Light emitting device and method for controlling light emitting device

Abstract

To quickly adjust a common voltage.SOLUTION: The light-emitting device (10) includes a power supply (31) configured to input a common voltage (Vin) common to the plurality of light-emitting units (21(i)) to the plurality of light-emitting units, and a control unit (32) configured to: A voltage acquirer (361) configured to acquire a first output voltage (Vout1 (i)) output from each light emitter at a first timing, an input voltage adjuster (34) configured to adjust the common voltage based on the first output voltage, and a voltage predictor (362) configured to predict an output voltage output from each light emitter as a first predicted voltage (Vp1) based on the first output voltage, wherein after the first timing, the input voltage adjuster adjusts the common voltage based on the first predicted voltage.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a light emitting device and a method for controlling a light emitting device. [Background technology]

[0002] Patent Document 1 discloses a technique for stabilizing the forward voltage of a light-emitting element. When a light-emitting element is made to emit light, it is preferable that the forward voltage fluctuate little in order to stabilize the brightness. However, the forward voltage fluctuates depending on various conditions, for example, temperature, and as a result, the brightness of the light-emitting element may vary from the original target brightness. In Patent Document 1, the voltage generated by a group of light-emitting elements is detected and the driving power supplied to the group of light-emitting elements is adjusted (see abstract). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-242477 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned conventional techniques have a problem in that it takes time to detect the voltage when there are a large number of light-emitting elements. It takes a certain amount of time to separately detect the voltages of a large number of light-emitting elements (or a large number of groups of light-emitting elements) and transmit the detected values ​​to one location. As a result, the driving power is not adjusted promptly. For example, when reducing the driving voltage, the delay in this adjustment results in a loss of power.

[0005] An object of one embodiment of the present invention is to provide a light-emitting device in which voltage can be quickly adjusted and a method for controlling the light-emitting device. [Means for solving the problem]

[0006] In order to solve the above problem, a light-emitting device according to one embodiment of the present invention comprises a power source that inputs a common voltage common to a plurality of light-emitting elements to the plurality of light-emitting elements, a voltage acquisition unit that acquires a first output voltage output from each of the light-emitting elements at a first timing based on the common voltage input to each of the light-emitting elements, an input voltage adjustment unit that adjusts the common voltage based on the first output voltage, and a voltage prediction unit that predicts the output voltage output from each of the light-emitting elements as a first predicted voltage based on the first output voltage, and from the first timing onwards, the input voltage adjustment unit adjusts the common voltage based on the first predicted voltage.

[0007] In order to solve the above problem, a control method for a light-emitting device according to one embodiment of the present invention is a control method for a light-emitting device for controlling a light-emitting device, wherein the light-emitting device has a power supply that inputs a common voltage common to a plurality of light-emitting elements to the plurality of light-emitting elements, and the control method for the light-emitting device includes a process of obtaining a first output voltage output from each of the light-emitting elements based on the common voltage input to each of the light-emitting elements, a process of adjusting the common voltage based on the first output voltage, a process of predicting the output voltage output from each of the light-emitting elements as a predicted voltage based on the first output voltage, and a process of adjusting the common voltage based on the predicted voltage. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to provide a light emitting device and a method for controlling a light emitting device that enable quick voltage adjustment. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram illustrating an example of a display device according to a first embodiment of the present invention. [Figure 2] 1 is a block diagram illustrating an example of a light emitting device according to a first embodiment of the present invention. [Figure 3] 2 is a schematic diagram illustrating an example of the configuration of a drive control unit according to the first embodiment of the present invention. FIG. [Figure 4]4 is a flowchart illustrating an example of a control method for the light emitting device according to the first embodiment of the present invention. [Figure 5] 1 is a graph showing an example of temperature characteristics of a light-emitting element. [Figure 6] FIG. 10 is a schematic diagram illustrating a method for predicting a voltage using a table. [Figure 7] 4 is a graph showing the difference in power loss between a conventional method and the method according to the first embodiment of the present invention. [Figure 8] 10 is a flowchart illustrating an example of a control method for a light emitting device according to a second embodiment of the present invention. [Figure 9] FIG. 10 is a block diagram illustrating an example of a light emitting device according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a schematic diagram illustrating an example of the configuration of a drive control unit according to a third embodiment of the present invention. [Figure 11] FIG. 10 is a flowchart illustrating an example of a control method for a light emitting device according to a third embodiment of the present invention. [Figure 12] FIG. 10 is a schematic diagram illustrating a method for predicting a voltage using a table. [Figure 13] FIG. 10 is a schematic diagram illustrating an example of a table. [Figure 14] FIG. 10 is a flowchart illustrating an example of a control method for a light emitting device according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Embodiment 1] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below. Fig. 1 is a block diagram showing an example of a display device 1 according to a first embodiment of the present invention.

[0011] The display device 1 includes a light emitting device 10 (light emitting unit 20, light emitting driver 30), a display section 40, a display driver 50, a signal processor 60, and a controller .

[0012] The light emitting device 10 illuminates the display unit 40 to make it easier to see the image displayed on the display unit 40. Details of the light emitting device 10 will be described later.

[0013] The display unit 40 is a display device that displays images, such as a liquid crystal display device. The display drive unit 50 drives the display unit 40 to display images. The signal processing unit 60 processes a video signal IS and sends it to the display drive unit 50 to display images on the display unit 40. The control unit 70 controls the entire display device 1.

[0014] 2 is a block diagram illustrating an example of the light emitting device 10 according to the first embodiment of the present invention. The light emitting device 10 includes a light emitting unit 20 and a light emission driver 30.

[0015] The light-emitting unit 20 emits light and has a plurality (n) of light-emitting sections 21(1) to 21(n) that can emit light independently of one another. Hereinafter, the light-emitting sections 21(1) to 21(n) may be collectively referred to as light-emitting section 21(i). The light-emitting sections 21(i) may be arranged, for example, in different regions on the display section 40, and the brightness of each region may be different. The number n is 1 or more, for example, several to several thousand. In each light-emitting section 21(i), a plurality of light-emitting elements (for example, LEDs: Light Emitting Diodes) are arranged in series.

[0016] The light emission drive section 30 includes a power supply 31, drive sections 32(1) to 32(n), output voltage detection sections 33(1) to 33(n), a power supply control section , a current detection section 35, and a drive control section .

[0017] The power supply 31 inputs a common voltage Vin common to the plurality of light-emitting units 21(i) to these plurality of light-emitting units 21(i). For example, the power supply 31 applies a voltage (common voltage) Vin to the anode terminals of the plurality of light-emitting units 21(i) to cause the light-emitting units 21(i) to emit light.

[0018] The driving units 32(1) to 32(n) control the driving (illumination) of each of the plurality of light-emitting units 21(i). The driving units 32(1) to 32(n) control the driving (illumination) of each of the plurality of light-emitting units 21(i) by, for example, a PWM (Pulse Width Modulation) signal.

[0019] The output voltage detection units 33(1) to 33(n) detect the output voltage Vout(i) output from each light-emitting unit 21(i) based on the common voltage Vin input to each light-emitting unit 21(i). The output voltage Vout(i) is, for example, the voltage at the cathode terminal of each of the multiple light-emitting units 21(1) to 21(n). The output voltage Vout(i) detected by the output voltage detection units 33(1) to 33(n) is acquired by the drive control unit 36 ​​(particularly, a voltage acquisition unit 361, which will be described later).

[0020] The power supply control unit 34 controls the operation of the power supply 31. That is, the power supply control unit 34 functions as an input voltage adjustment unit that adjusts the common voltage Vin based on the output voltage Vout(i).

[0021] Current detection unit 35 detects current I supplied from power supply 31 to multiple light-emitting units 21(i). This current I is expressed, for example, by a duty ratio in pulse waveform modulation (as an example, pulse width modulation). As described above, when drive unit 32(i) controls light-emitting unit 21(i) by, for example, a pulse width modulation signal, current I supplied from power supply 31 to multiple light-emitting units 21(i) can be expressed by a duty ratio in pulse waveform modulation.

[0022] The drive control unit 36 ​​controls the operation of the light-emitting drive unit 30. The drive control unit 36 ​​(particularly, the voltage prediction unit 362 described below) predicts the output voltage Vout(i) output from each light-emitting unit 21(i) as a first predicted voltage Vp1(i) based on the first output voltage Vout1(i). From a first timing described below onwards, the power supply control unit 34 (input voltage adjustment unit) adjusts the common voltage Vin based on the first predicted voltage Vp1(i).

[0023] Fig. 3 is a schematic diagram illustrating an example of the configuration of the drive control unit 36 ​​according to the first embodiment of the present invention. As shown in Fig. 3, the drive control unit 36 ​​includes a voltage acquisition unit 361, a voltage prediction unit 362, an output switching unit 363, a switch SW, and a flag F. In this diagram, the internal configuration of the drive control unit 36 ​​is represented by hardware, but this internal configuration may also be realized by software.

[0024] The voltage acquiring unit 361 acquires the output voltage Vout(i) from the output voltage detecting units 33(1) to 33(n). That is, the voltage acquiring unit 361 acquires the output voltage Vout(i) output from each light-emitting unit 21(i) based on the common voltage Vin input to each light-emitting unit 21(i). This acquisition can be performed at a first timing and a second timing, which will be described later. In this case, the voltage acquiring unit 361 acquires the first output voltage Vout1(i) (or the second output voltage Vout2(i)) output from each light-emitting unit 21(i) based on the common voltage Vin input to each light-emitting unit 21(i), based on the first timing (or the second timing), which will be described later. For example, all the light-emitting units 21(i) are turned on at a constant PWM duty ratio, and the voltage acquiring unit 361 acquires the cathode voltage values ​​of the plurality of light-emitting units 21(i) at this time as the output voltage Vout1(i).

[0025] The voltage prediction unit 362 predicts the output voltage Vout(i) that will be output from each light-emitting unit 21(i) thereafter (for example, currently) as a predicted voltage Vp(i) based on the output voltage Vout(i) previously acquired (for example, at the first or second timing).

[0026] When the first output voltage Vout1(i) is acquired at the first timing, the voltage prediction unit 362 predicts the output voltage Vout(i) output from each light-emitting unit 21(i) as a first predicted voltage Vp1(i) based on the first output voltage Vout1(i).

[0027] When the second output voltage Vout2(i) is acquired at the second timing, the voltage prediction unit 362 predicts the output voltage Vout(i) output from each light-emitting unit 21(i) as a second predicted voltage Vp2(i) based on the second output voltage Vout2(i).

[0028] The output switching unit 363 switches between the output voltage Vout(i) acquired by the voltage acquiring unit 361 and the predicted voltage Vp(i) predicted by the voltage predicting unit 362, and outputs the switched output voltage to the power supply control unit 34. Here, when the flag F is 0, the output switching unit 363 outputs the output voltage Vout(i) acquired by the voltage acquiring unit 361, and when the flag F is 1, the output switching unit 363 outputs the predicted voltage Vp(i) predicted by the voltage predicting unit 362.

[0029] The flag F is rewritten as appropriate by instructions from the control unit 70. For example, at a first timing, the flag F is set to 0, and the output voltage Vout(i) acquired by the output switching unit 363 from the voltage acquiring unit 361 is output. In other cases, the flag F is set to 1, and the predicted voltage Vp(i) predicted by the voltage predicting unit 362 is repeatedly, for example, periodically output from the output switching unit 363.

[0030] The switch SW is turned ON / OFF in accordance with the flag F. For example, when the flag F is 1, the switch SW is in the OFF state, and when the flag F is 0, the switch SW is in the ON state. When the switch SW is in the ON state, the output voltage Vout(i) previously acquired by the voltage acquisition unit 361 is input to the voltage prediction unit 362, and the voltage prediction unit 362 predicts the output voltage Vout(i) to be output subsequently as a predicted voltage Vp(i) based on the previous output voltage Vout(i).

[0031] 4 is a flow chart showing an example of a control method S1 for the light emitting device 10 according to the first embodiment of the present invention. The control method S1 for the light emitting device 10 will be described below.

[0032] (1) Generation of the first timing (S11) A first timing occurs. This first timing is, for example, when the light emitting device 10 (or the display device 1) is started up. As described above, the control unit 70 sets the flag F to 0 and causes the voltage acquisition unit 361 to proceed with acquisition of the output voltage Vout(i).

[0033] (2) Voltage acquisition process (S12) The voltage acquisition unit 361 acquires a first output voltage Vout1(i) output from each light-emitting unit 21(i) at a first timing from the output voltage detection unit 33(i) in response to the common voltage Vin input to each light-emitting unit 21(i). The first output voltage Vout1(i) is input to the power supply control unit 34 via the output switching unit 363.

[0034] (3) Power supply control process (S13) The power supply control unit 34 functions as an input voltage adjustment unit and adjusts the common voltage Vin based on the first output voltage Vout1(i). Adjusting the common voltage Vin facilitates effective use of power.

[0035] This will be explained in detail below. Fig. 5 is a graph showing an example of the temperature characteristics of a light-emitting element (e.g., an LED). As shown in Fig. 5, the light-emitting element has a characteristic in which the forward voltage Vf changes in response to temperature even when the current is constant. For example, as the temperature increases, the forward voltage Vf decreases, and as the temperature decreases, the forward voltage Vf increases.

[0036] Here, because the forward voltage Vf changes with temperature, it is preferable to determine the common voltage Vin taking into account the change in the forward voltage Vf. For example, if the common voltage Vin is set to correspond to a state in which the forward voltage Vf is low at high temperatures, there is a risk that the common voltage Vin will be insufficient when the forward voltage Vf increases at low temperatures. Conversely, if the common voltage Vin is set to correspond to a state in which the forward voltage Vf is high at low temperatures, there is a risk that an excess voltage will be applied to the driver 32(i) when the forward voltage Vf decreases at high temperatures, resulting in increased power consumption. In other words, by appropriately adjusting the common voltage Vin, it is possible to effectively utilize power.

[0037] As described above, in the case other than the first timing, the flag F is set to 1, and the predicted voltage Vp(i) predicted by the voltage prediction unit 362 is repeatedly output from the output switching unit 363, for example, periodically (for example, at intervals of several milliseconds (e.g., 8 milliseconds)). That is, the next voltage estimation process (S14) and power supply control process (S15) are repeated.

[0038] (4) Voltage estimation process (S14) The drive control unit 36 ​​(voltage prediction unit 362) predicts the first output voltage Vout1(i) based on the first output voltage Vout1(i). The drive control unit 36 ​​can predict the subsequent first output voltage Vout1(i) based on, for example, the current I (for example, the duty ratio in pulse width modulation (PWM)) detected by the current detection unit 35. Because there is a correspondence between the forward voltage Vf and the current I, the current output voltage Vout1(i) can be predicted based on the current I and the previous first output voltage Vout1(i).

[0039] In this way, the drive control unit 36 ​​(voltage prediction unit 362) may predict the first predicted voltage Vp(i) based on the first output voltage Vout1(i) and the current I. The drive control unit 36 ​​(current acquisition unit) may acquire the first current I1 supplied from the power supply 31 to the plurality of light-emitting units 21 from the first timing onwards, and the voltage prediction unit 362 may predict the first predicted voltage Vp1 based on the first output voltage Vout1(i) and the first current I1. The current I may be expressed as a duty ratio in pulse width modulation.

[0040] FIG. 6 is a schematic diagram showing a method for predicting voltage using a table. The output voltage Vout(i) changes in response to the current I. At this time, the current I obtained is the current of the light-emitting unit 21(i) as a whole, and does not necessarily match the current I(i) for each light-emitting unit 21(i). In other words, the effect of the current I on the output voltage Vout(i) differs depending on the light-emitting unit 21(i). For this reason, a table T is used that shows the relationship between the current I(i) and the output voltage Vout(i) of the light-emitting unit 21(i).

[0041] This table T indicates, for example, how the magnification A of the predicted voltage Vp(i) relative to the output voltage Vout(i) changes with respect to the current I and the light-emitting unit 21(i). For example, as shown in the following (1), the predicted voltage Vp(i) can be calculated by multiplying the magnification (coefficient) A(I,i) and the output voltage Vout(i).

[0042] Vp(i) = A(I,i) * V(i) ... Equation (1) Vp(i): Predicted voltage (predicted value of output voltage Vout(i)) A(I,i): A factor (coefficient) of the predicted voltage Vp(i) relative to the output voltage Vout(i), which is a function of the current I and the identifier i of the light-emitting unit 21. V(i): Measured value Vm(i) of output voltage Vout(i) or previous predicted value Vp(i)

[0043] The magnification A(I, i) is stored in, for example, a memory as a table T representing the relationship between the magnification A, the current I, and the identifier i, and is used to predict the voltage. Note that this relationship can be obtained through an experiment using the light emitting device 10.

[0044] This voltage estimation process (S14) can be executed at a higher speed than the voltage acquisition process (S12). This is because, while it takes time for the voltage acquisition unit 361 to acquire the output voltage Vout(i) from a plurality of output voltage detection units 33(i) depending on the number of output voltage detection units 33(i), it is sufficient to acquire the current I from one current detection unit 35, and so it does not take as much time.

[0045] (5) Power supply control process (S15) After the first timing, the power supply control unit 34 functions as an input voltage adjustment unit and adjusts the common voltage Vin based on the first predicted voltage Vp1(i). Adjusting the common voltage Vin facilitates effective use of power.

[0046] FIG. 7 is a graph showing the difference in power loss between the conventional method CA0 and the method CA1 according to the first embodiment of the present invention. In the conventional method CA0, all output voltages Vout(i) are constantly measured and the common voltage Vin is adjusted, whereas in the method CA1 according to the first embodiment of the present invention, the output voltages Vout(i) are predicted and the common voltage Vin can be adjusted. The time T1 required to predict the output voltage Vout(i) is shorter than the time T0 required to acquire the output voltage Vout(i). Therefore, the power loss PL1 in the first embodiment of the present invention is smaller than the conventional power loss PL0, which makes it easier to use power effectively.

[0047] As described above, the first embodiment of the present invention includes a power supply that inputs a common voltage common to a plurality of light-emitting units to the plurality of light-emitting units, a voltage acquisition unit that acquires a first output voltage output from each of the light-emitting units at a first timing based on the common voltage input to each of the light-emitting units, an input voltage adjustment unit that adjusts the common voltage based on the first output voltage, and a voltage prediction unit that predicts the output voltage output from each of the light-emitting units as a first predicted voltage based on the first output voltage, and after the first timing, the input voltage adjustment unit adjusts the common voltage based on the first predicted voltage. This makes it possible to realize a light-emitting device that quickly adjusts the common voltage.

[0048] [Embodiment 2] Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0049] 8 is a flow chart showing an example of a control method S2 of the light emitting device 10 according to the second embodiment of the present invention. The control method S2 of the light emitting device 10 will be described below.

[0050] Here, the second timing (S21) at which the predetermined state occurs occurs after the first timing (S11). In the voltage acquisition process S22, the drive control unit 36 ​​(voltage acquisition unit 361) acquires the second output voltage Vout2(i) output from each light-emitting unit 21 at the second timing (S21).

[0051] The predetermined state may be, for example, muting the video, increasing the brightness of the video, or the passage of a predetermined period of time.

[0052] The video muting occurs, for example, when the video signal IS is switched or when the broadcast wave (channel) is switched in the display device 1, and the control unit 70 of the display device 1 can detect the occurrence of the video muting.

[0053] An increase in the brightness of the image can be detected based on a change in the brightness information included in the image signal IS. Alternatively, a brightness sensor may be installed in the display device 1, and the control unit 70 may detect an increase in the brightness of the image by monitoring fluctuations in the brightness of the screen.

[0054] Here, the decrease in image brightness is not included because there is a difference in power reduction when the image brightness increases and decreases. When the screen becomes brighter, the temperature of the light-emitting unit 21 increases and the forward voltage Vf of the light-emitting unit 21 decreases. As a result, the output voltage Vout(i) increases. At this time, power can be reduced by reducing the common voltage Vin. On the other hand, when the screen becomes darker, the temperature of the light-emitting unit 21 decreases and the forward voltage Vf of the light-emitting unit 21 increases. As a result, the output voltage Vout(i) decreases. At this time, even if the common voltage Vin is increased, power is not substantially reduced.

[0055] The lapse of the predetermined period can be detected by a timer. This predetermined period can be, for example, from several milliseconds to several hundred milliseconds (for example, 100 milliseconds).

[0056] In either case, the control unit 70 detects a predetermined state, switches the flag F from 1 to 0, and causes the voltage acquisition unit 361 to acquire the output voltage Vout(i).

[0057] After the voltage acquisition process S22 and before the voltage estimation process S14, the power supply control unit 34 functions as an input voltage adjustment unit and can adjust the common voltage Vin based on the second output voltage Vout2(i) (power supply control process S23). This is because it may take some time after the voltage acquisition process S22 until the voltage estimation process S14 starts.

[0058] The drive control unit 36 ​​(input voltage adjusting unit) may adjust the common voltage Vin based on the first predicted voltage Vp1(i) from the first timing to the second timing, and may adjust the common voltage Vin based on the second predicted voltage Vp2(i) from the second timing onwards.

[0059] [Embodiment 3] Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0060] 9 is a block diagram illustrating an example of a light-emitting device 10 according to a third embodiment of the present invention. In this light-emitting device 10, the light-emitting unit 20 has one or more temperature sensors TS. Although n temperature sensors TS may be provided corresponding to the light-emitting sections 21(1) to 21(n), a light-emitting unit 20 may also have fewer than n temperature sensors TS (for example, one). By limiting the number of temperature sensors TS, the time required to acquire the temperature can be reduced, enabling faster processing.

[0061] 10 is a schematic diagram showing an example of the configuration of a drive control unit 36 ​​according to a third embodiment of the present invention. As in FIG. 3, the drive control unit 36 ​​has a voltage acquisition unit 361, a voltage prediction unit 362, an output switching unit 363, a switch SW, and a flag F. Here, information on the temperature Tmp acquired from the temperature sensor TS is input to the voltage prediction unit 362, and the voltage prediction unit 362 predicts the output voltage Vout(i) based on the temperature Tmp. In other respects, the configuration is not significantly different from that of FIG. 3, so a detailed description of FIG. 10 will be omitted.

[0062] 11 is a flow chart showing an example of a control method S3 for the light emitting device 10 according to the third embodiment of the present invention. A control method S2 for the light emitting device 10 will now be described.

[0063] Here, after the first timing, a temperature acquisition process (S31) is executed, and the drive control unit 36 ​​acquires the temperature of at least one of the plurality of light-emitting units 21(i). That is, the drive control unit 36 ​​functions as a temperature acquisition unit that acquires the temperature of at least one of the plurality of light-emitting units 21(i).

[0064] The voltage prediction unit 362 predicts a first predicted voltage Vp(i) based on the first output voltage Vout1(i) and the temperature Tmp.

[0065] As a result, the drive control unit 36 ​​(temperature acquisition unit) acquires a first temperature Tmp1 of at least one of the multiple light-emitting units 21(i) at a first timing, and the voltage prediction unit 362 predicts a first predicted voltage Vp1(i) based on the first output voltage Vout1(i) and the first temperature Tmp1.

[0066] The drive control unit 36 ​​(temperature acquisition unit) may acquire a second temperature Tmp1 of at least one of the multiple light-emitting units 21(i) at a second timing of a control method S4 of the light-emitting device 10 described below, and the voltage prediction unit 362 may predict a second predicted voltage Vp2(i) based on the second output voltage Vout2(i) and the second temperature Tmp2.

[0067] 12 is a schematic diagram showing a method for predicting a voltage using a table. Here, a predicted voltage Vp1(i) is predicted based on the output voltage Vout(i) and the temperature Tmp.

[0068] Here, the predicted voltage Vp1(i) is calculated using tables T1 and T2. Table T1 shows the multiplication factor A(I,i) expressed by the above-mentioned formula (1). Table T2 shows, for example, how the multiplication factor B of the predicted voltage Vp(i) with respect to the output voltage Vout(i) changes with respect to the temperature Tmp. For example, as shown in the following (2), the predicted voltage Vp(i) is calculated by multiplying the multiplication factor (coefficient) A(I,i), the multiplication factor (coefficient) B(Tmp), and the output voltage Vout(i).

[0069] Vp(i)=A(I,i)*B(Tmp)*V(i)...Formula (2) Vp(i): Predicted voltage (predicted value of output voltage Vout(i)) A(I,i): A factor (coefficient) of the predicted voltage Vp(i) relative to the output voltage Vout(i), which is a function of the current I and the identifier i of the light-emitting unit 21. B(Tmp): The multiplication factor (coefficient) of the predicted voltage Vp(i) relative to the output voltage Vout(i), which is a function of the temperature Tmp V(i): Measured value Vm of output voltage Vout(i) or previous predicted value Vp

[0070] 13 is a schematic diagram showing an example of table T2, in which the magnification B(Tmp) increases from 80% to 120% as the temperature Tmp increases from −10° C. to 60° C.

[0071] Here, the magnifications B(Tmp) of all the light-emitting units 21(i) are set based on the temperature Tmp measured by one temperature sensor TS. This speeds up temperature acquisition and processing.

[0072] Alternatively, the temperature Tmp(i) of each of the light-emitting units 21(i) may be obtained and the predicted voltage Vp(i) may be calculated based on the following equation (3):

[0073] Vp(i)=A(I,i)*B(Tmp(i))*V(i)...Equation (3) This formula (3) differs from formula (2) in that it uses the temperature Tmp(i) of each light-emitting unit 21(i) instead of the common temperature Tmp. In other respects, formula (3) is not substantially different from formula (2), and therefore a detailed description thereof will be omitted.

[0074] Here, it is also possible to use m temperature sensors TS (m is an integer equal to or greater than 2), which is less than the number n of light-emitting units 21(i). In this case, the n light-emitting units 21(i) are divided into m groups, and the detection value of one temperature sensor TS is applied to each divided light-emitting unit 21(i).

[0075] [Embodiment 4] Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0076] 14 is a flow diagram illustrating an example of a control method S4 for the light emitting device 10 according to the fourth embodiment of the present invention. The control method S4 adds a temperature acquisition process S31 to the control method S2 for the light emitting device 10. As a result, it becomes possible to predict the second predicted voltage Vp1(i) based on the second output voltage Vout2(i) and the second temperature Tmp2 acquired at the second timing.

[0077] [Modification] In the above, the prediction of the output voltage Vout(i) (calculation of the predicted voltage Vp(i)) and the control of the power supply 31 based on the predicted voltage Vp(i) are performed periodically. However, it is also possible to limit the control of the power supply 31 based on the predicted voltage Vp(i).

[0078] For example, when a single monitor, i.e., one display unit 40 (and one light-emitting device 10) is used in the display device 1, it is possible not to control the power supply 31 based on the predicted voltage Vp(i). That is, when a multi-monitor (multiple display units 40 and multiple light-emitting devices 10) is used, the power supply 31 is controlled based on the predicted voltage Vp(i). This is because the power reduction effect is greater in the case of a multi-monitor.

[0079] Furthermore, even at the first or second timing (for example, when the video is muted, when the video brightness is increased, or when a predetermined period of time has elapsed), the output voltage Vout(i) may not be acquired. For example, if there is no person near the light-emitting device 10 (or the display device 1), the output voltage Vout(i) may not be acquired, and the power supply 31 may be controlled based on the predicted voltage Vp(i). As a result, further power consumption can be reduced. The presence or absence of a person near the device can be determined by installing a camera, a motion sensor, or the like in the light-emitting device 10 (or the display device 1).

[0080] [Software implementation example] The functions of the light emitting device 10 and the display device 1 (hereinafter referred to as the "device") can be realized by a program that causes a computer to function as the device, and a program that causes a computer to function as each control block of the device (particularly each part included in the light emitting drive unit 30 and the control unit 70).

[0081] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The control device and storage device execute the program, thereby realizing the functions described in each of the above embodiments.

[0082] The program may be non-transitory and may be recorded on one or more computer-readable recording media. The recording media may or may not be included in the device. In the latter case, the program may be supplied to the device via any wired or wireless transmission medium.

[0083] Furthermore, some or all of the functions of the control blocks can be realized by logic circuits. For example, an integrated circuit in which a logic circuit that functions as each of the control blocks is formed is also included in the scope of the present invention. In addition, the functions of the control blocks can also be realized by, for example, a quantum computer.

[0084] 〔summary〕 A light-emitting device according to a first aspect of the present invention comprises a power source that inputs a common voltage common to a plurality of light-emitting elements to the plurality of light-emitting elements; a voltage acquisition unit that acquires a first output voltage output from each of the light-emitting elements at a first timing based on the common voltage input to each of the light-emitting elements; an input voltage adjustment unit that adjusts the common voltage based on the first output voltage; and a voltage prediction unit that predicts the output voltage output from each of the light-emitting elements as a first predicted voltage based on the first output voltage; and after the first timing, the input voltage adjustment unit adjusts the common voltage based on the first predicted voltage.

[0085] According to the above configuration, by predicting the output voltage output from each light-emitting unit as a first predicted voltage based on the first output voltage, it is possible to adjust the common voltage more quickly than by acquiring the output voltage.

[0086] In the light-emitting device of aspect 2 of the present invention, in the above-mentioned aspect 1, when a second timing at which a predetermined state occurs is after the first timing, the voltage acquisition unit acquires a second output voltage output from each of the light-emitting units at the second timing, the voltage prediction unit predicts a second predicted voltage based on the second output voltage, and the input voltage adjustment unit adjusts the common voltage based on the first predicted voltage from the first timing to the second timing, and adjusts the common voltage based on the second predicted voltage after the second timing.

[0087] According to the above configuration, it is possible to obtain the second output voltage at the second timing, and thereafter predict the second predicted voltage based on the second output voltage.

[0088] In the light emitting device of aspect 3 of the present invention, in aspect 2 above, the first timing may be when the light emitting device is started up, and the predetermined state may be muting the image, increasing the brightness of the image, or the passage of a predetermined period of time.

[0089] According to the above configuration, the output voltage is acquired when the light emitting device is started, when the image is muted, when the image brightness is increased, or when a predetermined period of time has passed, and the output voltage can be predicted based on this acquired output voltage. By acquiring the output voltage when the light emitting device is started, it becomes possible to appropriately control the light emission state of the light emitting device thereafter.

[0090] By acquiring the output voltage when the video is muted, the output voltage can be acquired without imposing a burden on the user watching the video. By adjusting the common voltage based on the output voltage when the video brightness increases, it is possible to reduce power loss when the video brightness increases. By acquiring the output voltage after a predetermined period has elapsed, it is possible to ensure the accuracy of the predicted voltage based on the acquired output voltage.

[0091] The light emitting device according to aspect 4 of the present invention may be, in accordance with aspect 2 above, further include a temperature acquisition unit that acquires the temperature of at least one of the plurality of light emitting units after the first timing, and the voltage prediction unit may predict the first predicted voltage based on the first output voltage and the temperature.

[0092] According to the above configuration, it is possible to more reliably predict the output voltage based on the temperature.

[0093] A light emitting device according to a fifth aspect of the present invention is the same as that of the fourth aspect, wherein the temperature acquisition unit acquires a first temperature or a second temperature of at least one of the plurality of light emitting units at the first timing or the second timing, and the voltage prediction unit predicts the first predicted voltage or the second predicted voltage based on the first output voltage and the first temperature, or the second output voltage and the second temperature.

[0094] According to the above configuration, it is possible to more reliably predict the output voltage based on the temperature at the first and second timings.

[0095] The light emitting device of aspect 6 of the present invention may be, in aspect 2 above, further include a current acquisition unit that acquires the current supplied from the power source to the plurality of light emitting units after the first timing, and the voltage prediction unit may predict the first predicted voltage based on the first output voltage and the current.

[0096] According to the above configuration, it is possible to more reliably predict the output voltage based on the current supplied from the power supply.

[0097] A light-emitting device according to a seventh aspect of the present invention is the same as that of the sixth aspect, wherein the current acquisition unit acquires a first current or a second current supplied from the power source to the plurality of light-emitting units at the first timing or the second timing, and the voltage prediction unit predicts the first predicted voltage or the second predicted voltage based on the first output voltage and the first current, or the second output voltage and the second current.

[0098] According to the above configuration, it is possible to more reliably predict the output voltage based on the current supplied from the power supply at the first and second timings.

[0099] A light emitting device according to an eighth aspect of the present invention is the light emitting device of the sixth or seventh aspect, wherein the current may be expressed as a duty ratio in pulse waveform modulation.

[0100] According to the above configuration, it is possible to more reliably predict the output voltage based on the duty ratio in pulse width modulation.

[0101] A control method for a light-emitting device according to aspect 9 of the present invention is a control method for a light-emitting device that controls a light-emitting device, wherein the light-emitting device has a power supply that inputs a common voltage common to a plurality of light-emitting elements to the plurality of light-emitting elements, and the control method for the light-emitting device includes a process of obtaining a first output voltage output from each of the light-emitting elements based on the common voltage input to each of the light-emitting elements, a process of adjusting the common voltage based on the first output voltage, a process of predicting the output voltage output from each of the light-emitting elements as a predicted voltage based on the first output voltage, and a process of adjusting the common voltage based on the predicted voltage.

[0102] According to the above configuration, by predicting the output voltage output from each light-emitting unit as a first predicted voltage based on the first output voltage, it is possible to adjust the common voltage more quickly than by acquiring the output voltage.

[0103] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. [Explanation of symbols]

[0104] 1 Display device 10 Light-emitting device 20 Lighting Unit 21 Light-emitting part 30 Light emitting drive unit 31 Power supply 32 Drive unit 33 Output voltage detection section 34 Power supply control unit (input voltage adjustment unit) 35 Current detection section 36 Drive control unit 40 Display section 50 Display driver 60 Signal Processing Unit 70 Control Unit 361 Voltage acquisition unit 362 Voltage Prediction Unit 363 Output switching unit

Claims

1. a power source that inputs a common voltage common to the plurality of light-emitting units to the plurality of light-emitting units; a voltage acquisition unit that acquires a first output voltage output from each light-emitting unit at a first timing based on a common voltage input to each light-emitting unit; an input voltage adjusting unit that adjusts the common voltage based on the first output voltage; a voltage prediction unit that predicts an output voltage output from each of the light-emitting units as a first predicted voltage based on the first output voltage, After the first timing, the input voltage adjusting unit adjusts the common voltage based on the first predicted voltage.

2. If a second timing at which a predetermined state occurs is after the first timing, the voltage acquisition unit acquires a second output voltage output from each of the light-emitting units at the second timing; the voltage prediction unit predicts a second predicted voltage based on the second output voltage; The input voltage adjusting unit adjusting the common voltage based on the first predicted voltage from the first timing to the second timing; The light emitting device according to claim 1 , wherein the common voltage is adjusted based on the second predicted voltage after the second timing.

3. the first timing is when the light emitting device is started up; The light emitting device according to claim 2 , wherein the predetermined state is muting an image, increasing brightness of an image, or the passage of a predetermined period of time.

4. a temperature acquisition unit that acquires a temperature of at least one of the plurality of light-emitting units after the first timing; The light emitting device according to claim 2 , wherein the voltage prediction unit predicts the first predicted voltage based on the first output voltage and the temperature.

5. the temperature acquisition unit acquires a first temperature or a second temperature of at least one of the plurality of light-emitting units at the first timing or the second timing; 5. The light emitting device according to claim 4, wherein the voltage prediction unit predicts the first predicted voltage or the second predicted voltage based on the first output voltage and the first temperature, or the second output voltage and the second temperature.

6. a current acquisition unit that acquires current supplied to the plurality of light-emitting units from the power source after the first timing; The light emitting device according to claim 2 , wherein the voltage prediction unit predicts the first predicted voltage based on the first output voltage and the current.

7. the current acquisition unit acquires a first current or a second current supplied to the plurality of light-emitting units from the power source at the first timing or the second timing; 7. The light-emitting device according to claim 6, wherein the voltage prediction unit predicts the first predicted voltage or the second predicted voltage based on the first output voltage and the first current, or the second output voltage and the second current.

8. The light emitting device according to claim 6 , wherein the current is expressed by a duty ratio in pulse waveform modulation.

9. A method for controlling a light emitting device, comprising: the light-emitting device includes a power supply that inputs a common voltage common to the plurality of light-emitting units to the plurality of light-emitting units; The method for controlling the light emitting device includes: a process of obtaining a first output voltage output from each light-emitting unit based on a common voltage input to each light-emitting unit; adjusting the common voltage based on the first output voltage; a process of predicting an output voltage output from each of the light-emitting units as a predicted voltage based on the first output voltage; adjusting the common voltage based on the predicted voltage. A method for controlling a light emitting device.

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