JPH11354832A - Proximity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drastically enhance the performance of a proximity sensor by enhancing the detection sensitivity thereof. SOLUTION: The proximity sensor 1 comprises a glass epoxy substrate 21 formed by covering a substrate 2 with a copper foil 21a substantially over the entire surface thereof, a sheet 22 for multilayer substrate to be pasted onto the glass epoxy substrate 21 with a bonding pattern 22b being formed on an opaque basic material 22a, and a black resist 23 covering the surface of the sheet 22 for multilayer substrate except the part of bonding pattern. In a conventional proximity sensor, a light emitting element and a light receiving element are mounted on one substrate and since light emitted from the light emitting element propagates through the substrate to the light receiving element, detection sensitivity is damaged. The substrate is thereby shielded completely with a laminate of the sheet 22 for multilayer substrate and the black resist 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of detecting the presence or absence of an object, or detecting proximity of the object by detecting the reflected light when light emitted from a light emitting element reaches an object to be detected and is reflected. It concerns a sensor.

[0002]

2. Description of the Related Art FIG. 3 shows an example of the configuration of a conventional proximity sensor 90 of this type. This proximity sensor 90 emits light by providing an appropriate interval on a single glass epoxy substrate 91. The element 92 and the light receiving element 93 are attached in the same direction. A light-shielding wall 94 is provided between the light emitting element 92 and the light receiving element 93.
The light from the light source does not directly reach the light receiving element 93, and the elements 92 and 93 are covered with transparent resin covers 95 and 96 for the purpose of preventing moisture.

The light emitting element 92 of the proximity sensor 90 thus formed is lit by applying a current. At this time, if an object to be detected (not shown) exists in the range irradiated by the light emitting element 92, the light emitting element 92
Is reflected by the object to be detected, and the reflected light reaches the light receiving element 93 to generate an output, so that the presence of the object to be detected can be detected from the output.

At this time, since the output of the light receiving element 93 includes a noise component N called a dark current or the like, the output is generated even when the detected object does not exist. Accordingly, the detection sensitivity of the proximity sensor 90 is determined at the time when the signal component S generated at the time when the detected object is present has a clear difference from the noise component N, in other words, at the time when S
/ N ratio.

[0005]

However, in the above-described proximity sensor 90 having the conventional configuration, the output from the light-receiving element 93 is obtained only by turning on the light-emitting element 92 despite the absence of the object to be detected. A phenomenon occurs in which the current increases, and the detection sensitivity is further reduced.

According to the result of the study by the inventor, this phenomenon is that, out of the light from the light emitting element 92, the reflected light at the boundary surface between the cover 95 covering the light emitting element 92 and the atmosphere reaches the substrate 91,
It has been found that the leakage component L propagates through the translucent epoxy resin and reaches the light receiving element 93. Accordingly, in the proximity sensor 90 having the conventional configuration, the detection sensitivity is S / S
(N + L), which naturally results in performance degradation.
The solution of this point was an issue.

[0007]

According to the present invention, there is provided a proximity sensor having a light emitting element and a light receiving element mounted on a single substrate, as a specific means for solving the above-mentioned conventional problems. A glass epoxy substrate covered with copper foil over substantially the entire area, a multilayer substrate sheet in which the bonding pattern for the two elements is formed on an opaque substrate adhered on the glass epoxy substrate, The object is achieved by providing a proximity sensor, which is provided with a black resist applied to the surface of the multilayer substrate sheet except for the bonding pattern portion.

[0008]

Next, the present invention will be described in detail based on an embodiment shown in the drawings. 1 and FIG.
Is a proximity sensor according to the present invention, and the proximity sensor 1 has a light emitting element 3 and a light receiving element 4 mounted on a single substrate 2. A light-shielding wall 5 is provided between
The light receiving element 4 and the light receiving element 4 are covered with covers 6 and 7, respectively, as in the conventional example.

In the present invention, the substrate 2 is composed of a glass epoxy substrate 21, a sheet 22 for a multilayer substrate, and a black resist 23. For example, the terminal part 2 as the substrate 2 is used.
The copper foil 21a provided on the upper surface is left as much as possible except for a portion requiring insulation such as a.

Since the copper foil 21a is used for the purpose of shielding light, as will be apparent from the following description, the material is not limited to copper as long as it is opaque. However, since those commercially available for printed wiring boards are already laminated with the copper foil 21a, it is most cost-effective to use it as it is,
In order to achieve the object, it is not necessary to form the glass epoxy substrate 21 with a metal foil other than copper.

The above-mentioned copper foil 21 of the glass epoxy substrate 21
Covering the a side, a sheet 22 for a multilayer substrate in which a copper foil is bonded to a film-like base material 22a is bonded using, for example, an epoxy resin adhesive, but prior to this bonding, an etching process is performed. The copper foil is formed as a bonding pattern 22b for die-bonding and wiring the light emitting element 3 and the light receiving element 4. Also,
At this time, a material having low transparency is selected as the base material 22a.

In addition, in the present invention, a black resist 23 is provided on the upper surface of the multilayer substrate sheet 22, and the black resist 23 covers the entire surface of the multilayer substrate sheet 22 except for the bonding pattern 22b. Provided. The light emitting element 3 and the light receiving element 4 are mounted on the substrate 2 configured as described above, wiring is performed, and the light shielding wall 5 and the covers 6 and 7 are formed to become the proximity sensor 1 of the present invention. .

Next, the operation and effects of the proximity sensor 1 of the present invention having the above-described configuration will be described. According to the present invention, the closest surface of the light emitting element 3 and the light receiving element 4 of the substrate 2 is covered with the black resist 23, so that the light emitting element 3 is turned on and the light from the light emitting element 3 is covered. Even if the light is reflected on the boundary surface with the atmosphere 6 and reaches the surface of the substrate 2, the light is almost completely prevented from entering the substrate 2 by the black resist 23.

Even if light enters, if the light-emitting element 3 is provided, the light-receiving element 4 is moved from the position where the light-emitting element 3 is provided because the base material 22a of the multilayer substrate sheet 22 is selected to have low transparency. The light attenuates by a considerable amount while propagating to the position where it is provided. In addition, since the black resist 23 is also provided on the light receiving element 4 side, a shielding effect by the black resist 23 occurs, and as a result, The effect on the light receiving element 4 due to propagation in the material 22a is minimal.

If the light penetrates into the base material 22a of the multi-layer board sheet 22 and this light passes through the base material 22a and reaches the glass epoxy substrate 21, the glass epoxy substrate 21 becomes relatively Since the degree of transparency is high, a greater effect on the light receiving element 4 can be considered.

In the present invention, the copper foil 21a provided on the glass epoxy substrate 21 is left over almost the entire surface of the glass epoxy substrate 21.
Since a is opaque, light does not pass through the copper foil 21a, and therefore, the base material 22
Even if light enters a, the light does not enter the glass epoxy substrate 21, so that the light receiving element 4 is not substantially affected.

Here, the results of a trial production and an experiment by the inventor for realizing the present invention will be described. By using the above-described structure of the substrate 2, the conventional light emitting element 3 is applied to the light receiving element 4 when it is turned on. It was confirmed that the amount of leakage can be reduced by 15 to 22% based on the amount of leakage, and approximately 1/5 on average.

Therefore, according to the present invention, the detection sensitivity of the proximity sensor 1 is improved approximately five times, and if the light from the light emitting element 3 is simply attenuated in inverse proportion to the square of the distance, the present invention The proximity sensor 1 of the present invention can detect even when the detected object is at a distance approximately twice that of the conventional example.

[0019]

As described above, according to the present invention, a glass epoxy substrate in which the substrate is covered with copper foil over substantially the entire area, and the two elements are mounted on an opaque substrate adhered on the glass epoxy substrate. Conventionally, a proximity sensor comprising a multilayer substrate sheet on which a bonding pattern is formed, and a black resist applied to the surface of the multilayer substrate sheet and excluding a portion of the bonding pattern is formed, so that a conventional single substrate is used. Since the light emitting element and the light receiving element were mounted on the upper side, the light from the light emitting element propagated in the substrate and reached the light receiving element to generate an output that impaired the detection sensitivity. And almost completely shielded by the lamination of black resist, thereby dramatically improving the detection sensitivity of this type of proximity sensor and exhibiting an extremely excellent effect on performance improvement. .

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a proximity sensor according to the present invention in a partially broken state.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Proximity sensor 2 ... Board 2a ... Terminal part 21 ... Glass epoxy board 21a ... Copper foil 22 ... Sheet for multilayer board 22a ... Base material 22b ... Bonding pattern 23 ... Black resist 3 ... Light-emitting element 4 Light-receiving element 5 Light-shielding wall 6, 7 Cover

Claims (3)

[Claims] 1. A proximity sensor in which a light emitting element and a light receiving element are mounted on one substrate, wherein the substrate has
A proximity sensor, wherein a metal foil covering substantially the entire area of the substrate is embedded. 2. The embedding of a metal foil in the substrate is performed by bonding a glass epoxy substrate covered with copper foil over substantially the entire area, and bonding the two elements to an opaque substrate adhered on the glass epoxy substrate. The proximity sensor according to claim 1, wherein the proximity sensor is performed by laminating a multi-layer substrate sheet on which a pattern is formed. 3. The proximity sensor according to claim 1, wherein a black resist is applied to a surface of the substrate except for a portion of the bonding pattern.