JP4836662B2 - Shutter speed inspection jig, shutter speed inspection method, and chart for shutter speed inspection - Google Patents

Description

  The present invention relates to a shutter speed inspection jig for inspecting an electronic shutter speed of an image sensor. The present invention also relates to a shutter speed inspection method for inspecting an electronic shutter speed of an image sensor. The present invention also relates to a shutter speed inspection chart suitable for such a shutter speed inspection jig and a shutter speed inspection method.

In order to evaluate the performance of the photographing apparatus and to control the quality, the shutter speed is inspected widely in the product development stage and the manufacturing stage. For example, Patent Document 1 below discloses a jig for inspecting the shutter speed of a film camera with a lens.
JP-A-6-161001

  According to Patent Document 1, the shutter speed is inspected in the following flow. First, the lens-equipped film camera collected as a recycled product is disassembled and the exposure unit is taken out. Next, the exposure unit is set on a jig. Then, the shutter speed for the exposure unit is inspected. The jig is provided with a sensor for receiving light that has passed through the shutter. The inspector looks at the output waveform of the light receiving sensor with an oscilloscope, for example, and confirms the period during which the light passes through the shutter. Based on the period, the shutter speed of the exposure unit is calculated.

  With regard to a silver halide camera equipped with another mechanical shutter, it is considered that the shutter speed can be inspected using the same jig as in Patent Document 1.

  On the other hand, in recent years, an imaging apparatus including an imaging element such as a CCD (Charge Coupled Devices) has been widely used. For example, a digital still camera or an electronic endoscope is known as an imaging apparatus including such an imaging element. It is considered that the shutter speed of such an image pickup apparatus provided with a mechanical shutter can be inspected using the same jig as in Patent Document 1.

  An image pickup apparatus using an image sensor is not limited to a type that employs a mechanical shutter, but a type that adjusts an exposure amount using an electronic shutter that is a function of the image sensor (hereinafter, abbreviated as “electronic shutter image pickup apparatus”). Widely used. The electronic shutter is inferior to the mechanical shutter in terms of smear resistance, but on the other hand, it can enjoy the advantage of downsizing the device. For this reason, the electronic shutter is particularly preferred and adopted in, for example, an electronic endoscope.

  Here, there is a demand to inspect the shutter speed of the electronic shutter type imaging apparatus. However, light cannot pass through the image sensor regardless of whether the electronic shutter is open or fully closed. Therefore, even if the electronic shutter-type imaging device is inspected using the same jig as in Patent Document 1 and the output of the light receiving sensor is viewed, the shutter open period cannot be measured. That is, with the jig similar to the above-mentioned Patent Document 1, the shutter speed of the electronic shutter cannot be inspected. In addition, at present, no proposal has been made regarding a jig suitable for realizing the inspection of the shutter speed for the electronic shutter type imaging apparatus.

  Therefore, in view of the above circumstances, the present invention provides a shutter speed inspection jig and method suitable for inspecting the shutter speed of an electronic shutter type imaging apparatus, and a shutter speed suitable for such a jig and method. It is an object to provide an inspection chart.

  A shutter speed inspection jig according to an aspect of the present invention that solves the above-described problem is for inspecting an electronic shutter speed of an image sensor. The shutter speed inspection jig includes a rotating plate having a chart surface on which a predetermined chart for inspecting an electronic shutter speed is drawn, a rotation driving unit that rotatably supports the rotating plate, and the imaging element. The image processing apparatus includes a fixing unit that fixes the screen in a state of facing the surface, and a display unit that displays an image of the chart surface captured by the imaging element.

  According to the thus configured shutter speed inspection jig, the rotating chart surface is displayed on the display unit. Since the chart surface is rotated, the chart is displayed on the display unit as a blurred image corresponding to the electronic shutter speed. The inspector can inspect the electronic shutter speed of the image sensor by visually recognizing this blurring state.

  The shutter speed inspection jig further includes a signal processing unit that converts a signal acquired by the image sensor into a signal of a predetermined display format so that the signal can be displayed on the display unit and outputs the signal to the display unit. May be.

  This predetermined display format is, for example, the NTSC format.

  The shutter speed inspection jig includes, for example, a synchronization signal acquisition unit that acquires a predetermined video synchronization signal from the signal processing unit, and a rotation that controls the rotation frequency of the rotating plate by the rotation driving unit based on the acquired video synchronization signal. Control means may be further provided.

  The rotation control unit may generate a reference frequency based on the frequency of the video synchronization signal, for example, and control the rotation frequency of the rotating plate with reference to the generated reference frequency.

  Further, the rotation control means may control the rotation frequency of the rotating plate so as to coincide with the reference frequency.

  The shutter speed inspection jig may further include, for example, a reference frequency adjusting unit that can adjust the reference frequency.

  Here, the video synchronization signal may be a vertical synchronization signal, for example.

  A shutter speed inspection jig according to another aspect of the present invention that solves the above-described problem is an imaging device including an imaging device, and can process and display an image acquired by the imaging device. This is for inspecting the electronic shutter speed of an image pickup apparatus. The shutter speed inspection jig includes a rotating plate having a chart surface on which a predetermined chart for inspecting an electronic shutter speed is drawn, a rotation driving unit that rotatably supports the rotating plate, and the imaging element. It is characterized by comprising a fixing portion that fixes the surface in a state of facing the surface.

  According to the shutter speed inspection jig configured as described above, the rotating chart surface is displayed on the display unit on the imaging apparatus side. Since the chart surface is rotated, the chart is displayed on the display unit as a blurred image corresponding to the electronic shutter speed. The inspector can inspect the electronic shutter speed of the image sensor by visually recognizing this blurring state. According to this shutter speed inspection jig, it is possible to inspect the electronic shutter speed of the image pickup device mounted on the image pickup apparatus. In addition, it is not necessary to provide electric devices such as a display unit on the shutter speed inspection jig side.

  A shutter speed inspection method according to an aspect of the present invention that solves the above problem is for inspecting an electronic shutter speed of an image sensor. The shutter speed inspection method includes a fixing step of fixing a chart surface on which a predetermined chart for inspecting an electronic shutter speed of the rotating plate and the imaging element are facing each other, and the rotating plate. A rotation step for rotating, an imaging step for imaging the rotating plate in a rotated state by the imaging device, a signal processing step for processing a signal acquired by the imaging device in the imaging step, and a signal processed in the signal processing step And an image display step of displaying an image of the chart surface using.

  According to such a shutter speed inspection method, the inspector can visually recognize the image of the rotating chart surface. Here, since the chart surface is rotating, the chart is displayed as a blurred image corresponding to the electronic shutter speed. The inspector can inspect the electronic shutter speed of the image sensor by visually recognizing this blurring state.

  The shutter speed inspection method may further include, for example, a video synchronization signal acquisition step of acquiring a video synchronization signal in accordance with the display format of the display unit that displays the chart surface image. In such a case, in the rotation step, the rotation frequency of the rotating plate is controlled based on the frequency of the video synchronization signal.

Also the shutter speed inspection method, for example image and the reference frequency generating step of generating a reference frequency based on the frequency of the synchronizing signal, the reference frequency may be further those containing a reference frequency adjustment step of adjusting the. In such a case, in the rotation step, the rotation frequency of the rotating plate is controlled to coincide with the reference frequency adjusted in the reference frequency adjustment step.

  A shutter speed inspection chart according to an aspect of the present invention that solves the above problem is a predetermined chart for inspecting an electronic shutter speed of an image sensor, and is rotated during the inspection. The shutter speed inspection chart includes at least one circle centered on the rotation center of the chart and a plurality of straight lines extending from the vicinity of the rotation center and intersecting each circle, and are parallel to each other with a predetermined interval. A plurality of straight lines are drawn so that The chart for checking the shutter speed of the at least one circle is such that when the electronic shutter speed is a predetermined value, the apparent contrast between the straight lines during the rotation of the chart is reduced on the circumference. It is characterized by a fixed radius.

  When the inspection is performed using such a shutter speed inspection chart, the inspector can easily inspect the electronic shutter speed at a position where the contrast is lowered on the chart.

  According to the present invention, a shutter speed inspection jig and method suitable for inspecting the shutter speed of an electronic shutter type imaging apparatus are provided. A shutter speed inspection chart suitable for such a jig and method is also provided.

  Hereinafter, a shutter speed inspection jig according to an embodiment of the present invention and a shutter speed inspection method using the jig will be described with reference to the drawings. In the following description, “shutter speed” means the electronic shutter speed of a CCD (imaging device).

  FIG. 1 is a diagram schematically illustrating the external appearance of a shutter speed inspection jig 100 according to the present embodiment and an electronic endoscope system 1 set on the shutter speed inspection jig 100.

  The electronic endoscope system 1 is a well-known system for observing and diagnosing the inside of a patient's body cavity, and includes an electronic endoscope 10, a processor (signal processing device with built-in illumination light source) 20, and a monitor (display device) 30. It has. The electronic endoscope 10 is a direct-view type endoscope, and a CCD (not shown) is held in the distal end portion 12 thereof. In the present embodiment, this CCD is an inspection object. The electronic endoscope system 1 has a known configuration and operation. The details are disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-215419 by the present applicant. Therefore, the detailed description in this specification about the electronic endoscope system 1 will be omitted.

  The shutter speed inspection jig 100 has a configuration in which a main body 120 and a grip 140 are installed on a base 110. FIG. 2 is a block diagram showing the configuration of the main body 120. The main body 120 will be described in detail with reference to FIG.

  The main body 120 includes a frequency conversion circuit 122, an input key 124, a phase comparator 126, a drive circuit 128, a DC motor 130, a rotary encoder 132, and a rotating plate 134.

  In the present embodiment, a signal line is drawn out from a timing generator (not shown) provided in the processor 20 to the frequency conversion circuit 122 and is electrically connected to each other. As a result, the pulse from the timing generator is input to the frequency conversion circuit 122 during the period when the electronic endoscope system 1 is performing the imaging process. Here, the pulse input to the frequency conversion circuit 122 is a vertical synchronization signal (hereinafter, for convenience of explanation, “Fs” is added to the vertical synchronization signal). In addition, the display format of the monitor 300 is an NTSC (National Television Standards Committee) system, and the processor 20 is also configured to perform signal processing corresponding thereto. Therefore, the vertical conversion signal Fs of 60 (Hz) is input to the frequency conversion circuit 122.

  The frequency conversion circuit 122 up-converts (or down-converts) the vertical synchronization signal Fs from the timing generator to a predetermined frequency and outputs the converted signal to the phase comparator 126. More specifically, the frequency conversion circuit 122 has a function of converting the vertical synchronization signal Fs to a frequency of k times (k> 0). The inspector can adjust the frequency conversion rate (that is, the coefficient k) by the frequency conversion circuit 122 by operating the input key 124. For convenience of explanation, a signal after frequency conversion by the frequency conversion circuit 122 is referred to as “frequency-converted signal Fs ′”.

  The phase comparator 126 is a known PLL (Phase Locked Loop) circuit that operates using the frequency-converted signal Fs ′ as a reference signal. The phase comparator 126 receives the frequency converted signal Fs ′ and the index pulse Ft. The index pulse Ft is a pulse output from the rotary encoder 132. The rotary encoder 132 outputs an index pulse Ft every time the DC motor 130 makes one rotation. The phase comparator 126 can detect the rotation frequency F of the DC motor 130 by receiving the index pulse Ft. Note that the index pulse Ft and the rotation frequency F are substantially the same value, but for the sake of convenience of description, both are given different symbols.

  The phase comparator 126 operates to match the phase and frequency of the frequency converted signal Fs ′ and the index pulse Ft. More specifically, the phase comparator 126 generates a drive signal based on the result of comparison with each other and outputs the drive signal to the drive circuit 128. The drive circuit 128 controls the drive of the DC motor 130 at a frequency corresponding to the drive signal. As a result, the DC motor 130 is driven at the rotational frequency F that matches the frequency of the frequency-converted signal Fs ′. At the same time, the rotational frequency F of the DC motor 130 is detected by the rotary encoder 132 and output to the phase comparator 126 as an index pulse Ft. The phase comparator 126 compares the index pulse Ft with the frequency converted signal Fs ′ again to generate and output a drive signal. By such negative feedback control, the rotational frequency F of the DC motor 130 immediately converges to a frequency that is substantially the same as the frequency-converted signal Fs ′, and is maintained at that frequency thereafter.

  FIG. 3A shows a front view of the rotating plate 134. FIG. 3B shows a side view of the rotating plate 134 and the DC motor 130. In addition, FIG. 3A is a diagram when the rotating plate 134 is observed from the direction of arrow A in FIG.

  According to FIG. 3A, the rotating plate 134 has a disc shape. A hole is formed at the center, and the hole is fitted into the rotating shaft 130 a of the DC motor 130. As a result, the rotating plate 134 is fixed and supported on the rotating shaft 130a. For this reason, when the DC motor 130 is driven and the rotating shaft 130a rotates, the rotating plate 134 also rotates.

  A chart necessary for inspecting the shutter speed of the CCD is drawn on the rotating plate 134. This chart specifically consists of four circles and two sets of line sections. The four circles are drawn concentrically. The center of each circle coincides with the center of the rotating plate 134 (that is, the center of rotation of the rotating shaft 130a). The letters “500”, “1000”, “1500”, and “2000” are attached close to each circle.

For convenience of explanation, the circle "500" is attached adjacent "circle C ₁ ', the circle" 1000 "is attached proximate" circle C _2', attached proximate the "1500" It was "circle C _3" the circle, the circle of "2000" is attached in close proximity referred to as "the circle C _4". The circle C ₁ , the circle C ₂ , the circle C ₃ , and the circle C ₄ have radii 5.3 (mm), 10.6 (mm), 15.9 (mm), and 21.2 (mm), respectively. The size of these circles is appropriately set as an index for inspection of the shutter speed of the CCD.

Each of the two sets of line portions is composed of four lines arranged in parallel to each other. These lines have a width W (mm) and are arranged at a pitch of W (mm). In this embodiment, W = 2. The length of each line is about the radius of the rotating plate 134. In addition, each line is drawn so as to extend from the vicinity of the center of the rotating plate 134 to the vicinity thereof. For convenience of explanation, one set of line portions is referred to as “L ₁ ”, and the other set of line portions is referred to as “L ₂ ”.

  Here, the description returns to FIG. As shown in FIG. 1, when the electronic endoscope system 1 is set on the shutter speed inspection jig 100, the grip portion 140 is positioned near the distal end portion 12 so that the imaging direction of the electronic endoscope 10 faces the rotary plate 134. Hold by. The grip part 140 has a known gripping mechanism. As such a gripping mechanism, for example, a mechanism in which the vicinity of the distal end portion 12 is sandwiched between two claw portions is assumed.

  A guide part (not shown) is formed in the grip part 140. When the electronic endoscope 10 is grasped by the grasping portion 140 while being guided by the guiding portion (that is, with the electronic endoscope 10 being placed along the shape of the guiding portion), the front surface of the distal end portion 12 (more accurately) The CCD light receiving surface) and the rotating plate 134 are located at a predetermined distance from each other and facing each other.

Next, the operation of the shutter speed inspection jig 100 when performing inspection will be described. The operation here is adjustment of the frequency conversion rate of the frequency conversion circuit 122 by the input key 124. When it is assumed that the number of sets of line portions on the rotating plate 134 is “Q” and each line portion is drawn every (360 / Q) degrees in the circumferential direction of the rotating plate 134, the following equation is obtained. It is preferable to set the frequency conversion rate so as to be established.
Q * Ft = kFs (= Fs ′) (1)

4A to 4C are diagrams for explaining the relationship between the image of the rotating plate 134 to be photographed and the equation (1). 4A, 4B, and 4C, respectively, are photographed when the input key 124 is operated to set the coefficient k to “0.5”, “1.0”, and “2.0”. The images for each field of the rotating plate 134 are arranged in time series. In the present embodiment, as described above, the vertical synchronization signal Fs is 60 (Hz), and the number of sets Q is two. Substituting these into equation (1) gives
Ft = 30k (2)
It becomes.

  When the coefficient k is “0.5”, the rotation frequency F of the rotating plate 134 (in other words, the index pulse Ft) becomes 15 (Hz) by the PLL control described above. Here, the field image is acquired every 1/60 seconds. For this reason, the rotating plate 134 rotates 90 degrees every time an image of one field is acquired. Therefore, the monitor 30 displays an image of the rotating plate 134 rotated by 90 degrees for each field.

According to FIG. 4A, two types of images in which the line portions L ₁ and L ₂ are arranged horizontally or vertically are displayed alternately on the monitor 30. In addition, these two types of images are displayed alternately at 60 (Hz). Therefore, an image as shown in FIG. 5A (image in which the line portion appears to be a cross shape on the rotating plate 134) appears as a still image in the eyes of the examiner.

  When the coefficient k is “1.0”, the rotation frequency F of the rotating plate 134 becomes 30 (Hz) by the PLL control described above. For this reason, the rotating plate 134 rotates 180 degrees every time an image of one field is acquired. Therefore, an image of the rotating plate 134 rotated 180 degrees for each field is displayed on the monitor 30.

  On the other hand, line portions on the rotating plate 134 are drawn every 180 (= 360 / Q) degrees in the circumferential direction. For this reason, even if the rotating plate 134 is rotated 180 degrees, the geometric pattern is reflected in the eyes of the examiner. Therefore, as shown in FIG. 4B, the substantially same image is continuously displayed on the monitor 30. Therefore, an image as shown in FIG. 5B (an image that looks almost the same as when the rotating plate 134 is stationary) appears in the eyes of the examiner as a still image.

  When the coefficient k is “2.0”, the rotation frequency F of the rotating plate 134 is 60 (Hz) by the PLL control described above. For this reason, the rotating plate 134 rotates 360 degrees every time an image of one field is acquired. Accordingly, the monitor 30 displays an image of the rotating plate 134 rotated 360 degrees (that is, one rotation) for each field. As a result, as shown in FIG. 4C, images that are substantially the same are continuously displayed on the monitor 30. In addition, a video as shown in FIG. 5C (substantially the same image as FIG. 5B) appears as a still image in the eyes of the examiner.

  By setting the coefficient k to an appropriate value as described above, the line portion is displayed on the monitor 30 as if it were stationary. In addition, the line portion is displayed without flickering. That is, according to the shutter speed inspection jig 100 of the present embodiment, it is possible to provide an inspector with an inspection image with excellent visibility.

  Next, actual inspection using the shutter speed inspection jig 100 will be described. 6 and 7 are diagrams for explaining how to read the chart.

When a blur amount (in other words, a moving amount) at a point P away from the rotation center of the rotating plate 134 at a certain exposure time (that is, shutter speed) t (sec) is ΔP (mm), The formula holds.
ΔP = 2πFRt (mm) (3)

  Here, according to FIG. 6, the bright part and the dark part formed by two adjacent lines appear relatively clearly between the rotation center of the rotary plate 134 and the position away from the distance r. On the other hand, the blur amount ΔP of each line is equal to or greater than the width W in a portion that is separated from the rotation center of the rotating plate 134 by a distance r or more. This means that two adjacent lines appear to completely overlap and even intersect. For this reason, to the examiner, the boundary between the bright part and the dark part becomes thinner in the vicinity of the part separated by the distance r or more, and the line part appears to have a relatively uniform density.

For example, when the coefficient k is “1.0” and an appropriate value (W = ΔP = 2, Ft = F = 30) is substituted for each parameter of the equation (3), the distance r can be expressed by the following equation.
r = 1 / (60πt) (4)

  FIG. 7A shows a still image of the rotating plate 134. FIG. 7B shows an image obtained by photographing the rotating plate 134 rotating at 30 (Hz) at a shutter speed of 1/500 (sec). FIG. 7C shows an image obtained by photographing the rotating plate 134 rotating at 30 (Hz) at a shutter speed of 1/1000 (sec). FIG. 7D shows an image obtained by photographing the rotating plate 134 rotating at 30 (Hz) at a shutter speed of 1/2000 (sec). Such a still image can be displayed on the monitor 30 by, for example, operating a well-known “freeze” function. “Freeze” is disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-215419 by the present applicant.

  For example, when the shutter speed is 1/500 (sec), the distance r is approximately 5.3 (mm) when calculated using the number (4). In the case of 1/1000 (sec), the distance r is approximately 10.6 (mm). In the case of 1/2000 (sec), the distance r is approximately 21.2 (mm).

Referring to FIG. 7 (b), it can be seen that the contrast of the line portion is reduced in the circle C ₁ neighborhood. Referring also to FIG. 7 (c), the it can be seen that the contrast of the line portion is reduced in the circle C ₂ vicinity. Referring to FIG. 7 (d), the it can be seen that the contrast of the line portion is reduced in the circle C ₄ neighbors. The inspector can inspect the current shutter speed of the CCD by viewing such an image on the monitor 30. That is, when the images in FIGS. 7B, 7C, and 7D are viewed, the shutter speeds are about 1/500 (sec), 1/1000 (sec), and 1/2000 (sec), respectively. Can be confirmed.

  The rotating plate 134 is manufactured according to the specification of the CCD to be inspected. This means that any CCD can be inspected using the shutter speed inspection jig 100 by appropriately setting circles and line portions on the rotating plate 134.

  When the shutter speed inspection jig 100 of this embodiment is used, it is possible to visually inspect the image captured by the CCD and inspect the shutter speed of the CCD. That is, since an inspection is performed using an image captured by the inspection object itself, a highly accurate inspection is expected.

  In addition, there is an advantage that it is not necessary to disassemble the electronic endoscope 10 at the time of inspection. As a secondary effect of such merit, it is possible to inspect the shutter speed of the CCD mounted on the electronic endoscope 10 (that is, the CCD in the actual state).

  The above is the embodiment of the present invention. The present invention is not limited to these embodiments and can be modified in various ranges. For example, in the present embodiment, an inspection image is acquired using the electronic endoscope system 1, but in another embodiment, an image signal processing apparatus and a monitor dedicated to inspection are used as an alternative to the processor 20 and the monitor 30. The inspection may be performed.

  Further, according to the shutter speed inspection jig 100 of the present embodiment, it is not necessary to strictly manage the distance between the rotating plate 134 and the distal end portion 12 when the electronic endoscope 10 is attached to the grip portion 140. The minimum requirement for the distance is only to attach the electronic endoscope 10 to the grip 140 so that the entire rotary plate 134 is within the CCD imaging range. This is because the size of the chart shown on the monitor 30 is not used as an index for measuring the shutter speed. Therefore, in another embodiment, a shape that regulates the distance between the distal end portion 12 and the rotating plate 134 may not be provided in the guide portion.

It is the figure which showed schematically the external appearance of the electronic endoscope system set to the shutter speed inspection jig | tool of embodiment of this invention, and a shutter speed inspection jig. It is the block diagram which showed the structure of the main-body part with which the shutter speed test | inspection jig | tool of embodiment of this invention was equipped. It is a front view of the rotating plate with which the main-body part of embodiment of this invention was equipped. It is a figure for demonstrating the relationship between the image of the rotating plate of embodiment of this invention, and Formula (1). It is a figure for demonstrating the relationship between the image of the rotating plate of embodiment of this invention, and Formula (1). It is a figure for demonstrating how to read the chart on the rotating plate of embodiment of this invention. It is a figure for demonstrating how to read the chart on the rotating plate of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic endoscope system 10 Electronic endoscope 20 Processor 30 Monitor 100 Shutter speed inspection jig 120 Main-body part 134 Rotating plate

Claims (13)

A shutter speed inspection jig for inspecting an electronic shutter speed of an image sensor,
A rotating plate having a chart surface on which a predetermined chart for inspecting an electronic shutter speed is drawn;
A rotation drive unit rotatably supporting the rotating plate;
A fixing portion for fixing the imaging device in a state of facing the chart surface;
And a display unit for displaying an image of the chart surface imaged by the imaging device.   The signal processing unit according to claim 1, further comprising a signal processing unit that converts a signal acquired by the image sensor into a signal of a predetermined display format so that the signal can be displayed on the display unit and outputs the signal to the display unit. Shutter speed inspection jig.   The shutter speed inspection jig according to claim 2, wherein the predetermined display format is an NTSC format. Synchronization signal acquisition means for acquiring a predetermined video synchronization signal from the signal processing unit;
The rotation control means which controls the rotation frequency of the said rotating plate by the said rotation drive part based on the acquired image | video synchronizing signal, It further provided with any one of Claim 2 or Claim 3 characterized by the above-mentioned. The shutter speed inspection jig described.   5. The rotation control unit according to claim 4, wherein the rotation control unit generates a reference frequency based on the frequency of the video synchronization signal, and controls the rotation frequency of the rotating plate with reference to the generated reference frequency. Shutter speed inspection jig.   The shutter speed inspection jig according to claim 5, wherein the rotation control unit controls the rotation frequency of the rotating plate to coincide with the reference frequency.   The shutter speed inspection jig according to claim 5, further comprising a reference frequency adjusting unit capable of adjusting the reference frequency.   The shutter speed inspection jig according to any one of claims 4 to 7, wherein the video synchronization signal is a vertical synchronization signal. A shutter speed inspection jig for inspecting an electronic shutter speed of an image pickup apparatus provided with an image pickup element and capable of processing and displaying an image acquired by the image pickup element,
A rotating plate having a chart surface on which a predetermined chart for inspecting an electronic shutter speed is drawn;
A rotation drive unit rotatably supporting the rotating plate;
A shutter speed inspection jig, comprising: a fixing portion that fixes the imaging device in a state of facing the chart surface. A shutter speed inspection method for inspecting an electronic shutter speed of an image sensor,
A fixing step of fixing a chart surface on which a predetermined chart for inspecting an electronic shutter speed of the rotating plate is drawn and the imaging element to face each other;
A rotating step of rotating the rotating plate;
An imaging step of imaging the rotating plate in a rotated state by the imaging device;
A signal processing step of processing a signal acquired by the imaging device in the imaging step;
An image display step of displaying an image of the chart surface using the signal processed in the signal processing step. A video synchronization signal acquisition step of acquiring a video synchronization signal according to a display format of a display unit that displays the image of the chart surface;
The shutter speed inspection method according to claim 10, wherein in the rotation step, the rotation frequency of the rotating plate is controlled based on the frequency of the video synchronization signal. A reference frequency generation step of generating a reference frequency based on the frequency of the video synchronization signal;
Further seen including and a reference frequency adjustment step of adjusting the reference frequency,
The shutter speed inspection method according to claim 11, wherein in the rotation step, the rotation frequency of the rotating plate is controlled to coincide with the reference frequency adjusted in the reference frequency adjustment step . It is a predetermined chart for inspecting the electronic shutter speed of the image sensor, and is a chart rotated during the inspection,
At least one circle centered on the rotation center of the chart and a plurality of straight lines extending from the vicinity of the rotation center and intersecting each circle, and arranged in parallel with each other at a predetermined interval A straight line is drawn,
When the electronic shutter speed is a predetermined value, the radius of the at least one circle is determined on the circumference so that the apparent contrast between the straight lines during chart rotation decreases. Characteristic shutter speed inspection chart.

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