This nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application Nos. 200.6-288405 and 2007-136915 filed in Japan on Oct. 24, 2006 and May 23, 2007, the entire contents of which are hereby incorporated by reference.
The present invention relates to a photo interrupter having an object passage on an optical path from a light-emitting device to a light-receiving device to detect the presence or absence of an object or passage of an object, a method of manufacturing the photo interrupter, and electronic equipment using the photo interrupter.
Conventional photo interrupters having connector terminals include a photo interrupter disclosed in JP 3176496 B2 (‘patent document 1’) and a photo interrupter disclosed in JP 2002-368255 A (‘patent document 2’).
First, patent document 1 will be described.
As shown in
Next, as shown in
Finally, as shown in
Next, patent document 2 will be described.
In
When light-emitting devices 27 and light-receiving devices 28 are inserted into the corresponding openings 26 of the lead frame sheet 21, the electrode terminals 29 of the light-emitting devices 27 and the light-receiving devices 28 are press-fitted to the associated connection structures of the lead frame sheet 21, and thereby the light-emitting device 27 and the light-receiving device 28 are electrically connected to the lead frame. After that, the lead frame sheet 21 is cut into individual devices to complete photo interrupters.
However, the conventional photo interrupters disclosed in patent document 1 and patent document 2 have problems as described below.
In patent document 1, with respect to the three individual components which are the lead frame 1, the connector 7, and the outer case 9, a process (spot welding, soldering, or the like) of connecting the connector 7 to the lead frame 1, and a process (thermal caulking) of coupling the lead frame 1 and the connector 7 which are connected with each other to the outer case 9 are required. Thus, there is a problem that because the number of components is large, the number of processes required for the assembling of the components is large accordingly.
In patent document 2, the lead frame sheet 21, the connector sections 23, and the capsules 24 are integrally molded, while the light-emitting devices 27 and the light-receiving devices 28 are separate, individual components. Thus, the number of components required is large. Also, the process of press-fitting the light-emitting devices 27 and the light-receiving devices 28 to the lead frame sheet 21 is required. In addition, in order to integrally mold the capsules 24 as outer cases onto each lead frame of the lead frame sheet 21, it is required to keep a region for formation of the capsule 24 on the lead frame, so that the device pitch of the lead frame sheet 21 becomes large. As a result, there is a problem that the number of photo interrupters obtained and manufactured from a fixed length lead frame sheet 21 becomes smaller.
In addition, the photo interrupter of patent document 1 has electrical connection points where the connector coupling sections 4, 5, and 6 of the lead frame 1 are electrically connected with the pins 8 of the connector 7 by spot welding, and the photo interrupter of patent document 2 has electrical connection points where the lead frame is electrically connected with the light-emitting device 27 and the light-receiving device 28 by press-fitting. For this reason, it is feared that the photo interrupters may be decreased in reliability.
It is therefore an object of the present invention to provide a photo interrupter allowing reduction in the number of components and simplification of the assembling process to achieve cost reduction, and having no electrical connection points to have high reliability, as well as providing a method of manufacturing the photo interrupter, and electronic equipment using the photo interrupter.
In order to solve the above problem, the present invention provides a photo interrupter, comprising:
a lead frame assembly having a lead frame, a light-emitting device and a light-receiving device which are mounted on the lead frame and each encapsulated in a light permeable resin, and a connector terminal for external connection provided at an end of the lead frame; and
an outer case for accommodating the lead frame assembly so as to be integrated with the lead frame assembly, the outer case being made of light-blocking resin and having a connector section,
wherein the connector terminal is adapted to be accommodated in the connector section when the lead frame assembly is accommodated in the outer case;
wherein the lead frame assembly has a connector mold made of a resin, the connector mold covering at least part of the connector terminal; and
wherein at least any one of the outer case and the connector mold is provided with a latching section for latching the connector mold to the outer case.
According to this configuration, components necessary for the assembling process can be made into two components, that is, a lead frame assembly in which a light-emitting device and a light-receiving device are encapsulated in resin on a lead frame and a connector mold (“mold” herein means a molded part) is also formed, and an outer case having a connector section. Thus, the number of components can be reduced, as compared with the conventional photo interrupters, thereby achieving cost reduction. In addition, when the lead frame assembly is accommodated in the outer case, the connector mold is latched to the outer case by the latching section provided on at least one of the outer case or the connector mold, and thereby the lead frame assembly is fixed to the outer case. Thus, as compared with the conventional photo interrupter disclosed in patent document 1, welding or the like is not required, thereby achieving easy assembly and cost reduction.
In addition, the connector mold is formed on the connector terminal and is latched to the outer case by the latching section, so that the connector terminal can be fixed to the outer case with a sufficient strength. Furthermore, the outer case and the lead frame assembly are produced separately, so that the lead frame sheet does not need space for forming outer cases, meaning that patterns necessary for devices can be arranged as close as possible on the lead frame sheet. Thus, the number of devices obtainable from a lead frame sheet having the same area can be increased, thereby achieving cost reduction. In addition, components handling electrical signals are gathered on only the lead frame so that there are no electrical junction points. Thus, high reliability can be obtained.
In one embodiment, a light-emitting mold having the light-emitting device encapsulated in light permeable resin and a light-receiving mold having the light-receiving device encapsulated in light permeable resin stand erect against a reference surface of the lead frame.
According to this embodiment, a light-emitting mold and a light-receiving mold stand erect against a surface of the lead frame, so that when the light-emitting mold and the light-receiving mold are erected by bending the lead frame, the distance (optical path length) between the light-emitting device and the light-receiving device can be reduced by the height of the optical axis, and the photocoupling efficiency can be thus increased. As a result, a lower-cost light-emitting device having a small amount of emitted light and a lower-cost light-receiving device having a small light-receiving area can be used, thus achieving more cost reduction.
In one embodiment, the light-emitting device and the light-receiving device are mounted on a same surface of the lead frame;
the light-emitting mold and the light-receiving mold stand erect on one side of the reference surface of the lead frame; and
any one of the light-emitting mold and the light-receiving mold has a light reflecting surface for turning direction of an optical path of light emitted from the light-emitting device or direction of an optical path of light to be entered into the light-receiving device.
According to this embodiment, the light-emitting device and the light-receiving device are mounted on the same surface of the lead frame, and the light-emitting mold and the light-receiving mold stand erect on the same side of the surface of the lead frame, so that the light-emitting surface of the light-emitting device and the light-receiving surface of the light-receiving device are directed in the same direction, and do not face each other. However, any one of the light-emitting mold and the light-receiving mold has a light reflecting surface for turning the direction of the optical path of light emitted from the light-emitting device or the direction of the optical path of light to be entered into the light-receiving device to the opposite side, so that the optical axis of the light-emitting device and the optical axis of the light-receiving device can be coupled.
In addition, since the light-emitting device and the light-receiving device are mounted on the same surface of the lead frame, the light-emitting device and the light-receiving device can be mounted on a usual manufacturing line without the need for a special jig or process, and the light-emitting devices and the light-receiving devices can be processed continuously. Thus, the cost of the production facilities can be kept low and the production efficiency can be increased, thereby achieving more cost reduction.
In one embodiment, the light-emitting mold and the light-receiving mold are formed on opposed first and second surfaces of the lead frame, respectively, and stand erect on one side of the reference surface of the lead frame, and the light-emitting device and the light-receiving device face each other.
According to this embodiment, the light-emitting device is mounted on one surface of the lead frame, while the light-receiving device is mounted on another surface of the lead frame, and the light-emitting mold and the light-receiving mold are erected on the same side of the lead frame, so that the light-emitting surface of the light-emitting device and the light-receiving surface of the light-receiving device face each other. Thus, the optical axis of the light-emitting device and the optical axis of the light-receiving device can be coupled easily. In addition, since the light-emitting device and the light-receiving device face each other, the photocoupling efficiency can be increased. Thus, a low-cost light-emitting device and a low-cost light-receiving device can be used, thereby achieving more cost reduction.
In one embodiment, the light-emitting device and the light-receiving device are mounted on a same surface of the lead frame. A lead frame portion associated with the light-emitting mold and a lead frame portion associated with the light-receiving mold are bent from the reference surface of the lead frame such that these molds stand erect on one side of the reference surface of the lead frame. And, the light-emitting device and the light-receiving device face each other.
According to this embodiment, the light-emitting device and the light-receiving device mounted on the same surface of the lead frame face each other in the state that the light-emitting mold and the light-receiving mold stand erect on the same side of the lead frame, so that the optical axis of the light-emitting device and the optical axis of the light-receiving device can be coupled easily. In addition, since the light-emitting device and the light-receiving device are mounted on the same surface of the lead frame, the light-emitting device and the light-receiving device can mounted on a usual production line without the need for a special jig or process, and the light-emitting devices and the light-receiving devices can be processed continuously. Thus, the cost of the production facilities can be kept low and the production efficiency can be increased, thereby achieving more cost reduction.
In one embodiment, connector terminals mechanically separated from each other exist in the connector mold, and the mechanically separated connector terminals are wired by wire bonding and electrically connected with each other.
According to this embodiment, the connector terminals in the connector mold are connected with each other by wire bonding, so that the pin arrangement of the connector terminals can be set freely. Thus, even when the light-emitting device and the light-receiving device having various pad arrangements are used, the pin arrangement of the connector terminals can be set as desired. In particular, when a small photo interrupter is produced, space for routing the wiring of the lead frame is small, so that it becomes difficult to set the pin arrangement of the connector terminals as desired depending on the pad arrangements of the light-emitting device and the light-receiving device. Also in such a case, the pin arrangement of the connector terminals can be set as desired without the need of developing light-emitting devices and light-receiving devices having a modified pad arrangement, thereby achieving cost reduction.
In one embodiment, a connector mold fixing section for fixing the connector mold to the outer case is provided on the outer case on at least one of opposite sides of the connector mold in a direction of extension of the connector terminal.
According to this embodiment, the connector mold is fixed to the outer case by the connector mold fixing section, so that a force applied to the connector terminals when a female connector is extracted from or inserted in the connector terminals is suppressed by the connector mold fixed to the outer case, and is not applied to the lead frame on which the light-emitting device and the light-receiving device are mounted. Thus, the lead frame can be prevented from deforming, thereby improving the reliability.
In one embodiment, the photo interrupter further includes a lead frame fixing column which is formed on the outer case and extends in a direction orthogonal to a direction of extension of a main body of the lead frame to fix the main body of the lead frame.
According to this embodiment, the main body of the lead frame is fixed by the lead frame fixing column formed on the outer case, so that a force applied to the connector terminals at extraction or insertion of a female connector is suppressed by the lead frame fixing column formed on the outer case, and is not applied to the lead frame on which the light-emitting device and the light-receiving device are mounted. Thus, the lead frame can be prevented from deforming, thereby improving the reliability.
In one embodiment, the photo interrupter further includes a groove-like notch formed in the connector mold, and a connector mold latching section shaped like a column which is provided on an inner surface of the outer case and is engaged with the notch to latch the connector mold.
According to this embodiment, the connector mold latching section shaped like a column provided on the inner surface of the outer case is engaged with the notch shaped like a groove formed in the connector mold to latch the connector mold, so that a force applied to the connector terminals at extraction or insertion of a female connector is suppressed by the connector mold latching section provided on the outer case, and is not applied to the lead frame on which the light-emitting device and the light-receiving device are mounted. Thus, the lead frame can be prevented from deforming, thereby improving the reliability.
In one embodiment, the light-emitting device and the light-receiving device are mounted on a same surface of the lead frame. And, the photo interrupter further comprises:
a first reflecting surface which is provided on an inner surface of the outer case in a position facing the light-emitting device for reflecting light emitted from the light-emitting device toward the light-receiving device, and a second reflecting surface which is provided on the inner surface of the outer case in a position facing the light-receiving device for reflecting light from the first reflecting surface to the light-receiving device; and
an optical axis of the light-emitting device and an optical axis of the light-receiving device are coupled by the first reflecting surface and the second reflecting surface.
According to this embodiment, a first reflecting surface reflecting light emitted from the light-emitting device toward the light-receiving device, and a second reflecting surface reflecting light from the first reflecting surface to the light-receiving device are provided on the inner surface of the outer case, and the optical axis of the light-emitting device and the optical axis of the light-receiving device are coupled by the first reflecting surface and the second reflecting surface, so that it is not necessary to erect the light-emitting mold and the light-receiving mold against a surface of the lead frame. Thus, the production process can be simplified, thereby achieving cost reduction.
In one embodiment, the light-emitting device and the light-receiving device are mounted on a same surface of the lead frame. And, the outer case is provided with an emitted light refractor in a position facing the light-emitting device for refracting light emitted from the light-emitting device to direct the light to an object to be detected, and an incident light refractor in a position facing the light-receiving device for refracting light reflected by the object to be detected to direct the light to the light-receiving device.
According to this embodiment, because the outer case is provided with the emitted light refractor refracting light emitted from the light-emitting device to direct the light to an object to be detected and the incident light refractor refracting light reflected by the object to direct the light to the light-receiving device, it is not necessary to erect the light-emitting mold and the light-receiving mold against the reference surface of the lead frame. Thus, the production process can be simplified, thereby achieving cost reduction.
The resin which the connector mold is made of may be a same light permeable resin as or a different resin from the light permeable resin encapsulating the light-emitting device and the light-receiving device.
In one embodiment, the resin which the connector mold is made of is different from the light permeable resin encapsulating the light-receiving device and the light-emitting device. Thus, resins most suitable for functions required for molds (i.e., molded parts) to be used can be selected as follows. For example, as a molding resin for the light-emitting mold and the light-receiving mold, selection can be made of a light permeable resin which has a high fluidity not so as to cut gold wires connecting the light-receiving device and the light-emitting device with the lead frame and which is pervious to light emitted from the light-emitting device. Such light permeable resin may be an epoxy resin or a silicone resin. As the epoxy resin, one that transmits infrared light but blocks visible light may be preferably selected because infrared LEDs are generally used as light-emitting devices. Furthermore, as the molding resin for the connector mold, a resin having a high mechanical strength can be selected. Examples of such a resin include PPS (polyphenylene sulfide) and liquid crystal polymers. In addition, a path for supplying the light permeable resin when forming the light-receiving mold and the light-emitting mold, and a path for supplying the molding resin when forming the connector mold are provided independent of each other, and thereby both of the paths can be made short and simple to stabilize the productivity.
In one embodiment, fillers are mixed in the resin which the connector mold is made of.
According to this embodiment, as the resin for the connector mold for which a high mechanical strength is required, resin in which fillers are mixed is used. Thus, the mechanical strength of the resin for the connector mold can be increased, and thereby the reliability of the photo interrupter can be more improved. Glass fibers, carbon fibers, or the like can be used as the fillers.
The present invention also provides a method of manufacturing the photo interrupter, comprising steps of:
mounting a light-emitting device and a light-receiving device on a lead frame which is formed with connector terminals and performing predetermined wiring for the light-emitting device and the light-receiving device;
forming a light-emitting mold and a light-receiving mold by encapsulating the light-emitting device and the light-receiving device on the lead frame in a light permeable resin;
forming a connector mold by encapsulating part of the connector terminal in a resin;
forming an outer case having a connector section at an end thereof by injection molding; and
inserting in the outer case the lead frame on which the light-emitting mold, the light-receiving mold, and the connector mold are formed such that the connector terminals of the lead frame are positioned in the connector section of the outer case, thereby accommodating the lead frame in the outer case,
wherein any one of said step of forming an outer case and said step of forming a connector mold comprises forming a latching section for latching the connector mold to the outer case; and
wherein the connector mold is latched and fixed, when accommodating the lead frame in the outer case, to the outer case by the latching section formed on at least one of the outer case or the connector mold.
According to this configuration, components necessary for the assembling process can be made two components, that is, a lead frame on which a light-emitting device and a light-receiving are encapsulated in resin and a connector mold is formed, and an outer case having a connector section, so that the number of components can be reduced as compared with the conventional photo interrupters, thus achieving cost reduction. In addition, when the lead frame is accommodated in the outer case, the connector mold is latched to the outer case by a latching section provided on at least any one of the outer case and the connector mold, and the lead frame is thus fixed to the outer case. Thus, as compared with the conventional photo interrupter disclosed in patent document 1, welding or the like is not required, thereby achieving easy assembly and cost reduction.
In one embodiment, the step of mounting a light-emitting device and a light-receiving device and performing predetermined wiring comprises mounting a plurality of light-emitting devices and a plurality of light-receiving devices on a lead frame sheet in which two or more sets of connector terminals are formed and performing predetermined wiring for the light-emitting devices and the light-receiving devices. The step of forming a light-emitting mold and a light-receiving mold comprises forming light-emitting molds and light-receiving molds for the respective light-emitting devices and the respective light-receiving devices. The step of forming a connector mold comprises forming connector molds for the respective sets of connector terminals. And, the method further comprises cutting tie bars placed at least on the peripheries of the light-emitting molds and the light-receiving molds, and cutting tie bars by which devices each having the light-emitting mold, the light-receiving mold, the connector mold, and the connector terminals are connected and fixed to a main body of the lead frame sheet to divide the lead frame sheet into the individual devices. The connector terminals are formed into their final shapes in any one of the step of cutting tie bars placed at least on the peripheries of the light-emitting molds and the light-receiving molds or the step of cutting tie bars by which devices each are connected and fixed to the main body of the lead frame sheet to divide the lead frame sheet into the individual devices.
In this embodiment, since the connector terminals are shaped into their final shapes, namely forming of the connector terminals is performed in the process of cutting tie bars, the connector terminals of various shapes and various terminal intervals can be formed only by changing the cutting die. Thus, the connector terminals of two or more patterns can be made from the same lead frame sheet. Accordingly, the cost necessary for making lead frames of two or more shapes can be reduced by sharing the use of the lead frame sheet, thus achieving more cost reduction.
In one embodiment, the method further comprises a plating step of covering the connector terminals with metal performed after the step of cutting tie bars including forming the connector terminals into their final shapes.
According to this embodiment, the reliability such as the anticorrosiveness can be improved by covering with metal the connector terminals having bared cut surfaces. In addition, the reliability of junction of the connector terminals can be improved by covering the connector terminals with the same kind of metal as the female connector.
The step of forming a light-emitting mold and a light-receiving mold and the step of forming a connector mold may be performed together in a same process by using a same light permeable resin material. Alternatively, the step of forming a light-emitting mold and a light-receiving mold and the step of forming a connector mold are performed separately by using different resin materials.
In one embodiment, the light-emitting mold and the light-receiving mold are made of resin different from that for the connector mold in a process different from that for the connector mold. Thus, resins most suitable for functions required for molds to be used can be selected to form the molds. In addition, supply paths for the resins can be made short and simple to stabilize the productivity.
In one embodiment, the step of forming a light-emitting mold and a light-receiving mold and the step of forming a connector mold are performed in a same process, in which process a light permeable resin supplied from a first resin supply source is used for the light-emitting mold and the light-receiving mold, while a resin different from the light permeable resin supplied from a second resin supply source is used for the connector mold.
According to this configuration, the light-emitting mold and light-receiving mold and the connector mold are formed in the same process using different resins. Thus, resins most suitable for functions required for the molds (molded parts) to be used can be selected to form the molds in one process. In addition, the resins are supplied from different resin supply sources, and thereby supply paths for those resins can be made short and simple to stabilize the productivity.
Electronic equipment according to the present invention includes the photo interrupter of the present invention.
Because the photo interrupter that the electronic equipment uses consists of a few components, has a lead frame and an outer case capable of being assembled in a simple process, and is reliable because of having no electrical junction points, the electronic equipment, such as a copying machine or a printer, can smoothly carry out detection of the presence or absence of a paper, detection of an edge of a paper, and so on. In addition, when a photo interrupter is used in which the connector mold is made of resin different from that for the light-emitting mold and the light-receiving mold to increase the mechanical strength of the connector mold, the reliability of the electronic equipment can be more increased.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not intended to limit the present invention, and wherein:
b are a top view and a cross-sectional view, respectively, showing the configuration of a photo interrupter according to a second embodiment of the present invention;
The present invention will be described in detail below with reference to the embodiments shown in the figures.
At first, the outline of this photo interrupter will be described briefly referring to
On the four corners of the bottom of the outer case 31, hooks 34 for attachment to an external substrate (not shown) or external equipment are provided. Furthermore, as shown in
Next, with reference to
The light-emitting mold 37 and the light-receiving mold 38 stand erect against a surface (reference surface) S of the lead frame 39. In such a manner, the optical axis 43 is provided at a predetermined height, and the distance between the light-emitting device and the light-receiving device (optical path length) is decreased at the height of the optical axis 43 to increase the photocoupling efficiency. In
Furthermore, the bases of the connector terminals 33 are fixed to the connector mold 35, and the connector mold 35 is fixed to the outer case 31 by the connector mold latching section 40. Thus, the connector terminals 33 are fixed to the outer case 31 with a sufficient strength. For this reason, when a female connector to be connected to the connector section 32 is inserted from external equipment, even if the female connector is twisted, deformation and/or breakage are not produced on the connector terminals 33 and/or the connector section 32. The structure of the connector mold 35 and the connector mold latching section 40 are, as shown in
In this embodiment, the lead frame 39 on which the connector mold 35, the light-emitting mold 37, and the light-receiving mold 38 are formed is pushed in the outer case 31 from underneath, and thereby the connector mold 35, the light-emitting mold 37, and the light-receiving mold 38 are engaged with and latched by the corresponding connector mold latching section 40, light-emitting mold latching section 41, and light-receiving mold latching section 42 by taking advantage of the elasticity of the light permeable resin which the molds are made of and the elasticity of the light-blocking resin which the latching sections are made of. As an example of the structures of the latching sections 40 to 42, engaging structures are shown. However, press-fitting, adhesion, or the like may be applied, and there are no restrictions on the latching method.
As shown in
As a result, even if the connector terminals 33 (i.e. the lead frame 39) are pulled or pushed by extraction or insertion of the female connector, the pulling force or the pushing force is transferred to the connector mold latching sections 49 through the connector mold 35, and are suppressed by the connector mold latching sections 49. Thus, both of the forces applied to the lead frame 39 can be prevented from being applied to the inside of the photo interrupter. As a result, the photo interrupter can be prevented from damages such as deformation of the light-emitting mold 37 and the light-receiving mold 38 on the lead frame 39.
In addition, as shown in
As shown in
In this embodiment, a lead frame having the frame line (test pad) 51 as shown in
Described above are two or more structures which prevent the lead frame 39 from being deformed by a pulling force or a pushing force applied to the lead frame 39 at extraction or insertion of the female connector. However, it is of course not necessary to employ all of the structures, and some of them may be selected as necessary in consideration of use conditions and the like.
Next, the detail structure of the photo interrupter of this embodiment will be described with reference to
At first, the first component will be described.
Next, in an area D1 and an area D2 positioned on a broken line D-D′ in
Finally, peripheral parts of the lead frame sheet 39 are cut to divide the lead frame sheet 39 into individual lead frame components, or lead frame assemblies 30 having molds 35, 37, and 38 as shown in
In this embodiment, as shown in
In this embodiment, the reflecting surfaces 37a and 37b are provided in the light-emitting mold 37. However, the present invention is not limited to this, and the reflecting surfaces may be provided in the light-receiving mold 38 to reflect light incident to the light-receiving device to bend the optical axis 43. In such a case, the light-emitting device 44 and the light-receiving device 45 may be formed on the surface of the lead frame 39.
Next, the second component will be described.
The first component and the second component formed as described above are assembled as follows. As shown in
As described with
Next, the wire bridges 52 will be described in detail with reference to
The photo interrupter of this embodiment is an electronic component and is mounted and used on electronic equipment, so that it needs to have pin arrangement required by the electronic equipment. Although there is no ideal pin arrangement, when pin arrangement is designated by electronic equipment, the required pin arrangement can be easily realized by using wire bridges 52.
The photo interrupter having the above configuration operates as follows. As shown in
The first component is fixed to the outer case 31 by a method similar to that for the above configuration shown in
In the first component having a configuration as described above, the light-emitting mold 37 is erected in areas F1, F2, and F3 positioned on a broken line F-F′ shown in
In this configuration, in order that the light-receiving mold 38 passes above the connector mold 35 and stands erect, the light-receiving mold 38 is on the same side as the connector mold against the broken line G-G′ where the lead frame 39 is bent, and is outside the connector mold 35, as shown in
As described above, in this embodiment, a photo interrupter consists of a “first component” comprising a lead frame on which the light-emitting mold 37, the light-receiving mold 38, and the connector mold 35 are formed, and a “second component” comprising an outer case 31 formed integrally with a connector section 32. The light-emitting mold 37, light-receiving mold 38, and connector mold 35 of the first component are inserted in a light-emitting mold insertion opening 53, a light-receiving mold insertion opening 54, and a connector mold insertion opening 55 formed in the second component, respectively, thereby inserting (press-fitting) the first component in the second component, and the light-emitting mold 37, light-receiving mold 38, and connector mold 35 of the first component are then latched by the light-emitting mold latching section 41, light-receiving mold latching section 42, and connector mold latching section 40 of the second component. Thus, the first component is accommodated in and fixed to the second component.
Consequently, a connector-equipped photo interrupter which comprises a few components and is assembled easily can be proposed. Furthermore, a photo interrupter which is reliable because of having no electrical contacts can be proposed.
In this embodiment, as shown in
In this embodiment, as shown in
With the above configuration, the process of erecting the light-emitting mold 62 and the light-receiving mold 64 against a surface (reference surface) S of the lead frame become unnecessary, and it is not required to keep patterns in portions for the erection on the lead frame 61, so that an area required per one device of the lead frame 61 can be reduced, as compared with the first embodiment.
In this embodiment, a first component, or lead frame assembly 60 having a lead frame 61, a light-emitting mold 62, a light-receiving mold 64, and a connector mold 67 has the same configuration as that of the second embodiment. However, the configuration of a second component comprising an outer case 81 integrally formed with a connector section 82 is different from that of the second embodiment. As shown in
In the above configuration, light emitted from the light-emitting mold 62 is refracted by the emitted light refractor 83 and is released in an oblique direction to a point on the center line, where the light is reflected by an object to be detected 85, and is then refracted by the incident light refractor 84 to enter the light-receiving mold 64. With such a configuration, not only a transmission photo interrupter as in the cases of the first and second embodiments but also a reflection photo interrupter can be realized, so that the height of a photo interrupter can be significantly decreased as compared with the first embodiment and the second embodiment. In
In each of the embodiments described above, the direction of insertion of the female connector can be changed by bending the connector terminals 91 against the main body of the lead frame 92 as shown in
As described above, a connector-equipped photo interrupter having a structure shown in each of the embodiments described above can be made by assembling roughly divided two components, that is, a first component including a lead frame on which the molds are formed, and a second component including an outer case integrally formed with a connector section. Thus, a connector-equipped photo interrupter which consists of a few components and can therefore be assembled easily is provided. Furthermore, a photo interrupter which is reliable because of having no electrical contacts is provided.
When photo interrupters of any of the embodiments described above are formed, it is desirable that as many photo interrupters as possible are mounted on one lead frame sheet because reduction of a cost per device is required. Furthermore, as shown in
Furthermore, in order that gold wires or the like connecting light-emitting devices 44 and light-receiving devices to lead frames 39 be not broken by injected light permeable resin, light permeable resin having high fluidity is usually used for light-emitting molds 37, 62 and light-receiving molds 38, 64. The light permeable resin having high fluidity generally has a low mechanical strength. On the other hand, when connector molds 35, 67 are made of the same resin as that for light-emitting molds 37, 62 and light-receiving molds 38, 64 as shown in
In this embodiment, a method is described which increases the strength of a photo interrupter to make it more reliable, and improves the production stability, while maintaining the features of each of the embodiments described above.
The configuration of the photo interrupter of this embodiment is almost identical to that of the photo interrupter shown in
Next, the method of manufacturing a photo interrupter of this embodiment will be described.
For the lead frame sheet 115 configured as described above, as shown in
At that time, in the connector molding process shown in
In either case, the connector molds 111 are formed in a molding process different from that for the light-emitting molds 109 and the light-receiving molds 110, so that the pattern of routing the molding resin supply passages can be simplified, the difference between the longest one of distances from the resin supply source (not shown) to the molds 109, 110, and 111 of the photo interrupters and the shortest one of the distances can be reduced, and the number of photo interrupters formed at the same time can be reduced. For this reason, the pouring of the molding resins can be stabilized, and the production stability can be thus improved.
The lead frame sheet 115 into which molding resins have been poured as described above are cut into individual ones through usual processes of tie-bar cutting, lead forming, and single piece cutting to form single-piece lead frame assemblies 104 shaped as shown in
The photo interrupter of this embodiment is fixed to an external substrate (not shown) or the mounting plate of external equipment, when put to use, by inserting four hooks 119 formed on the four bottom corners of the outer case 105 to the external substrate or the mounting plate. A female connector 120 matching the shape of the connector section 107 is then inserted in the connector section 107 to electrically connect the female connector 120 to the connector terminals 112. Wiring 121 of a given length extends from the female connector 120, and a signal representing the presence or absence of the intercepting object from the photo interrupter is input to electronic equipment (not shown) which is connected to the end of the wiring 121. On the basis of the signal, the electronic equipment is controlled.
When the female connector 120 is inserted in or extracted from the connector section 107 as indicated by the black arrow in
In that case, when the connector mold 111 has been made of light permeable resin (particularly high fluidity light permeable resin) like the light-emitting mold 109 and the light-receiving mold 110 in which importance is put on the optical characteristics, the connector mold 111 may be broken by a large force acting the inside of the connector mold 11. However, in this embodiment, the connector mold 111 has been made of molding resin having a high mechanical strength, in contrast to the light-emitting mold 109 and the light-receiving mold 110, in a molding process which is different from that for the light-emitting mold 109 and the light-receiving mold 110. Thus, the connector mold 111 can be prevented from being broken by the force acting the connector mold 11 at extraction or insertion of the female connector 120. In addition, the mechanical strength of the molding resin can be more increased by mixing fillers into the molding resin as appropriate to more improve the reliability.
Furthermore, on the upper part of the area in which the four lead frame sheets 115 are arranged like a matrix, a second resin supply source 124 is placed which supplies molding resin to four sets of light-emitting mold formation areas 117 which are each arranged in a row, and four sets of light-receiving mold formation areas 118 which are each arranged in a row, in two lead frame sheets 115. The second resin supply source 124 is connected with the light-emitting mold formation areas 117 and the light-receiving mold formation areas 118 through runners 125. Likewise, on the lower part of the area in which the four lead frame sheets 115 are arranged like a matrix, a third resin supply source 126 is placed which supplies molding resin to four sets of light-emitting mold formation areas 117, and four sets of light-receiving mold formation areas 118, in two lead frame sheets 115. The third resin supply source 126 is connected with the light-emitting mold formation areas 117 and the light-receiving mold formation areas 118 through runners 127.
In other words, in this embodiment, the first resin supply source 122 constitutes the second resin supply source, while the second resin supply source 124 and the third resin supply source 126 constitute the first resin supply source.
According to the configuration in
As described above, in the photo interrupter of this embodiment, the connector mold 111 is made of molding resin supplied through a molding resin supply passage which is different from that for the light-emitting mold 109 and the light-receiving molds 110, so that light-blocking resin in which, for example, fillers and the like are mixed can be used as molding resin for the connector mold 111, thereby increasing the strength of the connector mold 111. Thus, the reliability to a twisting stress and the like in the case that a female connector 120 is extracted from or inserted in the connector section 107 can be extremely improved. In addition, the pattern of routing the runners 123, 125, and 127 which are the molding resin supply passages can be simplified, and thereby the pouring of the molding resins can be stabilized to improve the production stability.
The photo interrupter of each of the embodiments described above is used much effectively as a paper detecting device of a printer, a copying machine, or the like. Electronic equipment such as a printer or a copying machine has a paper feeding function, and it can be found, by mounting the photo interrupter on each paper feeding mechanism, that a paper has been fed up to which paper feeding mechanism and has been processed, and the process of the electronic equipment can be executed smoothly. Furthermore, the photo interrupter is much effective also when a paper jam and the like has occurred because it is able to inform the user that which paper feeding mechanism has a paper jam.
Embodiments of the invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
Number | Date | Country | Kind |
---|---|---|---|
2006-288405 | Oct 2006 | JP | national |
2007-136915 | May 2007 | JP | national |