JP4157106B2 - Liquid crystal display device and life prediction method of liquid crystal display device - Google Patents

Description

  The present invention relates to a liquid crystal display device, and more particularly to a device for predicting the lifetime of a liquid crystal display device.

  A conventional light source lamp life prediction system will be described. The life prediction system 100 has a storage device that stores an energy decay curve model of a light source lamp. The energy attenuation curve equation represents the attenuation tendency of various light source lamps based on many past energy attenuation data, technical documents, literatures, and the like. An example of the energy decay curve equation is shown in FIG.

  The life prediction system 100 measures the energy value of the light source lamp, and uses the measured energy value to calculate a specific form of the energy decay curve equation. Then, the life prediction system 100 calculates a predicted life value at which the light source lamp will turn off based on the specific form of the calculated energy decay curve.

JP2003-157987

  The conventional life prediction system 100 has the following problems. The conventional life prediction system 100 has a problem that it is necessary to prepare an energy decay curve formula for each light source lamp in advance in order to predict the life of the light source lamp.

  Moreover, in the lifetime prediction system 100, it is not assumed in advance that the brightness of the light source lamp is adjusted by changing the brightness of the light source lamp during use. Therefore, there is a problem in that the lifetime prediction system 100 cannot be applied to a liquid crystal display device or the like that needs to adjust the brightness of the light source lamp and adjust the brightness to be constant.

Therefore, an object of the present invention is to provide a liquid crystal display device and a life prediction method for a liquid crystal display device that can easily perform life prediction .

  Means for solving the problems relating to the present invention and effects of the present invention will be described below.

(1) The liquid crystal display device according to the present invention is based on the illumination unit that provides brightness to the liquid crystal display unit, the measurement unit that measures the brightness of the illumination unit and generates measurement information, and the measurement information A control information generation unit that generates control information for controlling the brightness of the illumination unit to a set value, an illumination control unit that controls the brightness of the illumination unit to a set value based on the control information, and A life prediction unit that predicts the life of the illumination unit based on the control information.

  Thereby, even if it is a liquid crystal display device which controls the brightness of an illumination part to a setting value, the lifetime of an illumination part can be estimated.

(2) In the liquid crystal display device according to the present invention, the lifetime prediction unit is further control information acquired after acquiring the first control information and control information acquired at a predetermined time. Based on the second control information, the lifetime of the illumination unit is predicted.

  Thereby, when there is a predetermined relationship between the control information and the brightness of the illumination unit, the lifetime of the illumination unit can be easily predicted.

(3) In the liquid crystal display device according to the present invention, the life prediction unit further does not perform life prediction of the illumination unit until a predetermined time has elapsed after obtaining the first control information.

  Thereby, since the predetermined relationship between the control information and the brightness of the illumination unit can be determined with high accuracy, the lifetime of the illumination unit can be accurately predicted.

(4) In the liquid crystal display device according to the present invention, the life prediction unit further does not perform the life prediction of the illumination unit until the accumulated usage time of the illumination unit has passed a predetermined time.

  Thereby, since it is possible to prevent the lifetime prediction from being performed until the control information is stabilized until the accumulated usage time of the illumination unit reaches a predetermined time, an accurate lifetime prediction can be performed. it can.

(5) In the liquid crystal display device according to the present invention, the life prediction unit further does not perform life prediction of the illumination unit until a predetermined time elapses after the liquid crystal display device or the illumination unit is turned on.

  As a result, it is possible to prevent the lifetime from being predicted until the control information is stabilized after the liquid crystal display device or the lighting unit is turned on until a predetermined time elapses. Life prediction of the part can be performed.

(6) In the liquid crystal display device according to the present invention, when the life prediction unit further determines that the set value has been changed, the life prediction unit re-acquires the first control information.

  Thereby, even if the brightness of an illumination part is changed, the lifetime prediction of an illumination part can be performed correctly.

(7) In the liquid crystal display device according to the present invention, the lifetime prediction unit further holds first control information before the set value is changed.

  Thereby, even after the brightness of the illumination unit is changed, the first control information before the change can be used for the lifetime prediction, so that the lifetime of the illumination unit can be predicted efficiently.

(8) In the liquid crystal display device according to the present invention, the life prediction unit determines whether or not the set value has been changed based on the measurement information.

  Thereby, it can be easily determined whether or not the set value has been changed.

(9) In the liquid crystal display device according to the present invention, the illumination control information is a current value for controlling the illumination control unit.

  Thereby, since the value required in order to control the brightness of an illumination part can be utilized, the lifetime of an illumination part can be estimated easily.

(10) In the liquid crystal display device according to the present invention, the illumination control information is a voltage value for controlling the illumination control unit.

  Thereby, since the value required in order to control the brightness of an illumination part can be utilized, the lifetime of an illumination part can be estimated easily.

(11) The liquid crystal display device according to the present invention includes a life prediction result display unit for displaying the result of the life prediction.

  Thereby, the lifetime of an illumination part can be known easily.

(12) In the liquid crystal display device according to the present invention, the lifetime prediction unit further predicts the lifetime of the illumination unit by using linearity between the control information and the brightness of the illumination unit.

  Thereby, the lifetime prediction of an illumination part can be easily performed only by acquiring two sets of control information and the brightness of an illumination part.

(13) A liquid crystal display device according to the present invention includes a backlight that provides brightness to a liquid crystal panel, a light sensor that measures the amount of light of the backlight and generates measurement information, and the measurement information based on the measurement information A brightness control unit that calculates a PWM value for controlling the brightness of the backlight to a set value, an inverter circuit that controls the brightness of the backlight to a set value based on the PWM value, and a PWM value calculated at a predetermined time A first PWM value stored in the storage unit, a first PWM value stored in the storage unit, and a second PWM value calculated after the first PWM value is calculated, It has a life prediction unit for predicting the life of the backlight.

  As a result, the PWM value necessary for controlling the brightness of the backlight can be used, so that the lifetime of the backlight can be easily estimated.

(14) The method for predicting the lifetime of the liquid crystal display device according to the present invention measures the brightness of the illumination unit that provides brightness to the liquid crystal display unit, generates measurement information, and based on the generated measurement information, A life prediction method for a liquid crystal display device that generates control information for controlling the brightness of the illumination unit to a set value, and controls the brightness of the illumination unit to a set value based on the generated control information. First control information that is control information generated at a predetermined time is stored, second control information is generated after a lapse of a predetermined time after generation of the first control information, and stored in the storage unit Based on the control current value and the generated second control information, the lifetime of the illumination unit is predicted.

  Thereby, the lifetime of an illumination part can be estimated easily.

(15) In the lifetime prediction method for a liquid crystal display device according to the present invention, the linearity between the control information and the brightness of the illumination unit is further calculated based on the first control information and the second control information. The life of the illumination unit is predicted by using the feature.

  Thereby, the lifetime prediction of an illumination part can be easily performed only by acquiring two sets of control information and the brightness of an illumination part.

  Here, the correspondence relationship between the elements described in the claims and the elements in the embodiment is shown. The illumination unit is the backlight 13, the measurement unit is the optical sensor 15, the control information generation unit is the CPU 21, the illumination control unit is the inverter circuit 11, the life prediction unit is the CPU 21, the life prediction result display unit is the CPU 21 and the display output. This corresponds to each of the circuits 31.

The life prediction unit executes the processes of steps S10, S12 to S22, S31 to S34, S25 to S27, S51 to S53, S40 to S42, S65, S66, S68, S69, S72, S73, and S84.

  Examples of the liquid crystal display device according to the present invention will be described below.

1. Outline An outline of a liquid crystal display device according to the present invention will be described with reference to a functional block diagram shown in FIG. The liquid crystal display device includes a liquid crystal display unit M10, an illumination unit M11, a measurement unit M13, a control information generation unit M15, an illumination control unit M17, a life prediction unit M19, and a life prediction result display unit M21.

  The illumination unit M11 provides brightness to the liquid crystal display unit M10. The measurement unit M13 measures the brightness of the illumination unit M11 and generates measurement information. The control information generation unit M15 generates control information for controlling the brightness of the illumination unit M11 to a set value based on the measurement information. The illumination control unit M17 controls the brightness of the illumination unit M11 to a set value based on the control information.

  The life prediction unit M19 predicts the life of the illumination unit M11 based on the control information. The life prediction unit M19 is further configured based on the first control information that is control information acquired at a predetermined time and the second control information that is control information acquired after the acquisition of the first control information. Predict life.

  Further, the lifetime predicting unit M19 does not perform the lifetime prediction of the illumination unit M11 until a predetermined time has elapsed after acquiring the first control information. Further, the life prediction unit M19 does not perform life prediction of the illumination unit M11 until a predetermined time elapses after the liquid crystal display device or the illumination unit M11 is turned on. If the life prediction unit M19 further determines that the setting value has been changed, the life prediction unit M19 reacquires the first control information. The life prediction unit M19 further holds the first control information before the set value is changed. The life prediction unit M19 determines whether or not the set value has been changed based on the measurement information.

  The control information is a current value for controlling the illumination control unit M17.

  The life prediction result display unit M21 displays the life prediction result on the liquid crystal display unit M10.

  Thereby, even if it is a liquid crystal display device which controls the brightness of an illumination part to a setting value, the lifetime of an illumination part can be estimated. Further, when there is a predetermined relationship between the control information and the brightness of the illumination unit, the lifetime of the illumination unit can be easily predicted. Furthermore, since the predetermined relationship between the control information and the brightness of the illumination unit can be determined with high accuracy, the lifetime of the illumination unit can be accurately predicted. Furthermore, it is possible to prevent the lifetime from being predicted until the control information is stabilized after the liquid crystal display device or the illumination unit is turned on until a predetermined time elapses. Life prediction can be performed. Furthermore, even if the brightness of the illumination unit is changed, the lifetime of the illumination unit can be accurately predicted. Furthermore, since the value required for controlling the brightness of the illumination unit can be used, the lifetime of the illumination unit can be easily predicted. Furthermore, the lifetime of the illumination unit can be easily known. Furthermore, it is possible to easily predict the life of the illumination unit simply by acquiring two sets of control information and the brightness of the illumination unit.

2. Hardware Configuration The hardware configuration of the LCD monitor 1 which is a liquid crystal display device according to the present invention will be described with reference to FIG. The LCD monitor 1 includes an inverter circuit 11, a backlight 13, a light sensor 15, a CPU 21, a memory 23, a backlight on timer circuit 25, a backlight aging timer circuit 27, a display output circuit 31, and an LCD panel 33. ing.

  The inverter circuit 11 makes the brightness of the backlight 13 constant at a predetermined brightness based on the PWM value. The PWM value is a current value for controlling the inverter circuit 11. The backlight 13 provides brightness to the LCD panel 33. The optical sensor 15 measures the brightness of the backlight 13 and generates a sensor value.

  The CPU 21 performs processing based on other applications such as an automatic brightness correction program and a life prediction program recorded in the memory 23. The memory 23 provides a work area for the CPU 21. Further, the memory 23 stores a maximum brightness PWM value, a reference PWM value, a target PWM value, a backlight on count value, a lifetime prediction time, a luminance automatic correction program, a lifetime prediction program, and the like.

  Here, the maximum luminance PWM value will be described. In the relationship between the PWM value and the brightness (luminance) of the backlight, the luminance of the backlight does not change continuously between the minimum value and the maximum value of the PWM value. The brightness of the backlight becomes maximum at a certain PWM value. The PWM value at this time is set as the maximum luminance PWM value. Even if the PWM value is larger than the maximum luminance PWM value, the luminance of the backlight does not change. Since the maximum brightness PWM value differs for each LCD monitor 1, the maximum brightness PWM value is stored in the memory 23 of each LCD monitor 1 at the time of factory shipment.

  The reference PWM value is a PWM value that serves as a reference when the lifetime of the backlight 13 is predicted. The target PWM value is a PWM value used when the lifetime of the backlight 13 is predicted.

  The backlight on count value is an accumulated time during which the backlight 13 is turned on after the maximum brightness PWM value is stored in the memory 23 of the LCD monitor 1.

  The backlight on timer circuit 25 measures the time during which the backlight is lit between the set time and the present time. In this embodiment, the time when the maximum brightness PWM value is set for each LCD monitor 1 is used as the time when it is set. The backlight on timer circuit 25 calculates the backlight on count value by adding the time measured by the current backlight on timer circuit 25 to the previous backlight on count value, and calculates the calculated backlight. Temporarily store the ON count value.

  The backlight aging timer circuit 27 measures the time from when the power source of the LCD monitor 1 or the LCD panel 33 is turned on to the present time. The backlight aging timer circuit 27 temporarily stores the measured time as a backlight aging count value.

  The display output circuit 31 generates an image to be displayed on the LCD panel 33. The LCD panel 33 displays the image generated by the display output circuit 31.

3. Outline of Life Prediction An outline of life prediction of the backlight 13 in the LCD monitor 1 according to the present invention will be described with reference to FIG. It is the figure which showed the relationship between backlight lighting time at the time of operating the backlight adjustment system which maintains the brightness | luminance of the backlight 13 constant irrespective of the performance of the backlight 13, and a PWM value. In FIG. 3, there is no strict representation of the relationship between the backlight lighting time and the PWM value, but an outline thereof is shown.

In FIG. 3, the horizontal axis indicates the backlight lighting time, and the vertical axis indicates the PWM value. A point A indicates a point at which the PWM value becomes the maximum luminance PWM value. Here, the maximum luminance PWM value to _{P m.} Point D indicates the time when the backlight 13 was turned on by first turning on the power after setting the maximum luminance PWM value to the LCD monitor 1.

Further, the point E indicates the first point where the backlight lighting time and the PWM value have a substantially linear relationship. Point B is when the reference PWM value (reference PWM value) is acquired (time: T ₀ ), and point C is when the PWM value (target PWM value) for performing the lifetime prediction of the backlight 13 is acquired ( Time: T ₁ ) is shown. The time between point B and point C is 100 hours. As described above, the target PWM value is acquired after 100 hours and the lifetime of the backlight 13 is predicted. The linear relationship between the PWM value and the brightness of the backlight 13 is obtained to some extent when 100 hours pass. This is because the lifetime of the backlight can be predicted with high accuracy.

  As shown in FIG. 3, during the period from point E to point A, the PWM value increases in a linear function with respect to the backlight lighting time. That is, it can be said that the PWM value and the backlight lighting time are in a substantially linear relationship. On the other hand, between the point D and the point E, the PWM value increases logarithmically with respect to the backlight lighting time. That is, it cannot be said that the PWM value and the backlight lighting time are in a linear relationship.

In the LCD monitor 1, in the section from the point E to the point A (hereinafter referred to as a linear section), the backlight is based on the PWM value by utilizing the fact that the PWM value and the backlight lighting time are substantially linear. Life expectancy is performed. At time T ₁ in the linear interval, the reference PWM value P ₁ is acquired, and then the PWM value (target PWM value) P ₂ acquired at time T ₂ after 100 hours have elapsed. Since it is known that the PWM value and the backlight lighting time are in a substantially linear relationship in the linear section, the time (life time) T _X until reaching the maximum luminance PWM value P _m is expressed by the following equation: Can be obtained.

_{T X = (T 2 -T 1} ) (P m -P 1) / (P 2 -P 1) - (T 2 -T 1) ······· ( Equation 1)
As described above, the LCD monitor 1 can be easily performed without requiring a complicated preparation work of storing in the memory 23 a luminance deterioration curve indicating the degree of deterioration of the luminance of the backlight in advance for every type of backlight. In addition, the lifetime of the backlight can be predicted.

4. Operation of LCD Monitor 1 The CPU 21 of the LCD monitor 1 will be described with reference to the flowcharts shown in FIGS. 4 to 6, based on the automatic brightness correction program and the life prediction program.

4.1. Brightness Correction Process First, the automatic brightness correction process performed by the CPU 21 based on the automatic brightness correction program will be described with reference to the flowchart shown in FIG.

When the power of the LCD monitor 1 or the backlight 13 is turned on (S10), the CPU 21 executes an automatic brightness correction process (S11). The brightness automatic correction processing in this embodiment uses Japanese Patent No. 3193315 (Nanao Co., Ltd.). In the following, an outline of the automatic brightness correction process when Japanese Patent No. 3193315 is applied to the present embodiment will be described with reference to FIG.

  CPU21 acquires a sensor value from the optical sensor 15 (S2). Next, the CPU 21 acquires the brightness setting value set by the user via the brightness setting unit (S3). The CPU 21 calculates a target brightness sensor value based on the above-described maximum brightness and brightness setting value (S4).

  The CPU 21 compares the sensor value acquired in step S2 with the target luminance sensor value (S5). If the CPU 21 determines that the sensor value matches the target luminance sensor value, the process is terminated. On the other hand, if the CPU 21 determines that the sensor value does not match the target brightness sensor value, the PWM for controlling the inverter circuit 11 so that the sensor value detected by the optical sensor 15 approaches the target brightness sensor value. A value is calculated (S6). Then, the CPU 21 outputs the calculated PWM value to the inverter circuit 11 (S7). The inverter circuit 11 adjusts the brightness of the backlight 13 to cause the backlight to emit light with a substantially constant light amount.

4.2. Life Prediction Process Next, the life prediction process performed by the CPU 21 based on the life prediction program will be described with reference to the flowcharts shown in FIGS. 4 and 5.

  When the power of the LCD monitor 1 or the backlight 13 is turned on (S10), the CPU 21 acquires the backlight on count value from the memory 23 and sets it in the backlight on timer circuit 25 (S12). The CPU 21 operates the backlight on timer circuit 25 to start measuring time, and updates the backlight on count value of the backlight on timer circuit 25 (S13). Further, the CPU 21 determines whether or not the reference PWM value is stored in the memory 23 (S14).

  When the CPU 21 determines that the reference PWM value is not stored in the memory 23, the CPU 21 starts a reference PWM value acquisition process (S15).

  Here, the reference PWM value acquisition process will be described with reference to the flowchart shown in FIG. The CPU 21 initializes the backlight aging count value of the backlight aging timer circuit 27, that is, sets “0” (S31). The CPU 21 starts the time measurement by operating the backlight aging timer circuit 27 and updates the backlight aging count value (S32). The CPU 21 determines whether or not the backlight aging count value has reached 60 minutes (S33). When the CPU 21 determines that the backlight aging count value has reached 60 minutes, the CPU 21 acquires the PWM value (S34). In other words, the CPU 21 does not predict the lifetime of the backlight 13 without acquiring the PWM value until a predetermined time (60 minutes) has elapsed after the LCD monitor 1 is turned on. As described above, the PWM value is not acquired until a predetermined time elapses after the power of the LCD monitor 1 is turned on. The PWM value does not stabilize until the predetermined time elapses after the power is turned on, and does not settle. Because there is no.

  Returning to FIG. 4, the acquired PWM value is stored in the memory 23 as a reference PWM value (S16). Then, as shown in FIG. 5, the CPU 21 determines whether or not the backlight-on count value has exceeded 100 hours (S17). If it is determined in step S14 in FIG. 4 that the reference PWM value is stored in the memory 23, it is determined whether or not the backlight on count value has exceeded 100 hours as shown in FIG. 5 (S17). .

  When the CPU 21 determines that the backlight on count value of the backlight on timer circuit 25 has exceeded 100 hours, the CPU 21 executes target PWM value acquisition processing for acquiring a target PWM value in life prediction (S18). That is, the CPU 21 does not predict the lifetime of the backlight 13 without acquiring the target PWM value until 100 hours have elapsed after acquiring the reference PWM value. The target PWM value acquisition process is the same as the reference PWM value acquisition process (see FIG. 7: steps S31 to S34), and thus the description thereof is omitted.

  The CPU 21 stores the acquired PWM value as the target PWM value in the memory 23 (S19).

  The CPU 21 calculates the estimated lifetime of the backlight 13 based on the reference PWM value and the target PWM value stored in the memory 23 (S20). It should be noted that (Equation 1) described above is used in the calculation of the estimated life time. The CPU 21 stores the calculated estimated life time in the memory 23.

  Thereafter, the CPU 21 updates the reference PWM value in the memory 23 with the target PWM value acquired this time as the reference PWM value (S21). Further, the CPU 21 initializes the backlight on count value of the backlight on timer circuit 25 to “0” (S22).

4.3. Brightness Change Processing Next, the brightness change processing performed by the CPU 21 based on the life prediction program will be described with reference to the flowchart shown in FIG. When the CPU 21 determines that the luminance setting change information has been acquired from the luminance setting changing unit (S25), the CPU 21 deletes the reference PWM value stored in the memory 23 (S26). Then, the CPU 21 initializes the backlight on count value of the backlight on timer circuit 25 to “0” (S27). Thereafter, the CPU 21 repeats the processes after step S15 in FIG. As described above, when the CPU 21 determines that the setting value for the brightness of the backlight 13 has been changed, the CPU 21 reacquires the reference PWM value.

4.4. Life Expected Time Display Processing Next, life predicted time display processing performed by the CPU 21 based on the life prediction program will be described with reference to the flowchart shown in FIG. When the CPU 21 determines that the life prediction display information has been acquired (S51), the CPU 21 acquires the life prediction time from the memory 23 (S52). Then, the CPU 21 displays the acquired estimated life time on the LCD panel 33 via the display output circuit 31 (S53).

4.5. End Process Next, the end process performed by the CPU 21 based on the life prediction program will be described with reference to the flowchart shown in FIG. When the CPU 21 determines that the power of the LCD monitor 1 is turned off (S40), it stores the backlight on count value of the backlight on timer circuit 25 in the memory 23 (S41). Then, the CPU 21 turns off the power of the LCD monitor 1 (S42).

1. Overview In the first embodiment described above, the presence / absence of luminance setting change by the user is determined based on the presence / absence of luminance setting change information from the luminance setting unit. On the other hand, the LCD monitor 3 according to the present embodiment determines whether or not the user has changed the luminance setting based on a change in the sensor value acquired from the sensor 15 when the lifetime of the backlight 13 is predicted. Thereby, it is possible to easily determine whether or not the luminance setting has been changed.

2. Hardware configuration
The hardware configuration of the LCD monitor 3 is shown in FIG. The hardware configuration of the LCD monitor 3 is basically the same as that of the first embodiment. However, the data stored in the memory 73 is partially different from the first embodiment. In the following, a different part from Example 1 is demonstrated. In addition, about the structure similar to Example 1, the number similar to Example 1 is attached | subjected.

  The memory 73 provides a work area for the CPU 21. Further, the memory 73 stores the maximum luminance PWM value, the reference PWM value, the target PWM value, the backlight on count value, the lifetime prediction time, the luminance automatic correction program, the lifetime prediction program, and the like stored in the memory 23 in the first embodiment. In addition, a reference sensor value is stored. The reference sensor value refers to a sensor value that serves as a reference for determining whether or not the brightness (luminance) of the backlight 13 has been changed.

3. Operation of LCD Monitor 3 The CPU 21 of the LCD monitor 3 will explain the life prediction process performed based on the automatic brightness correction program and the life prediction program with reference to the flowcharts shown in FIGS. Since processes other than the life prediction process based on the life prediction program are the same as those in the first embodiment, a description thereof is omitted here.

3.1. Life Prediction Process The life prediction process performed by the CPU 21 based on the life prediction program will be described with reference to the flowcharts shown in FIGS. In the following, the same reference numerals as those in the first embodiment are assigned to the same processes as the life prediction process in the first embodiment.

  When the power of the LCD monitor 1 or the power of the backlight 13 is turned on (S10), the CPU 21 acquires the backlight on count value from the memory 73 and sets it in the backlight on timer circuit 25 (S12). The CPU 21 operates the backlight on timer circuit 25 to start measuring time, and updates the backlight on count value of the backlight on timer circuit 25 (S13). Further, the CPU 21 determines whether or not the reference PWM value is stored in the memory 73 (S14).

  If the CPU 21 determines that the reference PWM value is not stored in the memory 73, the CPU 21 starts a reference PWM value / sensor value acquisition process (S65).

  Here, the reference PWM value / sensor value acquisition processing will be described with reference to the flowchart shown in FIG. The CPU 21 initializes the backlight aging count value of the backlight aging timer circuit 27, that is, sets “0” (S31). The CPU 21 starts the time measurement by operating the backlight aging timer circuit 27 and updates the backlight aging count value (S32). The CPU 21 determines whether or not the backlight aging count value has reached 60 minutes (S33). When determining that the backlight aging count value has reached 60 minutes, the CPU 21 acquires the PWM value and the sensor value (S84). That is, the CPU 21 does not predict the lifetime of the backlight 13 without acquiring the PWM value / sensor value until a predetermined time (60 minutes) has elapsed since the power of the LCD monitor 1 is turned on. As described above, the PWM value and the sensor value are not acquired until a predetermined time elapses after the power of the LCD monitor 1 is turned on. The PWM value is not stable until the predetermined time elapses after the power is turned on. This is because the price is not settled.

  Returning to FIG. 12, the acquired PWM value is stored in the memory 73 as a reference PWM value, and the acquired sensor value is stored as a reference sensor value (S66). Then, as shown in FIG. 13, the CPU 21 determines whether or not the backlight-on count value has exceeded 100 hours (S17). If it is determined in step S14 in FIG. 12 that the reference PWM value is stored in the memory 73, as shown in FIG. 13, it is determined whether or not the backlight on count value has exceeded 100 hours (S17). .

  When the CPU 21 determines that the backlight-on-count value has exceeded 100 hours, the CPU 21 executes target PWM value / sensor value acquisition processing for acquiring a target PWM value in the life prediction (S68). That is, the CPU 21 does not predict the lifetime of the backlight 13 without acquiring the target PWM value until a predetermined time (100 hours) elapses after acquiring the reference PWM value. The target PWM value / sensor value acquisition process is the same as the reference PWM value / sensor value acquisition process (see FIG. 14: Steps S31 to S33, S84), and thus the description thereof is omitted.

  The CPU 21 determines whether or not the target sensor value that is the acquired sensor value is substantially the same as the reference sensor value (S69). Thus, the CPU 21 determines whether or not the set value has been changed based on the sensor value. When determining that the target sensor value and the reference sensor value are the same value, the CPU 21 stores the acquired PWM value in the memory 73 as the target PWM value (S19).

  The CPU 21 calculates the estimated lifetime of the backlight 13 based on the reference PWM value and the target PWM value stored in the memory 73 (S20). It should be noted that (Equation 1) described above is used in the calculation of the estimated life time. The CPU 21 stores the calculated estimated life time in the memory 73.

  After that, the CPU 21 updates the reference PWM value stored so far using the target PWM value acquired this time as the reference PWM value (S21). Further, the CPU 21 initializes the backlight on count value of the backlight on timer circuit 25 to “0” (S22).

On the other hand, when determining in step S69 that the target sensor value and the reference sensor value are not the same, the CPU 21 deletes the reference PWM value and the reference sensor value stored in the memory 73 (S72). Then, the CPU 21 initializes the backlight on count value of the backlight on timer circuit 25 to “0” (S73). Thereafter, the CPU 21 repeats the processing after step S65 in FIG.

[Other Examples]
(1) Variation of Life Prediction In the above-described first and second embodiments, the life prediction of the backlight 13 is not performed until 100 hours after the reference PWM value is acquired. But,
It is not limited to 100 hours.

  In the first and second embodiments described above, after acquiring the reference PWM value, the target PWM value is acquired after 100 hours have elapsed, the lifetime of the backlight 13 is predicted, and the target PWM value at that time is further determined as the reference PWM value. As a value, the lifetime of the backlight 13 was predicted after another 100 hours. That is, the lifetime of the backlight 13 is predicted every predetermined period such as 100 hours. However, the lifetime of the backlight may not be predicted every predetermined period. For example, a PWM value 100 hours before the time when the target PWM value is acquired this time is calculated based on the previous target PWM value and the reference PWM value, and the calculated PWM value 100 hours before is used as the reference PWM value for the backlight. You may make it perform 13 lifetime prediction.

  Further, in the first and second embodiments, the lifetime prediction of the backlight 13 may not be performed until the accumulated usage time of the backlight 13 has passed a predetermined time. By not performing the lifetime prediction of the backlight until the substantially linear relationship between the PWM value and the brightness of the backlight is ensured, a more accurate lifetime prediction is possible. For a general LCD monitor, it is considered appropriate to set an accumulated usage time of about 2000 hours.

  Further, in the above-described first and second embodiments, the lifetime prediction of the backlight 13 is not performed until 60 minutes have passed after the LCD monitor 1 is turned on. However, the time is not limited to 60 minutes as long as the PWM value is stable.

(2) Change in Brightness of Backlight 13 In the first and second embodiments, when the brightness (brightness) of the backlight 13 is changed by the user, the reference PWM value stored so far is used. The reference PWM value at the brightness after the change is deleted and re-acquired. However, the reference PWM value before changing the brightness of the backlight 13 may be stored. Thereby, for example, even when the user changes the brightness of the backlight 13 on a trial basis and then returns to the brightness of the original backlight 13, the lifetime of the backlight 13 can be predicted. it can.

  In the first and second embodiments, the brightness of the backlight 13 is changed by the user. However, the brightness of the backlight 13 may be automatically changed according to a change in environment. In this case, the usage time at each luminance in a predetermined time (for example, 100 hours) is calculated, while the predicted life time at each luminance is calculated, and the predicted life time is obtained by weighting the calculated predicted life time with the usage time. The predicted life time may be calculated by a weighted average.

(3) PWM value In the first and second embodiments, the lifetime of the backlight 13 is predicted using the PWM value. However, the present invention is not limited to this as long as the inverter circuit 11 can be controlled. For example, it may be a voltage value given to the inverter circuit 11 in order to control the brightness of the backlight 13 to be constant.

(4) Display of predicted life time In the above-described first and second embodiments, the predicted life time is displayed. However, an LCD monitor usage plan based on the predicted life time is displayed together with or instead of the display of the predicted life time. May be displayed. For example, when the user inputs a period for using the LCD monitor, the usage time for one day for using the LCD monitor within the period may be calculated and displayed.

(5) Automatic brightness correction process In the first and second embodiments, the automatic brightness correction process is performed based on Japanese Patent No. 3193315. However, the present invention is not limited to this as long as the automatic brightness correction process can be performed.

It is a functional block diagram of the liquid crystal display device in this invention. 2 is a diagram showing a hardware configuration of an LCD monitor 1. FIG. It is a figure for demonstrating the outline | summary of lifetime prediction. It is the flowchart which showed the brightness | luminance automatic correction process and the lifetime prediction process. It is the flowchart which showed the lifetime prediction process. It is the flowchart which showed the brightness | luminance automatic correction process. It is the flowchart which showed the reference | standard PWM value acquisition process and object PWM value acquisition process. It is the flowchart which showed the brightness | luminance change process. It is the flowchart which showed the lifetime prediction time display process. It is the flowchart which showed the end process. 2 is a diagram showing a hardware configuration of an LCD monitor 3. FIG. It is the flowchart which showed the lifetime prediction process. It is the flowchart which showed the lifetime prediction process. 5 is a flowchart showing a reference PWM value / sensor value acquisition process / target PWM value / sensor value acquisition process; It is a figure for demonstrating a prior art.

Explanation of symbols

M10: Liquid crystal display unit M11: Illumination unit M13: Measurement unit M15: Control information generation unit M17: Illumination control unit M19: Life prediction part M21 ... Life prediction result display part

Claims (13)

An illumination unit that provides brightness to the liquid crystal display unit;
A measurement unit that measures the brightness of the illumination unit and generates measurement information;
A control information generating unit that generates control information for controlling the brightness of the illumination unit to a set value based on the measurement information;
An illumination control unit that controls the brightness of the illumination unit to a set value based on the control information,
and,
A lifetime predicting unit that predicts the lifetime of the illumination unit based on first control information that is control information acquired at a predetermined time and second control information that is control information acquired after acquiring the first control information;
A liquid crystal display device comprising:
The life prediction unit further includes:
If it is determined that the set value has been changed, re-acquiring the first control information;
A liquid crystal display device. The liquid crystal display device according to claim 1,
The life prediction unit further includes:
Holding the first control information before the set value is changed;
A liquid crystal display device. Either of the liquid crystal display devices according to claim 1 or claim 2,
The life prediction unit
Determining whether the set value has been changed based on the measurement information;
A liquid crystal display device. In any one of the liquid crystal display devices according to claims 1 to 3,
The life prediction unit further includes:
Do not perform the lifetime prediction of the illumination unit until a predetermined time has elapsed after acquiring the first control information,
A liquid crystal display device. In any one of the liquid crystal display devices according to claims 1 to 4,
The life prediction unit further includes:
Do not perform the lifetime prediction of the lighting unit until the accumulated usage time of the lighting unit has passed a predetermined time,
A liquid crystal display device. In any one of the liquid crystal display devices according to claims 1 to 5,
The life prediction unit further includes:
Do not perform lifetime prediction of the illumination unit until a predetermined time has elapsed since the liquid crystal display device or the illumination unit was turned on,
A liquid crystal display device. The liquid crystal display device according to any one of claims 1 to 6,
The control information is a current value for controlling the illumination control unit;
A liquid crystal display device. The liquid crystal display device according to any one of claims 1 to 7,
The control information is a voltage value for controlling the illumination control unit;
A liquid crystal display device. The liquid crystal display device according to any one of claims 1 to 8, further comprising:
A life prediction result display unit for displaying the result of the life prediction;
A liquid crystal display device. In any one of the liquid crystal display devices according to claim 1 to claim 9,
The life prediction unit further includes:
Predicting the lifetime of the illumination unit using the linearity between the control information and the brightness of the illumination unit;
A liquid crystal display device. Backlight that provides brightness to the LCD panel,
An optical sensor that measures the amount of light of the backlight and generates measurement information;
A luminance control unit that calculates a PWM value for controlling the luminance of the backlight to a set value based on the measurement information;
An inverter circuit for controlling the brightness of the backlight to a set value based on the PWM value;
A storage unit for storing a first PWM value which is a PWM value calculated at a predetermined time;
and,
A lifetime prediction unit that predicts the lifetime of the backlight based on a first PWM value stored in the storage unit and a second PWM value that is a PWM value calculated after the calculation of the first PWM value;
A liquid crystal display device comprising:
The life prediction unit further includes:
If it is determined that the set value has been changed, re-acquiring the first PWM value from the brightness control unit;
A liquid crystal display device. Control information for measuring the brightness of the illumination unit that provides brightness to the liquid crystal display unit, generating measurement information, and controlling the brightness of the illumination unit to a set value based on the generated measurement information A lifetime prediction method for a liquid crystal display device that controls the brightness of the illumination unit to a set value based on the generated control information,
Storing first control information which is control information generated at a predetermined time;
After the generation of the first control information, the second control information is generated after a predetermined time has elapsed,
Based on the first control information stored in the storage unit and the generated second control information, predict the lifetime of the illumination unit,
If it is determined that the set value has been changed, re-acquiring the first control information;
A method for predicting the life of a liquid crystal display device. In the liquid crystal display device life prediction method according to claim 12,
Predicting the lifetime of the illumination unit based on the first control information and the second control information, using linearity between the control information and the brightness of the illumination unit;
A method for predicting the life of a liquid crystal display device.

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