Transmittance tester

Abstract

The utility model discloses a transmittance tester which comprises a host machine, and a tested object placing area used for measuring the transmittance of glass is arranged on the host machine; the light-emitting probe is arranged in the host, and the light-transmitting end of the light-emitting probe penetrates through the host and is arranged on the tested object placing area; and the receiving probe is arranged on the host, and the position of the receiving probe corresponds to the position of the light-emitting probe. According to the utility model, the current can be effectively reduced, and the driving current of the light source is the same as the current of a single-path light source; the service life of the light source can be effectively prolonged by reducing the current of the light source.

Description

Technical Field

[0001] The utility model relates to a tester, in particular to a transmittance tester. Background Art

[0002] Transmittance is the ability of light to penetrate a medium, which is the percentage of the luminous flux that penetrates the medium to the incident luminous flux. Most of the test objects are transparent or translucent materials such as glass and plastic. The transparency of the object under test is quantified and measured with numbers, and the test results are displayed on the display. Its test principle basically includes three parts: the emitting light source probe, the object under test and the receiving probe.

[0003] The transmittance testers on the market can be roughly divided into single-channel light source type and multi-channel light source (three-channel) type based on the light emitting structure;

[0004] Single-channel light source transmittance tester, because most light sources emit visible light, which is very close to natural white light, has a wide range of applicability. In theory, as long as it involves visible light penetrating the object being tested, if there are no special requirements (requirements on the frequency of light), a single-channel visible light transmittance tester can be used, and it can also meet most of our daily needs, such as the transmittance of window glass, transparent plastic bags, etc., which can well distinguish the degree of transmittance; Figure 1 As shown in the figure, the single-channel light source type transmittance tester uses only one light source (LED). As long as the light source and the receiving probe are on the same center line, the structure is simple and easy to use, and the test data is stable, which can meet most usage requirements.

[0005] The multi-channel light source (three-channel) type transmittance tester can select three LEDs with different luminous frequencies according to actual needs, such as visible light, ultraviolet light, and infrared light as an option, or ultraviolet light, infrared light, and blue light, and any combination is available. This type of transmittance tester mainly tests the transmittance of a certain frequency of light. For example, ultraviolet transmittance is an important parameter for sunglasses and car glass. For example, infrared transmittance is an important parameter for the receiving panel of an infrared remote control; Figure 2 As shown in the figure, for a multi-channel (three-channel) type transmittance tester, since the receiving probe cannot be aligned with the center line of the three light sources at the same time, three reflective and refracting glasses can only be added to make the emitted light of the three light sources be on the same center line with the receiving probe after reflection and refraction; this structure can basically meet the use requirements. Figure 1 , this tester can also be applied to more usage scenarios.

[0006] 1. From the test results, Figure 1 The structure shown is Figure 2The structure shown in the figure is more accurate, that is, the test result of the second structure is less accurate, but both can meet the test requirements, as shown in the following table. The same material is tested by two instruments separately, and the test data of the single-channel instrument is more stable. Because the multi-channel type adds three refraction mirrors, in order to achieve the same luminous flux as the single-channel type, this has higher requirements on the light source. The luminous brightness of the light source needs to be increased to offset the attenuation of light passing through the refraction mirror; because the number of refraction mirrors passed by the light emitted by each light source is different, all the attenuation is also different. This requires the use of a higher brightness light source, and the corresponding drive current will also increase. In theory, a small current is easier to control than a large current, and the life of the light source is also higher, so the test results of the single-channel type are also more stable.

[0007] 55% standard glass sheet test record

[0008] 2. It is difficult to accurately fix the reflectors. The reflection angles of the three reflectors need to be precisely in the same straight line with the light receiver, so the installation position of the reflectors needs to be very accurately fixed; this is also disadvantageous in terms of production, as process deviations are prone to occur. Utility Model Content

[0009] The technical problem to be solved by the utility model is to provide a transmittance tester to solve the test consistency problem of a multi-channel transmittance tester; the same accuracy as that of a single-channel transmittance tester can be achieved.

[0010] The utility model transmittance tester is realized by the following technical solutions, including:

[0011] A host computer, wherein the host computer is provided with a test object placement area for measuring the light transmittance of the glass;

[0012] A light-emitting probe, wherein the light-emitting probe is arranged inside the mainframe, and a light-transmitting end of the light-emitting probe passes through the mainframe and is placed on the area where the object to be measured is placed;

[0013] The receiving probe is arranged on the host, and the position of the receiving probe corresponds to that of the light emitting probe.

[0014] As a preferred technical solution, the interior of the main unit is hollow to form an installation cavity, and the light-emitting probe is arranged in the installation cavity.

[0015] As a preferred technical solution, a mounting bracket is provided on the main body, and the receiving probe is fixed on the mounting bracket.

[0016] As a preferred technical solution, the light-emitting probe includes a mounting base and a PCB board, and the interior of the mounting base is hollow to form a light guide groove; the PCB board is provided with three LED light sources in a herringbone structure; a transmission hole is provided at the light-transmitting end above the mounting base, and the transmission hole corresponds to the overlapping area of ​​the light spots of the three light sources, and the test glass is placed on the transmission hole.

[0017] As a preferred technical solution, a display and control panel is provided on the host, and the light-emitting probe and the receiving probe are connected and controlled via the display and control panel.

[0018] As a preferred technical solution, a constant current circuit is provided on the PCB board.

[0019] As a preferred technical solution, the constant current circuit is composed of R1, R2, R3, R4, RS and operational amplifiers U1 and U2; wherein Vref is the reference voltage for adjusting the constant current output; the constant current circuit incorporates negative feedback and positive feedback to make the output current more stable.

[0020] The beneficial effects of the utility model are:

[0021] 1. The utility model can effectively reduce this current through the structure of multiple light sources, and the driving current of the light source is the same as the current of a single light source; by reducing the current of the light source, the service life of the light source can be effectively increased.

[0022] 2. After the utility model is driven by constant current, the luminous intensity will not change due to the decrease of the internal resistance of the light source, thereby ensuring the stability of the test results and increasing the service life of the light source. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 The structure of the prior art is shown in FIG. Figure 1 ;

[0025] Figure 2 The structure of the prior art is shown in FIG. Figure 2 ;

[0026] Figure 3 This is a schematic diagram of the mainframe structure of the utility model;

[0027] Figure 4 This is a schematic diagram of the structure of the light-emitting probe of the utility model;

[0028] Figure 5 This is a schematic diagram of the PCB board structure of the utility model;

[0029] Figure 6 This is a schematic diagram of the light spot of the utility model;

[0030] Figure 7 This is a circuit diagram of the utility model.

[0031] Description of reference numerals:

[0032] 1. Main unit; 2. Light-emitting probe; 3. Receiving probe; 4. Mounting bracket; 5. Mounting seat; 6. PCB board; 7. Transmission hole; 8. Display and control panel; 9. Placement area for the object to be measured. DETAILED DESCRIPTION

[0033] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0034] like Figure 3-Figure 5 As shown, a transmittance tester of the utility model comprises:

[0035] A host 1, wherein the host 1 is provided with a test object placement area 9 for measuring the light transmittance of glass;

[0036] A light-emitting probe 2, wherein the light-emitting probe 2 is arranged inside the main unit 1, and a light-transmitting end of the light-emitting probe 2 passes through the main unit 1 and is placed on the measured object placement area 9;

[0037] The receiving probe 3 is arranged on the host 1 , and the position of the receiving probe 3 corresponds to that of the light emitting probe 2 .

[0038] In this embodiment, the main body 1 is hollow inside to form an installation cavity, and the light emitting probe 2 is disposed in the installation cavity.

[0039] In this embodiment, a mounting bracket 4 is provided on the main body, and the receiving probe 3 is fixed on the mounting bracket 4 .

[0040] like Figure 6As shown, the light-emitting probe 2 includes a mounting base 5 and a PCB board 6, and the mounting base 5 is hollow inside to form a light guide groove; the PCB board 6 is provided with three LED light sources in a triangular structure; a transmission hole 7 is provided at the light-transmitting end above the mounting base 5, and the transmission hole 7 corresponds to the overlapping area of ​​the light spots of the three light sources, and the test glass is placed on the transmission hole 7; the light sources of the multi-channel light source are arranged in a triangular shape, and the light source theoretically emits parallel light, but the actual production process cannot be completely parallel, and will present divergent light to varying degrees. At a certain distance from the light source, the light emitted by the three light sources will produce an overlapping area, and we use the light in the overlapping area to test the transmittance; assuming that the light emitted by the multi-channel light source is blue, red and green, respectively, the light they emit corresponds to the blue light spot, the red light spot and the green light spot. When the three light sources are arranged closely in a triangular shape, and the distance between the light spot and the light source is appropriately changed, the farther the distance, the larger the overlapping area of ​​the light spot, and of course the lower the brightness of the light spot. After determining the brightness and area of ​​the light spot, fix the distance between the light spot and the light source, take the light at the center of the overlapping area of ​​the light spot, and then reach the sensor after passing through the lens. Because there is no light attenuation like the refracting reflective glass plate in the middle, the driving current of the light source is the same as the driving current of the single-channel type. The experimental results also prove that the stability of the test results is the same.

[0041] After the three light sources are fixed on the PCB, the location of the transmission hole 7 is the overlapping area of ​​the light spot. The object to be measured is placed on the transmission hole 7. The light emitted by the light source passes through the transmission hole 7, then passes through the object to be measured, and reaches the sensor after being focused by the receiving end lens. In terms of structure, it is necessary to ensure that the center of the overlapping area of ​​the light spot, the center of the transmission hole 7, and the center of the lens are on the same line, so that the light signal received by the sensor is also the strongest, which is more conducive to the stability of the test results. The test results are as follows:

[0042] 55% standard glass sheet test record

[0043] In this embodiment, a display and control panel is provided on the host, and the light emitting probe and the receiving probe are connected and controlled via the display and control panel.

[0044] In this embodiment, a constant current circuit is provided on the PCB board; by optimizing the driving circuit structure of the light source in the light source, the original constant voltage drive is changed to a constant current drive, and the light source is used more scientifically and reasonably, so that the test results are stable and the service life of the light source is increased; Figure 7 As shown in the figure, RL is the light source LED and Vref is the voltage that controls the output current.

[0045] Figure 7As shown, the constant current circuit is composed of R1, R2, R3, R4, RS and operational amplifiers U1 and U2; Vref is the reference voltage for adjusting the constant current output; the constant current circuit incorporates negative feedback and positive feedback to make the output current more stable, and has better stability than the constant current source composed of a simple triode or an ordinary operational amplifier.

[0046] The characteristic of the light source LED is that the luminous intensity is closely related to the current passing through it. It can be basically assumed that when the current remains unchanged, the luminous intensity remains unchanged.

[0047] like Figure 7 In the circuit shown, negative feedback is performed on the voltage Vo1 on the left side of the sampling resistor RS, and the voltage Vo on the right side follows to the non-inverting input terminal to maintain a constant voltage across RS. For the op amp U1, R3 and R4 form a local negative feedback circuit, which still meets the virtual short condition. R1 and R2 belong to the non-inverting adder circuit, and the following derivation operation can be performed (assuming R1=R2=R3=R4).

[0048] Vin+ is the superposition of Vref and Vo2 at the in-phase terminal of op amp U1, that is,

[0049] Vin+ = 0.5 * Vref + 0.5 * V2o;

[0050] Because V1o = 2 * Vin-;

[0051] According to virtual short: Vin- = Vin+;

[0052] From the above three equations, we can get

[0053] V1o = 2 * Vin+ = Vref + V2o ,

[0054] Again V2o = Vo;

[0055] So: V1o = Vref + Vo

[0056] So V1o - Vo = Vref;

[0057] V1o - Vo is the voltage across RS, and its value is the input reference voltage Vref; because the current flowing into the positive input terminal of the operational amplifier U2 is 0, the current flowing through the load IL = Vref / RS, when RS = 500 ohms, for example, if Vref = 10V, then IL = 20mA, RS uses a low temperature drift precision resistor, then the load will flow through a precise constant current IL = Vref / RS;

[0058] As the instrument is used continuously, the light source (RL) will age to varying degrees, which is manifested as the internal resistance of the light source becoming larger or smaller. Assuming that the circuit was originally in a balanced state, when the current IL passing through RL becomes smaller due to some reason (such as aging of the light source), Vo will also become smaller, and after passing through the follower, V2o will also become smaller. The same-direction addition circuit formed by V2o and V causes Vin+ to become smaller, and also causes V1o to become smaller, so the voltage at both ends of RS has a process of decreasing, which is positive feedback; when V1o becomes smaller, it causes Vin- to become smaller, which is negative feedback that causes V1o to increase; under the joint action of positive feedback and negative feedback, the circuit reaches a new balance, and the voltage at both ends of RS is stabilized at Vref, which is equal to the input voltage.

[0059] The beneficial effects are as follows;

[0060] The more refracting and reflective glass the light from the light source passes through, the more obvious the light attenuation is. In order to achieve the same receiving intensity as a single-channel light source tester, a larger current is required. The improved structure of the multi-channel light source can effectively reduce this current, and the driving current of the light source is the same as that of the single-channel light source. By reducing the current of the light source, the service life of the light source can be effectively increased.

[0061] As the test instrument is used, the voltage will continue to fluctuate slightly. Even if a constant voltage circuit is added, the constant voltage will only change a little. As the light source is used for a longer time, the internal resistance of the light source will also change slightly. At this time, when the voltage remains unchanged, the current will also change the luminous intensity due to the change in internal resistance, thus affecting the test results. After changing to constant current drive, the luminous intensity will not change due to the decrease in the internal resistance of the light source, ensuring stable test results and increasing the service life of the light source.

[0062] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any changes or substitutions that are not conceived through creative work should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope defined in the claims.

Claims

1. A transmittance tester, characterized in that: include: A host (1), wherein the host (1) is provided with a test object placement area (9) for measuring the light transmittance of glass; A light-emitting probe (2), wherein the light-emitting probe (2) is arranged inside the main unit (1), and a light-transmitting end of the light-emitting probe (2) passes through the main unit (1) and is placed on the measured object placement area (9); A receiving probe (3), wherein the receiving probe (3) is arranged on the host (1), and the position of the receiving probe (3) corresponds to that of the light emitting probe (2).

2. The transmittance tester according to claim 1, characterized in that: The light-emitting probe (2) comprises a mounting seat (5) and a PCB board (6), and the mounting seat (5) is hollow inside to form a light-guiding groove; The PCB board (6) is provided with three LED light sources in a triangular structure; A transmission hole (7) is provided at the light-transmitting end above the mounting seat (5), and the transmission hole (7) corresponds to the overlapping area of ​​the light spots of the three light sources, and the test glass is placed on the transmission hole (7); A constant current circuit is arranged on the PCB board (6).

3. The transmittance tester according to claim 2, characterized in that: The constant current circuit is composed of R1, R2, R3, R4, RS and operational amplifiers U1 and U2; Among them, Vref is the reference voltage for adjusting the constant current output; the constant current circuit incorporates negative feedback and positive feedback to make the output current more stable.

4. The transmittance tester according to claim 1, characterized in that: The main unit (1) is hollow inside to form a mounting cavity, and the light emitting probe (2) is arranged in the mounting cavity.

5. The transmittance tester according to claim 1, characterized in that: The host is provided with a mounting bracket (4), and the receiving probe (3) is fixed on the mounting bracket (4).

6. The transmittance tester according to claim 1, characterized in that: The host (1) is provided with a display and control panel (8), and the light emitting probe (2) and the receiving probe (3) are connected and controlled via the display and control panel (8).

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