JPH0474643B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a tactile sensor using an optical sensor,
In particular, the present invention relates to a tactile sensor useful for mounting on the fingers of intelligent robots for assembly work.

<Prior Art> High-density arrays of optical sensors are considered promising as tactile sensors.

Conventionally, one way to create a high-density array of optical sensors is to integrate them onto a silicon substrate using IC manufacturing technology, but currently only flat-plate types can be manufactured; I can't do things. On the other hand, when arraying optical sensors in which light emitting diodes and phototransistors are paired on a flexible printed circuit board, the number of signal lines is large, which hinders high density.

<Problems to be Solved by the Invention> In a tactile sensor in which a large number of unit sensors are arranged in an array, one of the challenges is to reduce the number of signal lines.

In the case of an optical sensor using a pair of light emitting element and light receiving element as a unit sensor, the optical sensor 2 has four terminals as shown in FIG. That is, the light emitting element (light emitting diode) 21 has two terminals, and the light receiving element 22 has two terminals. Therefore, simply, [4 x number of used unit sensors] signal lines are required in the array portion.
When creating an array sensor on a silicon substrate, 4
Even when used as terminals, it is easy to create an array depending on how the master pattern is created. However, if the sensor array is to have a curved surface, a curved silicon substrate is required, which is not possible with current technology.

The present invention provides a flexible optical sensor-type tactile sensor that requires only a few signal lines even in a four-terminal optical sensor and enables high density.

<Means for Solving the Problems> A tactile sensor according to the present invention has optical sensors consisting of pairs of light emitting elements and light receiving elements arranged in M rows and N columns on a flexible printed circuit board, and light receiving elements in the row direction. are connected in parallel, the light emitting elements in the column direction are connected in series, and further a barrier is provided on the flexible printed circuit board to isolate the optical sensors, an elastic member is positioned above the optical sensors with a space, and each row an analog multiplexer connected to the light-receiving element, a row decoder that specifies the input of the analog multiplexer, an output amplifier that amplifies the output of the analog multiplexer, a driver that lights up the light-emitting elements of each column, and a column decoder that specifies the driver. It is equipped with the following.

<Function> In the above configuration, the base printed circuit board is flexible and the member on the optical sensor is an elastic member, so the tactile sensor becomes flexible and can be used in a curved shape, making it suitable for robots. Applicable to cylindrical fingers.

In addition, since the light receiving elements in the row direction are connected in parallel and the light emitting elements in the column direction are directly connected, only [number of rows + number of columns + 1] signal lines are required from the array section.
As a result, higher density becomes possible.

Furthermore, the presence of scanning circuitry such as analog multiplexers, row and column decoders, drivers, and output amplifiers further reduces signal cabling.

<Example> An example of the present invention will be described based on FIGS. 1 to 10.

FIGS. 1 and 2 show examples of the configuration of a tactile sensor in which optical sensors 2 are arranged in an array. 1 is a flexible film-like printed circuit board on which a circuit pattern is formed. Optical sensors 2, which are unit elements of a tactile sensor, are arranged in an array on a flexible printed circuit board 1 in M rows and N columns. The optical sensor 2 includes a light emitting element 21 and a pair of light receiving elements 22 such as phototransistors as shown in FIG. Here, a light emitting diode will be described as the light emitting element 21. Further, although a phototransistor is used as the light receiving element 22 in the description, a photodiode may also be used. Electronic components 3 to 7 that scan the optical sensor 2 are arranged on the flexible printed circuit board 1 at positions where no external force is applied. This electronic component includes a column decoder 3 for selecting a light emitting diode column, a row decoder 4 for selecting a phototransistor row, and an open collector type driver 5 for lighting the light emitting diode column.
, an analog multiplexer 6 for selecting an output channel of the phototransistor row, and an output amplifier 7. A cable 8 connects a power line, a selection signal, and an output between an external tactile sensor control 9 and the tactile sensor.

FIG. 3 shows the circuit configuration on the flexible printed circuit board 1. In FIG. 3, an array of 4 rows and 4 columns will be described, but there will be no problem if the array is expanded to M rows and N columns.

In FIG. 3, the connection pattern of 4×4=16 optical sensors 2 arranged in an array is as follows.

The light emitting diodes in the optical sensor 2 are connected in series in columns. In the figure, the anode common is used, but the cathode common may be used depending on the circuit configuration of the driver 5.

The phototransistors in the optical sensor 2 are connected in parallel row by row.

The column decoder 3 includes a tactile sensor controller 9
When a column selection code is received, a selection signal for the column is outputted, and the driver 5 receives this and lights up the light emitting diode column of the specified column.

The row decoder 4 includes a tactile sensor controller 9
When it receives a row selection code, it outputs a selection signal for the row and inputs it to a 4-channel analog multiplexer 6. Analog multiplexer 6 selects row decoder 4 among the 4 channels of input.
turns on the output of the phototransistor in the specified row (channel). The row decoder 4 is
This is not necessary if the analog multiplexer 6 has a built-in decoder.

The output amplifier 7 amplifies the sum of photocurrent outputs output from the phototransistors in the rows that are turned on.

Since the phototransistors are connected in parallel in the row direction, the output amplifier 7 obtains the total output within the row, but in reality, only the light emitting diodes in a specific column specified by the column selection code are lit. Therefore, the photocurrent output obtained from the turned-on row (channel) of the analog multiplexer 6 is mostly due to the phototransistor in the light sensor of the turned-on column in that row. The dark current from the phototransistor in the photosensor in the non-lit columns is a cause of error, but if you measure the output of each row in advance without lighting up all the light emitting diode columns, the dark current output becomes clear and this value can be calculated. The error can be easily corrected by subtracting from the data being measured.

As described above, although the phototransistors in one row are connected in parallel, by selecting a column, it is possible to obtain the output of a photosensor at a specific position in the matrix.

Also, by performing column scanning and row scanning by the action of column decoder 3 and row decoder 4,
The outputs of all the optical sensors 2 in the M rows and N columns array section can be sequentially detected.

FIG. 4 shows the pattern of the photosensor array part of the pattern of the flexible film-like printed circuit board. For a four-terminal optical sensor 2, as shown in FIG. 4, two signal patterns 14 and 15 are connected between the collector and emitter electrodes C and E of the phototransistor.
are drawn in the row direction and the light emitting diodes are connected in series with the signal pattern 16, so the optical sensors 2 can be densely mounted. 17 is a power supply pattern.

In addition, as shown in Figs. 2 and 4, the array part of the optical sensor can operate with one power supply line and [M+N] signal lines, and the flexible printed circuit board 1 can be constructed from a single-sided electrode pattern, resulting in high density. In addition, a tactile sensor with a low number of signal lines becomes possible.

Furthermore, the number of signals is further reduced by the electronic components 3 to 7 mounted on the flexible printed circuit board 1. In other words, Power supply: 1 line (however, the power supply is a single power supply) Ground: 1 line Output: 1 line Row code: An integer greater than or equal to log ₂ M (2 when M=4) Column code: An integer greater than or equal to log ₂ N ( (2 pieces when N=4) There are 7 pieces in total.

When the numbers M and N increase, for example when arrayed into 8x8, only 9 signal lines are required.

As described above, the tactile sensor of the present invention enables high-density array formation with a reduced number of signal lines while using the optical sensor 2 with a large number of terminals.

Next, FIGS. 6 and 7 show an example of how the robot is attached to a finger. In the present invention, a tactile sensor is constructed on a flexible printed circuit board 1, and can be wrapped in a cylindrical shape similar to a human finger. In the figure,
An elastic member 11 that is deformed by an external force is attached to the surface of a flexible printed circuit board 1 that is wound around a finger structure 10 of a robot or the like. The elastic member 11 not only changes the output of the optical sensor 2 by deformation, but also functions to protect the optical sensor 2 itself. The electronic components 3 to 7, such as the analog multiplexer, are wrapped so that they are placed on the dorsal side of the fingers, and the signal cable 8 is routed around the back of the robot's hand so as not to interfere with the movements of the robot's fingers. . Since the optical sensors 2 are arrayed around the periphery of the cylindrical object in this way, it is possible to perform advanced and complex functions such as those of a human finger or hand, instead of a parallel or flat grip that only performs conventional simple tasks. A finger with a tactile sensation can be realized.

Next, the structure of the elastic member 11 will be described.
(See FIGS. 8 to 10) The optical sensor 2 is a reflective optical sensor whose light emitting surface and light receiving surface face in the same direction. As shown in FIG. 8, the elastic member 11 serves as a reflective surface, and the characteristics of the distance l from the optical sensor 2 to the reflective surface and the output of the optical sensor 2 are as shown in FIG. In Figure 9, when l=0, the output is 0,
As l increases, the amount of reflected light increases and the output also rises, reaching a peak at l=L, and beyond this distance l
On the contrary, as the value increases, the output decreases.

FIG. 10 shows the structural relationship between the optical sensor 2 and the elastic member 11. Reference numeral 12 is an external object that causes a tactile sensation. In FIG. 10, the elastic member 11
A white one is used, and it is set at a position separated from the surface of the optical sensor 2 by the above-mentioned distance L. Therefore, between the optical sensor 2 and the elastic member 11, there is a thin barrier 1 that protrudes by a distance L.
3 is provided. The barrier 13 not only secures space but also reduces crosstalk caused by light leakage between the arrayed optical sensors 2. Note that the barrier 13 may be made of the same material as the elastic member 11, or may be integrally formed with the elastic member 11 by integral molding.
It is clear that interchanging the rows and columns of the array arrangement will have the same effect. Further, there is no restriction as to whether the row direction or the column direction should match the winding direction.

<Effects of the Invention> According to the tactile sensor of the present invention, the optical sensor consisting of a light emitting element and a light receiving element is arranged in an array on a flexible printed circuit board, so that it can be easily attached to a cylindrical finger like a human finger. It can be attached to.

Furthermore, since the light receiving elements in the row direction are connected in parallel and the light emitting elements in the column direction are connected in series, the number of signal lines from the array section is reduced, resulting in higher density.

In addition, having a scanning circuit further reduces the number of signal cables.

[Brief explanation of drawings]

1 to 10 relate to an embodiment of the tactile sensor of the present invention, in which FIG. 1 is a plan view showing an embodiment of a flexible printed circuit board, FIG. 2 is a side view thereof, and FIG.
Figure 4 is a circuit diagram, Figure 4 is a configuration diagram of an electrode pattern circuit, Figure 5 is an explanatory diagram of the structure of the optical sensor, Figure 6 is a schematic external view showing an example of the sensor being wrapped around a robot's finger, and Figure 7 is a diagram showing the structure of the optical sensor.
8 is an explanatory diagram of the operation of the optical sensor, FIG. 9 is a characteristic diagram of the optical sensor, and FIG. 10 is a sectional view of the optical sensor array portion of the tactile sensor. In the drawing, 1 is a flexible printed circuit board, 2 is an optical sensor, 3 is a column decoder, 4 is a row decoder, 5 is a driver, 6 is an analog multiplexer, 7 is an output amplifier, 8 is a cable, 9 is a tactile sensor controller, 10 is a finger structure, 11 is an elastic member, 12 is an external object, 13 is a barrier, 14, 15, 16, 17
21 is a pattern, 21 is a light emitting element, and 22 is a light receiving element.

Claims (1)

[Claims] 1 Optical sensors consisting of pairs of light-emitting elements and light-receiving elements are arranged in M rows and N columns on a flexible printed circuit board, and the light-receiving elements in the row direction are connected in parallel, and the light-emitting elements in the column direction are connected in series. , further comprising: on the flexible printed circuit board, a barrier for isolating the optical sensors; an elastic member positioned above the optical sensors with a space therebetween; and an analog multiplexer connected to the light receiving elements of each row;
A tactile sensor comprising a row decoder that specifies the input of an analog multiplexer, an output amplifier that amplifies the output of the analog multiplexer, a driver that lights up a light emitting element in each column, and a column decoder that specifies the driver.