CN109506776B - Photoelectric sensor - Google Patents
Photoelectric sensor Download PDFInfo
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- CN109506776B CN109506776B CN201811025712.3A CN201811025712A CN109506776B CN 109506776 B CN109506776 B CN 109506776B CN 201811025712 A CN201811025712 A CN 201811025712A CN 109506776 B CN109506776 B CN 109506776B
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- 238000006243 chemical reaction Methods 0.000 claims abstract description 18
- 238000010586 diagram Methods 0.000 description 17
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- 229920006395 saturated elastomer Polymers 0.000 description 5
- 238000001514 detection method Methods 0.000 description 4
- 230000010355 oscillation Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000005286 illumination Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J1/44—Electric circuits
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J1/44—Electric circuits
- G01J2001/4446—Type of detector
- G01J2001/446—Photodiode
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Abstract
The photoelectric sensor of the invention can expand the dynamic range even if the clamping circuit (2) is arranged. The photoelectric sensor of the present invention includes: an IV conversion circuit (1) having an OP amplifier (U1); a transistor (Q1) having a collector terminal connected to the inverting input terminal of the OP amplifier (U1) and an emitter terminal connected to the output terminal of the OP amplifier (U1); and a constant voltage source (V2) having a positive terminal connected to the base terminal of the transistor (Q1) and a negative terminal connected to ground.
Description
Technical Field
The present invention relates to a photoelectric sensor provided with a clamp circuit for an IV conversion circuit (current-voltage conversion circuit).
Background
Conventionally, in a light receiving circuit of a photosensor, a current generated in a photodiode PD is converted into a voltage by an IV conversion circuit (see, for example, patent document 1).
Fig. 10 shows an example of a configuration of a general light receiving circuit. As shown in fig. 10, the light receiving circuit includes a photodiode PD, an OP amplifier U1, a constant voltage source V1, a resistor R1, and a capacitor C1. Further, the OP amplifier U1, the constant voltage source V1, the resistor R1, and the capacitor C1 constitute an IV conversion circuit.
The photodiode PD generates a current corresponding to incident light. The photodiode PD has a cathode connected to the inverting input terminal of the OP amplifier U1 and an anode grounded.
The positive terminal of the constant voltage source V1 is connected to the non-inverting input terminal of the OP amplifier U1, and the negative terminal is grounded. Further, the resistor R1 has one end connected to the inverting input terminal of the OP amplifier U1 and the other end connected to the output terminal of the OP amplifier U1. Further, one end of the capacitor C1 is connected to the inverting input terminal of the OP amplifier U1, and the other end is connected to the output terminal of the OP amplifier U1.
In this photosensor, incident light is small under normal use conditions, and as shown in fig. 11A, the OP amplifier U1 operates in a dynamic range (linear region). On the other hand, when excessive light enters the photosensor, as shown in fig. 11B, the output of the OP amplifier U1 reaches a saturation region, and there is a case where the response is delayed. That is, a breakdown potential difference is generated due to a virtual short between the inverting input terminal and the non-inverting input terminal, so that the bias level is shifted, and the signal amount (peak value) P is reduced or made zero. In this case, the photoelectric sensor has problems such as an erroneous output determination operation (oscillation or output inversion) or a decrease in response speed (erroneous counting of signal processing). The incidence of the excessive light is caused by sunlight, illumination light (direct current light or inverted light (インバータ light)), reflected light by a glossy object (mirror, metal, or the like), use at a short distance, or the like.
Therefore, as shown in fig. 12, there is a photosensor in which a clamp circuit including a feedback diode D1 is added to the IV conversion circuit shown in fig. 10. The feedback diode D1 has a cathode connected to the inverting input terminal of the OP amplifier U1 and an anode connected to the output terminal of the OP amplifier U1. With this clamp circuit, as shown in fig. 13, the output voltage VOUT of the OP amplifier U1 is clamped by the voltage VF between the feedback diodes D1, and the output of the OP amplifier U1 can be prevented from being saturated.
However, in the configuration shown in fig. 12, the output voltage VOUT can be adjusted only in units of integral multiples of the voltage VF between the feedback diodes D1, and the dynamic range is reduced by the Vd (< VF) level shown in fig. 13. As an influence on the product, the range of distance setting of the photoelectric sensor is narrowed, which causes a restriction in installation, and thus the usability is deteriorated.
Further, although there is a method of switching the value of the resistor R1 (switching gain), the circuit scale increases, and the circuit is not resistant to noise, which is not preferable.
[ Prior art documents ]
[ patent document ]
[ patent document 1 ] Japanese patent laid-open No. 2007-and-298366
Disclosure of Invention
[ problem to be solved by the invention ]
As described above, in the conventional photoelectric sensor, the output voltage VOUT can be adjusted only in units of integral multiples of the voltage VF between the feedback diodes D1, which has a problem of narrowing the dynamic range.
The present invention has been made to solve the above-described problems, and an object thereof is to provide a photosensor capable of expanding a dynamic range even when a clamp circuit is provided.
[ MEANS FOR SOLVING PROBLEMS ] A method for producing a semiconductor device
The photoelectric sensor of the present invention is characterized by comprising: a current-voltage conversion circuit having an OP amplifier; a transistor having a collector terminal connected to an inverting input terminal of the OP amplifier and an emitter terminal connected to an output terminal of the OP amplifier; and a constant voltage source having a positive terminal connected to the base terminal of the transistor and a negative terminal grounded.
[ Effect of the invention ]
According to the present invention, since the above configuration is adopted, the dynamic range can be expanded even when the clamp circuit is provided.
Drawings
Fig. 1 is a circuit diagram showing an example of the configuration of a light receiving circuit included in a photosensor according to embodiment 1 of the present invention.
Fig. 2 is a diagram showing a voltage obtained by the IV conversion circuit shown in fig. 1 (in the case of incident excessive light).
Fig. 3 is a circuit diagram showing another configuration example of a light receiving circuit included in the photoelectric sensor according to embodiment 1 of the present invention.
Fig. 4 is a diagram showing a voltage obtained by the IV conversion circuit shown in fig. 3 (in the case where excessive light is incident).
Fig. 5 is a diagram showing an equivalent circuit of the photodiode PD in the light receiving circuit shown in fig. 1.
Fig. 6 is a circuit diagram showing an example of the configuration of a light receiving circuit included in a photosensor according to embodiment 2 of the present invention.
Fig. 7 is a diagram showing a voltage obtained by the IV conversion circuit shown in fig. 6 (in the case where excessive light is incident).
Fig. 8 is a circuit diagram showing another configuration example of a light receiving circuit included in a photosensor according to embodiment 2 of the present invention.
Fig. 9 is a diagram showing a voltage obtained by the IV conversion circuit shown in fig. 8 (in the case where excessive light is incident).
Fig. 10 is a circuit diagram showing an example of the configuration of a light receiving circuit included in a conventional photoelectric sensor.
Fig. 11A and 11B are diagrams showing voltages obtained by the IV conversion circuit shown in fig. 10, fig. 11A is a diagram showing a case of a normal use condition, and fig. 11B is a diagram showing a case where excessive light enters.
Fig. 12 is a circuit diagram showing another configuration example of a light receiving circuit of a conventional photoelectric sensor.
Fig. 13 is a diagram showing a voltage obtained by the IV conversion circuit shown in fig. 12 (in the case where excessive light enters).
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the drawings.
Fig. 1 is a diagram showing an example of the configuration of a light receiving circuit included in a photoelectric sensor according to embodiment 1 of the present invention.
As shown in fig. 1, the light receiving circuit includes a photodiode PD, an OP amplifier U1, a constant voltage source V1, a resistor R1, a capacitor C1, a transistor Q1, and a constant voltage source V2. In fig. 1, the OP amplifier U1, the constant voltage source V1, the resistor R1, and the capacitor C1 constitute an IV conversion circuit 1, and the transistor Q1 and the constant voltage source V2 constitute a clamp circuit 2.
The photodiode PD generates a current corresponding to incident light. The photodiode PD has a cathode connected to the inverting input terminal of the OP amplifier U1 and an anode grounded.
The positive terminal of the constant voltage source V1 is connected to the non-inverting input terminal of the OP amplifier U1, and the negative terminal is grounded.
The resistor R1 has one end connected to the inverting input terminal of the OP amplifier U1 and the other end connected to the output terminal of the OP amplifier U1.
One end of the capacitor C1 is connected to the inverting input terminal of the OP amplifier U1, and the other end is connected to the output terminal of the OP amplifier U1.
The transistor Q1 has a collector terminal connected to the inverting input terminal of the OP amplifier U1, and an emitter terminal connected to the output terminal of the OP amplifier U1. Further, a PNP type transistor is used as the transistor Q1.
The positive terminal of the constant voltage source V2 is connected to the base terminal of the transistor Q1, and the negative terminal is grounded.
In the light receiving circuit in embodiment 1, as shown in fig. 2, the clamp circuit 2 clamps the output voltage VOUT of the OP amplifier U1 to the constant voltage source V2+ the base-emitter voltage VBE of the transistor Q1, thereby preventing the output of the OP amplifier U1 from being saturated.
Further, by adjusting the constant voltage source V2, the dynamic range can be adjusted to be in front of the boundary of the saturation region.
Also shown above is the case where (the anode of) the photodiode PD is grounded. However, the present invention is not limited to this, and the photodiode PD may be connected to the constant voltage source V3 as shown in fig. 3. In this case, the anode of the photodiode PD is connected to the inverting input terminal of the OP amplifier U1, and the cathode thereof is connected to the constant voltage source V3. Further, an NPN-type transistor is used as the transistor Q1 in the clamp circuit 2. In this case, as shown in fig. 4, the output voltage VOUT of the OP amplifier U1 is clamped by the constant voltage source V2 — the base-emitter voltage VBE of the transistor Q1, and the output of the OP amplifier U1 can be prevented from being saturated.
As described above, according to embodiment 1, since the IV conversion circuit 1 includes the OP amplifier U1, the transistor Q1, and the constant voltage source V2, the IV conversion circuit 1 has the collector terminal of the transistor Q1 connected to the inverting input terminal of the OP amplifier U1, the emitter terminal connected to the output terminal of the OP amplifier U1, the positive terminal of the constant voltage source V2 connected to the base terminal of the transistor Q1, and the negative terminal connected to ground, the dynamic range can be expanded even when the clamp circuit 2 is provided.
In embodiment 1, a case is shown in which the clamp circuit 2 including the transistor Q1 and the constant voltage source V2 is used as shown in fig. 1. However, when the clamp is made by V2+ VBE as in the configuration shown in fig. 1, there is a problem that the gain increases.
The gain G at the time of clamping in the configuration shown in fig. 1 is expressed by the following formula (1). In equation (1), AV is the open-loop gain of the OP amplifier U1, Rpd is the equivalent resistance of the photodiode PD, and re is the emitter resistance of the transistor Q1. Further, an equivalent circuit 3 of the photodiode PD in fig. 1 is shown in fig. 5.
G＝AV×Rpd/re (1)
The emitter resistance re is expressed by the following formula (2). In equation (2), Vt is a thermal voltage, and Ic is a collector current of the transistor Q1.
re＝Vt/Ic (2)
The thermal voltage Vt is expressed by the following formula (3). In the formula (3), q is the charge of electrons, k is the boltzmann coefficient, and T is the absolute temperature.
Vt＝kT/q (3)
Here, q is 1.602 × 10-19[C]、k＝1.3805×10-23[J/K]Set T300K]In the case of (1), Vt is approximately 26[ mV [. ]]。
When excessive light enters the photodiode PD and the collector current Ic of the transistor Q1 flowing 1[ mA ], re ≈ 26[ Ω ].
In the case of the configuration shown in fig. 1, the voltage change at the inverting input terminal of the OP amplifier U1 is amplified by the open-loop gain AV, and the base voltage of the transistor Q1 is fixed by the constant voltage source V2. Therefore, the voltage change at the output terminal of the OP amplifier U1 is converted into a current by the emitter resistance re of the transistor Q1. This current is converted into a voltage by the equivalent resistance Rpd of the photodiode PD. For example, when the collector current of the transistor Q1 is 1[ mA ], the emitter resistance re is as small as 26[ Ω ], and the gain G is amplified due to the above-described reasons.
In addition, the increase in gain can also be confirmed by circuit simulation.
In this way, in the configuration shown in fig. 1, the clamp circuit 2 increases the gain, and the phase margin and the gain margin of the OP amplifier U1 become small, so that oscillation may occur triggered by temperature change, voltage fluctuation, or noise, and the oscillation may become unstable. As an influence on the product, there is a possibility that malfunction occurs in the case where a detection object is present in a short distance, the case where a glossy object is detected, or the like. Further, in an environment where sunlight or illumination light is incident, there is a fear that detection cannot be performed.
Therefore, embodiment 2 shows a configuration for suppressing an increase in gain during clamping. Fig. 6 is a diagram showing an example of the configuration of a light receiving circuit included in a photosensor according to embodiment 2 of the present invention. In the photosensor according to embodiment 2 shown in fig. 6, a resistor R2 is added to the photosensor according to embodiment 1 shown in fig. 1. The other structures are the same, and the same reference numerals are used to omit descriptions thereof. In embodiment 2, the clamp circuit 2 is configured by the transistor Q1, the constant voltage source V2, and the resistor R2.
The resistor R2 is interposed between the output terminal of the OP amplifier U1 and the emitter terminal of the transistor Q1.
When the resistance value of the resistor R2 is large, the stability of the light receiving circuit is improved, but the clamping performance of the clamp circuit 2 is lowered. Conversely, when the resistance value of the resistor R2 is low, the stability of the light receiving circuit is lowered, but the clamping performance of the clamp circuit 2 is improved. Therefore, the resistance value of the resistor R2 is designed in consideration of the relationship between the stability of the light receiving circuit and the clamping performance of the clamp circuit 2. As the resistance value of the resistor R2, for example, a resistance value of about several hundred Ω can be used.
With the clamp circuit 2 including the transistor Q1, the constant voltage source V2, and the resistor R2, as shown in fig. 7, the output voltage VOUT of the OP amplifier U1 is clamped by V2+ VBE + (Ic × R2), and the output of the OP amplifier U1 can be prevented from being saturated.
In the light receiving circuit according to embodiment 2, the resistor R2 is connected to the emitter terminal of the transistor Q1 in the feedback portion of the OP amplifier U1 with respect to the configuration shown in fig. 1, whereby only the gain during clamping can be suppressed.
The gain G at the time of clamping in the light receiving circuit of embodiment 2 is represented by the following formula (5).
G＝AV×Rpd/(re+R2) (5)
As shown in equation (5), since the external resistor R2 is added to the emitter resistor re of the transistor Q1, the gain G can be suppressed to about 1/10 when R2 is 200 Ω, for example.
In addition, the effect of gain suppression can also be confirmed by circuit simulation.
In this way, since only the gain during clamping can be reduced, stability can be easily ensured without changing the bandwidth, the open-loop gain, and the like of the OP amplifier U1. Stable detection without oscillation can be realized even in the presence of a detection object in a short distance or in an environment where sunlight or illumination light is incident when a glossy object (metal or the like) is detected.
Also shown above is the case where (the anode of) the photodiode PD is grounded. However, the present invention is not limited to this, and the photodiode PD may be connected to the constant voltage source V3 as shown in fig. 8, for example. In this case, the anode of the photodiode PD is connected to the inverting input terminal of the OP amplifier U1, and the cathode thereof is connected to the constant voltage source V3. Further, an NPN-type transistor is used as the transistor Q1 in the clamp circuit 2. In this case, as shown in fig. 9, the output voltage VOUT of the OP amplifier U1 is clamped by V2-VBE- (Ic × R2), and the output of the OP amplifier U1 can be prevented from being saturated.
As described above, according to embodiment 2, since the resistor R2 interposed between the output terminal of the OP amplifier U1 and the emitter terminal of the transistor Q1 is provided, it is possible to suppress an increase in gain during clamping and improve stability in addition to the effects of embodiment 1.
In the present invention, any combination of the embodiments, or any component of the embodiments may be modified or any component may be omitted in the embodiments within the scope of the invention.
Description of the symbols
1 IV conversion circuit
2 clamping circuit
3 equivalent circuit.
Claims (1)
1. A photoelectric sensor is characterized by comprising:
a current-voltage conversion circuit having an OP amplifier;
a transistor having a collector terminal connected to an inverting input terminal of the OP amplifier and an emitter terminal connected to an output terminal of the OP amplifier;
a constant voltage source having a positive terminal connected to the base terminal of the transistor and a negative terminal grounded; and
and a resistor interposed between the output terminal of the OP amplifier and the emitter terminal of the transistor.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017177892A JP2019054438A (en) | 2017-09-15 | 2017-09-15 | Photoelectric sensor |
| JP2017-177892 | 2017-09-15 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109506776A CN109506776A (en) | 2019-03-22 |
| CN109506776B true CN109506776B (en) | 2021-04-23 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201811025712.3A Active CN109506776B (en) | 2017-09-15 | 2018-09-04 | Photoelectric sensor |
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| Country | Link |
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| JP (1) | JP2019054438A (en) |
| CN (1) | CN109506776B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2021061456A (en) * | 2019-10-02 | 2021-04-15 | パイオニア株式会社 | Optical receiving circuit |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2202624A (en) * | 1987-03-23 | 1988-09-28 | Dr Basil Polychronopulos | Optimum biasing system for electronic devices |
| EP2302341A3 (en) * | 2009-09-22 | 2012-10-17 | Societe Francaise De Detecteurs, Infrarouges- Sofradir | Detection circuit with improved anti-blooming circuit |
Family Cites Families (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01253305A (en) * | 1988-04-01 | 1989-10-09 | Toshiba Corp | Light receiver |
| JP3136660B2 (en) * | 1991-06-24 | 2001-02-19 | 株式会社ニコン | Photometric circuit |
| JPH09246879A (en) * | 1996-03-14 | 1997-09-19 | Fujitsu Ltd | Preamplifier circuit |
| JPH09321562A (en) * | 1996-05-31 | 1997-12-12 | Matsushita Electric Ind Co Ltd | Limiter device |
| DE19907972A1 (en) * | 1999-02-24 | 2000-08-31 | Bosch Gmbh Robert | Image cell |
| JP2001196877A (en) * | 2000-01-06 | 2001-07-19 | Mitsubishi Electric Corp | Preamplifier circuit |
| JP3786556B2 (en) * | 2000-02-23 | 2006-06-14 | シャープ株式会社 | Receiver amplifier circuit |
| JP2003264434A (en) * | 2002-03-07 | 2003-09-19 | Opnext Japan Inc | Optical signal receiving circuit |
| KR100515078B1 (en) * | 2003-09-03 | 2005-09-14 | 삼성전기주식회사 | Current-voltage transforming circuit employing limiter circuit by means of current sensing |
| JP4068590B2 (en) * | 2004-05-06 | 2008-03-26 | 株式会社東芝 | Current-voltage conversion circuit |
| JP2007129533A (en) * | 2005-11-04 | 2007-05-24 | New Japan Radio Co Ltd | Transimpedance amplifier |
| JP5199942B2 (en) * | 2009-04-30 | 2013-05-15 | シリンクス株式会社 | Current-voltage conversion circuit |
| JP5071467B2 (en) * | 2009-12-09 | 2012-11-14 | Ｔｄｋ株式会社 | CURRENT / VOLTAGE CONVERSION CIRCUIT, OPTICAL DEVICE, AND OPTICAL DRIVE DEVICE |
| US8680911B2 (en) * | 2011-03-08 | 2014-03-25 | Honeywell International Inc. | High-linearity signal-processing amplifier |
| EP2797228B1 (en) * | 2013-04-26 | 2016-04-20 | Xenics N.V. | Method for detecting a photocurrent |
| KR102426677B1 (en) * | 2015-03-09 | 2022-07-28 | 삼성전자주식회사 | Vision sensor based on event and difference amplifier with reduced noise and offset |
| CN205642617U (en) * | 2016-04-21 | 2016-10-12 | 常州信息职业技术学院 | Portable luminance detector circuit |
| CN106505961B (en) * | 2016-12-29 | 2019-09-13 | 福建亿芯源半导体股份有限公司 | The automatic gain control circuit of quick response |
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2017
- 2017-09-15 JP JP2017177892A patent/JP2019054438A/en active Pending
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- 2018-09-04 CN CN201811025712.3A patent/CN109506776B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2202624A (en) * | 1987-03-23 | 1988-09-28 | Dr Basil Polychronopulos | Optimum biasing system for electronic devices |
| EP2302341A3 (en) * | 2009-09-22 | 2012-10-17 | Societe Francaise De Detecteurs, Infrarouges- Sofradir | Detection circuit with improved anti-blooming circuit |
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| CN109506776A (en) | 2019-03-22 |
| JP2019054438A (en) | 2019-04-04 |
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