JP4147095B2 - Light source device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light source device using a high-intensity discharge (HID) lamp such as a metal halide lamp or a mercury lamp.
[0002]
[Prior art and its problems]
For example, xenon lamps and halogen lamps are frequently used as light source devices for endoscopes, but recently, there are those using high-intensity discharge lamps such as metal halide lamps and mercury lamps.
[0003]
It is desirable that the high-intensity discharge lamp be lit within a preset temperature range so that its characteristics can be fully exerted. If the temperature is higher than this temperature range, the lamp life may be shortened. However, there is a possibility that a sufficient amount of light emission cannot be obtained. In addition, since the high-intensity discharge lamp does not cause dielectric breakdown between the discharge electrodes when the lamp bulb temperature is too high, once it is extinguished, it cannot be turned on again until the lamp bulb temperature falls below a predetermined temperature. ing.
[0004]
Such a light source device using a high-intensity discharge lamp is provided with a cooling fan as described in, for example, Japanese Patent Application Laid-Open No. 11-42212, and the high-intensity discharge lamp is forced by the cooling fan. It is cooling. However, since the cooling fan is always operated in the conventional light source device, when the high-intensity discharge lamp is started (discharge starts), the temperature of the lamp bulb does not rise immediately, and the discharge of the high-intensity discharge lamp does not occur. It takes time to reach a stable state (a state in which almost full light emission can be obtained).
[0005]
OBJECT OF THE INVENTION
An object of the present invention is to obtain a light source device capable of shifting the discharge of a high-intensity discharge lamp to a stable state in a short time at the start.
[0006]
SUMMARY OF THE INVENTION
The present invention detects a lamp voltage of a high-intensity discharge lamp, a cooling fan for forcibly cooling the high-intensity discharge lamp, and the high-intensity discharge lamp , and outputs a stable state signal L or H corresponding to the lamp voltage. A voltage detection unit; and a control unit that prohibits the operation of the cooling fan when the stable state signal L is input from the voltage detection unit and that operates the cooling fan when the stable state signal H is input. The logical product of the lamp current detection resistor through which the lamp current flows when the discharge lamp discharges, the comparator that compares the lamp voltage of the high-intensity discharge lamp with a predetermined voltage, and the voltage generated at both ends of this comparator and the lamp current detection resistor. It has an AND element to calculate, and a transistor that turns on and off the photocoupler according to the output of this AND element, and the lamp current flows If not, or if the lamp voltage of the high-intensity discharge lamp is less than the predetermined voltage, the photocoupler is turned off and a stable state signal L is output, and the lamp voltage of the high-intensity discharge lamp is greater than or equal to the predetermined voltage. When the lamp current is flowing, the photocoupler is turned on and a stable state signal H is output .
[0007]
The predetermined voltage for starting the operation of the cooling fan is a lamp voltage when the discharge of the high-intensity discharge lamp is in a stable state, and is actually preferably set to the rated voltage of the high-intensity discharge lamp. Or it is good also as a voltage equivalent to 80 to 90% of the rated voltage of a high-intensity discharge lamp.
[0008]
According to the above configuration, since the cooling fan does not operate until the discharge reaches a stable state after the discharge of the high-intensity discharge lamp is started, the lamp bulb of the high-intensity discharge lamp does not perform forced cooling from the cooling fan. The lamp bulb temperature rises faster without being affected. Thereby, the discharge can be shifted to a stable state in a short time after the discharge of the high-intensity discharge lamp is started. Further, according to the above configuration, the lamp bulb is forcibly cooled by the cooling fan after the discharge of the high-intensity discharge lamp has shifted to a stable state, so that the lamp bulb temperature during lamp operation does not become too high, and the high-intensity discharge The lamp life can be prevented from being shortened.
[0009]
The operation of the cooling fan is stopped immediately when the discharge of the high-intensity discharge lamp is stopped, for example. Alternatively, when the discharge of the high-intensity discharge lamp is stopped once and then restarted, the lamp bulb temperature of the high-intensity discharge lamp decreases to a temperature at which the high-intensity discharge lamp can be turned on again when the high-intensity discharge lamp is turned off. When it is stopped.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings. In the present specification, in the illustrated circuit components, a low (ground) level voltage is a logical value “L”, and a high level voltage is a logical value “H”.
[0011]
FIG. 1 is a block diagram showing a main configuration of a light source device according to an embodiment of the present invention. The light source device 1 uses a high-intensity discharge lamp (hereinafter simply referred to as “lamp”) 2 such as a metal halide lamp or a mercury lamp as a light source. As shown in FIG. 2, the lamp 2 includes a lamp bulb 2a serving as an outer tube and a base 2b fitted to the lamp bulb 2a. In the lamp bulb 2a, a luminescent material (mercury, argon gas, metal halide, etc.) is provided. And a pair of discharge electrodes inserted at both ends of the arc tube. The lamp 2 is mounted on the lamp holder 3 through the base 2b and can be used in combination with the reflection mirror 4. The light emitted from the lamp 2 is reflected by the reflecting mirror 4, collected at the condensing point P shown in FIG. 2, and emitted outward. The reflection mirror 4 is attached to the lamp holder 3. As is well known, the lamp 2 has the property that, if the temperature of the lamp bulb 2a is too high at the time of starting, dielectric breakdown does not occur between the discharge electrodes, and light cannot be emitted.
[0012]
The light source device 1 includes a microcomputer 10 as a control unit that summarizes the operation of the entire device. The microcomputer 10 is supplied with the voltage of the AC power supply line V as a constant voltage Vm by the AC / DC power supply 5.
[0013]
The microcomputer 10 is connected to a power switch SWM for turning on / off the main power supply and a lamp switch SWL for turning on / off the lamp 2 provided on the outer surface of the light source device 1. The microcomputer 10 is activated when the power switch SWM is turned on to detect the switch state of the lamp switch SWL. When the lamp switch SWL is on, the lamp lighting signal “H” is detected. When the lamp switch SWL is off, the lamp lighting signal “L” is output. 6 is output.
[0014]
The lamp lighting circuit 6 is a circuit for lighting or extinguishing the lamp 2 based on the lamp lighting signals “H” and “L” output from the microcomputer 10. FIG. 3 shows an example of the circuit configuration of the lamp lighting circuit 6. The lamp lighting circuit 6 includes a switch member SW, a rectifying / smoothing circuit 61, a switching circuit 62, an insulating transformer 63, an igniter (starter) 65, an igniter starting circuit 66, and a voltage monitor 67.
[0015]
The switch member SW electrically connects the lamp lighting circuit 6 and the lamp 2 when the lamp lighting signal “H” is output, and connects the lamp lighting circuit 6 and the lamp 2 when the lamp lighting signal “L” is output. Shut off. That is, the lamp lighting circuit 6 starts to operate in response to the lamp lighting signal “H” and stops operating in response to the lamp lighting signal “L”.
[0016]
The rectifying / smoothing circuit 61 is connected to the AC power supply line V, and the voltage from the AC power supply line V is rectified by the rectifying / smoothing circuit 61 and then supplied to the primary side of the insulating transformer 63 via the switching circuit 62. The switching circuit 62 functions as a DC / DC converter, and a high-frequency AC voltage is generated on the secondary side of the insulating transformer 63 by the high-speed switching operation of the switching circuit 62. The switching circuit 62 of this embodiment always performs a switching operation while the main power supply is on (while the voltage from the AC power supply line V is supplied via the rectifying and smoothing circuit 61). The igniter 65 is connected between the secondary side of the insulating transformer 63 and the negative electrode side of the lamp 2, and is activated between the discharge electrodes (between the positive and negative electrodes) of the lamp 2 when activated via the igniter activation circuit 66. A pulse voltage that causes dielectric breakdown is applied to the negative electrode side of the lamp 2. When dielectric breakdown occurs between the discharge electrodes of the lamp 2 by applying this pulse voltage, a current (lamp current) flows from the insulating transformer 63 side, and the lamp 2 discharges (lights and emits light). The igniter activation circuit 66 activates the igniter 65 when the lamp lighting signal “H” is input from the microcomputer 10.
[0017]
The voltage monitor 67 detects the lamp voltage Vr and the lamp current Ir of the lamp 2, and when the lamp voltage Vr does not reach the rated voltage of the lamp 2 or when the lamp current Ir does not flow, the stable state signal “L”. When the rated voltage has been reached and the lamp current Ir is flowing, the stable state signal “H” is output. The voltage monitor 67 includes a voltage divider 70, a comparator 71, a reference power supply 72, an AND element 73, a lamp current detection resistor 74, a transistor 75, and a photocoupler 76.
[0018]
The voltage divider 70 includes two resistors 70a and 70b connected in parallel to the secondary side of the insulating transformer 63 and the lamp 2, and the lamp voltage (voltage between the discharge electrodes) Vr of the lamp 2 is converted to the lamp voltage Vr ′. Take out as. This ramp voltage Vr ′ corresponds to (1 / N) times the actual ramp voltage Vr (N: real number, N> 0). The comparator 71 has a + side input terminal connected between the resistors 70a and 70b of the voltage divider 70 (position A shown in FIG. 3), a − side input terminal connected to the reference power source 72, and an input from the + side input terminal. The ramp voltage Vr ′ is compared with the reference voltage Vref input from the − side input terminal, and the comparison result is output. Here, comparing the lamp voltage Vr ′ with the reference voltage Vref is equivalent to comparing the actual lamp voltage Vr with the rated voltage of the lamp 2.
[0019]
The AND element 73 calculates the logical product of the output of the comparator 71 and the voltage generated in the lamp current detection resistor 74, and outputs the calculation result to the transistor 75. The lamp current detection resistor 74 is provided between the voltage divider 70 and the igniter 65, and a voltage is generated at both ends of the lamp current detection resistor 74 when the lamp current Ir flows through the lamp current detection resistor 74. The transistor 75 is turned on or off according to the output of the AND element 73, and the photocoupler 76 is turned on or off according to the output of the transistor 75. The output end of the photocoupler 76 is connected to the microcomputer 10, and the voltage monitor 67 side and the microcomputer 10 side are insulated by the photocoupler 76.
[0020]
In the present embodiment, when the lamp current Ir does not flow through the lamp current detection resistor 74 (when the lamp 2 is not lit), “L” is input to the AND element 73 from the lamp current detection resistor 74 side. At this time, the output of the AND element 73 is “L” regardless of the input on the comparator 71 side. When the lamp voltage Ir is flowing through the lamp current detection resistor 74 but the lamp voltage Vr ′ is less than the reference voltage Vref (when the lamp voltage Vr has not reached the rated voltage), the AND element 73 is connected to the comparator 71 side. Since “L” and “H” are input from the lamp current detection resistor 74 side, the output of the AND element 73 is “L” in this case as well. When the output of the AND element 73 is “L”, the transistor 75 is turned off, and the photocoupler 76 is also turned off. In the off state of the photocoupler 76, there is no output from the photocoupler 76, and the stable state signal input by the microcomputer 10 is "L" (unstable state). On the other hand, when the lamp current Ir flows through the lamp current detection resistor 74 and the lamp voltage Vr ′ exceeds the reference voltage Vref (when the lamp voltage Vr reaches the rated voltage), the AND element 73. “H” is input from the comparator 71 side and “H” is input from the lamp current detection resistor 74 side, and the output of the AND element 73 is “H”. When the output of the AND element 73 becomes “H”, the transistor 75 is turned on, and the transistor 75 turns on the photocoupler 76. In the ON state of the photocoupler 76, the stable state signal input by the microcomputer 10 becomes “H” (stable state) by the output from the photocoupler 76.
[0021]
A cooling fan 8 is further connected to the microcomputer 10 via a fan drive circuit 9. As shown in FIG. 2, the cooling fan 8 is provided at a position where air can be blown toward the entire periphery of the lamp including the lamp 2, the lamp holder 3, and the reflection mirror 4. The amount and intensity of the cooling fan 8 are adjusted in advance so that the temperature of the lamp bulb 2a can be maintained within a predetermined optimum operating temperature range when the lamp 2 is turned on.
[0022]
In the light source device 1 described above, the operation of the cooling fan 8 is prohibited after the discharge of the lamp 2 is started until the discharge is shifted to a stable state. FIG. 4 is a flowchart regarding the main operation of the light source device 1. The microcomputer 10 is activated when the power switch SWM is turned on, and repeatedly executes the following main operation while the power switch SWM is turned on.
[0023]
In this main operation, first, it is checked whether or not the lamp switch SWL is on (S11). If the lamp switch SWL is on, a lamp lighting signal “H” is output (S11; Y, S13). Then, the switch member SW in the lamp lighting circuit 6 is closed, the lamp lighting circuit 6 and the lamp 2 are electrically connected, and the lamp lighting circuit 6 starts to operate. At the same time, the igniter starting circuit 66 starts the igniter 65, and a pulse voltage that causes dielectric breakdown between the discharge electrodes of the lamp 2 is applied from the igniter 65 to the negative electrode side of the lamp 2. By applying this pulse voltage, dielectric breakdown occurs between the discharge electrodes of the lamp 2, current from the insulating transformer 63 flows between the discharge electrodes of the lamp 2, and discharge of the lamp 2 is started.
[0024]
When the lamp lighting signal “H” is output, it is checked whether or not the stable state signal from the voltage monitor 67 is “H” (S15). When the lamp 2 starts discharging, the lamp current Ir flows through the lamp current detection resistor 74 to generate a voltage at both ends of the lamp current detection resistor 74, and the temperature of the lamp bulb 2a rises. The lamp voltage also increases gradually. When the lamp voltage reaches the rated voltage of the lamp 2, the stable state signal output from the voltage monitor 67 is switched from “L” to “H”.
[0025]
If the stable state signal “H” is not input, the operation of the cooling fan 8 is stopped via the fan drive circuit 9 (if the cooling fan 8 is not originally operating, nothing is done), and the process returns to S15. (S15; N, S17). By S15 and S17, the cooling fan 8 is not operated until the stable state is reached after the discharge of the lamp 2 is started, and the forced cooling of the lamp 2 is prohibited.
[0026]
If the stable state signal “H” is input, the cooling fan 8 is operated via the fan drive circuit 9 to start forced cooling of the lamp 2, and the process returns to S11 (S15; Y, S19). Returning to S11, if the lamp switch SWL is continuously on, S11 to S15 and S19 are repeatedly executed. That is, while the lamp 2 is discharged in a stable state, forced cooling is continued by the cooling fan 8, and the temperature of the lamp bulb 2a does not become too high.
[0027]
On the other hand, if the lamp switch SWL is not turned on in the check of S11, a lamp lighting signal “L” is output (S11; N, S21). Then, the switch member SW is opened, the space between the lamp lighting circuit 6 and the lamp 2 is opened, and the discharge of the lamp 2 is stopped (extinguishes). By opening the lamp lighting circuit 6 and the lamp 2, the lamp current Ir is cut off, and the lamp current Ir does not flow through the lamp current detection resistor 74. Therefore, the stable state signal output from the voltage monitor 67 is immediately switched from “H” to “L” when the lamp 2 is turned off.
[0028]
When the lamp lighting signal “L” is output, it is detected that the stable state signal is “L” (S23), and the operation of the cooling fan 8 is stopped (S25). Thereby, the forced cooling of the lamp 2 is stopped until the lamp 2 is turned on again and the stable state signal becomes “H”.
[0029]
As described above, in this embodiment, since the cooling fan 8 is not operated until the discharge reaches a stable state after the discharge of the lamp 2 is started, the temperature rise of the lamp bulb 2a is accelerated. Thereby, the discharge of the lamp 2 can be shifted to a stable state in a short time. In addition, after the discharge of the lamp 2 has shifted to a stable state, the cooling fan 8 performs forced cooling, so that the temperature of the lamp bulb 2a does not become too high during the discharge, and the shortening of the life can be prevented.
[0030]
In the present embodiment described above, it is determined whether or not the discharge of the lamp 2 is in a stable state by comparing the lamp voltage of the lamp 2 and the rated voltage, but 80% to 9% of the lamp voltage and the rated voltage are determined. It may be determined whether or not the discharge of the lamp 2 is in a stable state by comparison with a voltage corresponding to 20%.
[0031]
In this embodiment, the operation of the cooling fan 8 is stopped as soon as the lamp 2 is turned off. However, another mode of operation stop timing of the cooling fan 8 is possible. For example, the cooling fan 8 is continuously operated even after the lamp is turned off, and the operation of the cooling fan 8 is stopped when the lamp 2 is turned on again, or the cooling fan 8 is continuously operated even after the lamp is turned off. The operation of the cooling fan 8 may be stopped when the lamp 2 is turned off and the temperature of the lamp bulb 2a is lowered to a temperature at which the lamp 2 can be turned on again.
[0032]
【The invention's effect】
According to the light source device of the present invention, since the operation of the cooling fan is prohibited from the start of the discharge of the high-intensity discharge lamp until the discharge reaches a stable state, the lamp bulb temperature rises quickly and for a short time. Thus, the high-intensity discharge lamp can be shifted to a stable state.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main configuration of a light source device according to the present invention.
FIG. 2 is a diagram illustrating the arrangement of lamps and cooling fans shown in FIG.
3 is a block diagram showing a specific configuration of the lamp lighting circuit shown in FIG. 1. FIG.
4 is a flowchart showing a main operation of the light source device shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Light source device 2 Lamp 2a Lamp bulb 2b Base 3 Lamp holder 4 Reflection mirror 5 AC / DC power supply 6 Lamp lighting circuit 8 Cooling fan 9 Fan drive circuit 10 Microcomputer 61 Rectification smoothing circuit 62 Switching circuit 63 Insulation transformer 65 Igniter 66 Igniter start-up Circuit 67 Voltage monitor 70 Voltage divider 71 Comparator 72 Reference power supply 73 AND element 74 Lamp current detection resistor 75 Transistor 76 Photocoupler

Claims (6)

A high intensity discharge lamp,
A cooling fan for forcibly cooling the high-intensity discharge lamp;
Voltage detection means for detecting a lamp voltage of the high-intensity discharge lamp and outputting a stable state signal L or H according to the lamp voltage ;
A control means for prohibiting the operation of the cooling fan when a stable state signal L is input from the voltage monitor, and for operating the cooling fan when a stable state signal H is input ;
The voltage detection means includes
A lamp current detection resistor through which a lamp current flows when the high-intensity discharge lamp is discharged;
A comparator that compares the predetermined voltage with the lamp voltage of the high-intensity discharge lamp;
An AND element that calculates the logical product of the output of the comparator and the voltage generated across the lamp current detection resistor;
A transistor for turning on and off the photocoupler according to the output of the AND element;
Have
When the lamp current is not flowing or when the lamp voltage of the high-intensity discharge lamp is less than a predetermined voltage, the photocoupler is turned off and a stable state signal L is output; and
When the lamp current is flowing and the lamp voltage of the high-intensity discharge lamp is equal to or higher than the predetermined voltage, the photocoupler is turned on and a stable state signal H is output;
A light source device characterized by the above. 2. The light source device according to claim 1, wherein the predetermined voltage for starting the operation of the cooling fan is a lamp voltage when discharge of the high-intensity discharge lamp is in a stable state. The light source device according to claim 1, wherein the predetermined voltage for starting the operation of the cooling fan is a rated voltage of the high-intensity discharge lamp. 4. The light source device according to claim 1, wherein the operation of the cooling fan is stopped when the discharge of the high-intensity discharge lamp is stopped. 5. 4. The light source device according to claim 1, wherein the operation of the cooling fan is stopped when the discharge of the high-intensity discharge lamp is once stopped and then restarted. 5. . 4. The light source device according to claim 1, wherein the operation of the cooling fan is performed when the discharge of the high-intensity discharge lamp is stopped, and a lamp bulb temperature of the high-intensity discharge lamp is set to the high intensity. A light source device that is stopped after the discharge lamp has been lowered to a temperature at which it can be relighted.

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