signal. The light amount can be corrected so as to be the light amount, whereby the user-set light amount can be set to the light amount with respect to the initial light amount value of 100% at the time of the new article, and the brightness of the display device can be adjusted with high accuracy. In addition, in order to enable the user-set light amount to be set to a light amount with respect to the initial light amount value of 100% at the time of a new product, the driving power to the lamp is increased. However, when the driving power exceeds a predetermined value, Since a warning indicating the replacement time is generated, it is convenient for the user to know the lamp life and the replacement time, and when the lamp is replaced, the lamp is always in a new light level. You can watch the video.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing a configuration of a lamp drive control device according to an embodiment of the present invention.

  The lamp drive control device includes a non-volatile memory 1, a control unit 2, a lamp drive circuit 3, a fluorescent tube 4 as a lamp for a backlight of a display device (see FIG. 2), a photosensor 5, a light quantity detection circuit 6, A A / D conversion circuit 7, a user-specified light amount setting circuit 8, and warning means 9 are included. The nonvolatile memory 1 stores programs and data necessary for the processing of the control unit 2, and the liquid crystal display device is in a new state, that is, the fluorescent tube is in a new state, statically or in a factory. A light quantity value (initial light quantity value) of 100% obtained by learning is stored.

  The control unit 2 controls the entire apparatus. In particular, as a component that characterizes the present embodiment, an initial light quantity value reading unit that reads an initial light quantity value into the nonvolatile memory 1 when the power is turned on. 21, a light amount detection value reading means 22 for reading a light amount detection value detected by the light amount detection circuit 6 with respect to the fluorescent tube 4 driven by the lamp driving circuit 3 according to the initial light amount value, and a light amount value set by the user A user-set light amount value reading means 23 for reading a certain user-set light amount value, a target light amount detection value is calculated based on the initial light amount value, the light amount detection value, and the user setting light amount value. A target light amount detection value calculating unit 24 for calculating a target light amount detection value by performing a calculation of target light amount detection value = initial light amount value−light amount detection value + user set light amount value; Whether the limit target light amount detection value until the applied voltage to the fluorescent tube 4 exceeds the rated voltage or / and the applied current exceeds the rated current is set as a limit value, and does the target light amount detection value exceed the limit value? A target light amount detection value determination means 25 for determining whether or not the limit value is applied to the inverter control of the lamp drive circuit 3 when it is determined that the target light amount detection value exceeds the limit value. Means 26 and inverter setting value calculation means 27 for calculating an inverter set value such that the light quantity detection value becomes the target light quantity detection value when it is determined that the target light quantity detection value does not exceed the limit value. Inverter set value application means 28 for applying the calculated inverter set value to inverter control, and whether or not the driving power of the fluorescent tube 4 exceeds a predetermined value Driving power determination means 29 for determining and warning signal output means for outputting a warning signal for generating a warning indicating the replacement timing of the fluorescent tube 4 when it is determined that the driving power of the fluorescent tube 4 has exceeded a predetermined value. 30.

  The lamp driving circuit 3 is lamp driving means for driving the fluorescent tube 4 by inverter control according to a control signal from the control unit 2. The optical sensor 5 receives light from the fluorescent tube 4 and converts it into an electrical signal, and is realized by a light receiving element such as a photodiode or CDS. The light quantity detection circuit 6 is a light quantity detection unit that detects the light quantity of the fluorescent tube 4 based on an electrical signal from the optical sensor 5. The A / D conversion circuit 7 converts an analog signal indicating the light amount from the light amount detection circuit 6 into a digital signal, and gives this digital signal to the control unit 2. The user-designated light quantity setting circuit 8 is for setting a light quantity value designated by a user operating an operation unit (not shown). In addition, although it demonstrated with the light quantity here, a brightness | luminance may be sufficient instead of a light quantity.

  The warning means 9 corresponds to an indicator for indicating the replacement time of the fluorescent tube 4 or a display unit for displaying a message indicating that the replacement time has come. A warning from the warning signal output means 30 of the control unit 2 is provided. In response to the signal, the indicator is turned on or a message is displayed on the display unit to warn the replacement timing of the fluorescent tube 4.

  FIG. 2 is an exploded perspective view showing the liquid crystal display module and the optical sensor of the liquid crystal display device in the present embodiment. In FIG. 2, the liquid crystal display module 10 includes an LCD panel 11, a diffusion sheet 12, a light collecting sheet 13, a fluorescent tube 4 as a backlight, a light guide plate 15, and a reflective sheet 16. The optical sensor 5 is attached to the sensor printed board 18, the sensor printed board 18 is attached to the board attaching part 17, and the board attaching part 17 is attached to the reflection sheet 16 side via the donut cushion 19. Therefore, the optical sensor 5 detects the amount of light from the fluorescent tube 4 leaking from the reflection sheet 16. Note that the position of the optical sensor 5 is not limited to the position shown in FIG. 2 and may be any position as long as the light from the fluorescent tube 4 can be received.

  FIG. 3 is a flowchart for explaining drive control of the fluorescent tube in the lamp drive control apparatus of this embodiment. The fluorescent tube drive control will be described with reference to this flowchart and FIGS.

  First, when a power key (not shown) is pressed by the user, the control unit 2 turns on the power of the apparatus. Thereby, the initial light quantity value reading means 21 of the control unit 2 detects that the power is turned on (step S1), and reads the initial light quantity value (product initial luminance value) from the nonvolatile memory 1 (step S2). . Next, the lamp driving circuit 3 determines control values (voltage and current) related to inverter control according to the initial light quantity value, and drives the fluorescent tube 4.

  Since the fluorescent tube 4 at this time emits 100% of the light amount when it is used for the first time, the light amount detection value reading means 22 of the control unit 2 includes the light sensor 5, the light amount detection circuit 6, and the A / Through each process of the D conversion circuit 7, a light amount detection value (original light amount) with respect to 100% light amount is read (step S3). Further, as the fluorescent tube 4 is used, the amount of light decreases. Therefore, even if the lamp driving circuit 3 performs inverter control of the fluorescent tube 4 according to the initial light amount value, the fluorescent light 4 is 100%. Since the light amount cannot be emitted, the light amount detection value reading means 22 reads a light amount detection value (current light amount) lower than the light amount detection value (original light amount) for 100% light amount (step S3).

  Here, the light amount detection value reading unit 22 detects a current light amount detection value (light amount value when the current light amount is 90%) lower than the initial light amount value (light amount value when the light amount is 100%). This process will be described below.

  In order for the user to set the liquid crystal display device to his / her preferred brightness, the user-designated light quantity setting circuit 8 is set with the user-designated light quantity by operating an operation unit (not shown). Note that the luminance may be set instead of the light amount, but here, description will be made assuming that the light amount is set. When the user-designated light quantity setting circuit 8 sets the user-designated light quantity, the user-designated light quantity value reading means 23 of the control unit 2 outputs the user-designated light quantity value, which is a light quantity value set by the user, from the user-designated light quantity setting circuit 8. Read (step S4). This user-set light amount value is a value representing what percentage of the user wants to use the liquid crystal display device with respect to the initial light amount value.

  Next, the target light amount detection value calculation unit 24 of the control unit 2 calculates a target light amount detection value based on the initial light amount value, the light amount detection value, and the user set light amount value (step S5). That is, if the initial light amount value is 100%, the light amount detection value is 90%, and the user set light value is 80%, for example, the user set light value is 80%. Even if the light amount is set, the light amount corresponding to the difference light amount (10%) obtained by subtracting the light amount detection value (90%) from the initial light amount value (100%) is attenuated due to the deterioration of the fluorescent lamp 4 due to the usage time. Therefore, the liquid crystal display device is not actually displayed with the light amount of 80% desired by the user.

  Therefore, the target light amount detection value calculation unit 24 conceptually calculates a 90% target light amount detection value corrected by adding a 10% difference light amount to the 80% user setting light amount value. That is, although the fluorescent tube 4 is deteriorated and the light amount is reduced by 10%, the lamp driving circuit 3 performs inverter control of the fluorescent tube 4 so that the target light amount detection value is 90%, so the light amount is reduced by 10%. However, if the user sets a user-set light amount value of 80%, 80% of the light amount at the time of the new article can be achieved. The corrected target light amount detection value is stored in the non-volatile memory 1 and is read from the non-volatile memory 1 when the power is turned on next time, and used as the initial light amount value.

  Next, the target light amount detection value determination means 25 of the control unit 2 determines whether or not the target light amount detection value exceeds a predetermined limit value (step S6). For example, it is assumed that the current light amount is reduced by 10% compared to the light amount when the fluorescent tube 4 is new, and the user sets the light amount to 80% at this time and the user-set light amount value is 80%. The lamp driving circuit 3 applies a voltage or a voltage to the fluorescent tube 4 so that the corrected light amount becomes 10%, and as a result, 90% light amount (90% light amount when the fluorescent tube 4 is deteriorated) is obtained. However, if the rated voltage or rated current of the fluorescent tube 4 is exceeded, the fluorescent tube 4 will be damaged, and a limit value is provided to prevent this. ing.

  In order to achieve the target light quantity detection value, if the applied voltage of the fluorescent tube 4 exceeds the rated voltage and / or the applied current exceeds the rated current, the fluorescent tube 4 is damaged. The limit target light amount detection value until the applied voltage exceeds the rated voltage and / or the applied current exceeds the rated current is set.

  Therefore, when it is determined that the target light amount detection value exceeds the limit value (step S6), the limit value application unit 26 of the control unit 2 also uses the limit value to prevent the fluorescent tube 4 from being damaged. This is applied to inverter control of the lamp driving circuit 3 (step S7). For example, the target light amount detection value is 98% target light amount detection value corrected by adding 10% difference light amount to 88% user set light amount value, and the limit value (limit target light amount detection value) is 95%. Assuming that the limit value of 95% is applied to the inverter control of the lamp driving circuit 3. Thereby, the lamp driving circuit 3 applies the voltage and current according to the limit value of 95% to the fluorescent tube 4 to drive the fluorescent tube 4 (step S8). Thereby, the voltage and the current applied to the fluorescent tube 4 are suppressed within the rating, and the fluorescent tube 4 can be prevented from being damaged.

  On the other hand, when it is determined that the target light amount detection value does not exceed the limit value (step S6), the inverter set value calculation means 27 of the control unit 2 sets the inverter set value such that the light amount detection value becomes the target light amount detection value. Is calculated (step S9). For example, the 90% target light amount detection value corrected by adding the 10% difference light amount to the 80% user set light amount value is equal to or less than the 95% limit value, so the target light amount detection value does not exceed the limit value. (Step S6), the inverter set value calculation means 27 of the control unit 2 sets the inverter set value (in the lamp drive circuit 3) so that the light amount detection value by the light amount detection circuit 6 becomes a target light amount detection value of 90%. (Voltage and current) are calculated (step S9).

  Then, the inverter setting value application means 28 of the control unit 2 applies the calculated inverter setting value to inverter control (step S10), whereby the lamp driving circuit 3 causes the fluorescent tube 4 to be connected according to the inverter setting value. The inverter is controlled and driven (step S8). Thus, the fluorescent tube 4 is driven and used as a backlight of a liquid crystal display device. When the power of the apparatus is turned off (step S11), this process ends. When the power is not turned off, the process proceeds to step S12 described below.

  By the way, in order to determine whether or not it is time to replace the fluorescent tube 4, the drive power determination means 29 of the control unit 2 determines whether or not the drive power supplied to the fluorescent tube 4 exceeds a predetermined value ( Step S12). In order to achieve the target light quantity detection value, if the applied voltage of the fluorescent tube 4 exceeds the rated voltage and / or the applied current exceeds the rated current, the fluorescent tube 4 is damaged. 4 indicates the maximum allowable power in a range where no damage occurs.

  If it is determined that the driving power supplied to the fluorescent tube 4 does not exceed the predetermined value, the process returns to step S6, and the same processing is performed, but the driving power supplied to the fluorescent tube 4 is the predetermined value. If it is determined that the fluorescent tube 4 has been exceeded, the fluorescent tube 4 will be damaged as it is, so that the warning signal output means 30 of the control unit 2 issues a warning for generating a warning indicating the replacement timing of the fluorescent tube 4. A signal is output to the warning means 5, and in response to this, the warning means 9 warns the replacement timing of the fluorescent tube 4 (step S13). When an indicator is used as the warning means 9, the user is notified of the replacement timing of the fluorescent tube 4 by turning on the indicator. Further, when a warning display unit 9 is used as a warning unit 9 or a display unit for displaying the operation contents of the operation unit, a message indicating that it is time to replace the fluorescent tube 4 is displayed on the display unit. As a result, the user is notified of the replacement time of the fluorescent tube 4. After warning of the replacement timing of the fluorescent tube 4 by such warning means 9, the automatic power-off means 31 of the control unit 2 turns off the power of the apparatus after a predetermined time (step S14).

  As described above, according to the present embodiment, even when the fluorescent tube 4 is used and the light amount decreases, the light amount can be corrected to the light amount at the time of a new product. % Can be set with respect to the initial light amount value, and the brightness of the display device can be adjusted with high accuracy. In addition, in order to enable the user-set light amount to be set to a light amount with respect to the initial light amount value of 100% at the time of a new article, the driving power to the fluorescent tube 4 is increased, but when the driving power exceeds a predetermined value, Since a warning indicating the replacement time of the fluorescent tube 4 is generated, it is convenient for the user to know the life and replacement time of the fluorescent tube 4, and when the fluorescent tube 4 is replaced, a new one is always available. The image of the display device can be viewed in the light intensity state.

  As described above, since the amount of light in the fluorescent tube (fluorescent lamp) 4 gradually decreases, the amount of light decreases to 50% during the life of the catalog specification. In view of this, the present embodiment aims to make it possible to view an image of the liquid crystal display device with the same amount of light as possible as much as possible by detecting the amount of light and controlling the amount of light. The amount of light (100%) at the time of a new article is calculated as how much the current amount of light is reduced from 100% assuming that it is stored in the nonvolatile memory 1 either statically or by learning at the factory. Based on this calculation result, the operation of inverter control in the lamp driving circuit 3 is changed to adjust the light quantity of the fluorescent tube 4. At this time, a limit value is determined, and if the value is exceeded, tracking of the light amount is stopped.

  This prevents an excessive voltage or current from flowing through the fluorescent tube 4. This works as a safety device, and the life of the fluorescent tube 4 can be detected. In adjusting the light amount, the previous adjustment value is stored in the nonvolatile memory 1 as the initial light amount value, and when the power is turned on, first, the lamp driving circuit 3 is driven with the initial light amount value. Thereafter, the amount of light is measured and the amount of light is made to follow. Also, if the initial light intensity data at the time of the new product is lost for some reason, the light intensity at the time of the new product is determined by using the predetermined initial light intensity value, so that the random light intensity in the event of an emergency Adjustment can be avoided.

  In the present embodiment, the light quantity control of the fluorescent tube used as the backlight in the liquid crystal display device has been described as the display device used in a liquid crystal television or a monitor device of a personal computer, but the fluorescent tube used as the backlight of the rear projection device. The same light amount control as in the present embodiment can also be applied to the light amount control. Further, although the fluorescent tube has been described as an example of the backlight lamp, the present invention is not limited to the fluorescent tube, and any other lamp that can be used for backlight illumination may be used.

  The lamp drive control device of the present invention can be used for light quantity control of a lamp used as a backlight of a liquid crystal television, a monitor device of a personal computer, a rear projection device or the like.

It is a block diagram which shows the structure of the lamp drive control apparatus which concerns on one Embodiment of this invention. It is a disassembled perspective view which shows the liquid crystal display module and optical sensor of a liquid crystal display device in the said embodiment. 6 is a flowchart for explaining drive control of a fluorescent tube in the lamp drive control device of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nonvolatile memory 2 Control part 3 Lamp drive circuit (lamp drive means)
4 Fluorescent tubes (lamps)
6 Light quantity detection circuit (light quantity detection means)
9 Warning means 21 Initial light quantity value reading means 22 Light quantity detection value reading means 23 User setting light quantity value reading means 24 Target light quantity detection value calculating means 25 Target light quantity detection value determining means 26 Limit value applying means 27 Inverter setting value calculating means 28 Inverter setting Value application means 29 Drive power determination means 30 Warning signal output means

Claims (4)

In a lamp drive control device that drives a lamp used as a backlight of a display device and controls the light amount of the lamp,
When the power is turned on, the initial light quantity value reading means for reading the initial light quantity value stored in the nonvolatile memory,
A light amount detecting means for detecting the light amount of the lamp;
Lamp driving means for driving the lamp by inverter control; and
A light quantity detection value reading means for reading a light quantity detection value detected by the light quantity detection means for the lamp driven by the lamp driving means according to the initial light quantity value;
User-set light amount reading means for reading a user-set light amount value that is a light amount value set by the user;
A target light amount detection value is calculated based on the initial light amount value, the light amount detection value, and the user-set light amount value, and conceptually, target light amount detection value = initial light amount value−light amount detection value + user setting light amount A target light amount detection value calculating means for calculating a target light amount detection value by performing a calculation called a value;
The limit target light amount detection value until the applied voltage to the lamp exceeds the rated voltage and / or the applied current exceeds the rated current is set as a limit value, and whether or not the target light amount detection value exceeds the limit value Target light quantity detection value determination means for determining whether or not
Limit value applying means for applying the limit value to inverter control of the lamp driving means when it is determined that the target light quantity detection value exceeds the limit value;
An inverter set value calculation means for calculating an inverter set value so that the light quantity detection value becomes the target light quantity detection value when it is determined that the target light quantity detection value does not exceed the limit value;
Inverter setting value application means for applying the calculated inverter setting value to inverter control;
Driving power determination means for determining whether or not the driving power of the lamp exceeds a predetermined value;
Warning signal output means for outputting a warning signal for generating a warning indicating the replacement time of the lamp when it is determined that the driving power of the lamp exceeds a predetermined value;
And a warning means for generating a warning in response to the warning signal. In a lamp drive control device that drives a lamp used as a backlight of a display device and controls the light amount of the lamp,
When the power is turned on, the initial light quantity value reading means for reading the initial light quantity value stored in the nonvolatile memory,
A light amount detecting means for detecting the light amount of the lamp;
Lamp driving means for driving the lamp by inverter control; and
A light quantity detection value reading means for reading a light quantity detection value detected by the light quantity detection means for the lamp driven by the lamp driving means according to the initial light quantity value;
User-set light amount reading means for reading a user-set light amount value that is a light amount value set by the user;
Target light quantity detection value calculating means for calculating a target light quantity detection value based on the initial light quantity value, the light quantity detection value, and the user set light quantity value;
Target light quantity detection value determining means for determining whether or not the target light quantity detection value exceeds a predetermined limit value;
Limit value applying means for applying the limit value to inverter control of the lamp driving means when it is determined that the target light quantity detection value exceeds the limit value;
An inverter set value calculation means for calculating an inverter set value so that the light quantity detection value becomes the target light quantity detection value when it is determined that the target light quantity detection value does not exceed the limit value;
Inverter setting value application means for applying the calculated inverter setting value to inverter control;
Driving power determination means for determining whether or not the driving power of the lamp exceeds a predetermined value;
Warning signal output means for outputting a warning signal for generating a warning indicating the replacement time of the lamp when it is determined that the driving power of the lamp exceeds a predetermined value;
And a warning means for generating a warning in response to the warning signal.   The target light quantity detection value calculating means conceptually calculates a target light quantity detection value by performing a calculation of target light quantity detection value = initial light quantity value-light quantity detection value + user set light quantity value. Item 3. The lamp drive control device according to Item 2.   The target light quantity detection value determining means sets a limit target light quantity detection value until an applied voltage to the lamp exceeds a rated voltage and / or an applied current exceeds a rated current as a limit value, and the target light quantity detection value The lamp drive control device according to claim 2, wherein it is determined whether or not the value exceeds the limit value.

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