JP2002231489A - Stroboscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and long service life stroboscope generating no malfunctioning or breaking noise in a built-in circuit of an observing moving body and peripheral equipment used for observation. SOLUTION: A light emitting diode 102 is used for an emitter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stroboscope for continuously observing the state of a rotating body or a moving body by emitting pulsed light, and relates to a non-contact tachometer, a high-speed phenomenon of a still image or a multiple image. It is used as a light source for photographing with a camera, a color shift inspection in the printing field, and a high-speed light shutter light source for a CCD camera in the image processing field.

[0002]

2. Description of the Related Art A stroboscope of a xenon tube type has been proposed. FIG. 1 is a circuit configuration diagram of a stroboscope using a xenon tube. The configuration of a conventional stroboscope will be described with reference to FIG.

The xenon tube 1 is provided with an anode 7 and a cathode 8 provided opposite each other, and a trigger probe 5 and a trigger probe 6 between them. The sparker 9 is provided near the cathode 8. The trigger probe 5 and the trigger probe 6 are electrodes for preliminary discharge having a function of stably and easily generating a main discharge of the xenon tube, and the sparker 9 has a function of stably generating a discharge of the xenon tube every time. Electrode.

The main capacitor 2 is connected to the anode 7 and the cathode 8 of the xenon tube 1, and a diode 10 for preventing a current from flowing back to the power supply when a high voltage is applied to the anode. Is inserted. Here, the main capacitor 2 is provided to supply a large amount of current to the xenon tube 1 instantaneously. Reference numeral 13 denotes a trigger input terminal, which is connected to a trigger circuit 12 for generating a trigger pulse of several hundred volts in response to a trigger signal. The output of the trigger circuit 12 is a primary side of a trigger transformer 11 provided for amplifying a voltage. It is told to. The secondary side of the trigger transformer has capacitors 14a to 14d and resistors 15a to
The anode 7, the trigger probe 5, the trigger probe 6, and the sparker 9 are connected via 15d.

Next, the operation of the conventional stroboscope will be described with reference to FIG. The power supply 4 charges the main capacitor 2 through the charging resistor 3 and applies a predetermined voltage between the anode 7 and the cathode 8. At this time, when a light emission control signal is applied to the trigger circuit 12 through the input terminal 13, a trigger pulse of several hundred volts is generated on the temporary side of the trigger transformer 11. The trigger pulse is amplified through the trigger transformer 11 to generate a trigger pulse of several kilovolts on the secondary side. The trigger pulse is applied to the anode 7, the trigger probe 5, the trigger probe 6, and the sparker 9.

First, a preliminary discharge occurs in the sparker 9, then a preliminary discharge occurs between the cathode 8 and the trigger probe 6, and then a preliminary discharge occurs between the trigger probe 6 and the trigger probe 5, thereby forming a preliminary discharge path. . Immediately thereafter, the main discharge between the anode 7 and the cathode 8 occurs along the preliminary discharge path,
This produces arc emission. By controlling this light emission with a trigger signal synchronized with the movement of the moving body to observe, it is possible to observe the movement of the moving body as if it were stopped, or to emit light at a predetermined cycle to perform multiple exposure shooting. Then, the trajectory of the moving body can be recorded.

[0007]

However, in the case of a xenon tube as in the case of a conventional stroboscope, a high voltage circuit is required for a trigger circuit for performing preliminary light emission. It takes. In addition, a large noise is generated from the trigger circuit and the trigger probe. It is very difficult to completely suppress this noise, and in a built-in circuit of a moving body or a peripheral device used for observation, a malfunction may occur due to the noise jumping, and in some cases, the circuit may be destroyed. . In addition, the xenon tube has a problem that the luminous intensity decreases as the usage time increases.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a low-cost, noise-free and long-life stroboscope by using a light-emitting diode as a light-emitting body. It is in.

[0009]

In order to solve the above-mentioned problems, a stroboscope according to a first aspect of the present invention is characterized in that the stroboscope has a light-emitting body comprising a light-emitting diode.

According to a second aspect of the present invention, in the transistor circuit for driving the light emitting diode, a capacitor is provided in parallel with a bias resistor connected to a base electrode of the transistor.

[0011]

FIG. 2 is a circuit diagram of a stroboscope according to the present invention. The configuration of the present embodiment will be described with reference to FIG.

The light emitting section 101 includes a white light emitting diode 102 which is a first feature of the present embodiment, and a current limiting resistor 1 for limiting the current of the white light emitting diode 102 to an optimum value.
03. The light emitting unit 101 is provided with a plurality of sets of a white light emitting diode 102 and a current limiting resistor 103 in order to secure light emission intensity. The cathode electrode side of the white light emitting diode 102 has a current limiting resistor 10
2 to the collector of the transistor 105.

On the other hand, the anode electrode side of the white light emitting diode 102 is connected to a power supply 104. Note that the light emitting unit 101 can be separated and extended from the drive circuit by connecting cables from the power supply 104 and the transistor 105, so that the light emitting unit 101 can be freely arranged according to the observation position. The trigger input terminal 108 is connected to the trigger circuit 107. The trigger circuit 107 includes a monostable multivibrator IC 107a, a capacitor 107b, and a volume 107c.

Here, the trigger circuit 107 is provided to control the light emission time of the stroboscope. The output of the trigger circuit 107 is connected to the bias circuit 106. The bias circuit 106 includes a speed-up capacitor 106a and a bias resistor 106b, which are the second feature of the present embodiment, and is further connected to the base electrode of the transistor 105. The bias circuit 106 is provided for operating the transistor 105 at high speed.

Next, the operation of the stroboscope in this embodiment will be described with reference to FIG. First, a trigger signal is applied to the trigger input terminal 108. The trigger signal is a pulse-like signal, and a signal having a constant period or a signal synchronized with the operation of the moving object is taken out from a built-in circuit of the moving object and applied according to the purpose. When measuring the number of revolutions or photographing the trajectory of the moving body, a signal having a constant period is applied to the trigger input terminal 108. In the case of observing the motion of the moving object while standing still, a signal synchronized with the operation is extracted from the built-in circuit of the moving object, and further applied to the trigger input terminal 108 via the pulse delay circuit.

By arbitrarily delaying the pulse, it is possible to change the point to be observed while standing still. Subsequently, the trigger signal is input to the trigger circuit 107. In the trigger circuit 107, the monostable multivibrator IC1
The trigger signal can be changed to an arbitrary pulse width by a capacitor 107b externally connected to the switch 07a and a volume 107c for controlling charging and discharging of the capacitor 107b. Since the emission time of the stroboscope is determined by the width of the pulse output from the trigger circuit 107,
By adjusting the volume 107c, it is possible to set an optimal light emission time for observation.

Next, the trigger signal whose pulse width has been adjusted is
The signal is input to the bias circuit 106. This is a circuit for appropriately operating the transistor 105. However, in order to ensure the accuracy of the light emission time determined by the trigger circuit 107, the transistor 105 is turned on / off at high speed so as not to cause a time delay in the operation of the transistor 105. It is important that Therefore, a transistor capable of high-speed operation is selected as the transistor 105, and the base current is optimized by the bias circuit 106 so that the transistor 105 can operate at high speed.

It is known that when a bipolar transistor as in the present embodiment is used for the switching operation, the operation is delayed when transitioning from the off state to the on state or from the on state to the off state. This is because when the transistor shifts from off to on, a certain amount of time needs to be accumulated in the base electrode, and when the transistor shifts from on to off, the collector current is reduced due to the carrier accumulation effect at the base electrode. This occurs due to a phenomenon that does not turn off immediately.

To avoid these problems, the bias circuit 106 has a speed-up capacitor 106a inserted in parallel with the bias resistor 106b to reduce the operation delay of the transistor 105. about this,
This will be described in detail with reference to FIG. 2 and FIG. 3 showing the base current of the transistor 105.

First, when the transistor 105 is shifted from the off state to the on state, the base current flows through the speed-up capacitor 106b and the bias resistor 106b. However, since the speed-up capacitor 106b is not charged, the base current overlaps with the current flowing through the bias resistor 106b. As a result, a charging current flows, and as a result, a peak bias current 201 in FIG. 3 is generated. This means that carriers can be sent to the base electrode at high speed, and the transistor 105 is turned on at high speed. Thereafter, when the speed-up capacitor 106b is charged, only the steady-state bias current 202 flowing through the bias resistor 106b becomes available, and during this time, the transistor 105 maintains the ON state.

On the other hand, when transitioning from the on state to the off state, the base of the transistor 105 is in a reverse bias state by the voltage of the electric charge accumulated in the speed-up capacitor 106a. Appears. As a result, the carriers accumulated in the base are forcibly extracted, and the transistor 105 is turned off at high speed. As described above, the transistor 105 is turned on / off at high speed by the bias circuit 106, and a current is supplied to the light emitting diode 102 at a predetermined period or at a timing synchronized with the operation of the moving object and only for a pulse width suitable for observation. It flows and emits light,
Observation of the moving body becomes possible.

In a stroboscope using a light emitting diode as a light emitting body as in this embodiment, the power supply voltage can be suppressed to about 5 volts because the forward voltage of the light emitting diode is about 3 to 4 volts. Therefore, the power supply 104
Can also serve as a power supply to the trigger circuit 107. Further, since there is no high-voltage circuit as in a xenon tube stroboscope, the circuit configuration is extremely simplified, and the manufacturing cost can be greatly reduced. In addition, since there is no high-voltage circuit, noise is not scattered to the surroundings, and a malfunction of a built-in circuit of the moving object or a peripheral device used for observation does not occur. Furthermore, since the light-emitting diode has a longer life as an element than a xenon tube, a long-life stroboscope can be formed.

As described above, the embodiment of the stroboscope according to the present invention has been described in detail, but the present invention is not limited to the above embodiment. For example, it is needless to say that the same effect can be obtained by using a light emitting diode of another color such as red, green, and blue as the white light emitting diode used for the light emitting body.

[0024]

In the stroboscope according to the present invention, first, since a high voltage circuit is not required by using a light emitting diode as a light emitting body, it is possible to extremely simplify the circuit configuration and reduce the manufacturing cost. It can be greatly reduced. In addition, since no noise is generated for the same reason, malfunction and destruction of the built-in circuit of the moving body to be observed and peripheral devices used for observation can be prevented. Further, since the light emitting diode has a longer life than a xenon tube, a stroboscope having a longer life can be constructed. Second, by inserting a capacitor in parallel with a bias resistor connected to the base electrode of the light emitting diode driving transistor, it is possible to configure a stroboscope that makes the light emitting diode emit light with high accuracy.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a conventional stroboscope.

FIG. 2 is a circuit diagram showing a stroboscope according to the present invention.

FIG. 3 is a conceptual diagram showing a bias current waveform of a light emitting diode driving transistor in the stroboscope of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Xenon tube 2 Main capacitor 3 Charging resistance 4 Power supply 5 Trigger probe 6 Trigger probe 7 Anode 8 Cathode 9 Sparker 10 Backflow prevention diode 11 Trigger transformer 12 Trigger circuit 13 Trigger input terminal 14a, 14b, 14c, 14d Capacitor 15a, 15b, 15c , 15d resistor 101 light emitting unit 102 white light emitting diode 103 current limiting resistor 104 power supply 105 transistor 106 bias circuit 106a speed-up capacitor 106b bias resistor 107 trigger circuit 107a monostable multivibrator IC 107b external capacitor 107c external volume 108 trigger input terminal 201 Peak bias current 202 Steady bias current 203 Reverse bias current

Claims (2)

[Claims] A stroboscope for continuously emitting pulsed light to observe the state of a rotating body or a moving body.
A stroboscope having a light emitting body comprising a light emitting diode. 2. The stroboscope according to claim 1, wherein the transistor circuit for driving the light emitting diode has a capacitor arranged in parallel with a bias resistor connected to a base electrode of the transistor.