JP2019057386A - Lighting control device - Google Patents

Abstract

To solve the problem that, when performing lighting control on LED through PWM control, a user may feel discomfort since luminosity of the LED is changed step by step, therefore, in order to cancel such a failure, it is known to make a change in luminosity as a whole smooth by using a different pulse signal for each group but this cannot be applied to a lighting control device for only one group of LED.SOLUTION: A duty ratio with luminosity before a luminosity change is defined as a pre-duty ratio, and a duty ratio with luminosity after the change is defined as a post-duty ratio. When shifting from the pre-duty ratio to the post-duty ratio, a predetermined number of times of periods of a pulse signal is set as a shift period and during this shift period, the pre-duty ratio and the post-duty ratio are mixed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a light control device that performs light control by changing the luminous intensity of a light emitter such as an LED stepwise.

  For example, when dimming the light intensity of a light emitting diode, in PWM control, the current flowing through the light emitter is controlled by a pulse signal having a constant period. The luminous intensity changes by changing the duty ratio of the pulse signal. When the duty ratio is high and the pulse signal is on for a long time, the luminous intensity is high (bright). Conversely, when the duty ratio is low and the pulse signal is on for a short time, the luminous intensity is low (dark). Therefore, in PWM control, the duty ratio of the pulse signal may be changed to change the luminous intensity.

  However, since the duty ratio changes stepwise, if the amount of change in the duty ratio is large, a stepwise change in luminous intensity may be felt, and a sense of discomfort may be felt. However, if the amount of change in the duty ratio is reduced, a new problem arises that the price of the PWM control device increases.

  Therefore, the LEDs are grouped into a plurality of series, and a PWM control device is provided for each group. By changing the timing and duty ratio of turning on the pulse signal for each group, the change in luminous intensity as a whole is changed. What is made loose is known (for example, refer patent document 1).

JP 2011-113793 A (Claim 1, FIG. 1)

  In the above-mentioned conventional device, since the change in luminous intensity as a whole is moderated by dividing the LEDs into a plurality of groups and using different pulse signals for each group, the LED dimming device having only one group. It cannot be applied to.

  In view of the above problems, an object of the present invention is to provide a light control device capable of changing the luminous intensity gradually even with a single group of light emitters.

  In order to solve the above problems, a light control device according to the present invention is a light control device that changes the light intensity of a light emitter by stepwise changing the current value supplied to the light emitter whose light intensity varies depending on the current value by PWM control. , The duty ratio of the pulse signal in PWM control, the duty ratio at the luminous intensity before changing the luminous intensity is the pre-duty ratio, the duty ratio at the luminous intensity after the change is the post-duty ratio, and from the previous duty ratio When shifting to the post-duty ratio, a predetermined number of cycles of the pulse signal is set as a transition period, and the pre-duty ratio and the post-duty ratio are mixed in the transition period.

  If the previous duty ratio and the rear duty ratio are mixed in the transition period, the average duty ratio in the transition period becomes a value between the previous duty ratio and the rear duty ratio. In other words, the average luminous intensity within the transition period is the luminous intensity between the luminous intensity before the change and the luminous intensity after the change, so the light intensity before the change is dimmed to the luminous intensity after the change through the intermediate luminous intensity in this transition period. As a result, the change in altitude during dimming becomes moderate.

  In addition, one kind of light intensity change may be inserted in this transition period. However, if a plurality of transition ratios are set and a plurality of transition periods are continued in descending order of the mixture ratio of the previous duty ratio, The luminous intensity can be changed gently.

  As is apparent from the above description, the present invention provides a transition period when changing the duty ratio of the pulse signal from the duty ratio before the change to the duty ratio after the change when changing the luminous intensity in the PWM control. By artificially generating an intermediate duty ratio in the middle of the change of the duty ratio, the luminous intensity can be gradually changed even if the number of light emitters is one.

The figure which shows the circuit of one Embodiment of the light modulation apparatus of this invention Diagram showing the relationship between luminous intensity and pulse width in duty control The figure explaining the transition period at the time of dimming from luminous intensity 5 to luminous intensity 4

  Referring to FIG. 1, this figure is an example of a circuit diagram of a light control device according to the present invention. PS is a DC power source for causing the LED 1 to emit light, and a DC power source such as a battery may be used. However, AC power supplied from an external commercial power source may be rectified to be used as the DC power source PS.

  The brightness, that is, the luminous intensity of the LED 1 is proportional to the forward voltage drop (VF). In the present invention, in order to increase or decrease VF, a resistor is connected in series with LED 1 and the resistance value is not varied, but the current flowing through LED 1 is increased or decreased by PWM control. That is, the light intensity of LED1 is changed by making the electric current which flows into LED1 into a pulse form, and increasing / decreasing the ON time of the pulse signal.

  In order to make the current flowing through the LED 1 into a pulse shape, a transistor 3 is provided in series with the LED 1. The transistor 3 was connected to the CPU 2 for PWM control. In accordance with the pulse signal output from the CPU 2 to the transistor 3, the transistor 3 is switched between on and off states.

  With reference to FIG. 2, the present embodiment is configured to adjust the luminous intensity of the lighting state of LED 1 in five levels from luminous intensity 1 to luminous intensity 5. At a luminous intensity of 5, the on-time of the pulse signal is the longest, and is set so that the on-time of the pulse signal is shortened each time the light is dimmed toward the luminous intensity of 1. A case where light intensity is adjusted from light intensity 5 to light intensity 4 will be described with reference to FIG.

  As shown in FIG. 3, the ON time of the pulse signal at a luminous intensity of 5 was set to 80% in one cycle, and at the luminous intensity of 4, the ON time was set to 65%. When dimming from luminosity 5 to luminosity 4, the on-time of the pulse signal is changed from 80% to 65%. At that time, the luminosity changes from luminosity 5 to luminosity so that the luminosity changes suddenly and does not give a sense of incongruity. A transition period was provided in the middle of changing to 4.

  Specifically, using the pseudo light intensity shown in the table of FIG. 3 as the transition period, the LED 1 is made to emit light with a pulse signal indicated by the light intensity 5 to the pseudo light intensity, and then the light signal 4 is a pulse signal with an on time of 65%. The LED 1 is caused to emit light. In this way, since the pseudo light intensity is sandwiched during the transition period, the change in light intensity becomes gentle.

  More specifically, in this embodiment, five periods are set as the transition period. Then, four types of combinations of pulse signals in the five cycles were set as shown in the table. That is, there are four types of pseudo luminous intensity “4.8”, “4.6”, “4.4”, and “4.2”.

  When dimming from luminous intensity 5 to luminous intensity 4, a combination of pulse signals indicated as luminous intensity 4.8 is performed for five cycles from the state where the luminous intensity is luminous. Subsequently, five cycles are performed with the combination indicated by the luminous intensity of 4.6. Further, after the light intensity of 4.4 and the light intensity of 4.2 are each carried out for five cycles, the light intensity of 4 is set. A total of 20 periods from the light intensity 4.8 to the light intensity 4.2 is the transition period. When the pulse signal is supplied in this way, the LED 1 is gradually dimmed from the luminous intensity 5 during the transition period to be in the luminous intensity 4 state, so that the change in luminous intensity is felt gently. In this embodiment, four types of pseudo luminous intensity are set and the transition period is set to 20 cycles. However, the type of pseudo luminous intensity and the number of cycles set as the transition period may be increased or decreased from the example shown here. . In the above embodiment, the case of dimming has been described. However, in the case of brightening, the reverse process is performed.

  In addition, this invention is not limited to an above-described form, You may add a various change in the range which does not deviate from the summary of this invention.

1 LED
2 CPU
3 transistors

Claims (2)

  In the dimming device that changes the luminous intensity of the luminous body by changing the current value supplied to the luminous body whose luminous intensity changes according to the current value in a stepwise manner by PWM control, the duty ratio of the pulse signal in PWM control, The duty cycle at the luminous intensity before changing the luminous intensity is the pre-duty ratio, the duty ratio at the luminous intensity after the change is the post-duty ratio, and a predetermined number of cycles of the pulse signal when shifting from the pre-duty ratio to the post-duty ratio Is set as a transition period, and the front duty ratio and the rear duty ratio are mixed in the transition period.   The dimming device according to claim 1, wherein a plurality of transition period mixture ratios are set, and the plurality of transition periods are continued in descending order of the pre-duty ratio mixture ratio.

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