JPH0224387B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a method for manufacturing a photointerrupter using an integral molding method.

<Background of the invention and prior art> A photointerrupter consists of a light-emitting element (often an infrared light-emitting diode) and a phototransistor or photodiode as a light-receiving element, or an element in which a signal amplifier, a waveform shaping circuit, etc. are integrated with the light-emitting element. It has a structure in which a light-shielding detection object is inserted between the two.
It is a photoelectric device that can detect the movement and position of an object, as well as detect the rotation angle and rotation speed by rotating a disk with slits cut into the outer periphery, without contact.
In recent years, photointerrupters have been used in audio equipment, OA
Photointerrupters are widely used in equipment, and as equipment becomes smaller, there is a demand for smaller photointerrupters themselves.

FIG. 1 shows a cross-sectional structure of a conventional photointerrupter. Devices 5 and 5' in which a light-emitting element and a light-receiving element are molded with translucent resin, respectively, are inserted into a separately formed holder case (frame body) 6, and held with adhesive 7, 7 or an alternative method. It is configured to be fixed to the case 6. This structure requires three members at the bare minimum: the light emitting element device 5, the light receiving element device 5', and the holder case 6. Miniaturizing each member makes assembly work difficult, and also hinders automation. Summer. Also,
As both devices 5 and 5' have become smaller and thinner, their package portions have become smaller, resulting in insufficient chip protection and lead terminal strength.

<Purpose of the Invention> The present invention meets the above-mentioned needs and provides a method for manufacturing a photointerrupter that does not require a holder case, takes productivity into consideration, and is easy to downsize by adopting a double molding method. be.

<Examples> Examples of the present invention will be described below with reference to FIGS. 2 to 11.

As shown in FIGS. 2 and 3, a chip 1 (infrared light emitting diode or phototransistor here) is mounted on a lead frame 2, and the other lead frame 2
After making the wire connection 3, primary molding is performed with a translucent resin 4. The same applies even if the chip 1 integrates, for example, a photodiode, a signal amplifier, a waveform shaping circuit, etc. If it is desired to form a slit as described later, it is preferable to make only a limited portion including the top of the chip 1 protrude as shown by reference numeral 8 in FIG. 4, and perform primary molding so that the left and right sides are stepped and lowered.

In Fig. 2, Fig. 3 or Fig. 2, Fig. 4,
The leads are continuously tied in a frame shape, and the tie bars are cut and removed using a mold or the like after the primary molding. The primary mold may be formed by either a transfer molding method or a casting method. The device up to the primary mold can basically be used as the light emitting element device 5 and the light receiving element device 5' of the conventional structure shown in FIG. 1, and the manufacturing method is almost the same.

Next, the light-emitting element device 5 and the light-receiving element device 5' after the primary molding are inserted into another cutting die case facing each other, and a light-shielding resin is injected to perform integral molding. FIG. 5 shows a perspective view after secondary molding, FIG. 6 shows a longitudinal sectional view, and FIGS. 7 and 8 show cross-sectional views. The examples shown in FIGS. 5 and 8 are cases in which slits are formed as shown in FIG. 4.

The light-shielding resin 9 used for the secondary mold is 2
It serves both the structural role of integrating the two devices 5 and 5' and the role of blocking disturbance light. Grooves 10 provided on the back surfaces of the devices 5 and 5',
Reference numeral 10 corresponds to a convex portion provided on the cutting die case during the secondary molding, and the convex portion provided on the die of the secondary mold comes into contact with the devices 5, 5'. The primary molding part is pushed forward, and the portions 11, 11 that serve as windows for light emission and light reception are pressed against the mold, thereby preventing the light-shielding resin 9 from wrapping around the window portions 11, 11.

The grooves 10, 10 are not partially covered with the light-shielding resin 9 and the primary molded part is exposed, but as is clear from the cross sections of FIGS. 7 and 8, the chip 1 By forming a groove immediately behind the back surface of the lead 2 on which the chip 1 is mounted, in a small package, there is practically no problem such as disturbance light reaching the chip 1. Further, the grooves 10, 10 can be conveniently used as positioning guides for other devices or equipment in the interrupter.

On the other hand, as shown in FIG. 4, by providing a protrusion 8 of a predetermined width on the front side of the chip of the translucent resin 4 and forming the periphery lower than this, the cross-sectional structure has a light-shielding property as shown in FIG. The resin 9 extends around areas other than the protrusion on the front side to limit the portion through which light passes, forming a so-called slit structure, thereby improving resolution.

In addition, there is no need to assemble the devices 5, 5' and the holder case 6 as in the past, and even if the devices 5, 5' are made smaller and thinner, the light-shielding resin 9 of the secondary mold can reduce the minimum thickness required. It has the advantage of ensuring sufficient thickness, increasing the protection against the chip, and increasing the strength of the lead terminals.

Other embodiments are shown in FIGS. 9 to 11. FIG. 9 is a perspective view of a primary molded light emitting element or light receiving element device 5, 5'.
A protrusion 12 is formed on the back surface of the next molded part. This protrusion 12 may be peak-shaped. FIG. 10 is a perspective view after secondary molding with light-shielding resin 9, and FIG. 11 is a longitudinal cross-sectional view of the same.

The protrusion 12 is similar to the protrusion provided on the cutting die case of the secondary mold in the previous embodiment, and in this case, the protrusion 12 and the die of the secondary mold come into contact with each other, so that when the secondary mold is made, Push out the primary molded parts of devices 5 and 5' to the front,
It functions to prevent the light-shielding resin 9 from being wrapped around the portions 11, 11 that serve as windows for light emission and light reception.

The light-transmitting resin 4 in each of the above embodiments may be a type of resin that blocks visible light when an infrared light emitting diode is used as a light emitting element.

<Effects of the Invention> As described above, according to the present invention, during secondary molding with a light-shielding resin, a part of the mold of the secondary mold and a part of the previously molded light emitting element device and light receiving element device are used. By a simple double molding method in which both devices are brought into contact and pushed forward, a method for manufacturing a photointerrupter that can be easily miniaturized and does not require a holder case can be provided.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view showing a conventional example, Fig. 2 is a perspective view showing the state before primary molding of an embodiment of the present invention, and Figs. 3 and 4 are different device examples after primary molding. FIG. 5 is a perspective view after secondary molding, FIG. 6 is a vertical sectional view, FIGS. 7 and 8 are different cross-sectional views, and FIG. 9 is another embodiment of the present invention. FIG. 10 is a perspective view showing the state before primary molding, FIG. 10 is a perspective view after secondary molding, and FIG. 11 is a longitudinal sectional view. 4...Transparent resin, 5...Light emitting element device,
5'... Light-receiving element device, 9... Light-shielding resin,
10...Groove portion, 11...Window portion, 12...Protrusion.

Claims (1)

[Scope of Claims] 1. Each light-emitting element device and light-receiving element device that are primarily molded with a light-transmitting resin are arranged facing each other, and both of the above devices are integrally molded with a light-shielding resin, and the above-mentioned light-shielding property is 2 by resin
During the next molding, a part of the mold of the secondary mold and a part of both the devices are pushed forward, and the light-shielding resin of the secondary mold is caused to emit light in both the devices. A method for manufacturing a photointerrupter, characterized in that it prevents received light from entering a window portion. 2. Parts of both devices are brought into contact with a convex part provided in a part of the mold of the secondary mold, and both the devices are pushed forward, and the light-emitting/light-receiving window portion of the light-shielding resin of the secondary mold is formed. 2. The method of manufacturing a photointerrupter according to claim 1, wherein the photointerrupter is prevented from being wrapped around the photointerrupter. 3. Push both devices forward by bringing the protrusions provided on each part of both devices into contact with the molds of the secondary mold, and push the light-shielding resin of the secondary mold into the light-emitting and light-receiving windows. 2. A method of manufacturing a photointerrupter according to claim 1, wherein the photointerrupter is prevented from wrapping around.