JPH0760749B2 - Damer control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a dimmer control device used for adjusting the brightness of a lamp or the like.

2. Description of the Related Art In recent years, automobiles have become more and more diversified and, for example, it is also beginning to adjust the illumination of car radios, car stereos, etc. in conjunction with the illumination on the vehicle side. Conventionally, there are two types of dimmer control methods. One is the so-called pulse method that controls the brightness by changing the duty while maintaining a constant cycle, and the other has several built-in resistance values that are mechanically switched to change the current value stepwise. This is the so-called volume method of controlling the brightness. FIG. 2 is a circuit diagram to which an example of a conventional pulse method is applied (FIG. 2A) and waveform diagrams showing its operation (FIGS. 2B and 2C), and FIG. FIG. 6 is a circuit diagram (FIG. 11A) to which an example of the volume method is applied and a waveform diagram (FIG. 11A) showing the operation thereof.

In FIG. 2A, the pulse signal Vi shown in FIG.
Is input, the PNP transistor (Tr) 1,
N, OFF operation is performed. Then, a pulse current flows from the power source 2 through a load such as a lamp (hereinafter referred to as a lamp) 3 between the emitter and the collector of Tr1. As a result, the average level of the voltage drop Vo across the lamp 3 changes according to the magnitude of the duty of the input pulse signal Vi as shown in FIG. Therefore, as is apparent from the above, the brightness of the lamp 3 depends on the magnitude of the duty of the input pulse signal Vi.

Also, in the case of the volume method, as shown in FIG.
The _{R 1, R 2, R 3} ... Rn and switching selected by the switch 4, so that the voltage drop Vo across the lamp 5 stepwise varied as shown in FIG. (B) change the brightness of the lamp 5 I have to. When the circuit of FIG. 1 or 2 is applied to a vehicle, the power source voltage + B is generally set to about 13v.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described pulse method for the dimmer control device, the voltage level of the input pulse signal is
Since it is a repetition of Ov and about 13v, if the above-mentioned dimmer control device is applied for illumination of car radios, car stereos, etc., the harmonic components of this pulse signal will become noise and will be greatly applied to car radios and car stereo receivers. It will have an impact. The influence of such noise can be avoided by applying the dimmer control device of the volume method shown in FIG. 3, for example. However, in the case of this device, the illuminance could not be finely and continuously changed, and it may not be applicable depending on the operation situation.

The present invention has been made in view of the above circumstances, and can be applied to any signal of the pulse method and the pull volume method,
Moreover, it is an object of the present invention to provide a dimmer control device capable of dimming a lamp without generating noise.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a signal determination means for determining whether the signal is a pulse signal or a step signal, and the determination result of the signal determination means. The present invention is characterized by comprising switching means for changing a current supply loop to the lamp and means for smoothing the pulse signal and outputting a signal corresponding to the duty ratio of the pulse signal.

Action The present invention has the following actions due to the above-mentioned configuration. That is, when a pulse signal or a step signal is input to this dimmer control device, the signal determining means determines which signal it is. Then, the switching means is controlled in accordance with the result of the determination to form a current supply loop corresponding to the pulse signal or a current supply loop corresponding to the step signal. If the input signal is a step signal, the brightness of the lamp is adjusted via the current supply loop corresponding to the step signal. If the input signal is a pulse signal, the brightness of the lamp is adjusted via a smoothing circuit that supplies a direct current corresponding to the duty ratio of the pulse signal.

Embodiment FIG. 1 (a) is a circuit diagram showing a dimmer control device according to an embodiment of the present invention.

This dimmer control device takes in a signal Vi such as a pulse signal or a step signal from a signal input terminal 10 and inverts it, and an inversion buffer 11 takes in a pulse signal via the inversion buffer 11 and smoothes it. Integrator circuit 12
A signal determining means 13 for inputting signals from the integrating circuit 12 and the inverting buffer 11 and determining whether the input signal is a pulse signal or a step signal, and a signal determining means.
13 judgment signals are input and the lamp is
Switching means 15 for switching the supply of the pulse signal or the step signal to 14 is provided.

The signal judging means 13 is a level judging unit 16 connected to the integrating circuit 12.
And a backflow prevention diode 17 provided on the output side of the level determination unit 16 and a period determination unit connected to the inverting buffer 11.
18 and a diode 19 for preventing backflow provided on the output side of the cycle determining unit 18.

The switching means 15 includes first and second switching portions 20 and 21 for respectively taking in the judgment signals of the signal judging means 13, and the Darlington connection circuit 2.
Has 2 and. The input side of the second switching section 21 is connected to the output side of the integrating circuit 2 in addition to the signal determining means 13 described above,
The output side of the switching unit 21 is connected to the base of the first-stage transistor 23 of the Darlington connection circuit 22. First
The input side of the switching section 20 of the
It is connected to the power supply terminal 24 of B. In addition, the output side of the switching unit 20 is connected to the collectors of the first and second stage transistors 23 and 25 of the Darlington connection circuit 22, respectively.
Together with 1, the Darlington connection circuit 22 is connected to the output side (that is, the emitter of the transistor 25 of the second stage) in a form of bypassing the Darlington connection circuit 22.

A lamp 14 is connected to the output side of the Darlington connection circuit 22, and the lamp 14 is connected to the signal input terminal 10 via a diode 26 for preventing backflow. A feedback circuit 27 is branched and connected between the lamp 14 and the diode 26. The feedback circuit 27 is connected to the output side of the signal judging means 13, and is controlled according to the judgment signal output from the signal judging means 13 to be grounded.

The operation of the dimmer control device configured as described above will be described. First, the input signal Vi is input to the inversion buffer 11 and then is supplied from here to the level determination unit 16 and the period determination unit 18 via the integration circuit 12. The level determination unit 16 checks whether the level of the input signal Vi is equal to or higher than a predetermined value. Here, if the level of the input signal Vi is equal to or higher than a predetermined value, the input signal Vi is determined to be a pulse signal.
This determination signal is sent to the second switching unit 21 via the diode 17. Then, the second switching unit 21 becomes conductive, the first switching unit 20 operates, and the current according to the power supply voltage + B is supplied to the lamp 14 through the Darlington connection circuit 22. At this time, the feedback circuit 27 is grounded and the current flowing to the lamp 14 flows to the ground of the circuit. That is, the pulse signal shown as the input signal Vi in FIG. 2B is converted into the direct current corresponding to the duty ratio of the pulse signal by the integrating circuit 12 and supplied to the switching unit 21. Then, the dimming of the lamp according to the duty ratio of the pulse signal is performed via the Darlington connection circuit.

Further, when the level of the input signal Vi is below a certain level, the level determination section 16 does not output a determination signal. Then, in this case, the second switching unit 21 is in the specific conduction state, and the Darlington connection circuit 22 is in the OFF state. Then, the power supply terminal 24 bypasses the Darlington connection circuit 22 and is directly connected to the lamp 14. At this time, the feedback circuit 27 also becomes non-conductive, and the current flowing through the lamp 14 forms a loop that returns to the signal input terminal 10 via the diode 26. The voltage V ₀ applied to the lamp 14 is the difference between the voltage + B applied to the power supply terminal 24 and the input signal V _i . That is, when the voltage of the step signal shown as the input signal V _i in FIG. 1C is small, the voltage V ₀ applied to the lamp 14 becomes large,
The voltage V ₀ applied to the lamp 14 decreases as the input signal V _i increases. As a result, dimming corresponding to this input signal Vi is performed.

On the other hand, the level determination unit 16 instantaneously measures the level of the input signal Vi, and the cycle determination unit 18 sequentially measures the rising and falling periodicity of the input signal Vi. If the signal Vi is a pulse signal and has no periodicity, it is determined to be a step signal. In this case, when the input signal Vi is a pulse signal, the second switching unit 21 is turned on, the bypass is cut by the first switching unit 20, and the power supply voltage + B is supplied via the Darlington connection circuit 22. It operates to supply current to the lamp 14. At this time, the feedback circuit 27 is grounded, the current flowing through the lamp 14 flows to the circuit ground, and the diode 26 becomes non-conductive.

In this way, if the input signal has a periodicity of its change, or if its level is equal to or greater than the specified level value, it is judged as a pulse signal, and if not, it is judged as a step signal and current is supplied to the lamp I am trying to switch the loop.

As is apparent from the above description, only one circuit of the level determination unit or the period determination unit is provided,
You may make it determine whether the signal input into this one circuit is a pulse signal or a step signal. This simplifies the device.

EFFECTS OF THE INVENTION As described above, the present invention can perform dimmer control with the same circuit configuration for any input of a pulse signal or a step signal, and when a pulse signal is input, remove the harmonic component thereof. Therefore, dimmer control can be performed without generating noise.

[Brief description of drawings]

FIG. 1 (a) is a circuit diagram showing a dimmer control device according to an embodiment of the present invention, and FIGS. 1 (b), (c), and (d) are signal waveform diagrams for explaining the operation of the dimmer control device. 2 (a) is a circuit diagram showing an example of a conventional dimmer control device using a pulse signal, FIGS. 2 (b) and (c) are signal waveform diagrams for explaining the operation of the dimmer control device, FIG. 3A is a circuit diagram showing an example of a conventional dimmer control device using a step signal, and FIG. 3B is a signal waveform diagram for explaining the operation of the dimmer control device. 12 …… Integrator circuit, 13 …… Signal judgment means, 14 …… Lamp,
15 …… Switching means.

Claims (1)

[Claims] 1. A signal judging means for identifying whether a pulse signal or a step signal is taken in, and a switching means for changing a current supply loop to a lamp according to a judgment result of the signal judging means, And a means for smoothing the pulse signal and outputting a signal corresponding to the duty ratio of the pulse signal.