JPH10267647A - Optical detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the productivity of an optical detecting apparatus by a method wherein a processing circuit by which the output signal of a light-receiving element is processed as an output in the form of an analog voltage according to a distance and a comparator circuit by which the output of the processing circuit is covered into an output in the form of one bit of an H/L changeover signal with reference to a set distance are provided inside the same package. SOLUTION: When a comparator circuit 14 is connected to an output terminal 15, an output in the form of an analog voltage is input to the comparator circuit 14 so as to be compared with an H/L changeover threshold voltage value 18 used to set a distance, and the output of one bit which is used as an H/L changeover signal is obtained from the output terminal 15 of the comparator circuit 14 with reference to an arbitrary distance. Then, when the main par of a processing circuit 12 and the main part of the comparator circuit 14 are integrated into an IC chip, the output in the form of the analog voltage and the output in the form of one bit are selected and changed over so as to be used. Thereby, irrespective of the form of an output, both circuits can be manufactured by the same production process, and the productivity of an optical detecting apparatus can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical detection device for detecting the position, inclination, distance to an object, and the like of an object by light using a triangular distance measuring method, and more particularly to an improvement in a method of outputting the distance measuring information. Regarding the common use of components and the simplification of the output adjustment method with the simplification of the external circuit,
Further, the present invention relates to improvement of distance measurement accuracy by improving the structure.

[0002]

2. Description of the Related Art As a device for measuring the distance to an object,
A triangulation type distance measuring system as shown in FIG. 6 is known. The pulse light from the light emitting element 50 such as a light emitting diode (LED) is converted into a thin beam by the light projecting lens 51 and projected on the measured objects 52a and 53b. Light reflected from the objects to be measured 52a and 53b is condensed by a light receiving lens 53 onto a light receiving element 54 such as a semiconductor light incident position detecting element (PSD).

Here, since the position of the light spot on the light receiving element 54 is different depending on the distance to the measured objects 52a and 53b, it is possible to measure the distance by processing a pair of signal outputs of the light receiving element 54. Will be possible. As the light receiving element 54, a split type photodiode having a plurality of light receiving surfaces can be used instead of the PSD.

As described above, the output method of the optical detection device detected by the triangulation method includes: (1) distance measurement information to the object by changing the output amount according to the distance as shown in FIG. And (2) a method in which the output is output as a “high (H)” or “low (L)” pulse for a distance set in an optical detection device as shown in FIG. The former (1) uses an 8-bit serial output digital output system, and the latter (2) uses an H / L 1-bit output system. Therefore, signal processing circuits (ICs and the like) having different configurations according to the respective output systems are manufactured.

In the 8-bit serial output shown in FIG. 7, reflected light from the object to be measured is condensed by a lens, and distance measurement data (analog data) corresponding to the condensing position of the PSD incident on the PSD element is converted. Since the signal is processed and output as an 8-bit signal, the output data becomes a variable output in each optical detection device due to a variation in the positional relationship between the PSD element and the lens. That is, assuming that the output characteristic curve D in FIG. 7 is a reference output characteristic curve, the output characteristic curve E or the output characteristic curve F shows the variation. The causes of the variation of the output characteristic curve E or the output characteristic curve F are as follows: (A) variation caused by variation in the assembly position accuracy of the light emitting element 50, the light projecting lens 51, the light receiving lens 53, and the light receiving element 54; B) those caused by variations in the light emitting characteristics and light receiving characteristics of the light emitting element 50 and the light receiving element 54, respectively.
(C) In order to synchronize the 8-bit serial output, a timing generation circuit and a signal processing circuit are required.

The 1-bit output shown in FIG. 8 is based on the distance information of the PSD whose output amount changes according to the distance shown in FIG.
The L switching distance is set, and the output when the distance is shorter than the set distance is “L output”, and the output when the distance is longer than the set distance is “H output”.

Therefore, although the output characteristic curve D in FIG. 7 is a reference output characteristic curve, if it varies like the output characteristic curve E or the output characteristic curve F, the 1-bit output H in FIG. The / L output naturally varies. for that reason,
Set the H / L threshold output to I
At present, the manufacturer or the user adjusts each sensor with a variable resistor connected to C to compensate for variations in the individual sensors and to cope with them. However, its H / L
Is adjusted by a variable resistor, errors in the H / L detection accuracy are likely to occur due to the accuracy of the variable resistor and the distance measurement accuracy of the sensor itself. At present, the error is about ± 10% to ± 20%. Had to be forced. For these reasons, in the conventional example, accurate distance measurement data cannot be obtained only from the output of the optical detection device, an external circuit is required, and further, adjustment and correction processing by the user is required. Met.

As a countermeasure against the cause of the above (A), the following conventional example is disclosed in Japanese Patent Application Laid-Open No. Hei 5-16455.
No. 3, Japanese Patent Application Publication No., title of the invention: optical detection device, applicant: Hamamatsu Photonics Co., Ltd. FIG. 9 shows a schematic cross-sectional view of a conventional optical detection device, and FIG. 10 shows a circuit configuration diagram of the conventional optical detection device.

In FIG. 9, a cap 57 is attached to a base plate 56 to constitute an optical detection device 55 composed of a single package. The light emitting element 50 and the light receiving element 54 are mounted on the upper surface of the base plate 56, and are bonded by wires 59 to external lead pins 58 provided through the base plate 56. A spacer 60 is interposed between the opening of the base plate 56 and the lead pin 58 to achieve electrical insulation.

A light projecting and light receiving window is formed in the head of the cap, and a light projecting lens 51 and a light receiving lens 53 are formed here.
Are formed. Further, a circuit for processing the output signal is formed in the light receiving element 54, and a drive circuit for the light emitting element 50 and a circuit for synchronizing them are also formed.

In FIG. 10, the circuit of the optical detection device includes a light emitting element 50 for projecting pulsed light and a light receiving element 54 (light receiving surfaces 54A and 54A) for receiving light reflected from an object to be measured.
B) and a circuit section 61 for performing detection signal processing and light emission driving
Constitutes a distance measurement module. Preamplifier 62
A, 62B are respectively amplifies the photocurrent output of the light receiving surface 54A, 54B, the capacitor C _A, AC via a C _B (pulse) component V _A, gives the V _B only the differential amplifier 63. The difference output V _C of the differential amplifier 63 is compared with a reference level V _REF by a comparator 64 and is provided to a signal processing circuit 65.

On the other hand, the -constant frequency clock pulse from the oscillation circuit 66 is applied to a timing generation circuit 67, and a drive pulse is applied to a signal processing circuit 65 and a driver 69 (output is V _PL ). It should be noted that the output V _OUT indicating far and near to the device under test is output to the outside from the output circuit 68 based on the logical output from the signal processing circuit 65.

According to the circuit configuration of this conventional example, when the object to be measured is distant, for example, the output of the light receiving element 54A is larger than the output of the light receiving element 54B, and when the object to be measured is close, the opposite is true. . Accordingly, a differential pulse signal corresponding to the distance to the device under test is output from the differential amplifier 63, and this is compared with the reference level V _REF by the comparator 93. For this reason, a pulse signal is supplied to the signal processing circuit 65 according to the distance to the device under test and the distance to the device under test (for example, a pulse is supplied only when the distance is short, or a pulse is supplied only when the distance is long). Or one of them). The signal processing circuit 65 determines a plurality of consecutive pulses from the comparator 64 (the number of times is determined by an internal circuit) in synchronization with the drive pulse from the timing generation circuit 66, and outputs a signal indicating the distance to the device under test (close to the device under test). (Logic output) to the output circuit 68. As described above, the signal indicating the distance to the object to be measured is output.

[0014]

However, the conventional optical detection device has a large variation in the distance measurement data.
Further, an external circuit for sensitivity adjustment is required, and further, individual adjustment is required on the user side, and a separate signal processing circuit IC according to the output format is required. Further, the positional accuracy between the light emitting element and the PSD is not sufficient, and the distance measuring accuracy is low.

[0015]

According to a first aspect of the present invention, there is provided an optical detecting device, comprising: a light emitting element; a light projecting optical system for projecting light emitted from the light emitting element onto an object to be detected; An optical system comprising a light receiving optical system for condensing light reflected from a detection object at different positions according to the incident direction thereof, and a light receiving element comprising a semiconductor position detecting element disposed at the condensing position of the reflected light A processing circuit for processing the output signal of the light receiving element as an analog voltage output in accordance with the distance, and an H / L switching signal for the set distance for the set distance. A comparator circuit for converting the output into a bit format is provided in the same package.

According to a second aspect of the present invention, in the optical detection apparatus, at least a main part of the processing circuit and a main part of the comparator circuit are formed as an IC chip, and the output in the form of an analog voltage and a one-bit signal are output. And an output of the selected item.

Further, an optical detection device according to a third aspect of the present invention is characterized in that the light emitting element, the light receiving element, and the IC chip are die-bonded and wire-bonded on the same lead frame. Things.

Further, in the optical detection device according to a fourth aspect of the present invention, the size of an output adjustment resistor provided at an output gain adjustment terminal of the processing circuit is selected.
The gain of the processing circuit is adjusted.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 5 are diagrams relating to an embodiment of the present invention. FIG. 1 is a diagram showing a circuit configuration of an optical detection device according to an embodiment of the present invention. FIG. 5 is a schematic sectional view of an optical detection device according to an embodiment of the present invention.

In FIG. 1, an output of a light receiving element (PSD: semiconductor position detecting element) 11 is a processing circuit 12 comprising an amplifier circuit 12a, a signal processing circuit 12b, and an output circuit 12c.
The distance measurement information corresponding to the distance is output from the output terminal 13 as an analog voltage output format. Further, the comparator circuit 1 is connected to the output terminal 13.
4, the output in the form of an analog voltage is input to the comparator 14 and compared with a threshold voltage value 18 for H / L switching for distance setting. A 1-bit output as a switching signal is obtained from the output terminal 15 of the comparator circuit 14.

By integrating the main part of the processing circuit 12 and the main part of the comparator circuit 14 on an IC chip using the present invention, the output in the form of analog voltage and the one-bit format The output of the shape can be selected and switched for use.

As a result, the processing circuit 12 for processing the distance information from the PSD 11 and the comparator circuit 14 can be used in common. The format can be switched, and the IC chip can be shared.

FIG. 2 is a diagram showing a circuit configuration 10 of an optical detection device according to an embodiment of the present invention. 2, an output gain adjusting terminal 16 is newly provided in the output circuit 12c of the processing circuit 12 having the configuration of FIG.
7 is provided. By selecting the size of the output adjustment resistor 17, the amplification degree of the output circuit of the processing circuit 12 can be adjusted.

FIG. 3 shows the output characteristics of the optical detector corresponding to the circuit configuration of the optical detector according to the embodiment of the present invention shown in FIG. Figure 3 shows the distance on the horizontal axis,
The vertical axis is an output characteristic curve showing the output of the analog voltage obtained from the output terminal 13, and the output characteristic curve A is a target curve.

In many cases, the individual output characteristic curves vary as shown in the output curve B or the output curve C in FIG. 3, but each of the light emitting element, the light projecting lens, the light receiving lens, and the light receiving element in the above (A). What is caused by the variation in assembly position accuracy can be reduced by the measures described later (see FIG. 5).
Therefore, the variation of the output curve B or the output curve C is caused by the variation of the light emitting characteristics and the light receiving characteristics of the light emitting element and the light receiving element of (B). Further, the output characteristic curves A, B, and C are substantially similar to each other, and the output characteristic curves B and C are adjusted at one point (for example, the point (X, Y) in FIG. 3) so that the output characteristic curves B and C are set as the target output characteristics. It can be almost fitted to the curve A.
Specifically, the output (for example, output Y) at a certain arbitrarily set distance (for example, distance X) is checked, the magnitude ratio of the output value to the set target output curve A is determined, and the amplifier gain is adjusted. The output characteristic curve A can be adjusted by adjusting the output adjustment resistor 17 of the adjustment terminal 16 to a large or small ratio.

Next, a description will be given of an output format of a 1-bit format (a system in which an output is outputted as a "high (H)" or "low (L)" pulse with respect to a set distance). Since the individual optical detection devices have been adjusted to the output characteristic curve A with respect to the distance by the above adjustment, FIG.
From the output characteristic curve A in FIG. 3, the output voltage for setting the H / L switching distance is set to H / L from the output characteristic curve A in FIG.
The threshold voltage value can be set to the same value for each sensor, so that a 1-bit output corresponding to an arbitrary distance can be easily and accurately obtained without adjusting the threshold voltage value with each sensor.

Specifically, for example, in FIG.
When it is desired to set the switching distance of / L to Xcm, the output of the analog voltage becomes the Y value of the output characteristic curve A. Therefore, the optical detection device always adjusts the Y value by adjusting the voltage with the output adjustment resistor 17 or the like in the amplifier circuit portion of the optical detection device so as to input the Y value to the comparator circuit 14 in FIG. At this time, the output is switched to H / L. At this time, since the output adjustment resistor 17 is constant with respect to the set distance, the adjustment may be performed only by adjusting the amplifier gain at the time of analog voltage output. Can be adjusted in the same manner.

FIG. 4 is a diagram showing a circuit configuration of an optical detection device according to an embodiment of the present invention. In FIG.
Since the analog voltage output can be output at the same timing as the 1-bit output, the oscillation circuit 22 for controlling the output timing is built in the signal processing circuit IC (23) for processing the ranging information, so that it can be output from the outside. Is unnecessary, and the optical detection device can have a terminal configuration of only the power supply V _CC (27) and the output 28. 11 is a light receiving element (PSD: semiconductor position detecting element), 22 is an oscillation circuit for controlling output timing, 23 is a signal processing circuit,
24 is a constant voltage circuit, 25 is a light emitting element (LED), 26 is a drive circuit, 29 is an external circuit including an A / D converter, and 30 is a microcomputer for controlling the external circuit.

FIG. 5 is a schematic sectional view of an optical detector according to an embodiment of the present invention. In FIG. 5, a PSD 11, an IC chip 31 including an oscillation circuit 22, a signal processing circuit 23, a constant voltage circuit 24, a driving circuit 26, and the like, and a light emitting element (LED) 25 are die-bonded and wire-bonded on a lead frame 35. Do. Next, these are molded with a light-transmitting resin 36, and the outside thereof is mounted and molded with a light-shielding resin case 37 and a lens case 38 which is a light-transmitting resin, whereby the optical detection device 34 is completed. A light projecting lens 39 and a light receiving lens 40 are formed in the lens case 38. The PSD 11 and the light emitting element (LED) 25 are a lead frame 37 having a guide hole.
In addition, since the die bonding and the wire bonding are performed in the same process, the positional relationship between the PSD 11 and the light emitting element (LED) 25 on the lead frame 37 is kept constant. further,
With reference to the guide holes of the lead frame 37, the resin case 37 and the lens case 38 are mounted and molded, and the light projecting lens 39 and the light receiving lens 40 provided in the lens case 38 are integrally formed. For,
As a result, the positional relationship among the light emitting element (LED) 25, the light projecting lens 39, the light receiving lens 40, and the PSD 11 is necessarily kept constant.

According to the present invention, the PSD 11 and the light emitting element 2 are die-bonded on the same frame.
The positional relationship with 5 is only a variation in the position at the time of die bonding, and can be set to about 0.03 to 0.1 mm or less. Therefore, the variation of the output characteristic curve described with reference to FIG. 3 can be reduced. For example, the variation of the analog output at the distance Xcm is ± 10% or less, and the variation of the H / L switching distance setting can be ± 10% or less.

Also, the IC chip 31 is die-bonded and wire-bonded on the same lead frame as the light emitting element 25 and the light receiving element 11, thereby simplifying the chip assembly process, which is the latter half of the semiconductor process, and improving the productivity. be able to. Further, in the wire bonding step of the IC chip 31, by changing the connection method, it is possible to obtain an optical detection device capable of selectively outputting the output in the form of the analog voltage and the output in the 1-bit format.

The size of the optical detector according to the present invention thus manufactured is, for example, 29 mm × 17 mm ×
It is about 13.5 mm, smaller and thinner than the conventional example.
It was able to be lightweight.

In FIG. 5, the IC chip 31 is connected to the oscillation circuit 2
2, signal processing circuit 23, constant voltage circuit 24 and drive circuit 2
1 has been described as an IC chip including the amplifier circuit 12a, the processing circuit 12 including the amplifier circuit 12a, the signal processing circuit 12b, and the output circuit 12c, and the comparator circuit 14
It is natural that the circuit including the above is used as the IC chip 31.

[0034]

As described above, according to the optical detecting device of the first aspect of the present invention, the light emitting element and the light projecting optical system for projecting the light emitted from the light emitting element to the object to be detected. A light receiving optical system for condensing light reflected from the detected object at different positions according to the incident direction thereof, and a light receiving element including a semiconductor position detecting element disposed at the condensing position of the reflected light. And a processing circuit for processing the output signal of the light receiving element as an output in the form of an analog voltage corresponding to the distance, and switching the output of the processing circuit between H / L with respect to the set distance. A comparator circuit for converting a signal into an output in a 1-bit format is provided in the same package. Optical detectors having different output formats can be manufactured in the same manufacturing process. ,
Productivity can be improved.

According to the optical detection device of the present invention, at least a main part of the processing circuit and a main part of the comparator circuit are formed as an IC chip, and the output in the form of an analog voltage and the output of the analog circuit are connected to one another. It is characterized in that bit-format output can be selected and output, and it is possible to integrate the first-half semiconductor process, simplify the chip assembly process as the second-half semiconductor process, and improve productivity. Further, the number of external parts can be reduced, and the size of the optical detection device can be reduced.

According to the optical detecting device of the third aspect of the present invention, the light emitting element, the light receiving element, and the IC
It is characterized by being die-bonded and wire-bonded to the chip on the same lead frame, which simplifies the chip assembly process, which is the second half of the semiconductor process, improves productivity, and achieves light emission. The accuracy of the positional relationship between the element and the light receiving element can be improved, and the size of the optical detection device can be reduced.

Further, according to the optical detecting device of the fourth aspect of the present invention, by selecting the size of the output adjusting resistor provided at the output gain adjusting terminal of the processing circuit, And the variation of the output characteristic curve can be reduced without adjusting the IC chip.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of an optical detection device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a circuit configuration of an optical detection device according to an embodiment of the present invention.

FIG. 3 is a diagram showing output characteristics of the optical detection device corresponding to the circuit configuration of the optical detection device according to the embodiment of the present invention shown in FIG. 2;

FIG. 4 is a diagram illustrating a circuit configuration of an optical detection device according to an embodiment of the present invention.

FIG. 5 is a schematic sectional view of an optical detection device according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating a conventional triangulation ranging system.

FIG. 7 is a diagram showing output characteristics of a conventional optical detection device.

FIG. 8 is a diagram illustrating output characteristics of a conventional optical detection device, and is a diagram illustrating H / L switching.

FIG. 9 is a schematic sectional view of a conventional optical detection device.

FIG. 10 is a diagram showing a circuit configuration of a conventional optical detection device.

[Explanation of symbols]

Reference Signs List 10 Circuit configuration of optical detection device 11 Light receiving element (PSD: semiconductor position detection element) 12 Processing circuit 12a Amplifying circuit 12b Signal processing circuit 12c Output circuit 13 Output terminal 14 Comparator circuit 15 Comparator output terminal 16 Output gain adjustment terminal 17 Output adjustment resistor 18 Threshold voltage value for H / L switching for distance setting 22 Oscillator circuit for controlling output timing 23 Signal processing circuit 24 Constant voltage circuit 25 Light emitting element (LED) 26 Drive circuit 27 Power supply V _CC 28 Output REFERENCE SIGNS LIST 29 external circuit 30 microcomputer 31 IC chip 34 optical detection device 35 lead frame 36 light-transmitting resin 37 light-shielding resin case 38 lens case that becomes light-transmitting resin 39 light-emitting lens 40 light-receiving lens

Claims (4)

[Claims] A light-emitting element, a light-projecting optical system for projecting light emitted from the light-emitting element to an object to be detected, and light reflected from the object to be detected at different positions according to the incident direction. In an optical detection device comprising a light receiving optical system for collecting light and a light receiving element comprising a semiconductor position detecting element disposed at a position where the reflected light is collected, an output signal of the light receiving element is converted into an analog voltage corresponding to a distance. And a comparator circuit for converting the output of the processing circuit into an output in the form of a 1-bit H / L switching signal for a set distance in the same package. An optical detection device characterized by comprising: 2. An optical detection device according to claim 1, wherein at least a main part of said processing circuit and a main part of said comparator circuit are formed as IC chips, and an output in the form of an analog voltage and an output in a 1-bit format are provided. An optical detection device characterized by being able to select and output an image. 3. The optical detection device according to claim 2, wherein the light emitting element, the light receiving element, and the IC chip are die-bonded and wire-bonded on the same lead frame. apparatus. 4. The optical detection device according to claim 2, wherein a gain of the processing circuit is adjusted by selecting a magnitude of an output adjusting resistor provided at an output gain adjusting terminal of the processing circuit. An optical detection device, characterized in that: