JP2005259426A - Light irradiation device and image sensor testing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light irradiation device capable of setting the nature of light irradiating to an image sensor of a testing target without using a mechanical driving mechanism, and to provide an image sensor testing device. <P>SOLUTION: A plurality of light sources 20 contain the light source irradiating light having several different colors, and intensity of the light of each color is controlled according to predetermined testing contents. The plurality of light sources 20 correspond to a plurality of bundles at an input end 31 of an optical fiber bundle 30 by one to one, and the irradiated light from the light source 20 is incident on the bundle corresponding to he input end 31. In the optical fiber bundle 30, since the optical fibers of each bundle of the input end 31 are dispersed at an output end 32, light from the plurality of light sources 20 incident on the input end 31 is emitted in a mixed state at the output end 31 of the optical fiber bundle 30. Light from the output end 32 is irradiated to the image sensor of the testing target through an optical system 40. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light irradiation apparatus that irradiates test light onto an image sensor such as a CCD (charge coupled device) sensor or a CMOS (complementary metal oxide semiconductor) sensor, and an image sensor test apparatus.

In the manufacturing process of an image sensor such as a CCD sensor or a CMOS sensor, a process for testing the photoelectric conversion characteristics of the image sensor is generally provided.
In this test process, the light receiving surface of the image sensor is irradiated with light of various conditions, the output signal of the image sensor corresponding to this is acquired, and a test is performed to determine whether the image sensor has the required characteristics. Is called.

  Conventionally, the light applied to the image pickup device in this test process is made by passing light emitted from a white light source such as a halogen lamp through an optical filter such as an ND (neutral density) filter or a color filter. An ND (neutral density) filter has a function of attenuating its intensity without changing the spectral composition of incident light, and a color filter is a filter having a function of selecting light having a specific spectral composition from incident light. Usually, a plurality of types of such optical filters are prepared and mechanically switched using a drive mechanism, so that light that meets test conditions is produced.

However, in the conventional method of mechanically switching the optical filter to produce test light, the test conditions such as light intensity and spectral composition are fixed by the optical filter used, and the properties of the irradiated light are finely adjusted. There is a problem that can not be.
Therefore, in order to set a desired test condition, it is necessary to specially facilitate an optical filter that matches the test condition, which is expensive. In addition, since the number of optical filters that can be automatically switched in the test apparatus is limited, if there are many items to be tested, the optical filters must be switched manually, and the efficiency of the test is not good. .

  Furthermore, since a mechanical drive mechanism is required, there is a problem that the apparatus becomes large in size and increases in weight, and there is a problem that failure due to wear of parts and the like cannot be avoided.

  In addition, the image sensor test process may include a test that simulates light such as a fluorescent lamp that blinks at a frequency of about several tens of hertz. However, in the conventional method, since the light can only be mechanically blocked using a shutter, the light cannot be blinked at a very high frequency. That is, there is a problem that the performance of the test for dynamically changing the property of the irradiation light is not good.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a light irradiation apparatus capable of irradiating light of various conditions onto an imaging device to be tested without using a mechanical drive mechanism. It is another object of the present invention to provide a test device for an image sensor having such a light irradiation device.

1st invention of this invention is a light irradiation apparatus which irradiates the light for a test to an image pick-up element, Comprising: It has several light sources which generate the light of a respectively different color, an optical fiber bundle, and a light source control part .
The optical fiber bundle includes a plurality of optical fibers bundled in a plurality at the input end and bundled in one at the output end, and light of different colors is incident on the plurality of bundles at the input end from the plurality of light sources. Is done. Further, the optical fibers of the bundles at the input end are dispersedly arranged at the output end so that the light incident on the bundles at the input end is mixed at the output end.
The light source control unit controls the intensity of light generated by the plurality of light sources in accordance with an input control signal.

  According to the first invention, when light of different colors is incident on the plurality of bundles at the input end of the optical fiber bundle from the plurality of light sources, the optical fibers of each bundle at the input end are connected to the output end. Therefore, incident lights of different colors are emitted in a mixed state from the output end of the optical fiber bundle. In the light source control unit, when the intensity of light emitted from the plurality of light sources is respectively controlled, the intensity of light of different colors mixed at the output end is set accordingly. As a result, the properties of light emitted from the output end (light intensity, spectral composition, etc.) are set.

In the first invention, the plurality of light sources may include a light source group that emits a plurality of lights having the same type of color, and the plurality of lights emitted from the light source group are respectively separated from the input terminals. It may be incident on the bundle.
When light having the same type of color is incident on a plurality of bundles at the input end, the dispersibility of light at the output end is improved as compared with the case where the light is incident on only one bundle. As a result, the light of different types is mixed more uniformly at the output end.

The light source control unit may uniformly control the intensity of a plurality of lights emitted from the light source group, or may divide the plurality of lights into a plurality of groups so that each group is independently controlled. You may control.
In the case of uniform control, it becomes possible to share a circuit necessary for controlling each light source of the light source group, and the circuit becomes simple. When the control is performed independently for each group, it is possible to finely control the intensity of the entire light emitted from the light source group as compared with the case where the control is performed uniformly.
In this case, at least some of the light sources included in the light source group may be grouped into a plurality of light source groups each including a different number of light sources that emit light of the same color. The unit may control the intensity of the emitted light independently for each of the groups in the light source group. Further, the number of light sources included in the light source group may be a number proportional to a power of two.

  Preferably, the light source includes a light emitting diode, and the light source control unit controls a current flowing through the light emitting diode.

  Preferably, the light source group includes one or a plurality of light emitting diode series circuits in which a plurality of light emitting diodes emitting light having the same type of color are connected in series, and the light source control unit includes the light emitting diode series. Controls the current flowing through the circuit.

  A second invention of the present invention is a test apparatus for an image sensor, wherein a light irradiation unit that irradiates light to an image sensor to be tested, and intensity of irradiation light of the light irradiation unit based on predetermined test contents And / or a test processing unit that performs a process of controlling the spectral composition and acquiring a signal output from the imaging device in accordance with the controlled irradiation light. The light irradiation unit includes a plurality of light sources that emit light of different colors and a plurality of optical fibers that are bundled together at the input end and bundled together at the output end. Light beams of different colors are incident on the plurality of bundles at the ends, and the optical fibers of the bundles at the input ends are mixed at the output ends so that the lights incident on the bundles at the input ends are mixed at the output ends. The optical fiber bundle is arranged in a dispersed manner, and a light source control unit that controls the intensity of light emitted from the plurality of light sources in accordance with instructions from the test processing unit.

  According to the second aspect of the invention, when light of different colors is incident on the plurality of bundles at the input end of the optical fiber bundle from the plurality of light sources, the optical fibers of each bundle at the input end are connected to the output end. Therefore, incident lights of different colors are emitted in a mixed state from the output end of the optical fiber bundle. When the intensity of light emitted from the plurality of light sources is controlled in accordance with an instruction from the test processing unit according to the predetermined test contents, the different colors mixed at the output end are accordingly controlled. The light intensity is set, and as a result, the image sensor is irradiated with light having properties (light intensity, spectral composition, etc.) according to instructions from the test processing unit. A signal output from the image sensor in response to the irradiation light is acquired by the test processing unit.

  According to the present invention, it is possible to continuously and finely set properties such as the intensity of light irradiated to the test image sensor and the spectral composition without using a mechanical drive mechanism.

  Hereinafter, two embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>

FIG. 1 is a diagram illustrating a configuration example of an image sensor testing apparatus according to the first embodiment of the present invention.
The imaging device test apparatus shown in FIG. 1 includes a light source control unit 10, a plurality of light sources 20, an optical fiber bundle 30, an optical system 40, a test table unit 50, a test processing unit 60, and a lens 70. Have.

The light source control unit 10 is an embodiment of the light source control unit of the present invention.
The plurality of light sources 20 is an embodiment of the plurality of light sources of the present invention.
The optical fiber bundle 30 is an embodiment of the optical fiber bundle of the present invention.

  The light source control unit 10 controls the intensity of light emitted from the plurality of light sources 20 according to the control signal Scont input from the test processing unit 60.

The plurality of light sources 20 include light sources that emit light of several different colors, and change the intensity of each radiated light according to the control of the light source control unit 10.
For the plurality of light sources 20, for example, light emitting diodes are used.

FIG. 2 is a diagram illustrating an example of a detailed configuration of the light source control unit 10.
The light source control unit 10 illustrated in FIG. 2 includes transistors Q1 to Q10 and Q20, resistors R1 to R10, ammeters M1 to M10 and M20, and a drive signal output unit 11.

  In the example of FIG. 2, the plurality of light sources 20 include light source groups 20-1 to 20-10 in which five light emitting diodes are connected in series.

  The variable resistor Ri (i is an integer from 1 to 10), the transistor Qi, the light source group 20-i, and the ammeter Mi are connected in series with each other. One end of this series circuit is connected to the ground line G, and the other end is connected to the power supply line Vcc via a series circuit of an ammeter M20 and a transistor Q20.

The variable resistor Ri is a resistor for manually changing the light emission intensity of the light source group 20-i.
The transistor Qi changes the light emission intensity of the light source group 20-i according to the drive signal Si.
The ammeter Mi is a measuring instrument for observing the current flowing through the light emitting diodes of the light source group 20-i.

The transistor Q20 is a switch for turning on and off all the light source groups (20-1 to 20-10) according to the drive signal S20. The transistor Q20 is used, for example, to generate light that blinks at a predetermined frequency.
The ammeter 20 is a measuring instrument for observing the total current flowing through all the light source groups (20-1 to 20-10).

  In the example of FIG. 2, the light source groups 20-1 and 20-2 are blue, the light source groups 20-3 and 20-4 are light blue, the light source groups 20-5 and 20-6 are green, and the light source group 20-7, 20-8 is yellow, and the light source groups 20-9 and 20-10 are red LEDs.

  The drive signal output unit 11 generates drive signals S1 to S10 and S20 to be input to the bases of the transistors Q1 to Q10 and Q20 in response to the control signal Scont from the test processing unit 60.

Returning to the description of FIG.
The optical fiber bundle 30 includes a plurality of optical fibers that are bundled at the input end 31 and bundled at the output end 32. Light from the plurality of light sources 20 is incident on the plurality of bundles at the input end 31 through the lens 70, respectively. That is, the emitted light of one light emitting diode in the light source groups 20-1 to 20-10 shown in FIG. 2 is incident on one bundle at the input end 31.

  Further, in the optical fiber bundle 20, the optical fibers of each bundle at the input end 31 are distributed and arranged at the output end so that the light incident on each bundle at the input end 31 is mixed at the output end.

  The optical system 40 guides the light emitted from the output end 32 of the optical fiber bundle 30 to the imaging device 51 to be tested.

The optical system 40 includes lenses 41 to 43 as shown in FIG.
The lens 41 converges the light emitted from the output end 32 of the optical fiber bundle 20 and enters the lens 42.
The lens 42 is a lens for making the illuminance distribution uniform. For example, a fly-eye lens in which single lenses are arranged in a matrix in the vertical and horizontal directions is used.
The lens 43 further converges the light whose illuminance distribution is made uniform in the lens 42 and irradiates the imaging device 51 to be tested.

  The test table unit 51 holds the light receiving surface of the image sensor 51 to be tested at an appropriate position with respect to the light irradiation position from the optical system 41. In addition, a probe (not shown) that is in electrical contact with the signal input / output pin of the image sensor 51 is included, and the test processing unit 60 and the image sensor 51 are electrically connected via this probe.

  The test processing unit 60 generates control signals Scont that respectively indicate the intensity of light emitted from the plurality of light sources 20 based on predetermined test contents, and inputs the control signals Scont to the light source control unit 10. Further, a signal (captured image signal or the like) output from the image sensor 51 to be tested in accordance with the light from the light source 20 is acquired via the test table unit 51. Based on the signal acquired from the image sensor 51, the test processing unit 60 evaluates whether the image sensor 51 has the required characteristics.

  Next, the operation of the image sensor testing apparatus having the above-described configuration will be described.

  First, the imaging device 51 to be tested is arranged on the test table unit 51, and the control signal Scont corresponding to the test content is output from the test processing unit 60.

The light source control unit 10 controls the light intensity in each of the plurality of light sources 20 according to the control signal Scont.
That is, the drive signal output unit 11 outputs the drive signals S1 to S10 corresponding to the control signal Scont, and the currents flowing through the light source groups 20-1 to 20-10 are set accordingly. Each light emitting diode of the light source groups 20-1 to 20-10 emits light having an intensity corresponding to the set current.
Accordingly, light of a plurality of colors having an intensity corresponding to the control signal Scont is incident on the input end 31 of the optical fiber bundle 30.

Light incident on each bundle at the input end 31 of the optical fiber bundle 30 is emitted from the output end 31 through an optical fiber constituting each bundle.
In the optical fiber bundle 30, since the optical fibers of each bundle at the input end 31 are distributed and arranged at the output end 31, the light from the light source 20 incident on each bundle was mixed with each other at the output end 31. It becomes a state. That is, the optical fiber bundle 30 mixes light emitted from the plurality of light sources 20.

In this way, the light obtained by mixing the light of a plurality of colors is converged by making the illuminance distribution uniform in the optical system 40, and is irradiated on the light receiving surface of the image sensor 51 to be tested.
A signal output from the image sensor 51 according to the irradiation light is input to the test processing unit 60 via the test table unit 50.
The test processing unit 60 acquires an output signal from the image sensor 51, and evaluates whether or not the image sensor 51 has the required characteristics based on the acquired signal.

As described above, the plurality of light sources 20 of the present embodiment include light sources that emit light of several different colors, and the intensity of light of each color depends on the content of a predetermined test. Each is controlled. The plurality of light sources 20 and the plurality of bundles at the input end 31 of the optical fiber bundle 30 have a one-to-one correspondence, and the emitted light from the light source 20 is incident on the corresponding bundle at the input end 31. In the optical fiber bundle 30, the optical fibers of the respective bundles at the input end 31 are distributed and arranged at the output end 32, so that the light from the plurality of light sources 20 incident on the input end 31 The light is emitted in a mixed state at the output end 31. The image sensor 51 to be tested is irradiated with light from the output end 32 via the optical system 40.
In this way, by controlling the intensity of the emitted light of each color in the plurality of light sources 20 according to the test contents, the intensity of light of different colors included in the light irradiated to the image sensor 51 to be tested is set, respectively. Therefore, it is possible to freely set properties such as the intensity and spectral composition of light applied to the image pickup device 51 to be tested according to the test contents without using a mechanical drive mechanism. It becomes possible.
Therefore, the apparatus can be reduced in size and weight as compared with the case where a mechanical drive mechanism is used, and failure due to wear of parts is eliminated, so that reliability is improved.

Further, by using a light emitting element such as a light emitting diode capable of continuously changing the intensity of radiated light according to a drive signal as the light source 20, the light included in the light irradiated to the imaging element 51 to be tested is different. It is possible to continuously change the intensity of each color light, and as a result, it is possible to continuously change the properties such as the intensity and spectral composition of the light applied to the imaging device 51 to be tested. Become.
Therefore, it is possible to continuously adjust the property of light applied to the image sensor to be tested.
This eliminates the need for specially easy optical filters that match the test conditions, thus reducing costs and eliminating the need for manual switching of optical filters, improving test efficiency. Can be

  In addition, by controlling the drive signal supplied to the light source 20, it is possible to change properties such as the intensity of light irradiated to the image sensor 51 to be tested and the spectral composition. Compared with the conventional method of changing, the speed of change can be increased. That is, the performance of a test that dynamically changes the properties of the irradiation light (such as a test that blinks the irradiation light) can be improved as compared with the conventional method.

  And according to this embodiment, the light source 20 which radiates | emits the light of the same kind forms the light source group (20-1 to 20-10), The some light radiated | emitted from each light source group is The light is incident on different bundles at the input end 31. Therefore, the light dispersibility at the output end 32 is improved as compared with the case where light of one kind is incident on only one bundle of the input ends 31. As a result, light of different types can be mixed more uniformly at the output end 32.

  In addition, according to the present embodiment, since the emitted light of the five light emitting diodes constituting one light source group is uniformly controlled, the control circuit can be simplified as compared with the case where these are controlled separately. .

<Second Embodiment>
Next, a second embodiment will be described.

FIG. 3 is a diagram illustrating an example of the relationship between the current flowing through the light emitting diode and the light emission intensity.
As shown in FIG. 3, the light emitting diode has a property that light emission hardly occurs when the current is smaller than the threshold current IL. Since the threshold current IL varies greatly from individual to individual, when a plurality of light emitting diodes are connected in series as shown in FIG. 2, the total light emission intensity of the light emitting diodes connected in series is the threshold of each light emitting diode. It changes discontinuously in the vicinity of the current IL. That is, there is a problem that the setting accuracy of the minute light emission intensity is deteriorated.

  FIG. 4 is a diagram illustrating an example of the configuration of the light source groups 20A-1 to 20A-10 according to the present embodiment, in which the deterioration of the emission intensity setting accuracy is improved. Other configurations of the test apparatus are the same as the configurations shown in FIGS. 1 and 2.

The light source groups 20A-1 to 20A-10 shown in FIG. 4 are obtained by replacing the light source groups 20-1 to 20-10 shown in FIG.
The light source group 20A-1 includes four blue light emitting diodes connected in series.
The light source group 20A-2 includes four light emitting diodes connected in series.
The light source group 20A-3 includes four green light emitting diodes connected in series.
The light source group 20A-4 includes four yellow light emitting diodes connected in series.
The light source group 20A-5 includes four red light emitting diodes connected in series.
The light source group 20A-6 includes one white light emitting diode.
The light source group 20A-7 includes two white light emitting diodes connected in series.
The light source group 20A-8 includes four white light emitting diodes connected in series.
The light source group 20A-9 includes eight white light emitting diodes connected in series.
The light source group 20A-10 includes 15 white light emitting diodes connected in series.

  According to the configuration of the light source shown in FIG. 4, the light sources that generate white light are grouped into five light source groups (20A-6 to 20A-10), and these groups correspond to the drive signals S5 to S10. Are controlled independently. Therefore, when the intensity of the white light is set to a minute intensity in the vicinity of the threshold current of the light emitting diode, only one white light emitting diode of the light source group 20A-6 needs to emit light. The above described setting accuracy does not deteriorate due to variations.

Further, by selecting an appropriate light source from the light source groups 20A-6 to 20A-10 according to the intensity of the white light to be set and causing the light to be emitted, the fine adjustment of the intensity of the white light can be performed by 1 This can be done by adjusting the current of the two white light emitting diodes. For example, when setting the light intensity in the range of 6 to 7 white light emitting diodes, the current of the transistor Q6 may be adjusted with the transistors Q7 and Q8 on and the transistors Q9 and Q10 off.
As described above, according to the present embodiment, the light emission intensity can be more finely adjusted than the method of uniformly controlling the currents flowing through the plurality of light emitting diodes.

In addition, since the number of light emitting diodes included in the light source groups 20A-6 to 20A-9 is a number proportional to a power of two, binary data is given as the intensity of white light from the test processing unit 60. In addition, the on / off states of the transistors Q7 to Q10 can be easily set in association with the bit values of each digit of the data.

  While two preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments.

For example, in the above-described embodiment, the lens 70 is provided between the light source 20 and the input end 31 of the optical fiber bundle 30, but the present invention is not limited to this.
When the directivity of light emitted from the light source 20 is sharp, for example, the light beam of the light source 20 may be directly incident on the input end 31 as shown in FIG.
It is also possible to collect the emitted light of the light source 20 at the input end 31 using a cylindrical mirror 71 (FIG. 5C) having a mirror surface on the inner surface or a spherical lens 72 (FIG. 5D). It is.

  In the above-described embodiment, the light emitting diode is used as the light source. However, the present invention is not limited to this, and various other light emitting elements capable of continuously changing the light emission intensity according to the drive signal may be used. .

  The circuits, the types and number of light sources, the configuration of the optical system, the arrangement, and the like shown in the above-described embodiments are merely examples for explanation, and can be arbitrarily changed.

It is a figure which shows the structural example of the testing apparatus of the image pick-up element which concerns on 1st Embodiment. It is a figure which shows an example of a structure of a light source control part and a light source group. It is a figure which shows an example of the relationship between the electric current which flows into a light emitting diode, and emitted light intensity. It is a figure which shows an example of a structure of the light source group which concerns on 2nd Embodiment. It is a figure which shows the example of the optical system inserted between a light source and an optical fiber bundle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Light source control part, 11 ... Drive signal output part, 20 ... Light source, 20-1-20-10, 20A-1-20A-10 ... Light source group, 30 ... Optical fiber bundle, 40 ... Optical system, 50 ... Test Table part, 60 ... Test processing part, 70 ... Lens, Q1-Q10, Q20 ... Transistor, R1-R10 ... Variable resistance, M1-M10, M20 ... Ammeter

Claims (8)

A light irradiation device for irradiating a test light to an image sensor,
A plurality of light sources that emit light of different colors,
A plurality of optical fibers bundled together at the input end and bundled together at the output end, and light of different colors is incident on the plurality of bundles at the input end from the plurality of light sources; An optical fiber bundle in which the optical fibers of each bundle at the input end are dispersed and arranged at the output end so that the light incident on each bundle is mixed at the output end;
A light source control unit for controlling the intensity of light emitted from the plurality of light sources, respectively, according to an input control signal;
A light irradiation apparatus. The plurality of light sources includes a light source group that emits a plurality of lights having the same type of color,
A plurality of lights emitted from the light source group are incident on different bundles of the input ends,
The light irradiation apparatus according to claim 1. The light source control unit uniformly controls all the intensity of a plurality of lights emitted from the light source group, or divides the plurality of lights into a plurality of groups, and controls each group independently.
The light irradiation apparatus according to claim 2. At least some of the light sources included in the light source group are grouped into a plurality of light source groups each including a different number of light sources that emit light of the same type of color,
The light source control unit independently controls the intensity of emitted light for each of the groups in the light source group;
The light irradiation apparatus according to claim 3. The number of light sources included in the light source group is a number proportional to a power of two.
The light irradiation apparatus according to claim 4. The light source includes a light emitting diode,
The light source control unit controls a current flowing through the light emitting diode;
The light irradiation apparatus according to claim 1. The light source group includes one or a plurality of light emitting diode series circuits in which a plurality of light emitting diodes that emit light having the same type of color are connected in series,
The light source control unit controls a current flowing through the light emitting diode series circuit;
The light irradiation apparatus as described in any one of Claims 2 thru | or 5. Based on the light irradiation unit that irradiates light to the image sensor to be tested, and predetermined test contents, the intensity and / or spectral composition of the irradiation light of the light irradiation unit is controlled, and the above-mentioned according to the controlled irradiation light An image sensor testing apparatus having a test processing unit for performing processing for acquiring a signal output from the image sensor,
The light irradiation part is
A plurality of light sources that emit light of different colors,
A plurality of optical fibers bundled together at the input end and bundled together at the output end, and light of different colors is incident on the plurality of bundles at the input end from the plurality of light sources; An optical fiber bundle in which the optical fibers of each bundle at the input end are dispersed and arranged at the output end so that the light incident on each bundle is mixed at the output end;
A light source control unit for controlling the intensity of light emitted from the plurality of light sources in accordance with instructions from the test processing unit,
Image sensor testing device.

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