Detection device for detecting oscillator

A detection device for detecting an oscillator is provided. The detection device includes an oscillator control circuit, a frequency-decreasing circuit and a display circuit. The oscillator control circuit is used for outputting the oscillator signal of the oscillator. The frequency-decreasing circuit is connected to the output of the oscillator control circuit and has a capacitor suitable for charging and discharging and a resistor, which can adjust the time constant of the oscillator signal. The display circuit is connected to the frequency-decreasing circuit for showing the output signal of the frequency-decreasing circuit. The detection device can decide whether the oscillator is normal or broken by observing a component of the display circuit, for example, the twinkling of a light emitting diode of the display circuit.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 95104696, filed on Feb. 13, 2006. All disclosure of the Taiwan application is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a detection device, and more particularly, to a detection device for detecting an oscillator.

2. Description of Related Art

FIG. 1is a flow diagram of a conventional method of measuring a quartz oscillator. As shown inFIG. 1, in the conventional method of measuring the oscillation of a quartz oscillator, the quartz oscillator to be tested is placed on a detection station in step S110. Then, in step S120, power supply and oscilloscope are connected to the quartz oscillator. After that, in step S130, the power supply outputs power signal to the quartz crystal to be tested. Next, in step S140, the oscilloscope is adjusted. Finally, in step S150, the waveform captured by the oscilloscope is observed to determine if the quartz oscillator under testing meets the standard specification.

Although the use of a power supply and an oscilloscope to screen out any faulty oscillator can be very accurate, the price of the power supply and oscilloscope is not low. As a result, the conventional technique of detecting the performance of the oscillator often costs too much. Therefore, a detection device capable of accurately detecting fault in any oscillator at a lower cost will be in great demand.

SUMMARY OF THE INVENTION

Accordingly, at least one objective of the present invention is to provide a detection device capable of effectively and conveniently detecting fault in any oscillator without using costly instruments such as an oscilloscope and power supply. Furthermore, the detection device in the present invention has the special characteristics of being light and not occupying too much space so that it is convenient to be used and carried around.

To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a detection device for detecting an oscillator. The detection device includes an oscillator control circuit, a frequency-decreasing circuit and a display circuit. The oscillator control circuit is used for outputting the oscillator signal of the oscillator. The frequency-decreasing circuit is connected to the output of the oscillator control circuit and has a capacitor suitable for charging and discharging and a resistor, which can adjust the time constant of the oscillator signal. The display circuit is connected to the frequency-decreasing circuit for showing the output signal of the frequency-decreasing circuit.

In one embodiment of the present invention, the oscillator control circuit has a NOR gate, one of the input terminals of the NOR gate connected to the oscillator and another of the input terminals of the NOR gate connected to a reference voltage source. Furthermore, the detection device also includes a switch connecting between the reference voltage source and a ground terminal. Moreover, the frequency-decreasing circuit has a first NOR gate and a second NOR gate. The capacitor is connected between the output terminal of the first NOR gate and the input terminal of the second NOR gate, and the resistor serially connects the reference voltage source to the capacitor. In addition, the output terminal of the second NOR gate is feedback connected to one of the input terminals of the first NOR gate and another of the input terminals of the first NOR gate is connected to the output terminal of the oscillator control circuit.

In one embodiment of the present invention, the frequency-decreasing circuit further includes a protective device serially connected between the capacitor and the reference voltage source. The protective device can be a diode. Furthermore, the detection device may include a frequency division circuit and a power converter. The frequency division circuit is connected between the display unit and the frequency-decreasing circuit. The power converter is connected to the oscillator control circuit, the frequency-decreasing circuit and the display circuit to output the reference voltage. In the meantime, the display circuit has a light emitting diode. The cathode of the light emitting diode is connected to the output terminal of the frequency division circuit and the anode of the light emitting diode is connected to the reference voltage source.

Accordingly, the detection device of the present invention inputs the oscillation signal from the oscillator control circuit to the frequency division circuit and the frequency-decreasing circuit and the resulting signal are used to drive the light emitting diode. Hence, by taking a visual observation of the brightness of the light emitting diode, an inspector can easily determine whether an oscillator is normal or broken.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2is a block diagram showing the circuit of a detection device according to one embodiment of the present invention. As shown inFIG. 2, the detection device200in the present invention includes a power converter210, an oscillator control circuit220, a frequency-decreasing circuit230, a frequency division circuit240and a display circuit250. The power converter210provides a reference voltage VDCto the oscillator control circuit220, the frequency-decreasing circuit230, the frequency division circuit240and the display circuit250. The oscillator control circuit220is used for outputting an oscillation signal S0to the oscillator124(shown inFIG. 3A) under testing. Furthermore, the frequency-decreasing circuit230is connected to the output terminal of the oscillator control circuit220for receiving the oscillation signal S0and lowering its frequency to produce another oscillation signal S0′. The frequency division circuit240is connected between the frequency-reducing circuit230and the display circuit250for receiving the oscillation signal S0′ and dividing the frequency to produce another oscillation signal S0″. The display circuit250is connected to the frequency division circuit240for receiving the oscillation signal S0″ and displaying a circuit action that corresponds to the oscillation signal S0″, for example, twinkling the light emitting diode.

On the other hand, if the frequency lowering capacity of the frequency-decreasing circuit230is able to meet the requirement of detection, the frequency division circuit240can be eliminated. In other words, the display circuit250is connected to the frequency-decreasing circuit230for directly receiving the oscillation signal S0′ and displaying the circuit action that corresponds to the oscillation signal S0′.

FIG. 3Ais a circuit diagram of an oscillator control circuit according to one embodiment of the present invention. As shown inFIGS. 2 and 3A, the oscillator control circuit220has a NOR gate222. One of the input terminals of the NOR gate222is connected to an oscillator224under test and another of the input terminals of the NOR gate222is connected to the power converter210through a resistor R2for receiving the reference voltage VDC. The oscillator control circuit220outputs an oscillation frequency S0. The oscillation frequency is equivalent to that of the oscillator224to be tested. Furthermore, the detection device200also includes a switch226connected between the resistor R2and a ground terminal.

As everyone knows, the NOR gate222only outputs a high logic level when the both input signals are at a low logic level. When the switch226is pushed, the input terminal of the NOR gate222connected to the resistor R2is at a low logic level. Therefore, when the oscillation waveform generated by the oscillator224under test drops below the low logic level, the NOR gate222will output an oscillation signal S0at a high logic level. Conversely, when the oscillation waveform generated by the oscillator224under test rises above the high logic level, the NOR gate222will output an oscillation signal S0at a low logic level.

FIG. 3Bis a circuit diagram of a frequency-decreasing circuit according to one embodiment of the present invention. As shown inFIGS. 2 and 3B, the frequency-decreasing circuit230can reduce the oscillation signal S0to the oscillation signal S0′. Furthermore, the frequency-decreasing circuit230has a capacitor C2suitable for charging and discharging and a resistor R4. The capacitor/resistor pair is used for adjusting the time constant of the oscillation signal S0. In addition, the frequency-decreasing circuit230has NOR gates232and234. The capacitor C2is connected between the output terminal of the NOR gate232and the input terminal of the NOR gate234. In the meantime, the resistor R4is serially connected the reference voltage of the power converter110to the capacitor C2. Furthermore, the output terminal of the NOR gate234is feedback-connected to one of the input terminals of the NOR gate232and the other input terminal of the NOR gate232is connected to the output terminal of the oscillator control circuit220. In one embodiment of the present invention, the frequency-decreasing circuit230may further include a protective device serially connected between the capacitor C2and the power converter210, and the protective device can be a diode D2, for example.

More specifically, after the NOR gate132has reduced the frequency of the oscillation signal S0, a signal Svbetween the high and low logic level is output. The signal Svcan determine the charge and discharge states of the capacitor C2. Furthermore, the product of the capacitor C2and the resistor R4can determine the frequency of the oscillation signal S0′ output by the NOR gate232. In general, the larger the product of the capacitor C2and the resistor R4, the smaller will be the frequency of the oscillation signal S0′. Conversely, the smaller the product of the capacitor C2and the resistor R4, the larger will be the frequency of the oscillation signal S0′. In addition, the diode D2is used for protecting the frequency-decreasing circuit230against possible interference and damage when the power converter210outputs an impulse.

If the foregoing frequency-decreasing circuit230has insufficient capacity to reduce the frequency, an additional frequency division circuit240is to divide the oscillation frequency S0′. For example, the oscillation frequency S0′ can be divided by two and the resulting oscillation frequency S0″ is output to the display circuit250.

FIG. 3Cis a circuit diagram of a display circuit according to one embodiment of the present invention. As shown inFIGS. 2 and 3C, the display circuit250has a light emitting diode242. The cathode of the light emitting diode242is connected to the oscillation signal S0″ output from the frequency division circuit240and the anode of the light emitting diode242is connected to the power converter210through a resistor R6. More specifically, when the oscillation signal S0″ is below the voltage of the reference voltage VDC, a current I2passes through the light emitting diode242so that the light emitting diode242lights up. On the other hand, when the oscillation signal S0″ is above the voltage of the reference voltage VDC, no current passes through the light emitting diode242so that the light emitting diode242remains unlit. Because the oscillation signal S0″ is a series of alternating high and low logic levels, the light emitting diode242reflects the voltage variation of the oscillation signal S0″ and appears to twinkle. By looking at the twinkling light emitting diode242, an inspector can determine if the oscillator224under test as shown inFIG. 3Ais normal or broken.

In summary, as shown inFIG. 2, the detection device200in the present invention utilizes the frequency-decreasing circuit230and the frequency division circuit240to lower the frequency of the oscillation signal S0produced by the oscillator control circuit220. Then, the resulting frequency-reduced oscillation signal S0″ is transmitted to the light emitting diode242so that the light emitting diode242can generate a visually identifiable twinkle to determine whether the oscillator224under test is normal or broken. For example, if the original oscillation signal S0generated by the oscillator control circuit220is 4 MHz, the frequency of the signal transmitted to the light emitting diode242after passing through the frequency-decreasing circuit230and the frequency division circuit240is 13 Hz. At a low frequency of 13 Hz, an inspector can easily determine if the oscillator224under test is normal by naked eye observation.