Optical components

Abstract

An optical accessory includes an interdigital capacitor, one or more electrical contacts electrically connected to the interdigital capacitor, and an insulating layer covering at least a portion of the interdigital capacitor. The one or more electrical contacts and a portion of the insulating layer are configured to receive a conductive adhesive. The optical accessory also includes a metal layer located between the interdigital capacitor and the portion of the insulating layer configured to receive the conductive adhesive.

Description

Technical Field

[0001] The present disclosure relates to compact photovoltaic modules. Background Art

[0002] Various consumer electronics and other devices include packaged light emitter or detector modules designed for precise light projection or detection applications. The spatial dimensions of such modules are typically very small, enabling them to be incorporated into portable devices. One technology suitable for micro-illuminators is high power vertical cavity surface emitting laser (VCSEL) devices and array devices.

[0003] In some cases, the optical output power of a bare VCSEL may often be so high that it may cause damage to a person's eyes or skin if the quality of the optical components is compromised. It is therefore important to ensure that high-power laser illuminators meet laser safety regulations when in operation. For example, the illuminator may be part of an accessory that maintains eye-safe operation under normal operating conditions by preventing a person from getting too close to the illuminator. However, in some cases, damage (e.g., cracks) to optical structures that modify the output beam for safe operation, or the presence of moisture or chemical contamination on the optical structures, may result in safety hazards. Similarly, safety may be compromised if the optical structures fall off or are removed.

[0004] It is therefore an object of the present disclosure to provide a photovoltaic module that addresses one or more of the above problems or at least provides a useful alternative. Summary of the invention

[0005] The above mentioned problems are sought to be overcome by enabling detection of damage on the optical structure or the presence of moisture or chemical contamination. The arrangement does this without compromising the optical performance of the module and enables straightforward manufacture.

[0006] According to an embodiment, an optical accessory is provided, the optical accessory including an interdigital capacitor, one or more electrical contacts electrically connected to the interdigital capacitor, and an insulating layer covering at least a portion of the interdigital capacitor. The one or more electrical contacts and a portion of the insulating layer are configured to receive a conductive adhesive. The optical accessory also includes a metal layer located between the interdigital capacitor and the portion of the insulating layer configured to receive the conductive adhesive.

[0007] In one embodiment, the optical assembly further includes circuitry configured to detect a change in capacitance of the interdigital capacitor.

[0008] In one embodiment, the interdigital capacitor comprises indium titanium oxide.

[0009] In one embodiment, the metal layer is transparent.

[0010] In one embodiment, the metal layer includes indium titanium oxide.

[0011] In one embodiment, the metal layer is embedded in the insulating layer.

[0012] In one embodiment, the metal layer is electrically floating, ie, no specific potential is applied to the metal layer by the circuit, but rather the potential of the metal layer is allowed to fluctuate or "float" under the influence of the electric field to which the metal layer is exposed.

[0013] In one embodiment, the metal layer is adjacent to one or more edges of the optical assembly.

[0014] In one embodiment, the conductive adhesive comprises a conductive adhesive layer having a first dimension in a plane parallel to the first surface of the optical assembly ranging from 100 μm to 600 μm.

[0015] According to another embodiment, an optical module is provided that includes an optical accessory, the optical accessory including an interdigital capacitor, one or more electrical contacts electrically connected to the interdigital capacitor, an insulating layer covering at least a portion of the interdigital capacitor, a circuit operable to detect a change in capacitance of the interdigital capacitor, and a conductive adhesive disposed on at least a portion of the one or more electrical contacts and a portion of the insulating layer and configured to maintain electrical connection between the circuit and the one or more electrical contacts. The optical accessory also includes a metal layer disposed between the interdigital capacitor and the portion of the insulating layer on which the conductive adhesive is disposed.

[0016] In one embodiment, the optical module further includes circuitry configured to detect a change in capacitance of the interdigital capacitor.

[0017] Finally, the present optical assembly disclosed herein utilizes a novel approach in which a metallic shielding layer is provided to shield the conductive traces used to detect changes in the optical assembly from the effects of the conductive adhesive on its capacitance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Some embodiments of the present disclosure will now be described, by way of example only, and with reference to the accompanying drawings, in which:

[0019] Figure 1 An optoelectronic module including a light emitting element and eye safety capability is shown;

[0020] Figure 2 The assembly is shown prior to application of a conductive adhesive;

[0021] Figure 3 shows the conductive adhesive after application. Figure 2 The components shown in;

[0022] Figure 4An arrangement including a shielding layer is shown;

[0023] Figure 5A An embodiment is shown prior to applying a conductive adhesive for contacting a terminal of one electrode of an interdigital capacitor;

[0024] Figure 5B The embodiment is shown after applying a conductive adhesive contacting a terminal of one electrode of an interdigital capacitor;

[0025] Figure 5C An embodiment is shown prior to applying a conductive adhesive for contacting a terminal of a second electrode of an interdigital capacitor;

[0026] Figure 5D The embodiment is shown after applying a conductive adhesive contacting a terminal of a second electrode of an interdigital capacitor;

[0027] Figure 6 shows the electric field generated in the absence of a shielding layer;

[0028] Fig. 7A shows the electric field generated in the absence of a shielding layer but in the presence of a conductive adhesive;

[0029] Figure 7B Shows Fig. 7A The capacitance of the interdigital capacitor varies with the width of the applied adhesive;

[0030] Fig. 8A shows the electric field generated in the presence of a shielding layer and a conductive adhesive;

[0031] Figure 8B Shows Fig. 8A The capacitance of the interdigital capacitor varies with the width of the applied adhesive;

[0032] Fig. 9A is a decomposed schematic diagram of the potential in the presence of a conductive adhesive but without a shielding layer;

[0033] Fig. 9B The potential of a 600 μm wide adhesive trace in the presence of a shielding layer is shown;

[0034] Fig. 9C The potential of a 200 μm wide adhesive trace in the presence of a shielding layer is shown;

[0035] Fig.9D shows the potential of the adhesive trace just above the shielding layer for a glue width of 100 um; and

[0036] Fig.9EThe potential of the adhesive trace directly above the shielding layer is shown for a glue width of 300um. DETAILED DESCRIPTION

[0037] Generally speaking, the present disclosure provides an optoelectronic module solution that provides high sensitivity to damage to optical components without compromising optical performance.

[0038] Some examples of solutions are given in the accompanying figures.

[0039] Figure 1 , an optoelectronic module 101 including a light emitting element and eye safety capabilities according to an embodiment is shown in FIG. The outer dimensions of the module may be in the range of 2000 μm×1700 μm×700 μm and 5000 μm×4000 μm×3000 μm. In this embodiment, the optoelectronic module includes glass 103 with an optical component 105 disposed above a light source 107. The optical component 105 is positioned to intersect the path of the (multiple) light beams generated by the light source 107. In the following discussion, it is assumed that the light source 107 is a vertical cavity surface emitting laser (VCSEL). However, other types of optical emitters or even detectors may be employed in the optoelectronic module 101 according to embodiments. Examples include VCSEL arrays, one or more light emitting diodes (LEDs), infrared (IR) LEDs, organic LEDs (OLEDs), infrared (IR) lasers, or edge emitting laser diodes. In embodiments, the light source 107 is operable to emit light within a specific wavelength or a relatively narrow wavelength range (e.g., infrared). In certain embodiments, the light source 107 is operable to produce coherent light.

[0040] VCSEL 107 is electrically connected to lead frame 109, and power is supplied to VCSEL 107 via lead frame 109. In an embodiment, power to VCSEL 107 may be controlled by a current driver controller or other electronic control unit (ECU) (not shown). The controller may reside, for example, in a host device (e.g., a smartphone) in which module 101 is integrated.

[0041] In the following discussion, it is assumed that the optical component 105 is a microlens array (MLA). However, other optical accessories may be used in place of the MLA according to embodiments, such as an optical diffuser, a lens, a refractive or diffractive optical element, a diffuser, a spectral filter, a polarization filter, and / or some other optical structure operable to modify the optical properties of an output beam of a light source incident on the optical accessory.

[0042] According to an embodiment, glass 103 is held in place over VCSEL 107 by spacer 111. Spacer has cavity 113 in which VCSEL 107 is mounted. Spacer 111 may be composed of, for example, an electrically insulating material such as molded epoxy (e.g., a liquid crystal polymer based material). Figure 1 In the embodiment of FIG. 1 , the MLA glass 103 resides in the socket 115 of the spacer 111. However, in other embodiments, there may be no socket and the glass 103 may rest on the uppermost surface of the spacer.

[0043] In this embodiment, the MLA 105 is located on the inner surface 117 of the glass 103, facing the VCSEL 107. In other embodiments, the MLA 105 can be positioned on the outer surface of the glass 103.

[0044] Conductive traces 119 are disposed on the surface of glass 103, including over the portion of the glass that includes MLA 105. Figure 2 It is more clearly shown in Figure 2 A detailed perspective view of glass 103 is shown. In this embodiment, MLA 105 is positioned toward the center of glass 103. Electrical traces 119 are disposed on surface 117 of glass 103. In this embodiment, conductive traces 119 are interdigitated capacitors. In some cases, traces 119 are composed of a material (e.g., indium tin oxide (ITO)) that is substantially transparent to the wavelength of light (e.g., infrared) generated by VCSEL 107. Thus, such conductive structures can at least partially overlap with the footprint of the light beam emitted by VCSEL 107. In other cases, the conductive structures can be composed of a material (e.g., chromium) that is substantially opaque to the wavelength of light generated by light emitter 107. In this case, conductive traces 119 preferably do not overlap with the footprint of the light beam emitted by VCSEL 107.

[0045] Traces 117 are electrically connected to electrical contacts 201 on surface 117 of glass 103. The electrical contacts may include conductive pads made of gold or silver or another suitable conductive material. In some cases, traces 117 are covered with an insulating layer 301. In an embodiment, the insulating layer may include SiO2 or another suitable insulating material. If an insulating layer is used, an opening in the insulating material is provided for electrical contacts 201.

[0046] Module 101 includes conductive leads 121 extending from socket 115 of spacer 111 and extending downward to lead frame 109. In other embodiments, the leads may be integrated into the wall of spacer 111, or otherwise arranged to provide an electrical connection from the portion of the spacer on which glass 103 is mounted to lead frame 109. In an embodiment, traces 119 are electrically connected to leads 121 via contacts 201 having conductive adhesive 123. In an embodiment, conductive adhesive 123 is silver epoxy. In other embodiments, another suitable conductive adhesive may be used. Therefore, traces 119 are connected to lead frame 109 via contacts 201, conductive adhesive 123, and leads 121.

[0047] In an embodiment, the conductive adhesive is deposited on top of the insulating layer of glass 103 as a strip extending down the sides of the MLA glass and interfacing with the electrical contacts 201. Figure 2 and Figure 3 is shown in FIG. 5A to FIG. 5D . Providing the conductive adhesive as a strip can advantageously enable the adhesive to be applied directly to the MLA glass, thereby facilitating manufacturing. Furthermore, when applied as a strip, in addition to providing an electrical connection, the conductive adhesive can also provide mechanical adhesion to a spacer or other element of the module package. Such mechanical adhesion via the conductive adhesive 123 can be provided to replace or supplement the use of another adhesive within the package that has only mechanical properties. In other embodiments, the conductive adhesive can take other suitable forms, such as dots or partial strips. Depending on the embodiment, the form and position of the conductive adhesive 123 can be selected depending on the design of the spacer or the positioning of the leads 121 and / or the electrical contacts 201.

[0048] In an embodiment, a strip of conductive glue on one side of the glass 3 is connected to one of the capacitor terminals 401 and is assigned a 1V potential via lead 121. A second strip of conductive glue 407 on the opposite side of the glass is connected to another terminal 405 in the trace 119 and to ground via lead 21, as shown. Figure 4 As shown in A to D.

[0049] exist Figure 1In the embodiment of the present invention, the function of trace 119 is to ensure the eye safety of the module. As described above, the unmodified optical output of the VCSEL may be sufficient to cause injury if incident on the human eye or skin. Therefore, it is important to alert the user to any conditions or damage that may impair the function of the optical module and thus cause changes in the optical output. In this embodiment, this is achieved by monitoring the capacitance of trace 119. The signal from the trace will change when the glass is broken or there is moisture on the MLA glass, both of which may compromise the eye safety of the package. Therefore, any change in the signal from the trace can indicate that the module is no longer eye safe and should be removed from use.

[0050] In an embodiment, the conductive trace 119 forms part of a circuit coupled to a current driver controller or other electronic control unit (ECU) that controls power to the VCSEL 107, as described above. In this embodiment, the controller is operable to monitor an electrical characteristic of the trace 119 (e.g., electrical continuity or capacitance, as the case may be) such that if the monitored characteristic changes by more than a predetermined amount, the controller adjusts the optical output of the VCSEL or other light source in accordance with an embodiment. In an embodiment, the controller is operable to monitor an electrical characteristic of the trace such that if the monitored characteristic changes by more than a corresponding predetermined amount, the controller stops the optical output produced by the light source. For example, the driver may shut down the VCSEL 107 so that it no longer emits light.

[0051] In order to be able to detect changes in the capacitance of the trace and therefore ensure the eye safety of the module, it is important to have a good understanding of the nominal capacitance of the trace. However, the amount of conductive adhesive present on the MLA glass will affect the capacitance of the trace 119. This is shown in Figures 5 and Figure 6 , as will now be explained in detail.

[0052] Figure 5 shows the Figure 2 An example of a 2D electric field generated by a capacitive trace 119 on the glass 103 is shown, where no metal sheet or any glue is present. A diagonal cross section of the glass is shown, where the MLA is visible on the upper surface. The trace is not visible in this figure, however, the shading indicates the electric field emanating from the trace 119. Figure 6 It can be seen that the electric field oscillates regularly across the surface of the glass as the two terminals of the trace alternate on the diagonal of the glass. In this example, the nominal ITO-C capacitance of the trace is 1.5293pF.

[0053] Figure 6 A shows when conductive strips of glue layer are added on either side of the glass (e.g. Figure 4 A-4D shows the change in capacitance. Fig. 7AA layer of conductive adhesive 123 is shown with a width of 600 μm. This is approximately 21% of the width of glass 103 (in one embodiment, the glass is 2800 μm wide and 2760 μm long, where the MLA has overall dimensions of 1600 μm x 600 μm) or 37.5% of the size of the MLA. Figure 6 and Fig. 7A By comparison, it is apparent that there is a large change in the 2D electric field caused by the presence of the conductive adhesive 123.

[0054] This change in Figure 7B Medium quantification, Figure 7B The percentage change in capacitance of the trace 119 is shown as the width of the conductive adhesive layer is changed. The percentage change shown in the third column of the table is the change in capacitance relative to the capacitance shown in the previous row. As can be seen from this table, the capacitance varies greatly with the width of the conductive adhesive. The change from 100 μm adhesive to 300 μm adhesive results in a more than five-fold increase in the capacitance of the trace.

[0055] Thus, dispensing conductive adhesive near capacitive ITO traces results in a significant increase in system capacitance. The latter is due to the interaction between the ITO and glue potentials, which creates an additional unwanted parallel capacitor. Because it is difficult to control the application width of the conductive adhesive at such a small scale, it is difficult to accurately quantify the effect on the capacitance of the glue layer. Therefore, the total system capacitance of different samples may vary significantly. Because the above-mentioned eye safety system relies on monitoring changes in the capacitance of the traces on the MLA glass, a good understanding of the capacitance of the traces is important for the effective operation of the eye safety features according to the embodiments.

[0056] In an embodiment, a metal shield layer 125 is provided on the MLA glass between at least a portion of the conductive traces 119 and the conductive adhesive 123 to alleviate the above-mentioned problems. Figure 4 It is shown in Figure 4 A cross section of a portion of glass 103 according to an embodiment is shown.

[0057] exist Figure 4In the arrangement of, a metal shielding layer 125 is embedded within the insulating layer 301 between the terminals of the traces 119 and the layer of conductive adhesive 123. In an embodiment, the shielding metal comprises ITO and is therefore transparent. In such an embodiment, the metal can at least partially overlap with the footprint of the light beam emitted by the VCSEL without affecting the optical performance of the module 101. In other embodiments, other suitable transparent or non-transparent metals may be used. In the case of a non-transparent metal, the metal layer preferably does not overlap with the footprint of the light beam emitted by the VCSEL 107. In an embodiment, the shielding layer is provided over the entire length of the diffuser. In another embodiment, the shielding layer is provided in the area of ​​the glass 103 where the conductive adhesive is applied. In the above embodiments, the metal shielding layer is provided at opposite edges of the MLA glass 103.

[0058] In one embodiment, the glass is formed by placing an initial SiO2 layer on the glass. Figure 4 The structure shown. ITO traces are then deposited on this initial layer and covered by another SiO2 protective layer. Several further ITO shielding layers and SiO2 protective layers can be added in this way.

[0059] Because according to an embodiment, the metal layer is embedded in an insulating layer of SiO2 or other layers of other insulating materials, the metal sheet is floating, ie it is not electrically connected to any other components in the module. In other embodiments, the metal sheet may be grounded.

[0060] A metal shielding layer is provided in addition to the metal traces 119 in order to disrupt the electric field lines emanating from the adhesive so that they do not interact with the sensing ITO traces 119. This effect is Fig. 8A and 8B In this example, there is a metal layer 125 3000 μm long and 700 μm wide on either side of the glass 103. Although the metal layer itself is Fig. 8A It is not visible in the figure, but its position is indicated by the reference numeral 125. Fig. 8A The 2D electric field generated by a capacitive trace for a glue width of 100 μm is shown in . From this figure it can be seen that the electric field of the trace is shielded over the entire area where the metal piece is present. Therefore, this will remain largely unaffected by the presence of glue in this area of ​​the glass. Therefore, the electric field will largely be invariant with the width of the glue.

[0061] Figure 8BThe table in shows the percentage change in capacitance as the width of the glue varies. While the nominal capacitance is much higher with the metal layer 125 present, the percentage change as a function of glue width is much smaller than for arrangements where the metal layer is not present. For example, the percentage change in capacitance from a glue with a 100μm glue width to a glue with a 300μm glue width results in a capacitance change of only 2.8%, compared to 537% without the shielding metal layer. Thus, the effect of the width of the applied adhesive on the capacitance of the trace can be largely mitigated by the presence of the metal shielding layer, enabling more precise control of the capacitance of the trace. This enables greater tolerance to variations in the width of the applied glue, facilitating manufacturing.

[0062] exist Figures 9A-9E The shielding effect of the metal layer on the electric field is further demonstrated in Fig. 9A is an exploded schematic diagram of the potential generated by the ITO trace and the conductive adhesive in the absence of a shielding layer. Although not visible in this figure, the potential of the trace will be affected below the area of ​​glue 801 and 803, and will therefore depend on the width of glue 801 and 803.

[0063] In contrast, Fig. 9B and 9C The potential of a trace of glue with 600 μm width and 200 μm width when a metal plate is present is shown. Fig.9D and 9E The potential of the trace just above the metal layer is shown. As can be seen in both figures, the electric field is shielded by the metal plate. Although there is a slight difference between the electric field in the 100μm and 300μm glue width cases, the electric field is essentially unchanged due to the presence of the metal shielding layer.

[0064] As shown above, a double-layer ITO arrangement according to an embodiment enables eye safety of a luminaire or other module to be ensured with little impact on the optical performance of the module.

[0065] Embodiments of the present disclosure may be employed in many different applications, including providing illumination for facial recognition sensors, such as time-of-flight sensors used in smartphones and other technologies, or in the automotive industry.

[0066] Reference numerals list

[0067] 101: Photovoltaic Module

[0068] 103:MLA Glass

[0069] 105: Optical components

[0070] 107: Light Source

[0071] 109: Lead frame

[0072] 111: Spacer

[0073] 113: Cavity

[0074] 115: Socket

[0075] 117: Surface

[0076] 119: Traces

[0077] 121: Lead

[0078] 123: Conductive Adhesive

[0079] 125: Metal layer

[0080] 201: Electrical contacts

[0081] 301: Insulation layer

[0082] 401: Capacitor terminal

[0083] 403: Conductive adhesive

[0084] 405: Terminal

[0085] 407: Conductive adhesive

[0086] 801: Glue area

[0087] 803: Glue area

[0088] 805 and 807: Metal layer

[0089] Those skilled in the art will appreciate that in the foregoing description and the appended claims, positional terms such as "above," "along," "side," etc., are made with reference to conceptual illustrations such as those shown in the accompanying drawings. These terms are used for ease of reference and are not intended to be limiting. Therefore, these terms should be understood to refer to an object when in an orientation as shown in the accompanying drawings.

[0090] Although the present disclosure has been described according to the preferred embodiments described above, it should be understood that these embodiments are illustrative only and the claims are not limited to those embodiments. In view of this disclosure, those skilled in the art will be able to make modifications and substitutions, which are considered to fall within the scope of the appended claims. Each feature disclosed or shown in this specification can be combined in any embodiment, either alone or in any appropriate combination with any other features disclosed or shown herein.

Claims

1. An optical accessory, comprising: An interdigitated capacitor having conductive traces (119); one or more electrical contacts (201) electrically connected to the conductive traces (119); as well as an insulating layer (301) covering at least a portion of the interdigital capacitor, wherein the one or more electrical contacts (201) and a portion of the insulating layer (301) are configured to receive a conductive adhesive (123), and in The optical assembly also includes a metal layer (125) located between the conductive trace (119) and the portion of the insulating layer (301) configured to receive the conductive adhesive (123).

2. The optical accessory of claim 1, further comprising a circuit configured to detect a change in capacitance of the interdigital capacitor.

3. An optical accessory according to claim 1 or 2, wherein the conductive trace (119) comprises indium titanium oxide.

4. The optical accessory according to any of the preceding claims, wherein the metal layer (125) is transparent.

5. The optical accessory according to claim 4, wherein the metal layer (125) comprises indium titanium oxide.

6. The optical component according to any of the preceding claims, wherein the metal layer (125) is embedded in the insulating layer (301).

7. The optical assembly according to any of the preceding claims, wherein the metal layer (125) is floating.

8. The optical component according to any one of the preceding claims, wherein the metal layer (125) is adjacent to one or more edges of the optical component.

9. An optical module (1), comprising: An optical accessory, comprising: An interdigital capacitor having a conductive trace (119), one or more electrical contacts (201) electrically connected to the conductive traces (119), and an insulating layer (301) covering at least a portion of the interdigital capacitor; circuitry operable to detect a change in capacitance of the interdigitated capacitor; and a conductive adhesive (123) disposed on at least a portion of the one or more electrical contacts (201) and a portion of the insulating layer (301) and configured to maintain electrical connection between the circuit and the one or more electrical contacts (201), The optical accessories also include: A metal layer (125) is located between the conductive trace (119) and the portion of the insulating layer (301) on which the conductive adhesive (123) is disposed.

10. The optical module of claim 9, wherein the conductive trace (119) comprises indium titanium oxide.

11. The optical module according to claim 9 or 10, wherein the metal layer (125) is transparent.

12. The optical module according to claim 11, wherein the metal layer (125) comprises indium titanium oxide.

13. The optical module according to any one of claims 9 to 12, wherein the metal layer (125) is embedded in the insulating layer.

14. The optical module according to any one of claims 9 to 13, wherein the metal layer (125) is floating.

15. The optical component according to any one of claims 9 to 14, wherein the metal layer (125) is adjacent to one or more edges of the optical component.

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