Patent Application
20160104698
The present invention relates to the field of electronic devices, and more particularly, to a method of making an optical proximity sensor.
Proximity sensors are designed to detect the presence of nearby objects without physical contact. Optical proximity sensors utilize light sensitive elements to detect objects.
An optical proximity sensor includes an optical transmitter and an optical receiver. Optical proximity sensing is based on emitting light from the optical transmitter, capturing light reflected back to the optical receiver by a nearby object, and processing the reflected light to determine the proximity of the object to the sensor.
Optical proximity sensors are used in many applications, including mobile communications devices. For example, an optical proximity sensor may be used to determine when a mobile phone is held close to a user's face so as to turn off the mobile phone's display to conserve power.
A typical optical proximity sensor includes an enclosure assembly that is attached to a connector plate assembly that includes the optical transmitter and the optical receiver. As illustrated in
The package housing 12 has an optical transmit opening 24 extending therethrough to the optical transmit cavity 14, and an optical receive opening 26 extending therethrough to the optical receive cavity 16. Positioned within the respective cavities 14, 16 is an optical transmit element 34 and an optical receive element 36. Glue 40 is deposited within the respective cavities 14, 16 to hold the optical transmit and receive elements 34, 36 in place. The optical transmit and receive elements 34, 36 protect the optical transmitter and receiver, as well as filter undesired light.
As dimensions of optical proximity sensors are reduced, it becomes more difficult to dispense glue on the package housing 10 within the optical transmit cavity 14 and the optical receive cavity 16. This slows down the throughput of making optical proximity sensors. This problem is further compounded with a corresponding reduction in thickness of the optical transmit and receive elements 34, 36. Consequently, there is a need to address these concerns as the dimensions of optical proximity sensors are reduced.
In view of the foregoing background, it is therefore an object of the present invention to provide a method for making an optical proximity sensor that simplifies attachment of optical transmit and receive elements within the sensor.
This and other objects, features, and advantages in accordance with the present invention are provided by a method for making an optical proximity sensor comprising forming a package top plate having an optical transmit opening and an optical receive opening extending therethrough, attaching an optical transmit element to the package top plate adjacent the optical transmit opening, and attaching an optical receive element to the package top plate adjacent the optical receive opening. The method may further comprise forming a package body onto the package top plate to define an optical transmit cavity receiving the optical transmit element and an optical receive cavity receiving the optical receive element.
The method may further comprising depositing glue on the package top plate adjacent the optical transmit opening and adjacent the optical receive opening before attaching the optical transmit and receive elements. By forming the package top plate separately from the package body, this advantageously provides plenty of room to dispense the glue.
Another advantage of separately forming the package body from the package body is that this may also allow for an increase in the throughput of making the optical proximity sensor since attachment of optical transmit and receive elements has been simplified.
The package body may comprise sidewalls around an outer perimeter of the package top plate, and a separation wall between the optical transmit cavity and the optical receive cavity. The package body may be formed so that there is a gap between the sidewalls and outer edges of the optical transmit and receive elements, and a gap between the separation wall and outer edges of the optical transmit and receive elements. In an alternate embodiment, the package body may be formed so that the sidewalls and the separation wall contact the outer edges of the optical transmit and receive elements.
The method may further comprise forming a connector plate assembly comprising an optical transmitter and an optical receiver. The connector plate assembly may be attached to the package body so that the optical transmitter is received by the optical transmit cavity and the optical receiver is received by the optical receive cavity.
The optical transmit element and the optical receive element may comprise glass, for example. A thickness of the optical transmit element and the optical receive element may be within a range of about 200-300 microns, for example.
The optical transmit element and the optical receive element may be rectangular shaped. Each side of the optical transmit element and the optical receive element may be within a range of about 0.5-1.00 millimeters, for example.
A diameter of the optical transmit opening and the optical receive opening may be within a range of about 0.3-0.5 millimeters, for example. The package top plate and the package top plate may be formed using thermoplastic molding material.
Another aspect is directed to an optical proximity sensor as described above where a joint line is formed at an interface between the package body and the package top plate.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements in alternative embodiments.
Referring now to the flowchart 50 illustrated in
The package top plate 102 may be formed using injection molding. The material used in the injection molding may be thermoplastic, for example. In the illustrated embodiment, the package top plate 102 has a planar surface.
Glue 140 is then deposited on the package top plate 102 at Block 56 adjacent the optical transmit opening 124 and adjacent the optical receive opening 126, as illustrated in
An optical transmit element 134 is positioned on the glue 140 at Block 58 adjacent the optical transmit opening 124, and an optical receive element 136 is positioned on the glue 140 at Block 60 adjacent the optical receive opening 126, as illustrated in
Separately forming the package top plate 102 may allow for an increase in the throughput of making the optical proximity sensor 100 since attachment of the optical transmit and receive elements 134, 136 has been simplified. This is particular so since a thickness of the optical transmit element 134 and the optical receive element 136 is typically within a range of about 200-300 microns, for example.
The illustrated optical transmit and receive elements 134, 136 are rectangular shaped. Each side of the optical transmit element 134 and the optical receive element 136 is within a range of about 0.5-1.00 millimeters, for example. In other embodiments, the optical transmit and receive elements 134, 136 may have a non-rectangular shape, such as a circular shape, for example.
Separately forming the package top plate 102 may allow for an increase in the throughput of making the optical proximity sensor 100 since attachment of the optical transmit and receive elements 134, 136 has been simplified, as readily appreciated by those skilled in the art.
A package body 104 is formed onto the package top plate 102 at Block 62 to define an optical transmit cavity 114 receiving the optical transmit element 134 and an optical receive cavity 116 receiving the optical receive element 136, as illustrated in
As with the package top plate 102, injection molding may be used to form the package body 104. The material used in the injection molding may be thermoplastic, for example. Prior to forming the package body 104 onto the package top plate 102, a groove 142 may be formed around the outer perimeter of the package top plate 102, as illustrated in
In the illustrated embodiment, the package body 104 is formed so that there is a gap 146 between the sidewalls 105 and outer edges of the optical transmit and receive elements 134 and 136. Similarly, there is also a gap 148 between the separation wall 107 and outer edges of the optical transmit and receive elements 134 and 136. In an alternate embodiment, the package body 104′ is formed so that the sidewalls 105′ and the separation wall 107′ contact the outer edges of the optical transmit and receive elements 134′, 136′, as illustrated in
A connector plate assembly 150 comprising an optical transmitter 152 and an optical receiver 154 is formed at Block 64. The optical transmitter 152 may be configured as an LED and the optical receiver 154 may be configured as a photo diode, for example. Other types of optical transmitters and receivers 152, 154 may be used, as readily appreciated by those skilled in the art. The connector plate assembly 150 includes connector pins 160 for the optical transmitter 152 and optical receiver 154.
The connector plate assembly 150 is attached to the package body 104 so that the optical transmitter 152 is received by the optical transmit cavity 114 and the optical receiver 154 is received by the optical receive cavity 116, as illustrated in
Another aspect is directed to an optical proximity sensor 100 as described above where a joint line 170 is formed at an interface between the package body 104 and said package top plate 102. The optical proximity sensor 100 includes a package top plate 102 having an optical transmit opening 24 and an optical receive opening 26 both extending through the package top plate. An optical transmit element 34 is attached to the package top plate 102 adjacent the optical transmit opening 24. An optical receive element 36 is attached to the package top plate 102 adjacent the optical receive opening 26.
A package body 104 is attached onto the package top plate 102 to define an optical transmit cavity 116 receiving the optical transmit element 134 and an optical receive cavity 114 receiving the optical receive element 136. The joint line 170 is formed at the interface between the package body 104 and the package top plate 102.
A connector plate assembly 150 includes an optical transmitter 152 and an optical receiver 154 attached to the package body 104 so that the optical transmitter is aligned with the optical transmit cavity 114 and the optical receiver is aligned with the optical receive cavity 116.
Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.
