JP2774010B2 - Xenon lamp protection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection circuit for a xenon lamp having an automatic irradiance control system for automatically adjusting radiant energy used in an accelerated weathering tester or the like.

[0002]

2. Description of the Related Art In a conventional accelerated weathering tester, a xenon lamp used as a light source has a aging characteristic in which radiant energy decreases with use as shown in FIG. 5, for example. Since the irradiance with respect to the sample changes with time based on this, there is a so-called xenon weather meter of a so-called automatic radiant energy adjustment type provided with an automatic control system for compensating the change. In this type of weather meter, for example, as shown conceptually in FIG. 4, a sample 17 is mounted on a sample rotating frame 16 that rotates around a xenon lamp 1 in a test chamber 15 to perform a predetermined weather resistance test. The irradiance measuring light receiver 2 is installed on the sample rotating frame 16 in order to receive the lamp radiation at the position of the sample surface so that the same conditions as those of the sample 17 are obtained, and the output thereof is derived through, for example, a slip ring mechanism. An automatic control system is provided which controls the lamp discharge power in accordance with the irradiance to the sample by supplying the control signal to the power control circuit 5 via the amplifier 3 and the adjustment circuit 4 as a control signal.

[0003]

Due to such a structure, the surface filter of the irradiance measuring light receiver 2 is contaminated by rainfall, dew, chemical substances coming out of the sample, dust due to wind, etc., due to the weathering test, and has a transmittance. Is reduced or the illuminance is reduced by blackening of the lamp arc tube by the lamp cooling water, the discharge power of the xenon lamp 1 is controlled to increase, and a large load is applied to the xenon lamp. Slight scratches on the arc tube shortened the life of the lamp, sometimes leading to accidents such as lamp damage. In addition, the sample under test receives radiant energy higher than the set irradiance, and there is a problem that an appropriate test cannot be performed. An object of the present invention is to protect a xenon lamp provided with the automatic irradiance control system described above when a large load is applied to the lamp.

[0004]

According to the present invention, a xenon lamp light source, a xenon lamp irradiance measuring photodetector, an amplifier, a control circuit, and a power control circuit for controlling the xenon lamp discharge power are provided. A memory circuit is inserted into the automatic irradiance control system for adjustment, and a timer circuit is connected to the memory circuit via a holding switch, so that the time required for the irradiance to stabilize after the xenon lamp is turned on is measured. The control signal at this time is held in the memory circuit as an initial value. By controlling the lamp discharge power by the following three methods, overload of the lamp is prevented.

(1) The lamp discharge power monitoring circuit connected to the power control circuit monitors the lamp discharge power, and when it exceeds a specified value, switches the control signal to the initial value held in the memory circuit. The xenon lamp is turned on with the same discharge power as the initial one. (2) After the initial value is held in the memory circuit, the xenon lamp is lit at a constant power thereafter using the initial value as a control signal. In this case, the output voltage of the memory circuit is programmed to change in accordance with the change over time of the radiant energy of the xenon lamp. Automatically controls the closed state to prevent contamination of the surface filter of the light receiver. (3) In addition to the configuration of (1) above, a comparison circuit that compares the irradiance measured by the light receiver with the specified value is provided.If the lamp discharge power controlled by the output of the memory circuit is too low, Then, the memory circuit is reset, the timer circuit is restarted, and the new stable value of the lamp discharge power is stored, so that the radiant energy of the xenon lamp follows the change with time.

[0006]

FIG. 1 is a block diagram showing an embodiment in which a protection circuit for a xenon lamp according to the present invention is applied to an accelerated weathering tester. In the figure, 1 is a xenon lamp as a light source for weather resistance test, 2 is a photodetector for irradiance measurement, 3 is an amplifier, 4
The PID adjusting circuits 4 and 5 comprising a proportional band (P) 41, a differentiating circuit (D) 42 and an integrating circuit (I) 43
A power control circuit comprising a CR control voltage output circuit 51 and a lamp lighting SCR circuit 52, 6 is a memory circuit, 7 is a holding switch, 8 is a timer circuit, 9 is an energy (irradiance) display, 10 is an irradiance integrator , 11 is a lamp discharge power monitoring circuit, 12 is an abnormality alarm means, and 13 is a changeover switch.

The irradiance measuring light receiver 2 is fixed to a rotating sample frame 16 which rotates around the xenon lamp 1 in a juxtaposition with a sample 17 like the conventional testing machine shown in FIG. The irradiance received from 1 to the sample 17 is measured. After the detection output of the light receiver 2 is amplified by the amplifier 3, it is converted into a control signal by an adjustment circuit 4 having a predetermined transfer characteristic so as not to be affected by a change in the atmosphere in the test chamber 15. The obtained control signal is supplied directly to one contact a of the changeover switch 13 and the memory circuit 6
And the read output is supplied to the other contact b. The control signal selected by the changeover switch 13 is applied to an SCR control voltage output circuit 51 of the power control circuit 5 to generate an SCR control voltage corresponding to the value, and controls the lamp lighting SCR circuit 52 to control the xenon lamp 1. Is adjusted to maintain the irradiance to the sample 17 constant.

A timer circuit 8 is connected to the memory circuit 6 via a holding switch 7 composed of a relay, and a changeover switch 13 is connected to a contact a at the time of initial setting of the tester, so that a normal automatic irradiance control system is provided. The xenon lamp 1 is turned on in the formed state, and then the time until the irradiance from the xenon lamp 1 is stabilized by the operation of the irradiance automatic control system, for example, 20 minutes, is measured by the timer circuit 8, and the holding switch 7 is turned on. I do. Thereby, the control signal at the time of initial stabilization is stored in the memory circuit 6. The lamp discharge power monitoring circuit 11 connected to the power control circuit 5 monitors the discharge power of the xenon lamp 1 while comparing it with a specified value corresponding to the discharge power at the time of initial stabilization. Similarly, when the discharge power exceeds the specified value due to a decrease in the transmittance of the surface filter of the light receiver or the blackening of the lamp arc tube, the changeover switch 13 is automatically switched, and the analog memory 6 is switched.
Is applied to the SCR control voltage output circuit 51 as a control signal to drive the xenon lamp 1 with the same discharge power as the initial one. Further, the lamp discharge power monitoring circuit 11 switches the control signal to the initial value, and at the same time, drives the abnormality alarm means 12 to issue an abnormality alarm of the lamp discharge power. As a result, the xenon lamp 1 is turned on with the discharge power at the time of initial stabilization, and the lamp load can be reduced and protected. The current value of the irradiance measured by the light receiver 2 is energy (irradiance)
The integrated value is displayed by the display 9 and the irradiance integrator 10
Is displayed.

FIG. 2 shows another embodiment in which the xenon lamp protection circuit according to the present invention is applied to an accelerated weathering tester. In the drawing, the same components as those in the embodiment shown in FIG. Reference numerals are given. In this embodiment, the changeover switch 13, the lamp discharge power monitoring circuit 11 and the abnormality alarm means 12 are omitted, and the timer circuit 8 set in advance when the discharge power of the xenon lamp 1 is stabilized by the automatic irradiance control system. Generates an output and the holding switch 7
And the memory circuit 6 holds the control signal at that time. Thereafter, the discharge power of the xenon lamp is set according to the value of the control signal output from the memory circuit 6, and if there is no change in the power supply voltage, the xenon lamp 1 continues to be lit with the same discharge power as the initial one. Thus, even if the surface filter of the light receiver 2 becomes dirty or the arc tube of the xenon lamp 1 becomes black, the load on the lamp does not become excessive.

In this case, the memory circuit 6 changes the value of the control signal output from the stored initial value to the value of xenon such that the value of the control signal corresponds to the aging characteristic of the radiant energy of the xenon lamp shown in FIG. It is programmed to change according to the usage time of the lamp 1. Further, a shield plate 20 that can be opened and closed is provided on the front surface of the light receiver 2 so that the shutter is automatically set to the closed state by the output of the timer circuit 8 from the open state at the time of initial setting. The filter can be prevented from being contaminated by rain, condensation, chemicals from the sample, dust from the wind, and the like. Alternatively, the light receiver 2 can be removed from the rotating sample frame 16 and stored in a cool and dark place.

FIG. 3 shows still another embodiment in which the xenon lamp protection circuit according to the present invention is applied to an accelerated weathering tester. In the figure, the same components as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals. In this embodiment, FIG.
In addition to the embodiment shown in FIG. 7, an irradiance comparison circuit 14 is connected to the energy (irradiance) display 9, and its output is the reset terminal R of the memory circuit 6, the start terminal S of the timer circuit 8, and the alarm means. It is configured to be supplied to the ALM. Since the irradiance comparison circuit 14 is provided separately from the timer circuit 8, the irradiance when the lamp is turned on with the output voltage of the memory circuit 6 is compared with the set irradiance, and the irradiance is compared with the set value. If the voltage is too low, the reset terminal R of the output voltage of the memory circuit 6 is operated, and at the same time, the set terminal S of the timer circuit 8 is operated and restarted, and the automatic irradiance control system is operated to set the irradiance to the set value. After the irradiance is stabilized, the timer circuit 8 finishes measuring the time, and causes the memory circuit 6 to hold the current value of the control voltage again. After that, the xenon lamp 1 is turned on with constant power according to the output voltage of the memory circuit 6. Thereafter, this is repeated.

Thereby, even if the radiant energy of the xenon lamp 1 decreases with the use time, the output voltage of the memory circuit 6 is automatically detected and corrected, and the lamp is always lit with constant power. it can. Further, by outputting an alarm signal from the irradiance comparison circuit 14, it is possible to detect sudden blackening of the lamp arc tube or sudden contamination of the surface filter of the light receiver 2 and stop the operation of the weather meter. is there.

[0013]

According to the present invention, as described above,
A protection circuit for the xenon lamp used in weather testers, etc., is configured, so that dirt on the surface filter of the irradiance measurement receiver provided in the irradiance automatic control system for automatic radiant energy control and lamp cooling The blackening of the lamp arc tube by water prevents the discharge power of the xenon lamp from increasing and imposing a large load, thereby effectively protecting the xenon lamp. Further, the protection circuit according to the present invention can follow the aging change of the radiant energy of the xenon lamp.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment in which a protection circuit for a xenon lamp according to the present invention is applied to an accelerated weathering tester.

FIG. 2 is a block diagram showing another embodiment in which the xenon lamp protection circuit according to the present invention is applied to an accelerated weathering tester.

FIG. 3 is a block diagram showing still another embodiment in which a protection circuit for a xenon lamp according to the present invention is applied to an accelerated weathering tester.

FIG. 4 is a conceptual diagram showing a configuration of a conventional accelerated weathering tester provided with an automatic control system for automatic adjustment of radiant energy.

FIG. 5 is a diagram showing a temporal change characteristic of radiant energy of a xenon lamp.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 xenon lamp 2 irradiance measurement light receiver 3 amplifier 4 control circuit 4 5 power control circuit 6 memory circuit 7 changeover switch 8 timer circuit 9 energy (irradiance) display 10 irradiance integrator 11 lamp discharge power monitoring circuit 12 abnormality Alarm means 13 Changeover switch 14 Irradiance comparison circuit 15 Test room 16 Sample rotating frame 17 Sample 20 Shield plate

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-80300 (JP, A) JP-A-58-157091 (JP, A) JP-A-60-235396 (JP, A) JP-A-62 51193 (JP, A) JP-A-5-21177 (JP, A) JP-A-5-21176 (JP, A) JP-A-54-51594 (JP, A) JP-A-62-113390 (JP, A) JP-A-62-290523 (JP, A) JP-A-1-135698 (JP, U) JP-A-3-63827 (JP, U) JP-A-46-8640 (JP, Y2) JP-A-46-8399 (JP, Y2) (58) Field surveyed (Int. Cl. ⁶ , DB name) H05B 41/16-41/29 G01N 17/00

Claims (3)

(57) [Claims] 1. A xenon lamp as a light source, a light receiver for measuring the irradiance of the xenon lamp, an adjustment circuit having a predetermined transfer characteristic to which an output of the light receiver is supplied, and an output from the adjustment circuit An automatic irradiance control system for automatically adjusting the radiant energy of the xenon lamp including a power control circuit for controlling the discharge power of the xenon lamp in response to the control signal received, and a control output signal of the automatic irradiance control system are stored. Memory
After turning on the xenon lamp and the xenon lamp,
Automatic control of the irradiance when the lamp light is stable
Timer for storing the system output control signal in the storage circuit
Circuit, an output control signal of the irradiance automatic control system, and the storage circuit
Select one of the initial setting values stored in
Switching means for supplying power to the power control circuit, and a switch for when the xenon lamp discharge power exceeds a specified value.
Activating the switching means to set the initial setting value of the storage circuit to
A lamp discharge power monitoring circuit to be supplied to the power control circuit.
Xenon lamp protection circuit
Road. 2. A xenon lamp as a light source, a light receiver for measuring the irradiance of the xenon lamp, an adjustment circuit having a predetermined transfer characteristic to which an output of the light receiver is supplied, and An irradiance automatic control system for automatically adjusting the radiant energy of the xenon lamp including a power control circuit for controlling the discharge power of the xenon lamp in response to the output control signal; A shielding plate, a storage circuit inserted and connected between the adjustment circuit and the power control circuit, and connected to the storage circuit to perform a storage operation when a predetermined time has elapsed after lighting of the xenon lamp. And a timer circuit for storing the output control signal of the adjustment circuit and controlling the shielding plate from the open state to the closed state, and the control circuit stores the control signal in the storage circuit. A protection circuit for a xenon lamp, wherein an output control signal of a storage circuit is supplied to the power control circuit, and a light receiving surface of the light receiver is shielded. 3. The protection circuit for a xenon lamp according to claim 1, further comprising: comparing the irradiance measured by the photodetector with a specified value; resetting the storage circuit if the irradiance is equal to or less than the specified value;
A comparison circuit for generating an output capable of restarting the timer circuit; and when the lamp discharge power controlled by the output control signal of the storage circuit is too low, the automatic irradiance control system is activated to store the stored data. A xenon lamp protection circuit characterized in that a new stable value of the lamp discharge power is stored in the circuit.