DESC:TECHNICAL FIELD

The present subject matter is related in general to a lens testing device, more particularly, but not exclusively to, a method and device for detecting photochromic coating property of lens.

BACKGROUND

Presently, many mechanisms and techniques are utilized for protecting eyes from harmful radiations of Ultraviolet (UV) rays. Ophthalmic lens industry has become concerned with growing eye diseases. This concern has prompted moves towards forming regulations which would require UV protection in eyeglasses. Such concern has also led optical manufacturers to find ways to incorporate UV absorbing compounds into ophthalmic lenses without blocking visible light. The result of such efforts has been the development of coatings which are essentially invisible. One such coating is photochromic coating by which ophthalmic glass darkens outdoors, when exposed to UV rays, and fades back to its initial transparent state indoors or behind a UV-filtered window. Since the coating is invisible and the lens absorbs UV radiation, there is no way for a user to visually determine the degree of protection being provided by the lens. Thus, the user is unable to judge, at the time of buying a lens, the level of UV protection provided by the lens.
Conventional approaches disclose method for detecting photochromic property in the lens. However, these methods may not consider various exposure of the lens to effectively detect the photochromic coating property of the lens.
The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
SUMMARY

In an embodiment, the present disclosure may relate to a method detecting photochromic coating property of lens. The method comprises projecting light on a lens placed on a lens receptacle configured in the photochromic detection device. The lens is placed between a LED source and a Light Dependent Resistor (LDR). The method comprises measuring a resistance value based on intensity of light transmitted through the lens based on the projection, measuring a voltage value at each predefined time interval, based on the resistance value measured by the LDR. The method further comprises calculating a light transmission level of the lens based on the voltage value at each predefined time interval and a reference voltage value of ambient light and detecting photochromic coating on the lens based on the calculated light transmission level of the lens.

In an embodiment, the present disclosure may relate to a photochromic detection device for detecting photochromic coating of lens. The photochromic detection device comprises a lens receptacle to hold a lens to be tested. Further, the photochromic detection device comprises a Light Emitting Diode (LED) source configured to project light on the lens. Furthermore, the photochromic detection device comprises a Light Dependent Resistor (LDR) configured to measure a resistance value based on intensity of light transmitted through the lens based on the projection. The lens receptacle is placed between the LED source and the LDR. Additionally, the photochromic detection device comprises a voltage divider circuit to measure a voltage value at each predefined time interval, based on the resistance value measured by the LDR. Further, a control unit is configured in the photochromic detection device to calculate a light transmission level of the lens based on the voltage value at each predefined time interval and a reference voltage value of ambient light and thereby detect photochromic coating on the lens based on the calculated light transmission level of the lens.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and/or methods in accordance with embodiments of the present subject matter are now described, by way of example only, and with reference to the accompanying figures, in which:

Fig.1a and Fig.1b illustrate exemplary environments of photochromic detection device for detecting photochromic coating property of lens in accordance with some embodiments of the present disclosure;

Fig.2 shows a flowchart illustrating a method for detecting the photochromic coating on a lens in accordance with some embodiments of the present disclosure; and

Fig.3 shows a flowchart for determining the presence or absence of photochromic coating property on lens using a predefined threshold range in accordance with some embodiments of the present disclosure.

It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present subject matter. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in computer readable medium and executed by a computer or processor, whether or not such computer or processor is explicitly shown.

DETAILED DESCRIPTION

In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the disclosure.
The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or method.
In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
The present disclosure relates to a method and a photochromic detection device for detecting photochromic coating on a lens. In an embodiment, the lens may be an uncut lens, prescription spectacles or sunglasses. The photochromic property of the lens is detected by checking the light transmission level of the lens. To test the photochromic coating property of the lens, the photochromic detection device is switched ON and resistance value associated with surrounding ambient light, may be measured. In an embodiment, the resistance value associated with the ambient light is converted into corresponding voltage value by a voltage divider circuit configured in the photochromic detection device. This voltage value is stored in memory as reference voltage value. Once the reference voltage value is measured, the lens to be tested may be placed on a lens receptacle of the photochromic detection device. Light is projected on the lens from a Light Emitting Diode (LED) source configured in the photochromic detection device. The LED source emits light of a predefined wavelength range. The light projected from the LED source transmits through the lens. The LDR placed on the other side of the lens receptacle measures the resistance value based on intensity of light transmitted through the lens. Depending on the resistance value at LDR, the voltage divider circuit measures a voltage value at each predefined time interval. Subsequently, light transmission level of the lens is calculated based on the voltage value at each predefined time interval and the reference voltage value of ambient light. Thus, based on the calculated light transmission level of the lens, photochromic coating property of the lens is detected. The present disclosure notifies percentage value of the photochromic coating provided by the lens, thereby aiding users in comparing various lenses/eyewear and selecting lenses/eyewear having highest photochromic coating property.
Fig.1a and Fig.1b illustrate exemplary environments of photochromic detection device for detecting photochromic coating property of lens in accordance with some embodiments of the present disclosure.

As shown in Fig.1a, an environment 100 includes an exemplary environment of photochromic detection device 101. The environment of the photochromic detection device 101 may include a Light Emitting Diode (LED) source 103, a lens receptacle 107 to hold a lens 105, a Light Dependent Resistor (LDR) 109 connected to a voltage divider circuit 111, a memory 113, a control unit 115 and a notification unit 117. In some implementations, the control unit 115 may be disposed in communication with the memory 113, for example Random Access Memory (RAM), Read Only Memory (ROM) and the like, via a storage interface (not shown in figures) configured in the photochromic detection device 101. The storage interface may connect to memory 113 including, without limitation, memory drives, removable disc drives, etc., employing various connection protocols. Further, the memory 113 may store a collection of program or database components, including, without limitation, user/application interface, an operating system of the control unit 115, and the like. In some embodiments, the memory 113 may be used to store reference voltage value and percentage of light transmission level of the lens 105. In an embodiment, the LED source 103 may be a standard LED which emits light radiation in a range of 395 nm, when powered by a suitable power source. The light emitted by the LED source 103 may be projected on the lens 105 placed in the lens receptacle 107. In an embodiment, the lens receptacle 107 may be an adjustable slot which may be adjusted to hold lenses of varying thickness. In an embodiment, the lens receptacle 107 may be configured between the LED source 103 and the LDR 109.

In an embodiment, the photochromic detection device 101 may undergo two types of calibration. In first calibration process, reference lenses may be used to calibrate the photochromic detection device 101. Voltage values of the reference lenses may be stored in the memory 111. These voltage values are non-erasable until the photochromic detection device 101 is re-calibrated by a service engineer for any inspection or maintenance purpose. Secondly, the photochromic detection device 101 is calibrated every time the photochromic detection device 101 is “switched ON” in its respective ambient lighting to suit to the environment where the photochromic detection device 101 is placed during testing. Fig.1b illustrates an exemplary embodiment of measuring reference voltage value based on ambient light. In an embodiment, the reference voltage value of the ambient light is obtained before the lens 105 is placed in the lens receptacle 107. In an embodiment, the LED source 103 may be activated only upon calibration. As shown in Fig.1b, ambient light from surrounding may fall on the photochromic detection device 101. Based on intensity of ambient light, the LDR 109 may measure resistance value. The measured resistance value from the LDR 109 may be converted into corresponding reference voltage value by the voltage divider circuit 111. The measured voltage value is stored in the memory 113 as reference voltage value. In an embodiment, the reference voltage value is erased and restored every time the photochromic detection device 101 is switched OFF or restarted. In an embodiment, the calibration of the photochromic detection device 101 is protected with a password which may be accessed by the user or operator of the photochromic detection device 101.
Returning to Fig.1a, once the photochromic detection device 101 is calibrated, the lens 105 to be tested is placed on the lens receptacle 107 as shown in Fig.1a. In an embodiment, upon projecting the light on the lens 105, the lens 105 may reflect and/or transmit a part of the light. The light transmitted through the lens 105 may pass through the LDR 109. The LDR 109 may measure resistance value based on intensity of the light transmitted through the lens 105. In an embodiment, the LDR 109 is a photoresistor which is a passive electronic component comprising a resistance which varies depending on the intensity of light. The resistance value measured at the LDR 109 may be inversely proportional to the intensity of light falling on the LDR 109. That is, for example, if the intensity of the transmitted light is high, then the resistance value measured at the LDR 109 may be low. Similarly, if the intensity of the transmitted light is low, then the resistance value measured at the LDR 109 may be high.

In an embodiment, the voltage divider circuit 111 may be connected to the LDR 109 for measuring voltage value at each predefined time interval based on the resistance value measured at the LDR 109. As an example, the lens 105 is placed in the lens receptacle 107 and within 7 seconds the resistance value is measured by the LDR 109. A person skilled in the art would understand that any other time limit, not mentioned explicitly may also be considered based on the requirement in the present disclosure. Further, the control unit 115 of the photochromic detection device 101 may calculate a light transmission level of the lens 105 based on the voltage value measured at each predefined time interval and the reference voltage value of ambient light. In an embodiment, the control unit 115 may calculate the light transmission level of the lens 105 by subtracting the reference voltage value from the voltage value measured based on the intensity of light transmitted through the lens 105.

In an embodiment, based on the reference voltage value and the measured voltage value at each predefined time interval, the light transmission level of the lens 105 may be calculated using a predetermined technique such as ‘K- factor’ measurement method. As an example, the K-factor calculation may be performed based as shown in Equation 1 below:

X = (A1/A2)*100
K Factor = (B/X)*1024
Run time calculation
Y = (A3/A2)*100
Actual Value
Z= (Y*K Factor)/1024……………………………………………………….(1)

Where, B = Light Transmission Min Lens reference %
A1 = LDR Analogue to Digital Conversion (ADC) value Voltage
A2 = Initial LDR ADC value Voltage
A3 = Measured ADC Value
X = Calibration, Initial value for K factor in %
Y = Run time, Initial Value in %
Z = Actual Value in %

Thus, based on the light transmission level, the control unit 115 detects the photochromic coating property on the lens 105. In an embodiment, the control unit 115 compares the light transmission level with a predefined threshold range. In an embodiment, lenses with photochromic coating property on exposure to light ray changes colour and turns dark and return to original state once cooled. For instance, while comparing, if the light transmission level is below the predefined threshold range and if the light intensity falling on the LDR 109 reduces due to darkening of the lens 105, the presence of photochromic coating in the lens 105 is indicated. Alternatively, if the light transmission level is greater than the predefined threshold range and there is no difference in the intensity of light falling onto the LDR 109, the lens 105 may be detected as non-photo chromatic lens. In an embodiment, the measured value of the light transmission level, in percentage value, may be notified to a user and/or an operator of the photochromic detection device 101 on the notification unit 117.

Fig.2 shows a flowchart illustrating a method for detecting the photochromic coating on a lens in accordance with some embodiments of the present disclosure.

As illustrated in Fig. 2, the method 200 may include one or more blocks illustrating a method of detecting photochromic coating on lens. The method 200 may be described in the general context of computer executable instructions. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, and functions, which perform specific functions or implement specific abstract data types.

The order in which the method 200 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method. Additionally, individual blocks may be deleted from the methods without departing from scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware, software, firmware, or combination thereof.

In an implementation, the photochromic detection device 101 is calibrated with respect to intensity of the ambient light, whenever the photochromic detection device 101 is triggered or switched ON. Based on the calibration, the reference voltage value of ambient light is measured and stored in memory 113. The reference voltage value of the ambient light is measured when the lens 105 is not placed in the lens receptacle 107.
At block 201, light emitted from a Light Emitting Diode (LED) source 103 is projected to a lens 105 to be tested. In an embodiment, the lens 105 may be placed on the lens receptacle 107 placed between the LED source 103 and the LDR 109.

At block 203, the resistance value is measured by the LDR 109 based on the intensity of light transmitted through the lens 105 based on the projection. In an embodiment, the resistance value is inversely proportion to intensity of light transmitted through the lens 105.

At block 205, the voltage value at each predefined time interval is measured by the voltage divider circuit 111 based on the resistance value measured by the LDR 109.

At block 207, the light transmission level of the lens 105 is calculated by the control unit 115 based on the voltage value at each predefined time interval and the reference voltage value of the ambient light. In an embodiment, the control unit 115 subtracts the reference voltage value of the ambient light with the voltage value in order to calculate the light transmission level of the lens 105. For example, based on the equation (1), the light transmission level may be calculated as:
X = (A1/A2) * 100
A1 = 880;
A2=896;
X=880/896*100 = 98.2 %
K Factor = (B/X) *1024
B=99;
K= (99/100) *1024 =1013.76
Run time calculation
Y = (A3/A2) *100
Y= (480/896)*100 =44.4%

Z = (44.4*1013.76)/1024 = 43.96%.

At block 209, the photochromic coating property on the lens 105 is detected by the control unit 115 based on the light transmission level. The detailed method for determining presence or absence of photochromic coating property on the lens 105 is shown in Fig.3.
Fig.3 shows a flowchart for determining the presence or absence of photochromic coating property on lens using a predefined threshold range in accordance with some embodiments of the present disclosure.

At block 301, after the light transmission level of the lens 105 is calculated, the control unit 115 may check whether the light transmission level is below/above the predefined threshold range. In an embodiment, the predefined threshold range may be detected based on calibration process. In case, the light transmission level is below the predefined threshold range, the method executes block 303. Alternatively, if the light transmission level is above the predefined threshold range, the method executes block 305.

At block 303, the control unit 115 detects the presence of photochromic coating on the lens 105 as the light transmission level is less than the predefined threshold range.

At step 305, the control unit 115 detects the absence of photochromic coating on the lens 105 as the light transmission level is greater than the predefined threshold range.

Returning to Fig.2, the method 200 may include notifying the measured light transmission level of the lens 105 to a user and/or an operator on the notification unit 117 of photochromic detection device 101. In an embodiment, the light transmission level may also be notified as a voice-based message provided to the user/operator using a speaker associated with the notification unit 117.

In an implementation, the notification unit 117 may be an input/output (I/O) interface (not shown in figures). In an embodiment, the I/O interface may employ communication protocols/methods such as, without limitation, audio, analog, digital, stereo, IEEE-1394, serial bus, Universal Serial Bus (USB), infrared, PS/2, BNC, coaxial, component, composite, Digital Visual Interface (DVI), high-definition multimedia interface (HDMI), Radio Frequency (RF) antennas, S-Video, Video Graphics Array (VGA), IEEE 802.n /b/g/n/x, Bluetooth, cellular (e.g., Code-Division Multiple Access (CDMA), High-Speed Packet Access (HSPA+), Global System For Mobile Communications (GSM), Long-Term Evolution (LTE) or the like), etc.
In some implementation, the control unit 115 may be disposed in communication with a communication network via a network interface (not shown in figures) configured in the photochromic detection device 101. The network interface may employ connection protocols including, without limitation, direct connect, Ethernet (e.g., twisted pair 10/100/1000 Base T), Transmission Control Protocol/Internet Protocol (TCP/IP), token ring, IEEE 802.11a/b/g/n/x, etc. In an implementation, the communication network can be implemented as one of the several types of networks, such as intranet, Local Area Network (LAN), wireless network and such within the organization. Using the network interface and the communication network, the photochromic detection device 101 may connect to one or more user devices and/or display terminals to indicate detection of photochromic coating on the lens 105.
In an embodiment, the present disclosure discloses a photochromic detection device 101 for detecting level of photochromic coating property on the lenses.

In an embodiment, the present disclosure uses standard Light Emitting Diodes (LEDs) of UV light transmitted through the lens, thereby making the apparatus portable, light-weight, and economical.

In an embodiment, the present disclosure may be calibrated with reference to ambient light, and hence provides accurate results of detecting photochromic coating on the lenses.

In an embodiment, the present disclosure notifies percentage value of the photochromic coating level provided by the lenses, thereby aiding users in comparing various lenses/eyewear and selecting lenses/eyewear having highest photochromic coating.

The terms "an embodiment", "embodiment", "embodiments", "the embodiment", "the embodiments", "one or more embodiments", "some embodiments", and "one embodiment" mean "one or more (but not all) embodiments of the invention(s)" unless expressly specified otherwise.

The terms "including", "comprising", “having” and variations thereof mean "including but not limited to", unless expressly specified otherwise.

The enumerated listing of items does not imply that any or all the items are mutually exclusive, unless expressly specified otherwise. The terms "a", "an" and "the" mean "one or more", unless expressly specified otherwise.

A description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary, a variety of optional components are described to illustrate the wide variety of possible embodiments of the invention.

When a single device or article is described herein, it will be clear that more than one device/article (whether they cooperate) may be used in place of a single device/article. Similarly, where more than one device or article is described herein (whether they cooperate), it will be clear that a single device/article may be used in place of the more than one device or article or a different number of devices/articles may be used instead of the shown number of devices or programs. The functionality and/or the features of a device may be alternatively embodied by one or more other devices which are not explicitly described as having such functionality/features. Thus, other embodiments of the invention need not include the device itself.

Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, the embodiments of the present invention are intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
Reference numerals

Reference Description
100 Environment
101 Photochromic detection device
103 LED source
105 Lens
107 Lens receptacle
109 LDR
111 Voltage divider circuit
113 Memory
115 Control unit
117 Notification unit

,CLAIMS:We claim:
1. A method for detecting photochromic coating on a lens, the method comprising:
projecting, by a Light Emitting Diode (LED) source (103) configured in a photochromic detection device (101), light on a lens (105) placed on a lens receptacle (107) configured in the photochromic detection device (101), wherein the lens receptacle (107) is placed between the LED source (103) and a Light Dependent Resistor (LDR) (109);
measuring, by the LDR (109) of the photochromic detection device (101), a resistance value based on intensity of light transmitted through the lens (105) based on the projection;
measuring, by a voltage divider circuit (111) configured in the photochromic detection device (101), a voltage value at each predefined time interval, based on the resistance value measured by the LDR (109);
calculating, by a control unit (115) configured in the photochromic detection device (101), a light transmission level of the lens (105) based on the voltage value at each predefined time interval and a reference voltage value of ambient light; and
detecting, by the control unit (115), photochromic coating on the lens (105) based on the calculated light transmission level of the lens (105).

2. The method as claimed in claim 1, wherein the reference voltage value of the ambient light is obtained before the lens (105) is placed in the lens receptacle (107).

3. The method as claimed in claim 1, wherein the reference voltage value is measured each time the photochromic detection device (101) is switched ON.

4. The method as claimed in claim 1, wherein the photochromic coating is detected to be present on the lens (105) when the light transmission level is below a predefined threshold range.

5. The method as claimed in claim 1 wherein the photochromic coating is detected to be absent on the lens (105), when the light transmission level is greater than a predefined threshold range.

6. The method as claimed in claim 1 further comprising providing a notification regarding one of presence and absence of photochromic coating on the lens (105).

7. A photochromic detection device (101) for detecting photochromic coating on a lens (105), comprising:
a Light Emitting Diode (LED) source (103) configured to project light on the lens (105);
an LDR (109) for measuring a resistance value based on intensity of light transmitted through the lens (105) based on the projection;
a lens receptacle (107) to hold the lens (105) to be tested, wherein the lens receptacle (107) is placed between the LED source (103) and the LDR (109);
a voltage divider circuit (111) to measure a voltage value at each predefined time interval, based on the resistance value measured by the LDR (109); and
a control unit (115) configured to calculate a light transmission level of the lens (105) based on the voltage value at each predefined time interval and a reference voltage value of ambient light and detecting the photochromic coating on the lens (105) based on the calculated light transmission level of the lens (105).

8. The photochromic detection device (101) as claimed in claim 7, wherein the reference voltage value of the ambient light is obtained before the lens (105) is placed in the lens receptacle (107).

9. The photochromic detection device (101) as claimed in claim 7, wherein the reference voltage value is measured each time the photochromic detection device (101) is switched ON.

10. The photochromic detection device (101) as claimed in claim 7, wherein the photochromic coating is detected to be present on the lens (105) when the light transmission level is below a predefined threshold range.

11. The photochromic detection device (101) as claimed in claim 7 wherein the photochromic coating is detected to be absent on the lens (105), when the light transmission level is greater than a predefined threshold range.

12. The photochromic detection device (101) as claimed in claim 7 comprising providing a notification by a notification unit (117) configured in the photochromic detection device (101) regarding one of presence and absence of photochromic coating on the lens (105).