JPS59166878A - Light source for testing image pickup device - Google Patents

Abstract

PURPOSE:To output an optical signal having high uniformity by switching a case when a testing optical signal is made to made to form an image on an image pickup device to be tested through a condensing lens and an image forming lens from a light emitting lamp, and a case when said signal does not pass through these lens systems. CONSTITUTION:A lens system 21 constituted of a condensing lens 14, a test chart 15 and an image forming lens is capable of moving mechanically to switch a case when it is inserted between a light emitting lamp 11 and an image pickup device to be tested, and a case when it is not inserted as shown in the figure. Accordingly, when uniform light is irradiated to the image pickup device to be tested, and the lens system 21 can be moved to shift from a signal path, therefore, uniform light required for the image pickup surface of the image pickup device to be tested is given by luminous flux having an extremely small solid angle, in the luminous flux emitted from the light emitting lamp 11, and the various characteristic tests of the image pickup device can be executed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an imaging device tester for testing various characteristics of an imaging device, and more particularly to an imaging device testing light source for applying a test optical signal to an imaging device under test.

<Background of the Invention> Solid-state image sensors have been developed and are being put into practical use for the purpose of downsizing and reducing power consumption of television cameras. As is well known, in a solid-state image sensor, a large number of photoelectric conversion cells made of semiconductors are arranged on one side, and the photoelectric conversion cells are sequentially selected one by one using a selection signal and irradiated onto the photoelectric conversion cells. A pixel signal corresponding to the amount of light is obtained, and the selection of the photoelectric conversion cells is sequentially switched to perform surface scanning to obtain an image signal. Here, since each photoelectric conversion cell is formed on a semiconductor substrate by a bond circuit manufacturing technique, defects may occur in the photoelectric conversion cell due to inconveniences in the manufacturing process.

Furthermore, there may be differences in photosensitive characteristics or dynamic ranges between the photoelectric conversion cells, or electrical leakage may occur between the cells.

One solid-state image sensor is constituted by approximately 500 x 500 photoelectric conversion elements, and the number of photoelectric conversion cells is a large value. Like this (many)'r.

Testing each electric conversion cell one by one for various characteristics is quite a difficult task.

FIG. 1 shows a conventional imaging device tester for testing such solid-state imaging devices. In the figure, reference numeral 101 indicates a solid-state image sensing device to be tested, which is configured in a CCD type, MOS type, or other format. Reference numeral 102 denotes a drive circuit that provides a cell selection signal to the solid-state image sensor 101. The driving circuit 102 selects the solid-state image sensor 101 according to the arrangement of each photoelectric conversion cell, and pixel signals are obtained one after another.

A pixel signal 103 obtained from the solid-state image sensor 101 is amplified by a preamplifier 104 and provided to an AD converter 105. The AD converter 105 converts the pixel signal into A in synchronization with a clock pulse of 1.00 given from the drive circuit 102.
The signal is converted into a digital pixel signal of, for example, 8 to 10 bits.

The digital pixel signal AD-converted by the AD converter 105 is taken into the memory 106. The memory 106 counts clock pulses given from the drive circuit 102 by an address counter 107, and sequentially increments the address by one address based on the count output thereof, and sequentially stores digital pixel signals output from the AD converter 105.

The digital pixel signals captured in the memory 106 are sequentially transferred to the data processor 108. This data processor 108 has various comparison and determination means, and this determination means determines whether the photoelectric conversion cell is good or not and the solid-state image sensor 101.
Determine the overall quality.

109 is a controller. This controller 109
starts and stops the drive circuit 102 and controls the data processor 108. Further, the controller 109 provides a control signal to the light source 111 to control the amount of light and mechanical position of the light source 111.

The configuration of this imaging device test light source 111 is shown in FIG. 2, for example. In FIG. 2, numeral 11 is a light emitting lamp, for example, a σ5 condensing lens for setting the laser beam. 12 is a color filter for determining the color of the test optical signal.

Reference numeral 13 denotes a neutral density filter for adjusting the amount of light of the test optical signal. Reference numeral 16 indicates an imaging lens, and ]01 indicates a solid-state image sensor to be tested. The light focused by the focusing lens 14 illuminates the test chart 15.

A test pattern necessary for testing the characteristics of the solid-state image sensor is drawn on the test chart 15. be done. This test pattern is
For example, in addition to the standard chart for television testing, there are also optional chart 1. - is used. 1 In this way, the test chart is imaged on the solid-state image sensor 101 under test, and the information of the solid-state under test and each photoelectric conversion cell of the image sensor 101 at that time is imported into the image sensor tester shown in FIG. 1 and judged as good or bad. etc.

When testing an imaging device, in addition to forming an image of the test chart from the light source onto the imaging device under test as described above, there are also cases in which the test chart is not imaged and a uniform light beam of -11 light traveling fi is applied to the test object. Tests may be performed by applying it to the imaging surface of an imaging device. That is, for example, when testing the sensitivity characteristics of each photoelectric conversion cell of an imaging device under test, or when testing the noise-to-noise ratio,
Or, when investigating defects in photoelectric conversion cells called scratch tests and stain tests, there is no need to image a test pattern, and it is necessary to apply an optical signal with a uniform amount of light to each photoelectric conversion cell1. In this case, the smaller the uniformity of the optical signal, that is, the smaller the variation in the amount of light given to each cell, the more accurate the test can be.

However, with the conventional light source for testing an imaging device shown in FIG. 2, it is not possible to obtain an optical signal with sufficient uniformity. In other words, when performing a sensitivity test or a signal-to-noise ratio test using a conventional light source for testing an imaging device, the test chart 15 shown in FIG. 2 is removed, but the test optical signal is 14. Since the optical signal is applied via the imaging lens 16, the uniformity of the optical signal cannot be set to a certain value, for example, 3 to 5% or more. This is because the light from the light-emitting lamp 11 is focused by the condensing lens 14 over the solid angle α to form the optical signal J, so that different amounts of light are added to the center and the ends of the condensing lens. Therefore, the larger the solid angle α is, the worse the uniformity of the optical signal applied to the imaging device under test becomes.

In this way, when conventional light sources for testing imaging devices are used to perform sensitivity tests by irradiating uniform light onto the imaging device under test, it is not possible to conduct highly accurate tests due to limitations in the uniformity and uniformity of the light. There wasn't.

<Object of the Invention> The present invention aims to provide a light source for testing an imaging device that can eliminate the above-mentioned drawbacks and output a uniform and highly accurate optical signal.

<Embodiments of the Invention> According to the present invention, there is a case where a test optical signal is imaged and applied from a light emitting lamp to a limb test S imaging device via a condensing lens and an imaging lens, and when these lens systems are applied. It is possible to switch between applying a uniform test optical signal to the imaging device under test from a light-emitting lamp without going through the
゜Therefore, when it is not necessary to image a test pattern on the imaging surface of the imaging device under test, such as in a sensitivity test, and it is sufficient to irradiate uniform light, the test optical signal is applied without going through the lens system. be able to. Therefore, the solid angle of the luminous flux emitted from the one-emission lamp 11 is extremely small, and therefore, the difference in illuminance at each position of the optical signal applied to the imaging surface is small, and a luminous flux with good uniformity can be obtained.

A third embodiment of the light source for testing an imaging device according to the present invention is described below.
The figure shows shock. In FIG. 3, parts common to those in FIG. 2 are given the same numbers. Condensing lens 14, test chart 15
The lens system 21, which is composed of an imaging lens, is mechanically movable, and can be switched between being inserted between the light-emitting lamp 11 and the imaging device under test, and not being inserted, as shown in the figure. It looks like this.

Therefore, when uniform light is irradiated onto the imaging device under test, the lens system 21 can be moved and removed from the signal path, and therefore only the light beam with an extremely small solid angle is emitted from the light emitting lamp 11. can provide the necessary uniform light to the imaging surface of the imaging device under test. Therefore, there is little difference in the luminous intensity of the optical signal at each position on the imaging surface, and therefore it is possible to obtain a highly uniform test optical signal, which is useful for sensitivity tests, signal-to-noise ratio tests, etc. Accuracy can be improved when testing by applying uniform light. For example, according to this embodiment, uniformity of approximately ±0.2% can be easily achieved.

In this embodiment, uniform light is obtained by mechanically moving the position of the lens system 21 along the optical axis, but the method is not limited to this method. For example, with the lens system fixed, the optical axis It is also possible to insert a required number of mirrors in parallel with the light emitting lamp so that the signal from the light emitting lamp is applied to the imaging device under test without passing through the lens system. That is, when applying the imaged pattern signal to the image pickup device under test, it passes through the lens system, and when applying uniform light, it does not pass through the lens system, and it is sufficient that these can be switched mutually.

As described above, according to the present invention, it is possible to obtain a bow for testing an imaging device with a high degree of uniformity, and therefore various characteristic tests of the imaging device can be performed with high accuracy.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the general configuration of an imaging device tester, FIG. 2 is a schematic diagram showing the configuration of a conventional imaging device testing light source, and FIG. 3 is an implementation of the imaging device testing light source according to the present invention. 1 is a schematic diagram of an example configuration; 11. Luminous lamp 12. color filter 13,
KI < Optical filter 14, condensing lens 15; Test chart 16: Imaging lens 101, Imaging device under test Patent applicant: Tagada Riken Nigyo Co., Ltd. Agent, Yasuo Muramatsu, patent attorney

Claims (1)

[Claims] In order to perform various tests on the imaging device, the imaging device trial light source applies a test optical signal to the imaging device under test. An imaging device characterized in that it is possible to switch between applying a test optical signal from a light-emitting lamp to an imaging device under test without passing through a condensing lens and an imaging lens. Light source for equipment testing.