JPS6229023A - Circuit for switch with illumination - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Object of the Invention (Field of Industrial Application) The present invention relates to a circuit for an illuminated switch, and more particularly to a circuit for an illuminated switch that can adjust the brightness of illumination using pulsed current. be.

(Prior Art) FIG. 2 shows a circuit for an illuminated switch using a conventional analog voltage control method using a light emitting diode as a light source, and is constructed using a resistor 10 whose voltage can be varied by operating a knob (not shown). A set voltage is input to the amplifier 11, and feedback control is performed between the transistor 12 and the resistors R and R to control the output voltage from the transistor 12, thereby supplying an appropriate number of light emitting diodes 4 connected in parallel. The current can be adjusted. Therefore, by changing the set voltage using the resistor 10, the brightness of the light emitting diode 4 can be adjusted.

(Problems to be Solved by the Invention) By the way, in the conventional illuminated switch circuit described above, that is, the circuit using the analog voltage control method,
In designing, it is necessary to consider the power consumption of the transistor 12, and depending on the power supply voltage and current, it is necessary to select a transistor 12 with an RC rating of 5 to 10 times the collector current (Ic) that will actually flow. There is a problem.

Furthermore, since the amount of heat generated by the transistor 12 is large, heat dissipation fins are required, which not only increases manufacturing costs due to an increase in the number of parts, but also increases the mounting space for the circuit, making it difficult to reduce the size and weight. There is also a problem.

Structure of the Invention (Means for Solving the Problems) In order to solve the above problems, the present invention uses a pulse oscillator equipped with an adjustment resistor whose duty can be varied and a switching element such as a transistor to generate at least one or more pulse oscillators. We adopted a circuit for an illuminated switch that is characterized by supplying pulsed current to a light emitting diode.

(Function) The set voltage is pulsed by a pulse oscillator, and a pulsed current is supplied to the light emitting diode, so the light emitting diode also emits light in a pulsed manner. If the pulse emission is more than
It appears to be constantly lit without flickering.

Therefore, by changing the duty of the pulse using an adjustment resistor, it is also possible to visually change the brightness of the illumination.

Furthermore, since the circuit of the present invention is driven by switching, it is sufficient to use transistors with actual Ic ratings, and waste of power due to heat generation is extremely small compared to transistors used in analog voltage control systems.

(Example) Hereinafter, an example in which the present invention is embodied in a circuit of a light switch with lines will be described with reference to FIGS. 1, 3, and 4.

The light switch with lines of this embodiment includes a synthetic resin case 2 equipped with an operation button 1 made of acrylic resin with lines shown in FIG. It is composed of a switch printed circuit board 3, a light emitting diode 4, and a rubber switch 5, and is soldered to a printed circuit board 7 via pins 6 together with other light switches with lines having a similar structure. Further, the circuit of the light switch with lines is formed on the printed circuit board 7, and its main part has the configuration shown in FIG. That is, by pressing the operation button l of the light switch with lines with a finger, a voltage is applied to the pulse oscillator 13, and the pulse voltage of the duty determined by the adjustment resistor 14 built into the oscillator 13 is applied to the transistor 12. is applied to the base of As a result, a constant pulse current is supplied from the collector to the light emitting diode 4 in the light switch with lines, and the light emitting diode 4 emits light in a pulsed manner. On the other hand, the human eye has an afterimage effect, and if the pulsed light is emitted at a certain frequency or higher, it appears to be lit steadily without flickering. Therefore, by appropriately controlling the duty cycle using the adjustment resistor 14, the part indicated by the line on the light switch appears to be lit at a predetermined brightness, and if the duty cycle is further changed, The brightness also appears to change.

In this way, the circuit for the lighting switch with lines of this embodiment causes the light emitting diode 4 to emit light by switching the transistor 12, so if the transistor 12 is selected to have an Ic rating that corresponds to the Ic that will actually flow. It is not necessary to select a large transistor with an Ic rating that is 5 to 10 times higher than the actual Ic as in conventional analog voltage control circuits. Therefore, not only the power consumption is reduced, but also the heat generation of the transistor 12 is reduced, so that the heat dissipation fin is not necessary or can be downsized, and the mounting space of the entire circuit can be reduced. Naturally, since the number of circuit parts is reduced, manufacturing costs are also reduced.

Note that the present invention is not limited to the above embodiments,
For example, as shown in another embodiment of FIG. 5, the design can be freely changed in its details without departing from the gist of the invention.

Effects of the Invention As detailed above, the illuminated switch circuit has the following effects:
Since the light-emitting diode is lit using a pulsed current, it is possible to directly downsize the transistor, and as a result, the amount of heat generated by the transistor is reduced, making it unnecessary or compact to use heat dissipation fins. This has the effect of reducing manufacturing costs and reducing the mounting space for the entire circuit.

Therefore, the above-mentioned circuit for an illuminated switch is an excellent invention that can be used in various circuits in a wide range of industrial fields where light weight and miniaturization are required.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing the main parts of an embodiment of the present invention, Fig. 2 is a circuit diagram for an illuminated switch using a conventional analog voltage control method, and Fig. 3 is a circuit diagram of an embodiment of the present invention. FIG. 4 is a perspective view showing the lettered light switch, FIG. 4 is a sectional view taken along line A-A, and FIG. 5 is a circuit diagram showing the main parts of another embodiment. 4...Light emitting diode, 12...Transistor, 13...
- Pulse oscillator, 14...adjustment resistor. Patent applicant Toyoda Gosei Co., Ltd. agent
Patent Attorney Hironobu Onda Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A circuit for an illuminated switch, characterized in that a pulse oscillator equipped with an adjustment resistor whose duty can be varied and a switching element supply a pulse current to at least one light emitting diode.