Device for testing exposure time of camera

Abstract

The invention provides a camera exposure time testing device. The camera exposure time testing device comprises a light source module which can generate a light beam emitted to a to-be-tested camera; the driving device drives the light beam to do circular motion with the radius being R at the rotating speed n; and calculating the exposure time by using the arc length L of a light spot track formed by the light beam in the photo shot by the camera to be tested, the rotating speed n and the radius R. The light source module can generate a stable point light source, the relative rotation of the point light source on the circular ring surface is controlled through the optical principle and a specifically designed optical element, the imaging effect can be accurately controlled, and thus the accuracy of a test result is improved. The method does not depend on natural light, so that stable and accurate test results can be obtained under different ambient light conditions, and the test reliability is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of photographic equipment, and in particular relates to a device for testing the exposure time of a camera. Background Art

[0002] In the process of photography, the exposure time of the camera has a crucial impact on the final imaging effect. Exposure time that is too long or too short will cause the photo to be overexposed or underexposed, affecting the photo quality. In order to ensure that the camera can obtain the best exposure effect in different shooting environments, the camera's exposure time needs to be accurately tested and adjusted. Existing testing methods mostly rely on experienced photographers to make subjective judgments, or use complex electronic equipment for measurement. These methods are not only cumbersome to operate, but also costly.

[0003] The patent with prior art application number 201910731777.8 discloses a system for testing the exposure time of a camera device, including a testing device and a camera device, the testing device including a turntable with a motor, a pointer fixed at the center of the turntable, a 360-degree angle scale is set on the periphery of one side of the turntable on which the pointer is fixed, and the center of the 360-degree angle scale is concentric with the center of the turntable; when testing the exposure time of the camera device, the motor is started, and after the turntable is driven by the motor to rotate according to a predetermined speed of the motor, the camera device captures image data including the pointer, the turntable and the angle scale to determine the exposure time of the camera device according to the fan-shaped trailing angle of the pointer captured in the image data.

[0004] However, the above-mentioned prior art still has some shortcomings. First, the system requires a motor to drive the turntable, which increases the complexity and cost of the device. Secondly, the rotation speed of the turntable needs to be precisely controlled, and the stability has an important impact on the accuracy of the test results. However, since the turntable is often huge, if the turntable shakes or rotates unevenly during rotation, it will directly affect the accuracy of the pointer drag, thereby affecting the measurement result of the exposure time. In addition, since the system does not have a light source system, it needs to use natural light for imaging. In practical applications, it may be affected by changes in ambient light, resulting in unstable and inaccurate test results. In addition, due to the mass of the turntable, the motor drives the turntable to rotate, and its speed is limited, and it cannot reach an extremely high speed. It can also reach a relatively high speed, but it requires a matching extremely high-performance motor and a turntable with extremely high strength and light weight, which is difficult to achieve. After our experimental verification, a turntable with a diameter of one meter cannot be made of carbon fiber or titanium alloy. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides a simple, low-cost and easy-to-operate camera exposure time test device. The device uses optical principles and specially designed optical elements and optical path systems to achieve accurate testing of camera exposure time.

[0006] In one aspect, the present invention provides a camera exposure time testing device, comprising:

[0007] Light source module: The light source module can generate a light beam that is directed toward the camera to be tested;

[0008] The driving device drives the parallel light beam to make a circular motion with a radius R at a rotation speed n;

[0009] The exposure time is calculated using the arc length L of the light spot track formed by the light beam in the photo taken by the camera to be tested, the rotation speed n, and the radius R.

[0010] Furthermore, the device for testing camera exposure time also includes an annular plate, the annular plate includes an annular surface, the circumference of the annular surface is marked with scales, and the parallel light beam performs circular motion with the annular surface as the background.

[0011] Furthermore, the accuracy of the scale is 1 mm.

[0012] Furthermore, the driving device is a servo motor with adjustable speed.

[0013] Furthermore, the light source module includes an incandescent lamp, a lamp holder and a light-shielding tube, the incandescent lamp is mounted on the lamp holder, the light-shielding tube is covered on the incandescent lamp, a light-transmitting hole is opened on the peripheral wall of the light-shielding tube, and the incandescent lamp generates a light beam propagating vertically through the light-transmitting hole.

[0014] Furthermore, a 45° conical mirror is integrally formed on the periphery of the annular plate, for reflecting the light beam propagating in the vertical direction into a light beam propagating in the horizontal direction.

[0015] Furthermore, the device for testing camera exposure time also includes: a main body support, which is L-shaped and includes an integrally formed horizontal section and a vertical section, the motor is installed on the vertical section, the output shaft of the motor is fixedly connected to the light shield, the light shielding tube is not in contact with the lamp holder and the incandescent lamp, and the circular ring plate is fixedly installed on the vertical section.

[0016] On the other hand, the present application provides a method for testing camera exposure time using the device for testing camera exposure time of the present application, the method comprising the following steps:

[0017] Fix the camera to be tested in front of the test device and ensure that the camera lens is aligned with the center of the circular plate with a radius of R;

[0018] Turn on the light source module, start the motor, and make the light shielding tube start to rotate at a speed n;

[0019] Use the camera to take a photo to obtain the arc length L of the light spot track in the photo;

[0020] According to the formula, camera exposure time Calculate camera exposure time.

[0021] Furthermore, the method also includes: adjusting the rotation speed n of the motor so that the arc length L of the light spot track in the photo is ≤2πR.

[0022] Furthermore, the method also includes: adjusting the rotation speed n of the motor multiple times, and taking an average value of the camera exposure time obtained at different rotation speeds.

[0023] Compared with the prior art, the beneficial technical effects of this application are:

[0024] The light source module of the present invention can generate a stable point light source. By controlling the relative rotation of the point light source on the annular surface through optical principles and specially designed optical elements, the imaging effect can be accurately controlled, thereby improving the accuracy of the test results. Fast and uniform rotation of the bright spot can be achieved, avoiding the jitter and uneven rotation problems that may be caused by the traditional turntable, and further improving the stability of the test. At the same time, unlike other devices with similar functions, it is not necessary to drive the turntable to rotate, thereby greatly improving the upper limit of the rotation speed, and then measuring a shorter exposure time. Since the present invention does not rely on natural light, stable and accurate test results can be obtained under different ambient light conditions, thereby improving the reliability of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 : Schematic diagram of the device for testing camera exposure time of the present application;

[0026] Figure 2 : Schematic diagram of the device for testing camera exposure time of the present application;

[0027] Figure 3 : A cross-sectional view of a device for testing camera exposure time of the present application;

[0028] Figure 4 : Schematic diagram of the optical path of the device for testing camera exposure time of the present application;

[0029] Figure 5 : Schematic diagram of photos taken by the camera of this application; DETAILED DESCRIPTION

[0030] The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the spirit and substance of the present invention, modifications or substitutions made to the methods, steps or conditions of the present invention all fall within the scope of the present invention.

[0031] like Figure 1 As shown, an embodiment of the present invention provides a camera exposure time testing device, comprising:

[0032] Light source module 1 The light source module 1 can generate a light beam 104 directed toward the camera 4 to be tested;

[0033] Driving device 3 The driving device drives the light beam 104 to make a circular motion with a radius R at a rotation speed n;

[0034] The exposure time is calculated using the arc length L of the light spot track formed by the light beam 104 in the photo taken by the camera 4 to be tested, the rotation speed n, and the radius R.

[0035] In some specific embodiments, Figure 2 and Figure 3 As shown, the light source module includes an incandescent lamp 101, a lamp holder 102, and a light shielding tube 103. The incandescent lamp 101 is mounted on the lamp holder 102, and the light shielding tube 103 is covered on the incandescent lamp 101. A light-transmitting hole 1031 is provided on the peripheral wall of the light shielding tube 103. The light generated by the incandescent lamp 101 generates a light beam propagating in a vertical direction through the light-transmitting hole 1031. In order to ensure the uniformity and stability of the light beam, the inner wall of the light shielding tube 103 may be coated with a material with high reflectivity to reduce light energy loss and improve the quality of the light beam.

[0036] In some other embodiments, the light source module may also be a laser generator, which can generate a highly stable light beam and convert the laser beam 106 into a parallel light beam 104 through a specially designed optical element, such as a lens 107, to ensure the accuracy of the test.

[0037] The device for testing camera exposure time of the present application includes a main body support 4, which is L-shaped and includes an integrally formed horizontal section 401 and a vertical section 402. The motor 3 is installed on the vertical section 402. The output shaft of the motor 3 is fixedly connected to the light-shielding tube 103. The light-shielding tube 103 is not in contact with the lamp holder 102 and the incandescent lamp 101. The circular ring plate 2 is fixedly installed on the vertical section.

[0038] The motor 3 can drive the light shielding cylinder 103 to rotate at a constant speed, so that the light beam emitted from the light transmission hole 1031 forms a stable bright spot on the annular surface. The relative rotation speed of the bright spot on the annular surface is equal to the rotation speed of the light shielding cylinder 103. By controlling the rotation speed of the motor 3, the rotation speed of the bright spot can be accurately controlled.

[0039] In certain embodiments, such as Figure 4 As shown, a 45° conical mirror 202 is integrally formed on the periphery of the annular plate 2, which can reflect the light beam propagating in the vertical direction into a light beam propagating in the horizontal direction. In this way, the rotation of the bright spot on the annular surface can be captured horizontally by a camera placed in front of the device for testing the exposure time of the camera of the present application, so that the exposure time test can be performed more conveniently.

[0040] In order to improve the accuracy of the test, the circumference of the annular surface 201 is marked with scales, which can be used to measure the angle of the bright spot smear, and then calculate the exposure time of the camera. In this way, the error that may be caused by using a traditional turntable can be avoided, because the accuracy of the scale can be very high, and because the motor only drives the light shielding cylinder to rotate, the rotation of the bright spot on the annular plate 2 will be very uniform and stable.

[0041] In the reference document, the motor drives the turntable to rotate, which will cause a large load on the motor, and the motor has high requirements, and the maximum speed that can be achieved is limited. In this application, the motor only needs to drive the shading tube to rotate. Since the shading tube is light, uniform in mass, and has a small rotation radius, the moment of inertia is small, the wind resistance torque is small, and the vibration is small during rotation. The upper limit of the speed can be easily increased, which increases the test upper limit of the device.

[0042] In the above embodiment, the principle of measuring the camera exposure time using the device for testing the camera exposure time of the present application is as follows: first, fix the camera in an appropriate position of the testing device to ensure that the camera lens is aligned with the center of the circular plate. Then, start the motor to rotate the light shielding tube to generate a bright spot. By adjusting the speed of the motor, the rotation speed of the bright spot on the circular surface can be controlled, thereby simulating different exposure time conditions.

[0043] During the test, the motor speed n is a known value, and then the rotating bright spot is photographed. The rotation speed of the bright spot on the annular surface is known, and through the image captured by the camera, the trailing shadow formed by the bright spot on the annular surface can be observed. The angle of the trailing shadow is proportional to the exposure time of the camera. Therefore, by measuring the angle of the trailing shadow through the scale on the annular surface, the actual exposure time of the camera can be calculated.

[0044] Specific as Figure 5 As shown, in some specific embodiments, the schematic diagram of the photo taken by the camera to be tested is as follows Figure 4As shown, the distance from the bright spot on the annular surface to the light source is R, the arc length of the bright spot trail is L, the speed of the motor 3 is n, the unit is r / s, then the exposure time of the camera to be tested is calculated as

[0045] T=(L / (2πRn))*1000ms

[0046] Wherein, T is the exposure time, L is the arc length of the bright spot shadow, R is the distance from the bright spot to the light source, and n is the speed of the motor in revolutions per second (r / s). The result is multiplied by 1000 to convert the result into milliseconds (ms).

[0047] The above formula can be used to accurately calculate the exposure time of the camera, thereby accurately evaluating the performance of the camera. The testing device of the present invention is not only suitable for testing professional cameras, but also suitable for testing the exposure time of portable devices such as mobile phone cameras.

[0048] For example, for a test device with R of 0.5m, the upper limit of the motor speed is 100r / min, and the scale accuracy on the reflective ring is 1mm, then the shortest exposure time that this test device can test is: 3.18×10-6s.

[0049] To improve the measurement accuracy of this device, the R value can be increased when designing the device size, thereby increasing the L length during imaging and reducing reading errors.

[0050] For the same test device, the rotation speed n can be increased or decreased to match the exposure time of different cameras.

[0051] For the same camera to be tested, the exposure time can be tested at different rotation speeds.

[0052] In some embodiments, when the motor rotates very fast, the bright spot may form a shadow on the annular surface that covers the entire circumference. To prevent this from happening, the motor speed can be adjusted to ensure that the shadows do not overlap with each other, thereby ensuring measurement accuracy.

[0053] In summary, the present application provides a device for testing the exposure time of a camera. The device has a simple structure, low cost, and stable and reliable operation. It can be adjusted according to the test requirements to improve the test accuracy, and can be used to test cameras with extremely short exposure times.

[0054] Although the present invention has been described in detail above by general description, specific implementation methods and experiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A device for testing camera exposure time, characterized in that: The device for testing camera exposure time comprises: Light source module (1) The light source module (1) is capable of generating a light beam (104) directed toward a camera (5) to be tested; The driving device (3) drives the light beam (104) to perform circular motion with a radius R at a rotation speed n; The exposure time is calculated using the arc length L of the light spot track formed by the light beam (104) in the photo taken by the camera (5) to be tested, the rotation speed n, and the radius R.

2. The device for testing camera exposure time as claimed in claim 1, characterized in that: The device for testing the exposure time of a camera also includes a circular plate (2), the circular plate (2) includes a circular surface (202), the circumference of the circular surface (202) is marked with scales, and the light beam (104) performs circular motion with the circular surface (202) as a background.

3. The device for testing camera exposure time as claimed in claim 2, characterized in that: The accuracy of the scale is 1 mm.

4. The device for testing camera exposure time as claimed in claim 2, characterized in that: The driving device (3) is a servo motor with adjustable speed.

5. The device for testing camera exposure time as claimed in claim 4, characterized in that: The light source module comprises an incandescent lamp (101), a lamp holder (102) and a light shielding tube (103); the incandescent lamp (101) is mounted on the lamp holder (102); the light shielding tube (103) is covered on the incandescent lamp (101); a light-transmitting hole (1031) is provided on the peripheral wall of the light-transmitting hole (1031); and the incandescent lamp (101) generates a light beam propagating in a vertical direction through the light-transmitting hole (1031).

6. The device for testing camera exposure time as claimed in claim 5, characterized in that: A 45° conical mirror (201) is integrally formed on the periphery of the annular plate (2) and is used to reflect the light beam propagating in the vertical direction into a light beam propagating in the horizontal direction.

7. The device for testing camera exposure time as claimed in claim 5, characterized in that: The device for testing the exposure time of a camera further comprises: a main body support (4), the main body support (4) being L-shaped and comprising an integrally formed horizontal section (401) and a vertical section (402), the constant speed motor being mounted on the vertical section (402), the output shaft of the constant speed motor being fixedly connected to the light shielding tube (103), the light shielding tube (103) not being in contact with the lamp holder (102) and the incandescent lamp (101), and the annular plate (2) being fixedly mounted on the vertical section (402).

8. A method for testing camera exposure time using the device for testing camera exposure time according to claims 1-7, characterized in that: The method comprises the following steps: Fix the camera to be tested in front of the test device and ensure that the camera lens is aligned with the center of the circular plate with a radius of R; Turn on the light source module, start the motor, and make the light shielding tube start to rotate at a speed n; Use the camera to take a photo to obtain the arc length L of the light spot track in the photo; According to the formula, camera exposure time Calculate camera exposure time.

9. The method for testing camera exposure time as claimed in claim 7, characterized in that: The method further comprises: adjusting the rotation speed n of the motor so that the arc length L of the light spot track in the photo is ≤2πR.

10. The method for testing camera exposure time as claimed in claim 8, characterized in that: The method further includes: adjusting the rotation speed n of the motor multiple times, and taking an average value of the camera exposure time obtained at different rotation speeds.

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