JPH04108898U - Dimmer with soft start function - Google Patents

Abstract

(57) [Summary] [Purpose] To realize smooth soft start at low cost and to simplify the dimming circuit. [Configuration] A diode bridge DB with the gate terminal and power supply terminal of the triac TR connected to the input side, and a CR charging circuit 6 connected to the output side of the diode bridge DB.
A variable constant voltage circuit 5 connected in parallel to the capacitor C1 of the CR charging circuit 6, and a transistor circuit 4 that is turned on when the charging voltage of the CR charging circuit is equal to or higher than a certain voltage and short-circuits the output side of the diode bridge DB. It consists of When the power switch 2 is turned on, the charging voltage of the capacitor C1 gradually increases every half cycle. According to this,
The timing at which the transistor circuit turns on, that is, the phase at which the triac TR turns on gradually advances. Since the charging voltage of the capacitor C1 does not exceed the constant voltage set by the variable constant voltage circuit 5, dimming can be performed by changing the constant voltage by this circuit.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention prevents voltage from being suddenly applied to the incandescent bulb load from the moment the power is turned on. A dimmer with a soft start function that allows voltage to be applied gradually to prevent Regarding the location.

0002

[Conventional technology]

When the power switch is turned on, a sudden current (rush current) flows to the load. It may be desirable to avoid this. For example, if the load is an incandescent light bulb , when you turn on the power switch when the phase of the power supply current is 90 degrees or 270 degrees, the white If a large current flows rapidly through a hot bulb and the filament temperature is low, the current will cause it to break. There may be a line. Therefore, in order to eliminate this inconvenience, a soft starter is used. is proposed. Conventional soft starters used dedicated ICs. Connect a gate element such as a diac to the gate of the triac that performs phase control. In addition, a CR charge is applied to the gate element so that the charging current increases every half cycle. Connect an electric circuit, etc. to speed up the phase at which the gate element turns on every half cycle. That's what I was doing.

0003

[Problem that the idea aims to solve]

However, methods using ICs have the problem of making the equipment expensive, and In the method of using a gate device with active state, the gate device is turned on every half cycle. Because it is necessary to perform control to advance the timing of , Also, soft start control to gradually advance the phase is unavoidably smooth. There was a problem that it did not become a base. In addition, the soft start function mentioned above also has a dimmer function. Adding additional functions makes the circuit configuration more complex and makes soft start difficult. There was a problem.

0004 The purpose of this invention is to create software that does not require the use of gate elements such as ICs or DIACs. It is possible to start, smooth soft start, and dimming. To provide a dimming device with a soft start function that can be performed using a simple circuit. The purpose is to

[0005]

[Means to solve the problem]

A triac connected in series with an incandescent bulb load, A diode block with the gate terminal and power supply terminal of the triac connected to the input side. Ridge and a CR charging circuit connected to the output side of the diode bridge; a variable constant voltage circuit connected in parallel to the capacitor of the circuit; When the charging voltage of the variable constant voltage circuit is higher than a certain voltage, it turns on and the diode A transistor circuit short-circuiting the output side of the bridge.

[0006]

[Effect]

A control system that includes a triac on the input side of the diode bridge and a CR charging circuit on the output side. Since the control part is connected, the output side of the diode bridge is shorted. Current flows directly from the power supply through the diode bridge to the gate of the triac. Ru. Therefore, this current turns on the triac and supplies current to the load. .

[0007] Since the CR charging circuit is connected to the output side of the diode bridge, the power supply When the switch is turned on, charging current begins to flow through this CR charging circuit. Also, this C A variable constant voltage circuit is connected in parallel to the capacitor of the R charging circuit, and the charging voltage is This prevents the voltage from being charged higher than the constant voltage set by this variable constant voltage circuit. ing. In this case, if the charging voltage of the CR charging circuit is lower than the variable constant voltage, then The charging voltage is directly output to the transistor circuit, and the above charging voltage becomes a variable constant voltage. In the above case, the constant voltage set by the variable constant voltage circuit becomes the output voltage. Above voltage When the voltage exceeds a certain voltage, the transistor circuit turns on. In other words, the above CR When charging current begins to flow through the charging circuit and the charging voltage reaches a constant voltage (within half a cycle) ) The transistor circuit turns on. When the transistor circuit is turned on, the diode bridge The output side of the switch is shorted. Then, the diode bridge is connected from the power supply as described above. Current flows through the gate of the triac, turning on the triac.

[0008] In the above operation, the charging voltage of the CR charging circuit is constant during the first half cycle. Since it takes a certain amount of time to reach the voltage, the phase at which the triac is turned on is I'm late. In the next half cycle, there is already a charge on the capacitor of the above CR charging circuit. The time it takes for the charging voltage to reach a constant voltage because the voltage is charged to a certain level The interval will be slightly shorter than the time during the previous half cycle. In other words, the trial turns on at a slightly faster phase than last time. The same behavior as above occurs for the next half cycle and below. As the process was repeated, the triac turned on by increasing the phase every half cycle. I'm going to go to the middle of the day. That is, a soft start is performed. In addition, the above CR charging circuit Because the charging voltage does not exceed the constant voltage set by the variable constant voltage circuit above, The phase at which the triac turns on can only advance to a position corresponding to this constant voltage. do not have. In other words, changing the constant voltage with a variable constant voltage circuit can control the dimming of an incandescent light bulb load. It is equivalent to doing.

[0009]

【Example】

FIG. 1 shows a circuit diagram of an embodiment of the present invention.

0010 The commercial power supply 1 includes a power switch 2, an incandescent light bulb load 3, a triac TR, and Chokes L are connected in series. The gate terminal of the triac TR is a diode. connected to one input terminal of the diode bridge DB, and the other input terminal of the diode bridge DB. The input terminal is connected to the power supply side via a resistor R1. The diode bridge The output side of DB is connected to the soft start control section. This soft start system The control section includes a transistor circuit 4, a variable constant voltage circuit 5, and a CR charging circuit 6. . Note that this embodiment further includes a discharge circuit 7 of the CR charging circuit 6.

[0011] The CR charging circuit 6 includes resistors R2, R3, a diode D1, and a capacitor C1. Consists of a series circuit. Diode D1 conducts charging current to capacitor C1. is set in the direction of

0012 The variable constant voltage circuit 5 is composed of a variable resistor R4, a transistor Q1, and a resistor R5. ing. The middle terminal of variable resistor R4 is connected to the base of transistor Q1, and the resistor R5 is connected to the emitter of transistor Q1, and the collector of transistor Q1 is connected to It is connected to one terminal of variable resistor R4. Variable resistor R4 is connected to resistor R3, die Connected in parallel to the series circuit of ode D1 and capacitor C1, charging capacitor C1 An electric voltage is applied to this resistor R4.

The charging voltage of the CR charging circuit 6 is input to the transistor circuit 4 via a resistor R6. The transistor circuit 4 includes a capacitor C2 for charging the input voltage, a transistor Q2 that turns on when the charging voltage of the capacitor C2 is higher than a certain voltage, a transistor Q3 that turns on when the transistor Q2 turns on, and a diode bridge DB. The transistor Q2 includes a resistor R7 and a resistor R8 that divide the output voltage of the transistor Q2 and supply the divided voltage to the base of the transistor Q2. In this transistor circuit, the voltage input to capacitor C2 via resistor R6 exceeds the voltage divided by resistor R7 and resistor R8 (strictly speaking, the voltage including V _BE of transistor Q2). At this time, transistors Q2 and Q3 are turned on. Since the collector and emitter of the transistor Q3 are connected to the output terminals of the diode bridge DB, when the transistor Q3 is turned on, the output side of the diode bridge DB is short-circuited. When this diode bridge DB is short-circuited, the current flowing from the resistor R1 passes through the diode bridge DB and the transistor Q3 and flows into the gate of the triac TR. This gate current turns on the triac TR.

[0014] Next, the operation of the above circuit will be explained.

[0015] When the power switch 2 is turned on, a charging current flows through the CR charging circuit 6. This charging The capacitor C1 is charged by the current. The charging voltage of capacitor C1 is When the voltage divided by resistors R7 and R8 is exceeded, transistors Q2 and Q3 are turned on and the transistor is turned on. A gate current flows into IAC TR. At this time, the incandescent light bulb 3 lights up.

[0016]In the first half cycle, since charging is started for the capacitor C1 whose charge is 0, the phase in which the triac TR is turned on is delayed considerably. Therefore, the incandescent light bulb 3 is hardly lit. In FIG. 2, time t ₀ is the timing (phase) at which the triac TR turns on in the first half cycle.

[0017] In the next half cycle, since the capacitor C1 now has the previously charged charge, the triac TR turns on a little earlier than in the first half cycle. In this way, the phase at which the triac TR is turned on becomes earlier every half cycle. In Figure 2, the phase in which the triac TR is turned on changes from time t ₀ to point P in the positive half cycle, and the phase in which the triac TR turns on changes from time t ₁ to Q in the negative half cycle. Indicates the state of Point P and point Q are determined by the constant voltage set by the variable constant voltage circuit 5. That is, it is determined by the setting position of variable resistor R4. When this variable resistor R4 is adjusted, the base current of the transistor Q1 changes, so that the voltage between the collector and emitter of the transistor Q1 also changes. The constant voltage is determined by the sum of the collector-emitter voltage of this transistor Q1 and the voltage across the resistor R5. The charging voltage of the capacitor C1 is input to the transistor circuit Q2 until the charging voltage of the capacitor C1 reaches this constant voltage, but once the charging voltage of the capacitor C1 reaches the above constant voltage, further No voltage is applied. The timing at which this happens is at point P and point Q in FIG. Therefore, dimming can be performed by adjusting the variable resistor R4.

[0018] In this way, a simple circuit consisting of two resistors R4 and R5 and a transistor Q1 Dimming can be done just by adding.

[0019] In this embodiment, in addition to the above circuit, a discharge circuit 7 for the capacitor C1 is provided. ing. This discharge circuit 7 is connected to the capacitor C1 when the power switch 2 is turned off. This is for discharging the charged charge. This discharge circuit 7 includes PUTQ4 and PUTQ4. Direct circuit of resistor R9 and diode D2 connected to the anode side of UTQ4 and The Zener diode ZD and the resistor R10 connected to the gate side of PUTQ4 and the voltage The capacitor C3 is connected between the power source and the capacitor C3. Zener diode ZD is connected in parallel to capacitor C1. This Zener diode ZD is This is to prevent the charging voltage of the capacitor C1 from becoming excessively large.

[0020] In the above circuit, while power switch 2 is on, the output of PUTQ4 is PUTQ4 is in an off state because the gate voltage is lower than the gate voltage. power switch When switch 2 is turned off, this voltage state is reversed. That is, the gate of PUTQ4 voltage becomes lower than the anode voltage. Then, PUTQ4 turns on and the capacitor The charging voltage of C1 rapidly discharges through PUTQ4. Turning off switch 2 Then, when the charge in capacitor C1 is discharged as described above, the power switch When 2 is turned on, operation starts from a state where the charge charged in capacitor C1 is 0. Therefore, no matter how many times you turn on the power switch, the soft start operation will always be the same. It will be done.

[0021]

[Effect of the idea]

Supplies gate current directly to the triac gate without using a gate element This makes the soft start extremely smooth. Also, The variable constant voltage circuit can be configured with a very simple circuit.

[Brief explanation of drawings]

FIG. 1 shows a circuit diagram of an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the above embodiment.

[Explanation of symbols]

1 Power supply 3 Incandescent light bulb load TR triac DB diode bridge 4 Transistor circuit 5 Variable constant voltage circuit 6 CR charging circuit

Claims (1)

[Scope of utility model registration request] 1. A triac connected in series to an incandescent light bulb load, a diode bridge having a gate terminal and a power supply terminal of the triac connected to an input side, and a CR charging circuit connected to an output side of the diode bridge. , a variable constant voltage circuit connected in parallel to the capacitor of the CR charging circuit, and a transistor circuit that turns on when the charging voltage of the variable constant voltage circuit is equal to or higher than a certain voltage, and short-circuits the output side of the diode bridge. Light control device with soft start function.