JPH0212720Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field This invention relates to a monitor circuit for discharge lamps, such as deuterium lamps.

(b) Prior art A deuterium lamp is used, for example, as a light source for measurement, and when lighting it, a well-known lighting drive circuit is used, as shown in FIG. In the figure, switch SW ₁ ,
With SW ₂ and SW ₃ off, switch SW ₁ is first turned on, and heater current is applied to the heater of lamp 1 by heater power supply V _f to heat the heater. When the heater heats up to a certain extent, switch SW ₂ is turned on, and the charged charge of capacitor C is transferred to the anode of lamp 1 through resistor R and diode d ₁ to trigger voltage,
That is, a discharge starting voltage is applied. As a result, once a discharge current flows through lamp 1, switch SW ₃
is turned on, and from then on a constant current is applied from the constant current source _Is to maintain the discharge. Conventionally, in this type of lamp lighting drive circuit, whether or not a steady discharge state has been reached and the lamp has been lit has been determined by a person's direct visual inspection, or by detecting the light from the lamp using a detector. ing.

(c) Problems to be solved by the invention However, the above method has the problem that confirmation is difficult when the lamp is incorporated into the device, and the latter method requires that the detector is for short wavelengths. In some cases, it is inconvenient to make a judgment based on the final measurement signal of the device.

In addition, lighting is achieved through the steps of heater heating, application of discharge starting voltage, and steady discharge, but due to changes in the ambient temperature and discharge starting voltage, etc., it may be difficult for electrons to fly, and conventionally no lighting has been confirmed. Then, the user had to turn on the switch and go through the same procedure again, which was cumbersome to handle.

This invention has been made in view of the above-mentioned problems, and is intended to provide a discharge lamp monitor circuit device that can easily confirm whether the lamp is lit and can easily turn on the lamp even if the lamp is not lit.

(d) Means and operation for solving the problem The discharge lamp monitor circuit device of this invention comprises a discharge lamp, a lighting circuit including a heater heating power source for the discharge lamp, a discharge starting voltage power source, a steady discharge power source, and the above-mentioned lighting circuit. command signal output means for time-sequentially outputting command signals for heating a discharge lamp heater, applying a discharge starting voltage, and steady discharge operation to the lighting circuit; and circuit means for extracting a minute current from the current flowing through the lighting circuit; A light emitting element that emits light when the minute current flowing through the minute current extraction circuit means exceeds a certain value; a current determining means that determines whether the minute current is above the certain value; and a control means for repeating the output of the command signal within a predetermined number of times.

In this discharge lamp monitor circuit, when the discharge lamp of the lighting circuit is lit, a minute current exceeds a certain value and the light emitting element emits light. Therefore, lighting of the discharge lamp can be confirmed. On the other hand, even if the command signals of heater heating, discharge starting voltage application, and steady discharge operation are sequentially given to the discharge lamp of the lighting circuit, if the above-mentioned minute current is below a certain value, the minute current remains constant within a predetermined number of times. The command signals for heater heating, discharge starting voltage application, and steady discharge operation are repeatedly input to the discharge lamp until the value is exceeded. Thereby, the discharge lamp of the lighting circuit can be reliably lit.

(e) Examples This invention will be explained in detail below using examples shown in the drawings.

FIG. 1 is a circuit connection diagram of a deuterium lamp lighting circuit according to an embodiment of this invention. In FIG. 1, 1 is a deuterium lamp that is lit by discharge. Further, a constant current circuit is configured by a Zener diode ZD, transistors Tr1 and Tr2, and resistors R1, R2, R3, and R4. This constant current circuit is connected to the cathode K of the deuterium lamp 1. Although not shown, the deuterium lamp 1 itself already has a well-known drive circuit, such as a heater circuit similar to that shown in FIG. 4, and the heater is first heated when the switch SW ₁ is turned on. . After heating the heater, the switch SW ₂ is turned on and a discharge starting voltage is applied to the anode for a certain period of time, so that the deuterium lamp 1 starts discharging. When the discharge is started, the switch _SW3 is turned on to enter a steady discharge, and due to the operation of the constant current circuit described above, a constant current is flows through the resistor R4.

Here, a series connection of a resistor R5 and a light emitting diode LED1 is further inserted in parallel with the resistor R4.
It is configured to flow to LED1. This minute current im has a value so small that it does not significantly affect the steady discharge of the deuterium lamp 1. Further, the phototransistor PT is optically coupled to the light emitting diode LED1, and forms a photocoupler 2 together with the light emitting diode LED1. The output of the phototransistor PT is connected via a buffer amplifier 3 so as to be applied to a light emitting diode LED2.

When the deuterium lamp 1 is currently in a steady discharge state and lit, the minute current im flows through the light emitting diode LED 1.
The light from the light emitting diode LED1 supplies an output to the phototransistor PT, which causes the light emitting diode LED2 to emit light. Since the light emitting diode LED2 is placed on the panel surface of the device, the person measuring the light can know whether the deuterium lamp 1 is lit by looking at the light emission state.

If the deuterium lamp 1 is not lit, very little current im will flow through the light emitting diode LED1.
It also does not emit light. Therefore light emitting diode LED
2 also does not emit light.

In addition, in the lighting circuit shown in Fig. 1, photocoupler 2
is used for level matching and noise removal, but in order to simplify the device, the minute current is may be passed directly to the light emitting diode LED2. Conversely, the light emitting diode LED1 may be used for display purposes.

FIG. 2 is a block diagram of an embodiment of this invention.

In FIG. 2, 4 is a lamp circuit including the deuterium lamp 1 and its lighting drive circuit, and 5 is a constant current circuit shown in FIG. Reference numeral 6 denotes a microcomputer circuit, which includes a photocoupler 2, a buffer amplifier 3, a light emitting diode LED 2, and a microcomputer connected to the output of the buffer amplifier 3 shown in FIG.

In the discharge lamp monitor circuit of the embodiment shown in FIG. 2, when the deuterium lamp 1 is lit, the light emitting diode LED 2 emits light, but when the deuterium lamp 1 is not lit, the microcomputer 6 This is determined by sequentially sending out the heater heating command signal A, the discharge starting voltage application command signal B, and the steady discharge operation command signal C, and by sequentially inputting these command signals A, B, and C, the switch SW ₁ ,
SW ₂ and SW ₃ (see FIG. 4) are turned on sequentially to automatically control the lighting so that the lighting of the deuterium lamp 1 can be constantly monitored.

The operation of the embodiment circuit shown in FIG. 2 will be explained according to the control flow by the microcomputer shown in FIG.

When the circuit starts operating, first, in step 11, a heater heating command signal A is output, and the heater power source is switched on by this heater heating command signal A, and the heater is heated. Next, in step 12, t
Determine whether ≧T1. T1 is the set heater heating time, and this step remains until T1 elapses after the start of heater heating. The microcomputer 6 measures the time from the start of heating the heater, and when the time t has passed T1, the judgment is YES.
In step 13, a discharge starting voltage application command B is output, and this command B turns on the switch for applying the discharge starting voltage, and the discharge starting voltage is applied.Furthermore, in step 14, a steady discharge starting command C is output,
Turn on the steady discharge switch and start steady discharge.

After issuing the steady discharge start command, a further wait is performed for a certain period of time in step 15. Elapsed time T2 with constant time
If it exceeds the threshold, the judgment is YES and the process moves to step 16, where it is judged whether a constant current is flowing to the cathode. If a constant current is flowing, the process moves to step 17, and the predetermined operation of the measuring device etc. is started. Step 16: It is determined that constant current is not flowing to the cathode. If NO, proceed to Step 1.
8, it is determined whether the operations from step 11 to step 16 have been repeated a certain number of times (N times).
Then step until N repetitions are performed.
Since the judgment in ST18 is NO, return to step 1.
The same lighting operation as described above, including heating the heater, applying a discharge starting voltage, and issuing a steady discharge starting command, is repeated. Repeat steps 11 to 16 with N
If a constant current is still not flowing through the cathode even after the circuit is cycled, an error message will be displayed.

As described above, heater heating, discharge starting voltage applied,
By repeating each command for the steady discharge operation N times, it is possible to reliably bring the discharge state into a discharge state if the discharge operation has not been reached simply due to changes in the ambient temperature, discharge starting voltage, etc. On the other hand, if the steady current still does not flow and discharge does not occur even after repeating the process N times, this is determined to be an abnormality of the lamp, and an error message is displayed.

(F) Effect of the invention According to this invention, a minute current is extracted from the constant current flowing through the lighting circuit, and this minute current causes the light emitting element to emit light. Therefore, the discharge lamp is lit depending on whether or not the light emitting element emits light. You can check whether it is present or not.

In addition, when the minute current is below a certain value, the command signals for heater heating, discharge starting voltage application, and steady discharge operation are sequentially outputted to the lighting circuit repeatedly and repeatedly. Even if there are unstable factors such as fluctuations in ambient temperature, discharge starting voltage, etc., the discharge state can be reliably achieved.

[Brief explanation of the drawing]

Fig. 1 is a circuit connection diagram of a deuterium lamp lighting circuit according to an embodiment of this invention, Fig. 2 is a circuit block diagram showing an embodiment of this invention, and Fig. 3 is a control flow of the circuit of the embodiment shown in Fig. 2. FIG. 4 is a circuit diagram of a well-known lighting drive circuit for a deuterium lamp. 1; Deuterium lamp, 2; Photocoupler, 3; Buffer amplifier, ZD; Zener diode, Tr1, Tr
2; Transistor, LED1, LED2; Light emitting diode, PT; Phototransistor, 4; Lamp circuit, 5; Constant current circuit, 6; Microcomputer circuit.

Claims (1)

[Scope of utility model registration request] A lighting circuit including a discharge lamp, a heater heating power source for the discharge lamp, a discharge starting voltage power source, and a steady discharge power source, and each command signal for heater heating, discharge starting voltage application, and steady discharge operation of the discharge lamp is transmitted to the lighting circuit. a command signal output means for time-sequentially outputting a command signal; a circuit means for extracting a minute current from the current flowing through the lighting circuit; and a light emitting element that emits light when the minute current flowing through the minute current extraction circuit means exceeds a certain value; The present invention is characterized by comprising a current determining means for determining whether the minute current is above a certain value, and a control means for repeating the output of the command signal up to a predetermined number of times when the minute current is not above the certain value. Discharge lamp monitor circuit device.