Light emission control device

Abstract

To provide a light emission control device that can perform different light emission control for multiple light emitting elements.SOLUTION: A light emission control device 1 includes a control unit 2 that outputs a serial signal S that includes light emission drive signal components, a light emission drive unit 3 that receives the serial signal S and outputs light emission drive signals, and multiple light emitting elements 4 that emit light according to the light emission drive signals output from the light emission drive unit 3. The control unit 2 is configured to be able to output the serial signal S that includes different multiple light emission drive signal components. The light emission drive unit 3 is configured to output different light emission drive signals individually to the plurality of light emitting elements 4 and is configured to be able to adjust the luminance of light emission for each light emitting element 4.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a light emission control device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, as a light emission control device, for example, as described in Patent Document 1, a device that has a plurality of light emitting elements and adjusts the light emission of the light emitting elements using PWM (Pulse Width Modulation) control is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-114904 A Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned device has room for improvement in that it is difficult to perform different dimming for multiple light-emitting elements. For example, in the above-mentioned device, if it is attempted to perform different dimming for multiple light-emitting elements, multiple different PWM signals are required, which makes it difficult to achieve this.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a light emission control device capable of performing different dimming control for a plurality of light emitting elements. [Means for solving the problem]

[0006] In other words, the light emission control device of the present invention comprises a control unit that outputs a serial signal including a light emission drive signal component, a light emission drive unit that receives the serial signal and outputs a light emission drive signal, and a plurality of light emitting elements that emit light in response to the light emission drive signal output from the light emission drive unit, wherein the control unit is capable of outputting the serial signal including a plurality of different light emission drive signal components, and the light emission drive unit is configured to output different light emission drive signals individually to the plurality of light emitting elements, making it possible to adjust the light emission brightness of each of the light emitting elements. Effect of the Invention

[0007] According to the light emission control device of the present invention, different light adjustments can be performed for a plurality of light emitting elements. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing an outline of the configuration of a light emission control device according to an embodiment. [Diagram 2] FIG. 2 is an explanatory diagram of a serial signal in the light emission control device according to the embodiment. [Diagram 3] FIG. 3 is an explanatory diagram of a light emission drive signal in the light emission control device according to the embodiment. [Figure 4] FIG. 4 is a diagram showing an outline of the configuration of a light emission control device of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment. In addition, the components in the following embodiments include those that are replaceable and easy for a person skilled in the art, or those that are substantially the same.

[0010] [Embodiment] This embodiment relates to a light emission control device. As shown in Fig. 1, the light emission control device 1 according to this embodiment is a device that controls the light emission of a plurality of light emitting elements 4, and is used, for example, as a backlight of a display device mounted on a vehicle. The light emission control device 1 includes a control unit 2, a light emission drive unit 3, and the light emitting elements 4. The control unit 2 is a controller that controls the light emission of the light emission control device 1, and is configured, for example, by a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The control unit 2 is electrically connected to the light emission drive unit 3, and outputs a serial signal S to the light emission drive unit 3.

[0011] As shown in FIG. 2, the serial signal S includes a plurality of light emission drive signal components. The horizontal axis of FIG. 2 indicates time, and the vertical axis indicates level. The serial signal S is a signal that transmits a plurality of light emission drive signal components in series, and includes, for example, five light emission drive signal components d1 to d5. The control unit 2 is configured to be able to output the serial signal S that includes a plurality of different light emission drive signal components. For this reason, the light emission control device 1 can individually control the light emission of the five light emitting elements 4 by the five light emission drive signal components d1 to d5. When the five light emitting elements 4 are turned on without dimming, the plurality of light emission drive signal components d1 to d5 are all the same signal components. Also, when some of the five light emitting elements 4 are turned on with dimming, some signal components are different from the other signal components. The light emission drive signal components d1 to d5 may be configured as pulse waveforms, or may be configured as signal data that generates a light emission drive signal.

[0012] The control unit 2 generates a serial signal S according to the light emission luminance of the plurality of light-emitting elements 4. For example, the control unit 2 has a light emission luminance set for each of the plurality of light-emitting elements 4, and sets a light emission drive signal component according to the light emission luminance of the light-emitting element 4 to generate the serial signal S. The control unit 2 may be configured to change the setting of the light emission luminance of the light-emitting element 4 according to the usage environment of the light-emitting control device 1, the vehicle state, or the like.

[0013] 1, the light emission drive unit 3 outputs a light emission drive signal to the light emitting element 4, and receives a serial signal S to output the light emission drive signal to each of the plurality of light emitting elements 4. For example, the light emission drive unit 3 is electrically connected to each of the first light emitting element 41, the second light emitting element 42, the third light emitting element 43, the fourth light emitting element 44, and the fifth light emitting element 45, and outputs a light emission drive signal Sd1 to the first light emitting element 41, a light emission drive signal Sd2 to the second light emitting element 42, a light emission drive signal Sd3 to the third light emitting element 43, a light emission drive signal Sd4 to the fourth light emitting element 44, and a light emission drive signal Sd5 to the fifth light emitting element 45.

[0014] The light emission drive unit 3 generates the light emission drive signals Sd1 to Sd5 based on the light emission drive signal components d1 to d5 of the serial signal S. For example, when the first light emitting element 41, the second light emitting element 42, the third light emitting element 43, the fourth light emitting element 44, and the fifth light emitting element 45 are all caused to emit light with the same luminance, the light emission drive unit 3 generates the light emission drive signals Sd1 to Sd5 as the same light emission drive signals. Also, for example, when the first light emitting element 41 and the second light emitting element 42 of the first light emitting element 41, the second light emitting element 42, the third light emitting element 43, the fourth light emitting element 44, and the fifth light emitting element 45 are caused to emit light with reduced brightness, the light emission drive unit 3 generates the light emission drive signal Sd1 and the light emission drive signal Sd2 as light emission drive signals different from the light emission drive signals Sd3 to Sd5.

[0015] As shown in FIG. 3, for example, when the first light emitting element 41 is dimmed, the light emission drive signal Sd1 is a pulse signal with a duty ratio of 50 percent. The light emission drive signals Sd1 to Sd5 are pulse signals, and have a plurality of divided signal components, and are made into signals with a desired duty ratio by setting an on level or an off level for each divided signal component. For example, the light emission drive signals Sd1 to Sd5 are signals with a period of 10 ms, and are composed of ten divided signal components of 1 ms connected in series. Therefore, as shown in FIG. 3, the light emission drive signal Sd1 becomes a pulse signal with a duty ratio of 50 percent by setting five divided signal components to an on level (high level) and five divided signal components to an off level (low level). In other words, the light emission drive signal Sd1 can be made into a signal with a dimming ratio of 10 to 100 percent in 10 percent increments by setting an on level or an off level for the ten divided signal components.

[0016] The light emission drive unit 3 sets the on level or off level of each divided signal component according to the light emission luminance of the light emitting element 4. For example, the light emission drive unit 3 communicates with the light emitting element 4 every 1 ms, and when the divided signal component is at the on level, the light emitting element 4 is turned on, and when the divided signal component is at the off level, the light emitting element 4 is turned off. In this case, the light emission drive signal is equivalent to a signal that has a duty control with a period of 10 ms. Therefore, the light emission control device 1 can easily perform dimming control individually for the multiple light emitting elements 4. Cl in FIG. 3 is a signal that outputs a pulse P at a constant period, and is a clock signal used for the communication timing of the light emission drive unit 3. Note that, if the communication from the light emission drive unit 3 to the light emitting element 4 is performed in a time shorter than the period of the light emission drive signal, the light emission drive signal may be a signal with a time other than 10 ms, and the communication from the light emission drive unit 3 to the light emitting element 4 may be performed every time other than 1 ms.

[0017] In FIG. 1, the plurality of light-emitting elements 4 are, for example, composed of five light-emitting elements: a first light-emitting element 41, a second light-emitting element 42, a third light-emitting element 43, a fourth light-emitting element 44, and a fifth light-emitting element 45. As the light-emitting element 4, for example, an LED (Light Emitting Diode) is used. For example, the five light-emitting elements 41, the second light-emitting element 42, the third light-emitting element 43, the fourth light-emitting element 44, and the fifth light-emitting element 45 are composed of LEDs with the same specifications. Note that FIG. 1 shows a case where the plurality of light-emitting elements 4 are composed of five light-emitting elements: a first light-emitting element 41, a second light-emitting element 42, a third light-emitting element 43, a fourth light-emitting element 44, and a fifth light-emitting element 45, but the plurality of light-emitting elements 4 may be composed of four or less or six or more light-emitting elements 4.

[0018] Next, the operation of the light emission control device 1 according to this embodiment will be described.

[0019] 1, first, the emission luminance of the light-emitting element 4 is set. In the control unit 2, the emission luminance is set for each of the first light-emitting element 41, the second light-emitting element 42, the third light-emitting element 43, the fourth light-emitting element 44, and the fifth light-emitting element 45. For example, the emission luminance may be appropriately changed depending on the usage environment of the light-emitting control device 1 or the vehicle state.

[0020] Then, a serial signal S is output from the control unit 2 to the light emission drive unit 3. As shown in Fig. 2, the serial signal S is a signal including, for example, five light emission drive signal components d1 to d5. The light emission drive signal components d1 to d5 are signal components corresponding to the light emission luminance of each of the first light emitting element 41, the second light emitting element 42, the third light emitting element 43, the fourth light emitting element 44, and the fifth light emitting element 45.

[0021] The light emission drive section 3 outputs a light emission drive signal Sd1 to the first light emitting element 41, a light emission drive signal Sd2 to the second light emitting element 42, a light emission drive signal Sd3 to the third light emitting element 43, a light emission drive signal Sd4 to the fourth light emitting element 44, and a light emission drive signal Sd5 to the fifth light emitting element 45. The light emission drive signals Sd1 to Sd5 are signals that correspond to the light emission luminance of the first light emitting element 41 to the fifth light emitting element 45.

[0022] For example, when the first light emitting element 41 and the second light emitting element 42 are set to a 50% reduced light emission luminance, and the third light emitting element 43 to the fifth light emitting element 45 are set to a 20% reduced light emission luminance, the light emission drive signals Sd1 and Sd2 of the first light emitting element 41 and the second light emitting element 42 are set to signals in which five of the ten divided signal components are at the on level and five are at the off level, and the light emission drive signals Sd3 to Sd5 of the third light emitting element 43 to the fifth light emitting element 45 are set to signals in which two of the ten divided signal components are at the on level and eight are at the off level. As a result, the first light emitting element 41 and the second light emitting element 42 emit light with a 50% reduced light emission, and the third light emitting element 43 to the fifth light emitting element 45 emit light with a 20% reduced light emission.

[0023] At this time, the light emission drive unit 3 generates the light emission drive signals Sd1-Sd5 by setting the on / off levels of the divided signal components of the light emission drive signals Sd1-Sd5, so that it is easy to generate the light emission drive signals Sd1-Sd5 with different duty ratios. In contrast, in general PWM control, a triangular wave signal or a sawtooth wave signal is generated, and this triangular wave signal or sawtooth wave signal is input to a comparator to generate a pulse signal with an adjusted duty ratio. For this reason, five generators and comparators for triangular wave signals or sawtooth wave signals are required to generate the light emission drive signals Sd1-Sd5 with different duty ratios, which makes the circuit configuration complicated.

[0024] Fig. 4 shows a light emission control device 100 serving as a comparative example. As shown in Fig. 4, the light emission control device 100 includes a control unit 102, a light emission drive unit 103, a first light emitting element 104a to a fifth light emitting element 104e, and a dimming circuit 105. The control unit 102 outputs a control signal to the light emission drive unit 103, and the light emission drive unit 103 outputs a light emission drive signal Sd to the first light emitting element 104a to the fifth light emitting element 104e. The light emission drive signal Sd is a signal for causing the first light emitting element 104a to the fifth light emitting element 104e to emit light, and is not a signal for causing the light to be dimmed.

[0025] The first light emitting element 104a and the second light emitting element 104b are electrically connected to the dimming circuit 105. The dimming circuit 105 outputs a dimming signal Sr to the first light emitting element 104a and the second light emitting element 104b. The dimming signal Sr is a pulse signal with an adjusted duty ratio. Therefore, the first light emitting element 104a and the second light emitting element 104b are controlled to emit light in a dimmed state. However, it is not possible to perform dimming such that the first light emitting element 104a and the second light emitting element 104b emit light in the same dimmed state and the first light emitting element 104a and the second light emitting element 104b emit light with different luminances. In addition, the third light emitting element 104c to the fifth light emitting element 104e are electrically connected to the power supply line +V. Therefore, the third light emitting element 104c to the fifth light emitting element 104e cannot emit light in a dimmed state. In this way, the light emission control device 100 cannot perform different dimming for the first light emitting element 104a to the fifth light emitting element 104e. In this light emission control device 100, in order to perform different dimming for the first light emitting element 104a to the fifth light emitting element 104e, five dimming circuits 105 are required, which makes the circuit configuration complicated.

[0026] In contrast, the light emission control device 1 according to this embodiment can perform different dimming for the multiple light emitting elements 4 by outputting different light emission drive signals to the multiple light emitting elements 4. For example, the light emission control device 1 according to this embodiment generates a light emission drive signal by successively dividing a multiple number of divided signal components, and sets an on level or off level for each divided signal component to set a duty ratio. Therefore, the light emission control device 1 according to this embodiment can easily generate light emission drive signals with different duty ratios, and can easily perform different dimming for the multiple light emitting elements 4.

[0027] As described above, the light emission control device 1 according to this embodiment can perform different light adjustments for the multiple light emitting elements 4 by outputting different light emission drive signals to the multiple light emitting elements 4.

[0028] In addition, the light emission control device 1 of this embodiment can adjust the duty ratio by setting the on level or off level for the divided signal components of the light emission drive signal, so that different dimming can be easily performed for multiple light emitting elements 4.

[0029] The light emission control device according to the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the claims. The light emission control device 1 according to this embodiment may be configured by appropriately combining the components of the above-described embodiment and modified examples.

[0030] For example, in the above-described embodiment, the light emission control device 1 is described as being used as a backlight for a display device in a vehicle, but the light emission control device according to the present invention may also be applied to devices that are not mounted on a vehicle. [Explanation of symbols]

[0031] 1: Light emission control device 2: Control unit 3: Light emitting driver 4: Light emitting element S: Serial signal Sd1, Sd2, Sd3, Sd4, Sd5: Light emission drive signal

Claims

1. A control unit that outputs a serial signal including a light emission drive signal component; a light emission driving unit that receives the serial signal and outputs a light emission driving signal; a plurality of light-emitting elements that emit light in response to the light-emitting drive signal output from the light-emitting drive unit; the control unit is capable of outputting the serial signal including a plurality of different light emission drive signal components; The light emission drive unit outputs different light emission drive signals to the plurality of light emitting elements individually, thereby making it possible to adjust the light emission luminance of each of the light emitting elements. Light emitting control device.

2. the light emission drive signal is a pulse signal, and has a plurality of divided signal components, and a duty ratio is adjusted by setting an on level or an off level for each divided signal component; The light emission control device according to claim 1 .

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