Infrared heater / dryer

Abstract

To provide a heater / dryer that can offer a wider working distance than conventional infrared heaters / dryers. [Solution] A heater / dryer is disclosed that includes an array of one or more vertical-cavity surface-emitting lasers (VCSELs) arranged on a substrate. A lens assembly or array, including at least one lens per VCSEL, is arranged on the opposite side of the VCSEL array from the substrate, and each lens is spherical or aspherical, with the convex side of the lens facing away from the VCSEL. The substrate may be a ceramic substrate. The side of the substrate opposite to one or more VCSELs may be bonded to a substrate which may be a metal-core printed circuit board (MCPCB) and / or a water-cooled chiller plate. A method of using this heater / dryer is also disclosed.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 712,094, filed on October 25, 2024, the content of which is incorporated herein by reference in its entirety.

[0002] This disclosure relates to irradiating heaters / dryers, particularly collimated VCSEL - based infrared heaters / dryers.

Background Art

[0003] One existing solution for infrared heaters / dryers is to use an array of vertical cavity surface emitting lasers (VCSELs), relying on the natural divergence of the light (e.g., laser light) output by the VCSELs so that the light overlaps to provide uniform illumination. This existing solution works, but the light output by the VCSELs has a large divergence angle (e.g., about 20°), so the working distance, i.e., the distance between the VCSELs and the product or workpiece to be dried, is typically short, e.g., about 50 - 100 mm.

[0004] Another existing solution is to use an array of edge - emitting lasers with complex projection optics. The light output from this type of configuration is divergent and thus covers the intended area for a specific operating distance, but this range is also limited by this divergence.

Summary of the Invention

Problems to be Solved by the Invention

[0005]

Means for Solving the Problems

[0006] A VCSEL-based heater / dryer, such as an infrared heater / dryer, is disclosed, which may include one or more molded collimator lenses to reduce the overall divergence of light emanating from a VCSEL mounted on a thermally conductive substrate. The collimator lenses may be part of a lighting assembly including a VCSEL mounted on a thermally conductive substrate. Each collimator lens may be a low-cost molded lens that can withstand standard PCB reflow. The collimator lenses may be formed by completely overmolding the VCSEL mounted on the thermally conductive substrate, or by first depositing an overmolding layer on the VCSEL mounted on the thermally conductive substrate and then attaching individual molded lenses to the side of the overmolding layer opposite the VCSEL.

[0007] Collimator lenses can be designed to operate slightly out of focus to provide better uniformity, so that a crisp, sharp, or focused image of the light output by the VCSEL is not formed on the workpiece positioned at the target operating distance from the heater / dryer.

[0008] Multiple lighting assemblies can be arrayed to constitute a heater / dryer. Since the light from a VCSEL, and therefore the output, does not spread as rapidly as when the VCSEL is used without a collimator lens, a collimator lens in each lighting assembly can provide a wider range of possible working distances. This can also mean that the workpiece can be placed away from the heater / dryer, and as a result, the likelihood of the heater / dryer being contaminated by airborne particles or condensates during workpiece drying can be reduced. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of a heater / dryer according to the principles of this disclosure, and a single lighting assembly also according to the principles of this disclosure. [Figure 2A]This is a cross-sectional view of the lighting assembly in Figure 1 in different assembly states. [Figure 2B] This is a cross-sectional view of the lighting assembly in Figure 1 in different assembly states. [Figure 3] Figure 1 is a perspective view of an exemplary heater / dryer based on the principle of this disclosure, formed from an array of lighting assemblies shown. [Figure 4A] This is a model of the irradiance of an exemplary heater / dryer, also shown in Figure 3, without a lens, at working distances of 55 mm and 105 mm between the top surface of the heater / dryer and the workpiece 16 shown in Figure 3. [Figure 4B] This is a model of the irradiance of an exemplary heater / dryer, also shown in Figure 3, without a lens, at working distances of 55 mm and 105 mm between the top surface of the heater / dryer and the workpiece 16 shown in Figure 3. [Figure 4C] This is a model of the irradiance of the exemplary heater / dryer shown in Figure 3, which has a lens, at working distances of 200 mm and 400 mm between the top surface of the heater / dryer 4 shown in Figure 3 and the workpiece 16 shown in Figure 3. [Figure 4D] This is a model of the irradiance of the exemplary heater / dryer shown in Figure 3, which has a lens, at working distances of 200 mm and 400 mm between the top surface of the heater / dryer 4 shown in Figure 3 and the workpiece 16 shown in Figure 3. [Modes for carrying out the invention]

[0010] Next, various non-limiting embodiments will be described with reference to the attached figures, in which similar reference numerals correspond to similar or functionally equivalent elements or features.

[0011] When used herein, terms relating to space or direction, such as “left,” “right,” “inside,” “outside,” “top,” “bottom,” “summit,” and “bottom,” relate to this disclosure as shown in the figures depicted. However, it should be understood that this disclosure may assume various alternative orientations, and therefore such terms should not be considered limiting. Furthermore, when used herein, it should be understood that all numerical values ​​used in this specification and in the claims, representing dimensions, physical properties, processing parameters, amounts of components, reaction conditions, etc., are in all cases modified by the term “approximately” or “about.” Therefore, unless otherwise indicated, the numerical values ​​described in the following specification and claims may vary depending on the desired properties to be obtained by this disclosure.

[0012] At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the claims, each number should be interpreted by applying ordinary rounding techniques, at least in light of the reported number of significant figures. Furthermore, all ranges disclosed herein should be understood to include the starting and ending values ​​of the range, as well as any and all subranges contained between them. For example, the range "1 to 10" should be understood to include any and all subranges between the minimum value of 1 and the maximum value of 10 (and including the minimum value of 1 and the maximum value of 10), i.e., all subranges that start with a minimum value of 1 or more and end with a maximum value of 10 or less, e.g., 1 to 3.3, 4.7 to 7.5, 5.5 to 10, etc. "One (a)" or "one (an)" refers to one or more.

[0013] As used herein, “joined,” “connected,” and similar terms refer to two or more elements that are joined, linked, fastened, connected, communicated, or otherwise related to each other (e.g., mechanically, electromagnetically, fluidly, optically, or transmissibly). In various examples, these elements may be related directly or indirectly. For example, element A may be directly related to element B. In another example, element A may be indirectly related to element B, for example, through another element C. It should be understood that not all relationships between the various elements disclosed are necessarily shown. Therefore, other connections may exist that are not depicted in the figures.

[0014] When used herein, the phrase “at least one” means that, when used with a list of items, one or more different combinations of the enumerated items may be used, and only one of each item in the list may be required. For example, “at least one of item A, item B, and item C” may include, but is not limited to, item A, or item A and item B. This example may also include item A, item B, and item C, or item B and item C. In other examples, “at least one” may, for example, two of item A, one of item B, and ten of item C, four of item B, and seven of item C, as well as other suitable combinations.

[0015] Referring to Figure 1, a single lighting assembly 2 of a heater / dryer 4 (shown in Figure 3) according to the principles of the present disclosure may include an array of one or more VCSELs 6 supported by a thermally conductive substrate 8, such as a ceramic substrate. The lighting assembly 2 shown in Figure 1 includes a 2x2 array of VCSELs 6, but this is not intended to limit the present disclosure, as the array of VCSELs 6 may include one or more VCSELs 6 of any number of XxY arrays (X≧1, Y≧0). For illustrative purposes only, the present disclosure will be described in relation to the 2x2 array of VCSELs 6 shown in Figure 1. However, this is not intended to limit the present disclosure.

[0016] The illumination assembly 2 may include a lens assembly or array 10 comprising one or more lenses 12 positioned on the side of the VCSEL 6 opposite to the thermally conductive substrate 8 of the array. The lens assembly or array 10 shown in Figure 1 includes a 2x2 array of lenses 12, but the lens assembly or array 10 may include one or more lenses 12 in any number of XxY arrays (X≧1, Y≧0), so this is not to be construed as limiting the disclosure. For purely illustrative purposes, the disclosure is described in relation to the 2x2 array of lenses 12 shown in Figure 1. However, this is not to be construed as limiting the disclosure.

[0017] In one example, placing multiple VSCEL6 within a single lighting assembly 2 may be preferable due to the lower cost per unit output. However, if the lighting assembly 2 is too large, a thermal expansion mismatch may occur between the lens assembly or array 10 and lens 12 and the array of VCSEL6 supported by the thermally conductive substrate 8. Therefore, in one example, the heater / dryer 4 shown in Figure 3 may contain a 2x2 array of VCSEL6 per lighting assembly 2.

[0018] In one example, the lens assembly or array 10 may be formed from any suitable and / or desirable material having a desired refractive index. The lens assembly or array 10 may be formed by overmolding an array of VCSELs 6 supported by the thermally conductive substrate 8 over the entire lens assembly or array 10 including the lenses 12, or by first depositing an overmold layer 14 over the array of VCSELs 6 and then attaching the individual lenses 12 to the side of the overmold layer 14 opposite the VCSELs 6. In one example, the lens assembly or array 10 and the lenses 12 may be made from polydimethylsiloxane (PDMS) having a refractive index n of about 1.41, e.g., n = 1.41 ± 0.05.

[0019] In one example, the lens 12 is arranged on the work 16 (shown as a line in FIG. 3) to be heated / dried, which is on the side of the lens assembly or array 10 opposite to the array of VCSELs 6 supported by the thermally conductive substrate 8, to provide better uniformity, so that the light output by the VCSEL array forms an unfocused image in the Z direction, i.e., a blurry, sharp, or out-of-focus image does not form. In other words, the light output by the VCSEL array to the work 16 arranged at the target or desired operating distance through the lens assembly or array 10 is not focused on the surface of the work 16 facing the lens assembly or array 10.

[0020] A plurality of lighting assemblies 2 can be arrayed to form an exemplary heater / dryer 4 shown in FIG. 3, i.e., a 10×28 array of lighting assemblies 2. The lens assembly or array 10 of each lighting assembly 2 of the exemplary heater / dryer 4 shown in FIG. 3 can provide a wider range of workable distances as light because it does not spread its output as rapidly as conventional infrared heaters / dryers. This also means that the work 16 may be placed further away from the heater / dryer 4, thereby also avoiding contamination of the work 16 by any possible floating particles or condensates.

[0021] In one example, each lens 12 of the lens assembly or array 10 may be positioned or disposed over an individual VCSEL 6. Each lens 12 may be spherical or aspherical and can include a concave surface of the lens 12 facing the VCSEL 6 and a convex surface of the lens 12 facing away from the VCSEL 6.

[0022] In one example, in heating / drying applications, where it may be necessary to make the infrared heat to the work 16 as uniform as possible, the position of the lens 12 can be shifted in the Z direction or defocused to blur the VCSEL image. The design of the lens 12 of each lighting sub-assembly 2 may be slightly varied to create a further difference in defocus to assist with heating / drying uniformity.

[0023] In one example, the thermal conductive substrate 8 of each lighting assembly 2 can be made of a high thermal conductivity material such as ceramic, which can provide a good thermal path from the VCSEL 6 to the thermal conductive substrate 8, and this thermal conductive substrate 8 can also be electrically insulating so that the VCSEL 6 can be electrically connected, for example, in series, when it is considered necessary, appropriate, and / or desirable to apply an electrical stimulus to the VCSEL 6. In another example, the thermal conductive substrate 8 of each lighting assembly 2 can be made from a molded copper lead frame or printed circuit board (PCB) embedded with copper slag, and the metal core PCB (MCPCB) (discussed below in relation to Figure 3) to which these thermal conductive substrates 8 are mounted is electrically insulating.

[0024] Next, a method for forming an exemplary lighting assembly 2 will be described with reference to Figures 2A and 2B.

[0025] First, a VCSEL (e.g., a VCSEL die) 6 can be mounted on a thermally conductive substrate 8, such as a ceramic substrate, and then a wire bond 18 can be mounted to electrically connect the VCSEL 6 and the heat sink 8. The thermally conductive substrate 8 may include conductors (e.g., screen-printed conductors) with a suitable pattern for electrically connecting the VCSEL 6 and the wire bond 18. These conductors can be formed in a manner known in the art so that a suitable electrical bias can be applied to the VCSEL 6 via the wire bond 18 and the back surface of the VCSEL 6 from one or more external power sources (not shown) and earth (not shown), thereby electrically stimulating the VCSEL 6 and generating light in a manner known in the art.

[0026] Next, the silicone interface 20 is molded to cover the VCSEL 6 side of the thermally conductive substrate 8, protecting the VCSEL 6 and providing a space for the lens 12. Then, one or more molded lens assemblies or arrays 10 (each molded lens assembly or array 10 containing one or more lenses 12) can be attached to the side of the silicone interface 20 opposite to the VCSEL 6 to form a completed lighting assembly 2. These latter two steps may be combined into a single possible, appropriate, and / or desirable step.

[0027] Next, referring to Figure 3 and all subsequent figures, several completed lighting assemblies 2 are mounted (for example, by surface mounting and reflow) onto a metal core PCB (MCPCB) 22, and the PCB can be coupled to a water-cooled chiller plate 28 to form a complete heater / dryer 4.

[0028] The complete heater / dryer 4 may comprise an array of lighting assemblies 2 mounted on an MCPCB 22 via a thermal conductive substrate 8, for example, an array of 10 × 28, each of which may include a thin layer of solder 26 on the mounting pad 24 of the thermal conductive substrate 8 to minimize or avoid tilting of the lighting assemblies 2. The side of the MCPCB 22 opposite to the lighting assemblies 2 may then be fixed to a water-cooled chiller plate 28 to help cool the complete heater / dryer 4 combination during use.

[0029] As can be seen by referring to Figures 4A to 4B and all subsequent figures, the irradiance pattern models of the exemplary heater / dryer in Figure 3, which does not have a lens assembly or array 10 including lens 12, are similar at working distances of 55 mm (Figure 4A) and 105 mm (Figure 4B) between the top surface of the heater / dryer 4 and the workpiece 16 (the irradiance pattern shown in Figure 4B is more out of focus than the irradiance pattern shown in Figure 4A).

[0030] As can be seen by referring to Figures 4C-4D and all subsequent figures, the irradiance pattern model of the exemplary heater / dryer in Figure 3 with a lens assembly or array 10 including lens 12 at working distances of 200 mm (Figure 4C) and 450 mm (Figure 4D) between the top surface of the heater / dryer 4 and the workpiece 16 is similar to the irradiance pattern model of the exemplary heater / dryer in Figure 3 without a lens assembly or array 10 including lens 12, shown in Figures 4A-4B. Also, as can be seen, although the illustrated irradiance patterns are similar, the longer working distance in Figure 4D is preferable to the irradiance pattern shown in Figure 4B. Therefore, as can be understood, the same configuration of heater / dryer 4 having a lens assembly or array 10 including lens 12 can have a working distance that may be between approximately 3 and 6 times that of heater / dryer 4 without a lens assembly or array 10 including lens 12, as shown in Figures 4A and 4B, having a similar irradiance pattern, as shown in Figures 4C and 4D.

[0031] A method for heating or drying a workpiece 16 may include the steps of providing a heater / dryer 4 and positioning the workpiece 16 at a distance from the side of the lens assembly or array 10 opposite to the substrate 8, such that the light emitted onto the workpiece 16 by one or more VCSELs 6 through the lens assembly or array 10 does not focus on the surface of the workpiece 16 facing the lens assembly or array 10. Then, one or more VCSELs 6 can be made to emit light onto the surface of the workpiece 6 facing the lens assembly or array 10.

[0032] Other non-limiting examples or embodiments of this disclosure are described and illustrated in the following numbered sections.

[0033] Item 1: A heater / dryer comprising an array of one or more VCSELs arranged on a substrate, and a lens assembly or array arranged on the opposite side of the VCSEL array from the substrate, each including at least one lens per VCSEL, wherein each lens is spherical or aspherical, and the convex surface of the lens faces away from the VCSEL.

[0034] Item 2: The heater / dryer according to Item 1, wherein the substrate may be a ceramic substrate.

[0035] Item 3: The heater / dryer described in Item 1 or 2 may further include the side of the substrate opposite to the one or more VCSELs placed on the substrate.

[0036] Item 4: The heater / dryer according to any one of items 1 to 3, wherein the base substrate may include a metal core printed circuit board (MCPCB), a water-cooled chiller plate, or both.

[0037] Item 5: The heater / dryer according to any one of items 1 to 4, wherein an array of one or more VCSELs arranged on the substrate and a lens assembly or array including at least one lens per VCSEL arranged on the opposite side of the VCSEL array from the substrate can form a lighting assembly, and the heater / dryer can comprise an array of two or more lighting assemblies arranged on a substrate.

[0038] Item 6: The heater / dryer according to any one of items 1 to 5, wherein the base substrate may include a metal core printed circuit board (MCPCB), a water-cooled chiller plate, or both.

[0039] Item 7: The heater / dryer according to any one of items 1 to 6, wherein the array of the lighting assemblies may be located on the side of the MCPCB opposite to the water-cooled chiller plate.

[0040] Item 8: The heater / dryer according to any one of items 1 to 7, wherein the array of one or more VCSELs can prevent light irradiated onto a workpiece positioned on the side of the lens assembly or array opposite to the substrate from being focused on the surface of the workpiece facing the lens assembly or array.

[0041] Item 9: The heater / dryer according to any one of items 1 to 8, wherein the lens assembly or array may comprise an overmolded layer disposed on the array of one or more VCSELs, and at least one lens per VCSEL disposed on the side of the overmolded layer opposite to the substrate.

[0042] Item 10: The heater / dryer according to any one of items 1 to 9, wherein the lens assembly or array may be made from polydimethylsiloxane (PDMS).

[0043] Item 11: The heater / dryer according to any one of items 1 to 10, wherein the lens assembly or array may have a refractive index of 1.41.

[0044] Item 12: A method for heating or drying a workpiece, comprising the steps of: providing a heater / dryer according to any one of items 1 to 11; positioning the workpiece at a distance from the side of the lens assembly or array opposite to the substrate such that the light emitted to the workpiece by the array of one or more VCSELs through the lens assembly or array does not focus on the surface of the workpiece facing the lens assembly or array; and causing the one or more VCSELs to emit light onto the surface of the workpiece facing the lens assembly or array.

[0045] This disclosure has been described in detail for illustrative purposes, based on what is currently considered to be the most practical and preferred embodiments. However, such details are for that purpose only, and this disclosure is not limited to the disclosed embodiments. Rather, it is intended to encompass modifications and equivalent configurations within the spirit and scope of the appended claims. For example, this disclosure assumes, to the extent possible, that one or more features of any embodiment can be combined with one or more features of any other embodiment. [Explanation of Symbols]

[0046] 2 Lighting Assembly 4 Heater / Dryer 6. Vertical Cavity Surface Emitting Laser (VCSEL) 8 Thermally conductive substrate 10. Lens assembly or array 12 lenses 14 Overmolding layer 16 Work 18 Wire bond 20 Silicone Interfaces 22 Metal Core Printed Circuit Boards (MCPCBs) 24 mounting pads 26 Solder 28 Water-cooled chiller plate

Claims

1. One or more arrays of VCSELs arranged on a substrate, A lens assembly or array comprising at least one lens per VCSEL, arranged on the opposite side of the substrate to the array of VCSELs, wherein each lens is spherical or aspherical, and the convex surface of the lens faces away from the VCSEL, and A heater / dryer equipped with the following features.

2. The heater / dryer according to claim 1, wherein the substrate is a ceramic substrate.

3. The heater / dryer according to claim 1, further comprising the side of the substrate opposite to the one or more VCSELs arranged on the substrate.

4. The heater / dryer according to claim 3, wherein the base substrate includes a metal core printed circuit board (MCPCB), a water-cooled chiller plate, or both.

5. An array of one or more VCSELs arranged on the substrate and a lens assembly or array including at least one lens per VCSEL arranged on the opposite side of the substrate from the array of VCSELs form an illumination assembly. The heater / dryer according to claim 1, wherein the heater / dryer comprises an array of two or more lighting assemblies arranged on a substrate.

6. The heater / dryer according to claim 5, wherein the base substrate includes a metal core printed circuit board (MCPCB), a water-cooled chiller plate, or both.

7. The heater / dryer according to claim 6, wherein the array of lighting assemblies is located on the side of the MCPCB opposite to the water-cooled chiller plate.

8. The heater / dryer according to claim 1, wherein the array of one or more VCSELs prevents light from being focused on the surface of the workpiece facing the lens assembly or array, on the side opposite to the substrate, that is irradiated onto the workpiece.

9. The heater / dryer according to claim 1, wherein the lens assembly or array comprises an overmolded layer arranged on the array of one or more VCSELs, and at least one lens per VCSEL arranged on the side of the overmolded layer opposite to the substrate.

10. The heater / dryer according to claim 1, wherein the lens assembly or array is made from polydimethylsiloxane (PDMS).

11. The heater / dryer according to claim 1, wherein the lens assembly or array has a refractive index of 1.

41.

12. A method for heating or drying a workpiece, The steps of providing the heater / dryer according to claim 1, The steps of positioning the workpiece at a distance from the side of the lens assembly or array opposite to the substrate, such that the light emitted onto the workpiece through the lens assembly or array by the array of one or more VCSELs does not focus on the surface of the workpiece facing the lens assembly or array, The steps include: emitting light from one or more VCSELs onto the surface of the workpiece facing the lens assembly or array; A method that includes this.

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