Light source of testing light sensor, test apparatus and method

A light source of testing a sensor, a test apparatus and a method are disclosed. The test apparatus includes a light source, a photo-mask and a sensor bearing area. The light source includes a plurality of light emitting diodes with parallel connection for emitting a test light. The light source is disposed in a photo-mask. The photo-mask has a diffuser interface. The test light is then diffused to the outside of the photo-mask through the diffuser interface. The sensor bearing area is for bearing the sensor. The sensor bearing area is disposed at the outside of the photo-mask and locates at a position to enable the test light to reach. Therefore, the test light emitted by the light source is used to test the sensor.

FIELD OF THE INVENTION

The present invention relates to a light source of testing a light sensor, a test apparatus and a method and, more particularly, to utilize a plurality of Light Emitting Diodes with parallel connection to be the light source of testing the light sensor, the test apparatus and the method.

BACKGROUND OF THE INVENTION

Currently, in a test technique for an image sensor, a test light is usually projected onto the image sensor. Sensed image data is transmitted by the image sensor to a processor. The image sensor is calibrated based on the test light conditions. If there is an error in the test light source, the image quality of the sensor is greatly affected. Therefore, the test light source characteristics must be very stable. The test light optical spectrum should not change with the driving current and voltage. The output intensity should not change with the temperature. The operation cycles of the light source should be more than 10K hours.

However, the light source for use in emitting the test light, its optical properties may be influenced by external driving circuits so as to produce flickers for the test light, darkness, or generated too much heat for the light source. For instance, a Cold Cathode Fluorescent Light (CCFL) can be taken into the light source for a thin-film transistor liquid-crystal display (TFT LCD). However, CCFL is a temperature sensitive component and the brightness changed with the ambient temperature. The second instance, the brightness of a fluorescent light may dim in cold weather. Furthermore the fluorescent light has flicker noise. The third instance, a calibrated incandescent or halogen light generates excessive heat and its lifetime is shorter. A calibrated incandescent light source has a typical of 100 operating hours. In addition, the incandescent light is multidirectional radiators. Thus, reflectors are needed. All the aforesaid light sources are not suitable for the test technique of the sensor in the mass production environment.

Moreover, White Light Emitting Diode (WLED) with serial connection has longer lifetimes, stable brightness and its radiation angle is less than 30°. Therefore, the WLED is a better choice for the light source of testing a sensor. However, the WLED with serial connection must serial connect seven-WLED in order to satisfy the test requirement for the brightness of the test light. The serial seven-WLED needs 22˜24V forward voltages. If a direct current/direct current booster is used to adjust the forward voltages to 22˜24V, the wave form of voltages may produce ripples and the stability of the brightness of the test light is also influenced.

Therefore, to enable the light source to emit a stable test light for ensuring the accuracy of the test outcome, the inventor of the present invention based on years of experience on related optical research invents a light source of testing a sensor, a test apparatus and a method to overcome the foregoing shortcomings of the prior arts.

SUMMARY OF THE INVENTION

Accordingly, the object of the present invention is to provide a light source of testing a sensor, a test apparatus and a method. A plurality of light emitting diodes (LEDs) with parallel connection is utilized to be the light source for emitting a test light steadily.

The test apparatus is utilized to test the quality of a sensor. The test apparatus includes a light source, a photo-mask and a sensor bearing area. The light source includes a plurality of LEDs with parallel connection for emitting the test light. The sensor bearing area could bear the sensor. The light source is disposed inside the photo-mask. The photo-mask includes at least one diffuser interface. The test light is diffused by the diffuser interface to the outside of the photo-mask. The sensor bearing area is disposed at the outside of the photo-mask and is at an ambit where the test light can reach from the photo-mask. Therefore, the test light emitted by the light source could reach the sensor bearing area through the diffuser interface and the sensor can be tested by using the test light.

Moreover, the test apparatus disclosed by the present invention further includes a closed shell and a processor. The closed shell is an opaque material for disposing the light source, the photo-mask, the sensor bearing area and the sensor. The processor is for receiving a test data generated by the sensor. The responsivity of the light sensor is then determined based on the test data.

The light sensor is usually a Charge Coupled Device (CCD) or a Complementary Metal-Oxide Semiconductor (CMOS) photodiode. The photo-mask further includes at least one shell. An inside of the shell is a smooth black material for surrounding the diffuser interface and the light source. The diffuser interface is used to enable the test light to diffuse to the outside of the photo-mask uniformly. The plurality of LEDs is seven-White Light Emitting Diodes (WLED) which receive working current provided by a power supply port to emit the test light. The position allocation of the WLEDs is that one WLED is surrounded by six WLEDs. The spacing between any two WLEDs is equivalence. In addition, the light source includes a resistor adjustment unit. The resistor adjustment unit is coupled between the power supply port and the WLEDs in order to adjust brightness of the test light. Because the light source of the present invention uses the LED with parallel connection, the forward voltage required for the test light can be reduced. A liner voltage regulator is also used. The wave form of voltages would not produce ripple effect after regulating.

Other features and advantages of the present invention and variations thereof will become apparent from the following description, drawings, and claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG. 1, a circuit diagram illustrates a light source of testing a sensor according to an embodiment of the present invention. The light source10includes an adjustment unit12and a Light Emitting Diode (LED) module11. The light source10receives working current provided by a power supply port VCC through a voltage regulator13. A test light is then emitted for testing a light sensor. The adjustment unit12is for controlling amperes of working current to adjust brightness of the test light. The LED module11is a plurality of LEDs111with parallel connection. One end of the LEDs111is coupled to a ground. Another end is coupled to the adjustment unit12. Therefore, the LEDs111could receive working current adjusted by the adjustment unit12to emit the test light.

Moreover, the adjustment unit12is composed of five variable resistors VR for fine tuning voltages V1of a coupled point between the adjustment unit12and the LED module11. In other words, working current is adjusted to change the brightness of the test light. In addition, every variable resistor VR is serial connected to a switch S1. The number of the variable resistors VR can be changed by opening or closing the switch S1in order to increase the efficiency of voltages V1. The LED is White Light Emitting Diode (WLED). The number of the WLED has better to be seven.

The sensor is a Charge Coupled Device (CCD) or a Complementary Metal-Oxide Semiconductor (CMOS) photodiode. The light source10is disposed inside a test apparatus. The test apparatus further includes a photo-mask, a sensor bearing area, a closed shell and a processor. The test light is then utilized to test the light sensor to receive a test data generated by the light sensor. The responsivity of the light sensor is further determined.

Referring toFIG. 2andFIG. 3, a top view and a side elevation illustrate a position allocation of LEDs according to embodiments of the present invention. InFIG. 2, the position allocation of the LEDs111is that one LED111is surrounded by six LEDs111. Any two adjacent LEDs111which are at the outside and a central LED111are formed 60° included angle. The spacing between two LEDs11is D1. InFIG. 3, the angle of the test light emitted by every LED111is 30°. The light source10could be disposed inside the photo-mask. The photo-mask has a cylinder shell31with a diameter D2and a diffuser interface32with a diameter D2. The better position for disposing the diffuser interface32is determined through the angle 30° and the diameter D2. There is no need to dispose any reflector.

Referring toFIG. 4, a top view and a side elevation illustrate the closed shell of the test apparatus according to an embodiment of the present invention. An inside portion of the closed shell40is extremely black and smoothly. The closed shell40is an opaque material. A central position of the top within the closed shell40has a cylinder photo-mask41. The diameter and the height for the cylinder photo-mask41are D2.

Referring toFIG. 5and referring toFIG. 1toFIG. 4,FIG. 5is a side elevation illustrates the test apparatus according to an embodiment of the present invention. The test apparatus includes the light source10, the photo-mask41and a sensor bearing area51. The light source10is disposed inside the photo-mask41. The photo-mask41is composed of the cylinder shell41and the diffuser interface32. The sensor bearing area51is disposed at the outside of the photo-mask41and locates on the diffuser interface32. The light source10has a plurality of LEDs111with parallel connection and the adjustment unit12. The light source10is coupled to the voltage regulator13in order to receive required working current from the power supply port. The test light is then emitted from the LEDs. An interior wall of the cylinder shell31is a smooth black material for surrounding the diffuser interface32and the light source10. The test light may not be diffused to the outside of the photo-mask41from the shell31. The diffuse interface32is for uniformly diffusing the test light. The diffuse interface32could help the test light to diffuse to the outside of the photo-mask41. The brightness of the test light which is diffused to the outside of the photo-mask41is identically. The sensor bearing area51is for bearing a light sensor52. The light sensor52then receives the test light to generate a test data.

In addition, as shown inFIG. 1, the adjustment unit12is composed of five variable resistors VR with parallel connection. The adjustment unit12is for adjusting working current to change the brightness of the test light. Every variable resistor VR is serial connected to a switch S1in order to increase the efficiency of voltages V1. The LED is White Light Emitting Diode (WLED). The number of the WLED has better to be seven. A position allocation of the plurality of LEDs with parallel connection is as shown inFIG. 2andFIG. 3. The structure of the cylinder shell31is a cylinder with a diameter D2. The diffuser interface32is a circular object with a diameter D2. Therefore, when the test light is diffused to the outside of the photo-mask41from the diffuser interface, the irradiation range is a circular area with a diameter D2which is on the diffuser interface.

Moreover, the test apparatus disclosed by the present invention further includes the closed shell40as shown inFIG. 4. The closed shell40is an opaque material for preventing the outside light beam and is for disposing the light source10, the photo-mask41, the sensor bearing area51and the light sensor52. In addition, the test apparatus further includes a processor (not shown) for receiving the test data generated by the light sensor52. The test data is further processed to determine the quality of the light sensor52. The light sensor52is a CCD or a CMOS photodiode.

Referring toFIG. 6, a flowchart illustrates a test method according to an embodiment of the present invention. The method includes steps as follows:

Step S61: A light sensor is born by a sensor bearing area.

Step S62: A light source which has a plurality of LEDs with parallel connection is disposed inside a photo-mask.

Step S63: A test light is emitted by the light source. The test light is diffused to the outside of the photo-mask through a diffuser interface of the photo-mask.

Step S64: The sensor bearing area is disposed at the outside of the photo-mask and is at an ambit where the test light can reach from the photo-mask in order to test the light sensor.

The test method further includes utilizing an opaque closed shell to dispose the light source, the photo-mask, the sensor bearing area and the light sensor. Furthermore, a Lux meter is used to adjust the test light diffused from the diffuser interface. The light source further includes the adjustment unit for fine tuning the brightness of the test light while adjusting. In step S63, the test light could be diffused to the outside of the photo-mask through the diffuser interface. After step S64, a processor is further used to receive the test data generated by the light sensor and the responsivity of the light sensor is then determined. The light sensor is a CCD or a CMOS photodiode. The LED is WLED. The number of the WLED has better to be seven. The position allocation is that one WLED is surrounded by six WLED. The spacing between any two WLED is equivalence. The photo-mask does not only include the diffuser interface; but also includes a shell which is made by a smooth black material. The shell is for surrounding the diffuser interface and the light source.

Although the features and advantages of the embodiments according to the preferred invention are disclosed, it is not limited to the embodiments described above, but encompasses any and all modifications and changes within the spirit and scope of the following claims.