TWI414764B - Method and device for measuring luminous flux - Google Patents

Abstract

A method and device for measuring luminous flux are disclosed, in which the measuring device is composed of: a reflection surface, a light meter, and a light source. Operationally, light emitted from the light source is projected upon the reflection surface where it is reflected to the light meter so as to obtain an illuminance value relating to the light projection. Then, a luminous flux can be calculated using the illuminance value an effective illuminated area of the light meter and reflective index of the reflection surface. In an embodiment of the present disclosure, the reflection surface is formed as an ellipse with two focal points, and the light meter is disposed at one focal pint selected from the two while the light source is being arranged at another focal point.

Description

Luminous flux measuring device and measuring method thereof

The invention relates to a luminous flux measuring device and a measuring method thereof, in particular to a reflecting surface with a double focus, which can concentrate the whole luminous flux on the photometric device, and has the advantages that the measuring light emitting diode can be applied and the auxiliary lamp is not needed. Light flux measuring device and measuring method thereof, which are convenient, fast, cheap, easy to manufacture, small in chromaticity variation, small in angle variation, low in measurable light, and small in error source.

Nowadays, the luminous flux measurement method includes two kinds of integrating spheres and a light distribution curve meter. The integrating sphere is also called a light-passing sphere, and has a hollow shell, which can be a global body or a hemisphere, on the inner wall of the casing. A white diffuse reflective material, such as barium sulfate, is applied to provide light diffusion to diffuse light evenly at various points on the inner wall of the housing.

Referring to the first figure, the principle of the traditional integrating sphere illuminance and luminous flux is explained. The illuminance generated by the light source S at an arbitrary point B on the inner wall of the spherical casing 90 is superimposed by the illuminance generated by the multiple reflected light. As shown in the figure, after the light source S is projected at the point B, it can be reflected to the point A, the point C and then back to the point B, or the light source S is projected at the point A, and can be reflected to the point C and then reflected to the point B, by the integral theory. The principle is obtained, the illuminance E of point B is:

In the formula (1), E ₁ is the illuminance at which the light source S is directly projected on the point B, and the magnitude of E _{1 is} related not only to the position of the point B but also to the position of the light source S in the spherical casing 90. If a screen (not shown) is placed between the source S and the point B, and the light directly directed to the point B is blocked, E ₁ =0, and thus the illuminance at the point B is:

In the formula (2), R is an integrating sphere radius, and ρ is a reflectance of the inner wall of the spherical casing 90. Both R and ρ are constant, so the illuminance E at any position on the inner wall of the casing (after blocking direct illumination) is proportional to the luminous flux Φ of the light source S. The luminous flux Φ of the light source S can be obtained by measuring the illuminance E on the window (not shown) of the spherical casing 90.

However, the traditional integrating sphere has many shortcomings. In addition to its complicated structure, inconvenient use, high price, large chromatic variation, and large angular variation, when applied to narrow-angle light sources (such as light-emitting diodes), the measurement error is quite Large, and long-term use, the diffuse reflective material coated on the inner wall will deteriorate, the auxiliary lamp must be set to compensate, and the equivalent standard lamp is needed before the measurement, and the integral formula calculation error, reflective material coating and The scattering error, the baffle, the lamp holder, the self-absorption of the housing itself, the opening error and other factors are the factors that cause the measurement error.

In view of the above circumstances, the present invention provides a luminous flux measuring device and a measuring method thereof, wherein an elliptical spherical reflecting surface has the characteristics of a double focus, and the entire luminous flux can be concentrated on the photometric device, and is applicable to measuring the luminous dipole. Body, no need for auxiliary lamps, convenient and fast, cheap, easy to manufacture, small chromatic variation, small angle variation, low light measurable, small error source and so on.

In order to achieve the above object, the present invention provides a luminous flux measuring device, comprising: a casing, an inner wall of which is a reflecting surface, the reflecting surface has an optical double focus; and a photometric device disposed on one of the bifocal points, The optical value of the measured light source disposed on the other of the bifocal points is measured. In order to achieve the above object, the present invention further provides a method for measuring the luminous flux, comprising: receiving, by a light metering device, a reflective surface to reflect a measured light source. And illuminating the illuminance by the photometric device and obtaining an illumination value, the illumination value, the effective illuminance area of the photometric device, and the reflectance of the reflective surface to calculate the luminous flux.

In order to enable your review committee to have a better understanding and recognition of the structural purpose and efficacy of the present invention, the detailed description is as follows.

The technical means and efficacy of the present invention for achieving the object will be described below with reference to the drawings, and the embodiments listed in the following drawings are only for the purpose of explanation, and are understood by the reviewing committee, but the technical means of the present invention are not limited to List the schema.

Referring to the second figure, the luminous flux measuring device 10 of the present invention has an elliptical spherical hollow casing 11 which shows an axial sectional structure of the casing 11, and the casing 11 can be It is made of a reflective material or coated with a specular reflection material on the inner wall of the casing 11, so that the inner wall of the casing 11 forms a reflecting surface 12, and since the casing 11 has an elliptical shape, it has a bifocal characteristic according to the elliptical shape. A light source 13 is disposed at one of the focus positions, and a light metering device 14 is disposed at another focus. The light source 13 can be a globally illuminated light emitting element or a directivity light emitting diode. The light metering device 14 may be an illuminometer, a spectrometer or a charge-coupled device (CCD). Since the light source 13 and the photometric device 14 are respectively disposed at two focus positions of the elliptical hollow casing 11, the light source 13 can not directly project the light L1 in the photometric device 14, the light L2 emitted from the light source 13 can be completely reflected to the photometric device 14 after being irradiated on the reflective surface 12, and the light source 13 used in the second embodiment is a globally illuminated light-emitting element. , The fixture 15 consists of a light source 13 provides power and extend into focus.

In another embodiment, shown in FIG. 3, the luminous flux measuring device 20 is composed of a casing 21, a reflecting surface 22, a measured light source 23, and a photometric device 24. The reflecting surface 22 is an elliptical surface. The difference between the embodiment and the second embodiment is that the light source 23 of the embodiment is a non-global light-emitting element. As shown in the figure, the light-emitting area of the light source 23 is concentrated in the front half, and the light-emitting diode has such light. Therefore, the volume of the casing 21 can be reduced, and the casing 21 can be removed from the portion of the light, and the area between the light source 23 and the focus position set by the photometric device 24 can be retained. Similarly, the light source 23 and the photometric device 24 The light source 23 is not only directly projected by the light source L3 in the photometric device 24, but also the light L4 emitted from the light source 23 is irradiated on the reflective surface 22, It can be completely reflected to the photometric device 24, that is, the photometric device 24 can receive the total light collected by the reflective surface 22.

It should be noted that, besides the characteristic that the elliptical surface has a double focus, the paraboloid also has the characteristic of collecting light. The invention is characterized in that the light source and the photometric device are respectively disposed on the two focuss by using the bifocal property of the elliptical surface or the paraboloid surface. Position, the above embodiment only uses an elliptical shape as a specific illustrative example. Other various curved surfaces can collect light to obtain a luminous flux after multiplying the illuminance by the effective area.

Please refer to the third figure to illustrate the method of calculating luminous flux in this case. It is based on the luminous flux calculation formula shown below: F=(E*A)÷ρ.........Formula (3)

Wherein, the F is the luminous flux, and the E is the illumination value obtained by the photometric device 24 sensing the illuminance, the A is the effective illuminance area, and the ρ is the reflectivity of the reflective surface 22, which may be the material of the reflective surface 22 itself or coated The reflection material of the cloth, according to the current technology, the reflectivity ρ can reach 96%.

The above formula (3) calculates the reflected light projected on the photometric device 24 together with the direct projection light. If more precise calculation is required, the illuminance of the direct projection light can be separately measured, and the present invention is matched with the object. One of the direct projection light measuring devices can be separately taken.

Referring to the fourth figure, the first sub-measurement device 40 includes a cover 41. The cover 41 is non-reflective. The cover 41 can be provided with a light source 43 and a photometric device 44. Since the inner wall of the cover 41 does not have The light-receiving device 44 is only capable of receiving the directly projected light L7. In the present embodiment, the outer cover 41 is an elliptical sphere, and the purpose is to position the light. Light source 43 And the position of the photometric device 44, that is, the two focus positions of the elliptical spherical cover 41. However, since the outer cover 41 is not reflective, the outer cover 41 can be of any shape, and the design focus is on the light source 43 and the photometric device 44. The distance must be in accordance with the bifocal distance of the housing having the reflecting surface. For example, when the fourth figure structure is combined with the third figure structure, the distance D2 between the light source 43 of the first sub-measuring device 40 and the photometric device 44 must be The distance D1 between the light source 23 and the photometric device 24 of the luminous flux measuring device 20 is the same as that of the third figure. Thus, the overall illuminance can be measured by the luminous flux measuring device 20 in the third figure, and the first sub-measurement of the fourth figure is measured. The device 40 measures the illuminance of the direct projection light L7.

According to the above embodiment, the second sub-measurement device 50 shown in FIG. 5 is derived, which includes a first positioning frame 51 and a second positioning frame 52. The first positioning frame 51 is configured to set the light to be measured. The source 53 is configured to set the photometric device 54. The form of the first positioning frame 51 and the second positioning frame 52 are not limited, and the light source 53 and the photometric device 54 can be disposed thereon. The distance D3 between the light source 53 and the photometric device 54 may be the same as the distance D1 between the light source 23 and the photometric device 24 of the third figure, and the other portions other than the first positioning frame 51 and the second positioning frame 52 are transparent. In this state, therefore, the photometric device 54 can only receive the directly projected light L9, and the light L8 projected by the light source 53 in other directions is directly emitted without reflection.

The first sub-measurement device 40 and the second sub-measurement device 50 shown in the fourth and fifth figures can measure the light directly projected by the light source on the photometric device, and the fifth figure is an illustrative example, the luminous flux thereof. The calculation formula is as follows: F=((E*A)÷ρ)-((E'*A)*(1-ρ)).........Formula (4)

Wherein F is the luminous flux, and the E is the second or third light of all the light The illuminance value obtained by the line, the A is the effective illuminance area, the ρ is the reflectance of the reflecting surfaces 12, 22, and the E' is in the fourth or fifth figure, and the photometric device 44, 54 senses the The direct illumination values obtained by the light sources 43 and 53 directly projected to the illuminance of the photometric devices 44 and 54 can be obtained by the calculation of the above formula (4) to obtain more precise luminous flux values.

The optical simulation experiments prove that the above formulas (3) and (4) are indeed implementable, and the third figure is an example. Among them, D11 is a semi-major axis, D12 is a semi-minor axis, and D13 is a semi-focal length. D11 is 10 cm, D12 is 5 cm, the reflectance (ρ) of the reflecting surface 22 is 100%, the radius of the light source 23 is 0.1 cm, and the ideal luminous flux is 100 lm. The actual calculation result is 99.9994 lm, and the error is 0.0006%. When the reflectance (ρ) of the reflecting surface 22 is 96%, it is calculated by the formula (3), 96.05958/0.96=100.0620625, and the error is 0.06%. If the precise calculation is performed by the formula (4), 100.0620625-(0.04*1.495347) = 100.00224, the error is 0.00224%, from which it can be seen that the present invention is not only implementable, but also has extremely low error.

In summary, the luminous flux measuring device and the measuring method provided by the present invention are completely different from the traditional method of using a spherical integrating sphere structure and integrating the luminous flux, and have a bifocal reflecting surface for concentrating the total luminous flux on the photometry. The device has the characteristics of being suitable for measuring the light-emitting diode, no need for the auxiliary lamp, convenient and fast, cheap, easy to manufacture, small chromatic variation, small angle variation, low light measurable, and small error source.

However, the above description is only for the embodiments of the present invention, and the scope of the invention is not limited thereto. That is to say, the equivalent changes and modifications made by the applicant in accordance with the scope of the patent application of the present invention should still fall within the scope of the patent of the present invention. I would like to ask your review committee to give a clear explanation and pray for it.

Prior art:

A, B, C‧‧ points

S‧‧‧ light source

90‧‧‧Spherical shell

this invention:

10, 20‧‧‧ Luminous flux measuring device

11, 21‧‧‧ shell

12, 22‧‧‧reflecting surface

13, 23, 43, 53‧ ‧ light source

14, 24, 44, 54‧‧‧ metering device

40‧‧‧First sub-measurement device

50‧‧‧Second secondary measuring device

41‧‧‧ Cover

51‧‧‧First positioning frame

52‧‧‧Second positioning frame

D1, D2, D3‧‧‧ distance

D11‧‧‧Half long axis

D12‧‧‧ semi-short axis

D13‧‧‧Half focal length

L1, L2, L3, L4, L5, L6, L7, L8, L9‧‧‧ rays

The first figure is a schematic diagram of the structure of a conventional spherical integrating sphere.

The second figure is a schematic diagram of the architecture of the first embodiment of the present invention.

The third figure is a schematic diagram of the architecture of the second embodiment of the present invention.

The fourth figure is a schematic diagram of the first embodiment of the sub-measurement apparatus of the present invention.

Figure 5 is a schematic view showing the structure of a second embodiment of the sub-measurement apparatus of the present invention.

10. . . Luminous flux measuring device

11. . . case

12. . . Reflective surface

13. . . light source

14. . . Photometric device

L1, L2. . . Light

Claims (13)

A luminous flux measuring device comprising: a casing, an inner wall of which is a reflecting surface, the reflecting surface has an optical double focus; and a photometric device disposed on one of the bifocal points to measure the bifocality The optical value of the other measured light source. The luminous flux measuring device according to claim 1, wherein the reflecting surface is coated with an optically reflective substance. The luminous flux measuring device according to claim 1, wherein the casing is made of an optically reflective material. The luminous flux measuring device according to claim 1, wherein the reflecting surface is an elliptical surface, a paraboloid, and a free curved surface. The luminous flux measuring device according to claim 1, wherein the photometric device is an illuminometer, a spectrometer, or a charge coupled device (CCD). A method for measuring a luminous flux, comprising: receiving, by a light metering device, a reflecting surface for reflecting light of a measured light source; and measuring, by the light measuring device, an illumination value, the illumination value, an effective illumination area of the photometric device, and the The reflectivity of the reflective surface to calculate the luminous flux. The method of measuring a luminous flux according to claim 6, wherein the reflecting surface is an inner wall of a casing and has an optical bifocal point, and the photometric device is disposed at one of the focus positions, and the light source is located at another A focus position. The method for measuring the luminous flux according to claim 6, further comprising: measuring a light directly projected by the light source to the photometric device by using a second sub-measurement device, wherein the second sub-measurement device comprises a first a positioning frame and a second positioning frame, wherein the distance between the first positioning frame and the second positioning frame is the same as the distance between the two focus positions of the reflective surface, the first positioning frame is configured to set the light source, and the second A positioning frame is used to set the photometric device. The method for measuring luminous flux according to claim 6, wherein the reflecting surface is an elliptical surface, a paraboloid, and a free curved surface. The method of measuring a luminous flux according to claim 6, wherein the photometric device is an illuminometer, a spectrometer or a charge coupled device (CCD). The luminous flux measurement method according to claim 6, wherein the luminous flux calculation formula is as follows: F=(E*A)÷ρ, wherein the F is a luminous flux, and the E is the illumination value, and the A is effective. The illuminance area, which is the reflectance of the reflecting surface. The method of measuring a luminous flux according to claim 6, wherein the photometric device further receives light that is directly projected by the light source to the photometric device. The luminous flux measuring method according to claim 6, wherein the luminous flux calculation formula is as follows: F=((E*A)÷ρ)-((E'*A)*(1-ρ)) Wherein F is the luminous flux, the E is the illumination value, the A is the effective illuminance area, the ρ is the reflectivity of the reflective surface, and the E′ is the illumination value directly projected by the light source to the photometric device.