JPH1131593A - Lamp-lighting device, and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lamp-lighting device, which can surely detect load current, even if the case where a load current is small. SOLUTION: A current, which flows in a current-detecting resistor R11 in the normal direction with respect to a diode D1, is converted to voltage so as to detect the voltage of the current-detecting resistor R11 with a load current detecting circuit 16. A V-f converting circuit 17 converts the voltage into frequency, and a drive circuit 3 controls electric field effective transistors Q1, Q2. In an inverter circuit 2, when the switching frequency of the electric field effective transistors Q1, A2 becomes high, the output voltage of the inverter circuit 2 is lowered, and the current which flows in the current detecting resistor R11 becomes large, and the output voltage of the inverter circuit 2 is lowered so as to maintain the load current constant. Load current can be detected, even if a load current is small by converting the current into a voltage with the current-detecting resistor R11 and detecting voltage of the both ends of the current-detecting resistor R11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a lamp lighting device and a lighting device for detecting a lamp current and controlling the output.

[0002]

2. Description of the Related Art Conventionally, as a lamp lighting device of this kind, a configuration shown in FIG. 4 is known. In the lamp lighting device shown in FIG. 4, an input terminal of a full-wave rectifier circuit 1 of a diode bridge is connected to a commercial AC power supply e, and an output terminal of the full-wave rectifier circuit 1 is connected to a smoothing capacitor C1. An inverter circuit 2 is connected to the capacitor C1. The inverter circuit 2 is connected to a series circuit of a field effect transistor Q1 and a field effect transistor Q2. A drive circuit is connected to the gates of the field effect transistor Q1 and the field effect transistor Q2. 3 are connected.

[0003] A ballast choke L1, a DC cut capacitor C2, and a shunt resistor R1 connect one end of each of the filaments FL1 and FL2 of the fluorescent lamp FL between both terminals of the field effect transistor Q2 of the inverter circuit 2. It is connected.

[0004] A capacitor C3 and a primary winding Tr1 of a transformer Tr are connected to both ends of the field effect transistor Q2. The filament preheating winding Tr2 and the filament preheating winding Tr3 of the transformer Tr are respectively connected to a fluorescent lamp.
It is connected to FL filaments FL1 and FL2 of FL. Also,
Fluorescent lamp via capacitor C2 and shunt resistor R1
Ballast choke between FL filaments FL1 and FL2
A capacitor C4 that resonates with L1 is connected.

A connection point between the filament FL2 of the fluorescent lamp FL and the shunt resistor R1 is connected to the drive circuit 3 via the diode D1 and the load current detection circuit 4.

Then, the AC voltage of the commercial AC power supply e is full-wave rectified by the full-wave rectifier circuit 1 and smoothed by the smoothing capacitor C1. Further, in the drive circuit 3, the field effect transistor Q1 and the field effect transistor Q2 are alternately switched at a high frequency to turn on the fluorescent lamp FL at a high frequency.

Further, the current flowing through the shunt resistor R1 is converted into a voltage, rectified by the diode D1, detected by the load current detection circuit 4, and the drive circuit 3 drives the field effect transistor Q1 and the field effect transistor according to the load current. The switching of the transistor Q2 is controlled to keep the load current constant.

[0008]

However, in the case of the configuration described in the above-mentioned conventional example, since the voltage of the shunt resistor R1 is rectified by the diode D1, the voltage drop due to the diode D1 is very large and the load current is small. However, there is a problem that the load current cannot be detected.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a lamp lighting device and a lighting device which can reliably detect a load current even when the load current is small.

[0010]

According to the present invention, there is provided a lamp lighting device comprising: a lamp lighting means for supplying an alternating voltage to a lamp with a variable voltage; a series circuit of a current detection resistor and a diode connected in series to the lamp; And current detection means having a diode connected in parallel to the series circuit of the current detection resistor and the diode and connected in reverse polarity to the diode, and using a terminal voltage of the current detection resistor as a load current detection signal; Control means for controlling the output of the lamp lighting means based on the load current detection signal of the current detection means. The load current is converted into a voltage value by the current detection resistance, and the potential difference of the current detection resistance is detected by the load current detection. The control means controls the output of the lamp lighting means according to the load current detection signal. Current is reliably detected load current by a current-sense resistor decreases, and controls the lamp lighting circuit.

According to a second aspect of the present invention, there is provided a lamp lighting device, comprising: a lamp lighting means for supplying an AC voltage to the lamp with a variable voltage; a current detecting resistor connected in series to the lamp; Current detecting means having a diode connected thereto and using the terminal voltage of the current detecting resistor as a load current detecting signal; and control means for controlling the output of the lamp lighting means based on the load current detecting signal of the current detecting means. The load current is converted into a voltage value by the current detection resistor, the potential difference of the current detection resistor is used as a load current detection signal, and the control means controls the output of the lamp lighting means by the load current detection signal. Therefore, even if the load current decreases, the load current is reliably detected by the current detection resistor, and the lamp lighting circuit is controlled.

According to a third aspect of the present invention, in the lamp lighting device according to the first or second aspect, the lamp lighting means has a switching element for converting the output, and the control means controls the switching frequency of the switching element. The output of the lamp lighting means is changed by changing the output, and the output of the lamp lighting means is easily controlled by changing the switching frequency of the switching element by the control means.

According to a fourth aspect of the present invention, in the lamp lighting device according to the first or second aspect, the lamp lighting means has a switching element for output conversion, and the control means controls the on-duty of the switching element. The output of the lamp lighting means is changed by changing the output, and the output of the lamp lighting means is easily controlled.

According to a fifth aspect of the present invention, there is provided a lighting device including the lamp lighting device according to any one of the first to fourth aspects; and a fixture main body provided with the lamp lighting device, and has respective functions.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a lighting device according to an embodiment of the present invention. Parts corresponding to those of the conventional example shown in FIG.

FIG. 1 is a circuit diagram showing a lamp lighting device, and FIG. 2 is a perspective view showing an appearance of the lighting device.

As shown in FIG. 2, a reflecting surface 12 is formed on the lower surface of the apparatus main body 11, and lamp sockets 13 are attached to both ends of the reflecting surface 12.
A fluorescent lamp FL, which is a discharge lamp, is mounted between 3 and 13, and a lamp lighting device 14 shown in FIG.

In the lamp lighting device 14, as shown in FIG. 1, the input terminal of the full-wave rectifier circuit 1 of the diode bridge is connected to a commercial AC power source e.
Is connected to a smoothing capacitor C1, a half-bridge type inverter circuit 2 as lamp lighting means is connected to the capacitor C1, and the inverter circuit 2 is a field effect transistor as a switching element.
A series circuit of Q1 and a field effect transistor Q2 is connected, and a drive circuit 3 is connected to the gates of the field effect transistor Q1 and the field effect transistor Q2.

A ballast choke L for current limiting is provided between both terminals of the field effect transistor Q2 of the inverter circuit 2.
1. It is connected to one end of each of filaments FL1 and FL2 of a fluorescent lamp FL as a discharge lamp via a DC cut capacitor C2, a current detection resistor R11 and a diode D11. Further, a diode D12 having a polarity opposite to that of the diode D11 is connected in parallel with the series circuit of the current detection resistor R11 and the diode D11. The connection point between the diode D11 and the current detection resistor R11 is connected to the drive circuit 3 via the load current detection circuit 16 and the Vf conversion circuit 17, and is connected to the full-wave rectifier circuit 1 via the capacitor C11. These are connected to a negative electrode, and these form a current detecting means 18.

Further, a capacitor C3 and a primary winding Tr1 of a transformer Tr are connected to both ends of the field effect transistor Q2, and the filament preheating winding Tr2 and the filament preheating winding Tr3 of the transformer Tr are respectively connected to a fluorescent lamp.
It is connected to FL filaments FL1 and FL2 of FL. Also,
Capacitor C2, diode D11 and current detection resistor R1
A capacitor C4 that resonates with the ballast choke L1 is connected between the filaments FL1 and FL2 of the fluorescent lamp FL via 1.

The connection point between the filament FL2 of the fluorescent lamp FL and the current detection resistor R1 is connected to the drive circuit 3 via the diode D1 and the load current detection circuit 4.

Next, the operation of the above embodiment will be described.

First, the AC voltage of the commercial AC power supply e is full-wave rectified by the full-wave rectifier circuit 1 and smoothed by the smoothing capacitor C1. Further, in the drive circuit 3, a field effect transistor
Q1 and the field effect transistor Q2 are alternately switched at a high frequency to turn on the fluorescent lamp FL at a high frequency.

The forward current is converted to a voltage by the diode D11 flowing through the current detection resistor R11, and the voltage of the current detection resistor R11 is detected by the load current detection circuit 16 and the detected voltage is detected by the Vf conversion circuit 17. The drive circuit 3 controls the field effect transistor Q1 and the field effect transistor Q2. The inverter circuit 2 includes a field effect transistor Q1 and a field effect transistor Q2.
The switching frequency of the inverter circuit 2
When the current flowing through the current detection resistor R11 increases, the output voltage of the inverter circuit 2 decreases, and the load current becomes constant.

As described above, since the current is converted into a voltage by the current detecting resistor R11 and the voltage between both ends of the current detecting resistor R11 is detected, a rectifying diode is not required unlike the related art. Is small, the load current can be detected. Therefore, it is possible to sufficiently cope with a case where the output current of the inverter circuit 2 is variable for dimming and the load current is reduced for dimming.

Next, a lamp lighting device according to another embodiment will be described with reference to FIG.

FIG. 3 is a circuit diagram showing a lamp lighting device according to another embodiment. The embodiment shown in FIG. 3 is obtained by removing the diode D11 from the embodiment shown in FIG.

In the embodiment shown in FIG.
Diode D12 detects current in the reverse blocking direction as current detection resistor
The voltage is converted into a voltage by R11 and controlled in the same manner as in FIG. In this case, the operation is the same as that of FIG. 1 while reducing the number of diodes.

It should be noted that the inverter circuit 2 is not limited to a two-bridge half-bridge type, but may be a single-bridge or three-bridge or any other type.

Further, the output control of the inverter circuit 2 is not limited to the control based on the frequency, but the same effect can be obtained even if the on-duty is changed.

[0031]

According to the first aspect of the present invention, the load current is converted into a voltage value by the current detection resistor, the potential difference of the current detection resistor is used as the load current detection signal, and the control is performed by the load current detection signal. Since the means controls the output of the lamp lighting means, there is no voltage drop due to the diode. Therefore, even if the load current decreases, the load current can be reliably detected by the current detection resistor and the lamp lighting circuit can be controlled.

According to the lamp lighting device of the second aspect,
The load current is converted into a voltage value by the current detection resistor, and the potential difference of the current detection resistor is used as a load current detection signal. The control means controls the output of the lamp lighting means by the load current detection signal. Therefore, even if the load current decreases, the load current can be reliably detected by the current detection resistor and the lamp lighting circuit can be controlled.

According to the lamp lighting device of the third aspect,
In addition to the lamp lighting device according to claim 1 or 2, the lamp lighting means has a switching element for output conversion, and the control means changes the switching frequency of the switching element to change the output of the lamp lighting means. By changing the switching frequency of the switching element by the means, the output of the lamp lighting means can be easily controlled.

According to the lamp lighting device of the fourth aspect,
In addition to the lamp lighting device according to claim 1, the lamp lighting means has a switching element for output conversion, and the control means changes the on-duty of the switching element to change the output of the lamp lighting means. The output of the lighting means can be easily controlled.

According to the illuminating device of the fifth aspect, since the apparatus main body provided with the lamp lighting device of any one of the first to fourth aspects is provided, each effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a lamp lighting device of the present invention.

FIG. 2 is a perspective view showing an appearance of the lighting device.

FIG. 3 is a circuit diagram showing a lamp lighting device according to another embodiment of the present invention;

FIG. 4 is a circuit diagram showing a conventional lamp lighting device.

[Explanation of symbols]

2 Inverter circuit as lamp lighting means 11 Appliance body 14 Lamp lighting device 18 Current detection means D11, D12 Diode FL Fluorescent lamp Q1, Q2 Field effect transistor R11 as switching element R11 Current detection resistor

Claims (5)

[Claims] A lamp lighting means for supplying an alternating voltage to the lamp with a variable voltage; a series circuit of a current detection resistor and a diode connected in series to the lamp; and a series circuit of the current detection resistor and the diode. Current detecting means having a diode connected in parallel and having a polarity opposite to that of the diode, and using the terminal voltage of the current detecting resistor as a load current detecting signal; lamp lighting means based on the load current detecting signal of the current detecting means Control means for controlling the output of the lamp. 2. A lamp lighting means for supplying an alternating voltage to a lamp with a variable voltage; a current detection resistor connected in series to the lamp; and a diode connected in parallel to the current detection resistor. A lamp comprising: current detection means for setting a terminal voltage of the current detection resistor to a load current detection signal; and control means for controlling an output of the lamp lighting means based on the load current detection signal of the current detection means. Lighting device. 3. The method according to claim 1, wherein the lamp lighting means has a switching element for converting the output, and the control means changes the output of the lamp lighting means by changing a switching frequency of the switching element. 2. The lamp lighting device according to 2. 4. The lamp lighting device according to claim 1, wherein the lamp lighting device has an output conversion switching element, and the control device changes an output of the lamp lighting device by changing an on-duty of the switching element. 2. The lamp lighting device according to 2. 5. A lamp lighting device according to any one of claims 1 to 4, and an instrument body provided with the lamp lighting device.
A lighting device, comprising: