JP2006189332A - Optical sensor circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sensor circuit for enhancing detection accuracy on whether an object exists or not without lowering sensor scan resolution. <P>SOLUTION: In this optical sensor circuit 1, a light emission electric current selecting circuit 101 supplies light emission electric current 102 to a light emitting element 104 selected by a light emission clock selecting circuit 103, a light receiving element 105 for receiving light emitted by the emitting element 104 is selected by a light receiving sensor selecting circuit 106, and an electric current outputted by the selected receiving element 105 is detected by an on/off determining part 115 to determine whether an object exists or not. This sensor circuit 1 is characterized by being equipped with: a light emission block select part 120 for outputting a light emission block selection signal 109 to the selecting circuit 103 in order to select the emitting element 104 in synchronization with light emission selecting timing generated by a timing generation part 112; and a light receiving sensor select part 119 for outputting a sensor select signal 108 to the selecting circuit 106 in order to select the receiving element 105 in synchronization with a basic clock 118 generated by the timing generation part 112. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical sensor circuit, and more particularly to an optical sensor circuit that controls a light emission current supplied to a light emitting element and an output signal from a light receiving element.

Conventionally, in automatic ticketing machines that are installed in transportation facilities, etc. that issue tickets and air tickets, or in automatic transaction devices that are installed in financial institutions and convenience stores, etc., for transactions such as cash deposits and withdrawals, An optical sensor circuit for detecting the presence or absence of a medium such as a ticket or cash is provided.
10 is a block diagram of a conventional optical sensor circuit, FIG. 11 is a block diagram of a light emitting element and a light receiving element switching unit of the conventional optical sensor circuit, and FIG. 12 is a diagram illustrating the operation of the conventional optical sensor circuit. This will be described using the time chart shown.

In FIG. 10, reference numeral 1 denotes an optical sensor circuit which controls a light emission current supplied to a light emitting element that emits light, detects an electric signal output from the light receiving element that receives the light, and detects a medium between the light emitting element and the light receiving element. It is a control circuit which determines the presence or absence of.
A light emission current switching circuit 101 is a circuit that switches the light emission current 102 supplied to the light emitting element to a predetermined current value set by a CPU (Central Processing Unit) (not shown).

Reference numeral 104 denotes a light emitting element, which includes a light emitting diode that emits light by supplying a light emission current 102.
Reference numeral 103 denotes a light emission block switching circuit, which is a circuit that selects and switches the light emitting element 104 that is blocked to supply the light emission current 102. The light-emitting element 104 that is made into a block refers to a group of light-emitting elements 104 (hereinafter referred to as “light-emitting blocks”) obtained by dividing a plurality of light-emitting elements 104 into 8 blocks.

A light receiving element 105 includes a phototransistor that receives light emitted from the light emitting element 104, converts the light into a current signal, and outputs the current signal.
A light receiving sensor switching circuit 106 is a circuit that selects and switches one light receiving element 105 among a plurality of light receiving elements 105. By switching the light receiving sensor switching circuit 106, the sensor output signal 110 input from the desired light receiving element 105 can be output as the select sensor output signal 111.

  A sensor control circuit 107 includes a timing generation unit 112, an on / off determination unit 115, a storage unit 116, and a light emission block / light reception sensor selection unit 130. This sensor control circuit 107 determines the presence / absence of an object between the light emitting element 104 and the light receiving element 105 from the input select sensor output signal 111, and outputs a light emission block switching signal / light reception select sensor signal 109.

The timing generation unit 112 includes a crystal transmission circuit, a counter circuit, and the like, detects that a predetermined time has elapsed, stores the sensor data read timing 113 to the on / off determination unit 115, and stores the sensor data write timing 114. The basic clock 118 is output to the light emitting block / light receiving sensor selector 130 to 116.
The on / off determination unit 115 is composed of an A / D (Analog / Digital) conversion circuit or the like, and synchronizes the input sensor data output signal 111, which is input analog data, with the input sensor data read timing 113 to convert it into digital data. The converted digital data is compared with the set value to determine the presence or absence of an object between the light emitting element 104 and the light receiving element 105 and stored. For example, if the converted digital data is a value greater than or equal to a set value, it is determined that there is an object, and if it is less than the set value, it is determined that there is no object.

Here, the presence of an object is determined to be on, and the absence of an object is determined to be off. The on / off determination unit 115 outputs an on / off determination result to the storage unit 116 as on / off data 117.
The storage unit 116 is configured by a storage element such as a memory, and extracts and stores on / off information determined by the on / off determination unit 115 in synchronization with the sensor data write timing 114. The stored on / off information can be read out by a CPU (not shown).

  The light emitting block / light receiving sensor selector 130 is composed of a switching element such as a transistor and the like. The light emitting block / light receiving sensor selection unit 130 is synchronized with the inputted basic clock 118 and selects one block of the eight light emitting element 104 groups and a plurality of light receiving elements 105. The light-emission block switching signal / light-receiving sensor select signal 121 for selecting one of them is output to the light-emission block switching circuit 103 and the light-receiving sensor switching circuit 106. The basic clock 118 is output from the timing generator 112 every 10 microseconds.

  Receiving the light emission block switching signal / light receiving sensor select signal 121, the light emission block switching circuit 103 supplies a light emission current to the selected light emission block to cause the light emitting element 104 to emit light. The light receiving sensor switching circuit 106 that has received the light emitting block switching signal / light receiving sensor select signal 121 selects the sensor output signal 110 output from the light receiving element 105 and supplies the select sensor output signal 111 to the sensor control circuit 107.

Next, a light emitting element and a light receiving element switching unit of a conventional optical sensor circuit will be described with reference to FIG.
In FIG. 11, (1) to (64) indicate sensor numbers, indicating that there are 64 light emitting elements 104 and light receiving elements 105.
There are eight light emitting blocks to be switched by the light emitting block switching circuit 103, and eight light emitting elements 104 and a light receiving element 105 (not shown) are configured corresponding to one block. For example, one sensor block (1), (9), (17), (25), (33), (41), (49), (57) constitutes one light emitting block.

  One light-emitting block is selected by the light-emitting block switching signal output from the light-emitting block / light-receiving sensor selector 130, and the light-emitting element 104 of the light-emitting block emits light when the light-emitting current 102 flows. The light receiving element 105 that has received the light is selected by a light receiving sensor select signal output from the light emitting block / light receiving sensor selection unit 130, and the select sensor output signal 111 output from the light receiving element 105 is detected as a sensor. Input to the control circuit 107.

In this way, 64 sensors can be controlled by repeating selection of the light-emitting block and the light-emitting element from sensor numbers (1) to (64). The light emitting blocks and the light emitting elements are selected in the order of (1) to (64).
Next, the operation of one sensor will be described with reference to a time chart showing the operation of the conventional optical sensor circuit of FIG.

The sensor scan time 20 is the total time for reading the select sensor output signal 111 output from one light receiving element 105, and is 10 microseconds. Here, the sensor scan refers to the operation of the optical sensor circuit 1 that reads the select sensor output signal 111 output from one light receiving element 105 that has emitted light from the light emitting element 104 and received the light.
The sensor scan time 20 is synchronized with a pulse signal generated by the basic clock 118 every 10 microseconds, starts the sensor scan when the basic clock 118 rises, and further rises the basic clock 118 after 10 microseconds. The process ends when

  The sensor lead timing 113 is generated 5 microseconds after the start of the sensor scan which is the center of 10 microseconds of the total sensor scan time. With this sensor lead timing 113 as an opportunity, the on / off determination unit 115 determines whether the object is on or off from the select sensor output signal 111. The sensor read timing 113 is negative logic, and informs the on / off determination unit 115 of the timing for reading the select sensor output signal 111 and determining on / off at the falling edge of the signal.

  The sensor data write timing 114 occurs 8 microseconds after the start of the sensor scan. The on / off information determined by the on / off determination unit 115 triggered by the sensor data write timing 114 is extracted and stored in the storage unit 116. The sensor data write timing 114 is negative logic, and notifies the storage unit 116 of an opportunity to read the on / off data 117 at the falling edge of the signal.

Thus, some conventional optical sensor circuits detect the presence or absence of a medium.
In some cases, a plurality of light receiving processes are simultaneously performed using a common light receiving element (see, for example, Patent Document 1).
Furthermore, there are some that reduce the number of wirings connecting a plurality of optical sensor circuits (for example, see Patent Document 2).
Japanese Patent Laid-Open No. 11-14455 (paragraphs “0011” to “0023”, FIG. 1) Japanese Patent Laid-Open No. 10-207835 (paragraphs “0006” to “0021”, FIG. 1)

  However, in the above-described conventional technology, the time until the light emitting element starts to emit light and the maximum light emission amount are reached after the light emitting current starts to flow through the light emitting element due to a change in ambient temperature or aging of the light emitting element of the sensor. In such a case, the output signal of the light receiving element is not stable, so the presence or absence of a medium cannot be accurately detected. There is a problem that it may be judged that there is no concern, or it may be judged that there is none.

  In order to solve the above problem, it is conceivable to detect the output current from the light receiving element after securing a sufficient time after the light emitting current starts to flow through the light emitting element. In this way, it is possible to control a plurality of sensors. In this optical sensor circuit, since it takes a long time to control one sensor, it takes a long time to control all the sensors, and the resolution is lowered.

  An object of the present invention is to solve such a problem.

  Therefore, according to the present invention, the light emission current switching circuit supplies the light emission current to the light emitting element selected by the light emission block switching circuit, and the light receiving sensor switching circuit selects the light receiving element that receives the light emission of the light emitting element. Light-emitting block switching signal for selecting a light-emitting element in synchronization with the light-emitting current switching timing generated by the timing generation unit in the optical sensor circuit that detects the current output from the light-receiving element by the on / off determination unit and determines the presence or absence of an object Is provided with a light-emission block selection unit that outputs the light-emission block to the light-emission block switching circuit, and a light-receiving sensor selection unit that outputs a sensor selection signal for selecting the light-receiving element in synchronization with the basic clock generated by the timing generation unit. It is characterized by that.

In the present invention thus configured, the on / off determination unit can determine the stable output signal of the light receiving element after a certain time has elapsed since the light emission current started to flow through the light emitting element. The effect that detection accuracy can be improved is obtained.
Further, since the sensor scan time, which is the time for controlling the sensor, is not lengthened, the effect that the resolution is not lowered can be obtained.

  Embodiments of an optical sensor circuit according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an optical sensor circuit showing a first embodiment.
In FIG. 1, reference numeral 1 denotes an optical sensor circuit, which controls a light emission current supplied to a light emitting element that emits light, detects an electric signal output from the light receiving element that receives the light, and detects a medium between the light emitting element and the light receiving element. It is a control circuit which determines the presence or absence of.
A light emission current switching circuit 101 is a circuit for switching the light emission current 102 supplied to the light emitting element to a predetermined current value set by a CPU or the like (not shown).

Reference numeral 104 denotes a light emitting element, which includes a light emitting element such as a light emitting diode that emits light when a light emission current 102 is supplied.
Reference numeral 103 denotes a light emission block switching circuit, which is a circuit that selects and switches the light emitting element 104 that is blocked to supply the light emission current 102.
A light receiving element 105 includes a light receiving element such as a phototransistor that receives light emitted from the light emitting element 104, converts the light into a current signal, and outputs the current signal.

A light receiving sensor switching circuit 106 is a circuit that selects and switches one light receiving element 105 among a plurality of light receiving elements 105. By switching the light receiving sensor switching circuit 106, the sensor output signal 110 input from the desired light receiving element 105 can be output as the select sensor output signal 111.
A sensor control circuit 107 includes a timing generation unit 112, an on / off determination unit 115, a storage unit 116, a light receiving sensor selection unit 119, and a light emission block selection unit 120. The sensor control circuit 107 determines the presence / absence of an object between the light emitting element 104 and the light receiving element 105 from the input select sensor output signal 111, and outputs a light emission block switching signal 109 and a sensor select signal 108.

The timing generation unit 112 includes a crystal transmission circuit, a counter circuit, and the like, detects that a predetermined time has elapsed, stores the sensor data read timing 113 to the on / off determination unit 115, and stores the sensor data write timing 114. The basic clock 118 is output to the light receiving sensor selection unit 119 to 116 and the light emission block selection unit 120.
The on / off determination unit 115 includes an A / D conversion circuit and the like, and converts the selected sensor output signal 111, which is input analog data, into digital data in synchronization with the input sensor data read timing 113. The set digital data and the set value are compared, and the presence / absence of an object between the light emitting element 104 and the light receiving element 105 is determined and stored. For example, if the converted digital data is a value greater than or equal to a set value, it is determined that there is an object, and if it is less than the set value, it is determined that there is no object.

Here, the presence of an object is determined to be on, and the absence of an object is determined to be off. The on / off determination unit 115 outputs an on / off determination result to the storage unit 116 as on / off data 117.
The storage unit 116 is configured by a storage element such as a memory, and extracts and stores on / off information determined by the on / off determination unit 115 in synchronization with the sensor data write timing 114. The stored on / off information can be read out by a CPU (not shown).

The light receiving sensor selection unit 119 is composed of a switching element such as a transistor, and a sensor select signal 108 for selecting one of the plurality of light receiving elements 105 in synchronization with the input basic clock 118 is sent to the light receiving sensor switching circuit 106. Output. The basic clock 118 is output every 10 microseconds.
Upon receiving this sensor select signal 108, the light receiving sensor switching circuit 106 selects the sensor output signal 110 output from the light receiving element 105 and supplies the select sensor output signal 111 to the sensor control circuit 107.

The light emission block selector 120 is composed of a switching element such as a transistor and the like, and a light emission block switching circuit is synchronized with the sensor data write timing 114 inputted with the light emission block switching signal 109 for selecting one block of the eight light emission blocks. 103 is output.
Upon receiving the light emission block switching signal 109, the light emission block switching circuit 103 supplies a light emission current to the selected light emission block to cause the light emitting element 104 to emit light.

In addition, since the light emitting element and the light receiving element switching part of the optical sensor circuit are the same as the conventional one, the description thereof is omitted.
The operation of the above-described configuration will be described with reference to a time chart showing the operation of the optical sensor circuit according to the first embodiment shown in FIG.
The sensor scan time 20 is the total time for reading the select sensor output signal 111 output from one light receiving element 105, and is 10 microseconds. Here, the sensor scan refers to the operation of the optical sensor circuit 1 that reads the select sensor output signal 111 output from one light receiving element 105 that has emitted light from the light emitting element 104 and received the light.

The sensor scan time 20 is synchronized with a pulse signal generated by the basic clock 118 every 10 microseconds, starts the sensor scan when the basic clock 118 rises, and further rises the basic clock 118 after 10 microseconds. The process ends when
Here, the light emission block switching signal 109 is output to the light emission block switching circuit 103 in synchronization with the fall of the sensor data write timing 114 of the previous sensor number, which is 2 microseconds before the start of the sensor scan, thereby emitting light. A light emission current 102 is passed through the element 104. The sensor data write timing 114 is negative logic, and notifies the light emission block switching signal 109 of timing to output to the light emission block selector 120 at the fall of the signal.

  The sensor lead timing 113 is generated 5 microseconds after the start of the sensor scan which is the center of 10 microseconds of the total sensor scan time, that is, 7 microseconds after the light emission current 102 is applied to the light emitting element 104. In response to this sensor read timing 113, the on / off determination unit 115 determines whether the object is on or off from the select sensor output signal 111, and stores the result. The sensor read timing 113 is negative logic, and informs the on / off determination unit 115 of the timing for reading the select sensor output signal 111 and determining on / off at the falling edge of the signal.

  The sensor data write timing 114 occurs 8 microseconds after the start of the sensor scan. The on / off information determined by the on / off determination unit 115 triggered by the sensor data write timing 114 is extracted and stored in the storage unit 116. The sensor data write timing 114 is negative logic, and notifies the storage unit 116 of an opportunity to read the on / off data 117 at the falling edge of the signal.

Further, in synchronization with the sensor data write timing 114, the light emission block switching signal 109 is output to the light emission block switching circuit 103, and the light emitting element 104 corresponding to the next sensor number is switched.
In this embodiment, the sensor scan time 20 has been described as 10 microseconds, but is not limited thereto, and may be, for example, 5 microseconds, 20 microseconds, or the like.

  As described above, in the first embodiment, the light emission block selection unit 120 and the light receiving sensor selection unit 119 are separated, and the light emission block switching signal 109 is sent to the light emission block switching circuit 103 2 microseconds before the sensor scan is started. By outputting, the on / off determination unit 115 can determine a stable select sensor output signal 111 after 7 microseconds from when the light emission current 102 is passed through the light emitting element 104. The effect that the accuracy can be improved is obtained.

Further, since the sensor scan time 20 which is a time for controlling the sensor is not increased, the effect that the resolution is not lowered can be obtained.
FIG. 3 is a block diagram of an optical sensor circuit showing a second embodiment of the present invention. Note that parts similar to those of the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.
The timing generation unit 112 includes a crystal transmission circuit, a counter circuit, and the like. The sensor data read timing 113 is sent to the on / off determination unit 115, the sensor data write timing 114 is stored in the storage unit 116, and the basic clock 118 is sent to the light receiving sensor selection unit 119. The light emission current switching timing 321 is output to the light emission block selector 120.

The light emission block selector 120 outputs a light emission block switching signal 109 for selecting one of the eight light emission blocks to the light emission block switching circuit 103 in synchronization with the inputted light emission current switching timing 321.
The operation of the above configuration will be described with reference to a time chart showing the operation of the optical sensor circuit of the second embodiment shown in FIG.

The sensor scan time 20 is the total time for reading the select sensor output signal 111 output from one light receiving element 105, and is 10 microseconds. The sensor scan time 20 is synchronized with a pulse signal generated by the basic clock 118 every 10 microseconds.
Here, the light emission block switching signal 109 is output to the light emission block switching circuit 103 in synchronization with the fall of the light emission current switching timing 321 of the previous sensor number that is 4 microseconds before the start of the sensor scan, thereby emitting light. A light emission current 102 is passed through the element 104. Note that the light emission current switching timing 321 is negative logic, and notifies the light emission block switching signal 109 when the light emission block switching signal 109 is output at the falling edge of the signal.

  The sensor lead timing 113 is generated 5 microseconds after the start of the sensor scan, which is the center of 10 microseconds of the total sensor scan time, that is, 9 microseconds after the light emission current 102 is applied to the light emitting element 104. With this sensor lead timing 113 as an opportunity, the on / off determination unit 115 determines whether the object is on or off from the select sensor output signal 111. The sensor read timing 113 is negative logic, and informs the on / off determination unit 115 of the timing for reading the select sensor output signal 111 and determining on / off at the falling edge of the signal.

Also, after the sensor data read timing 113 is generated, the light emission current switching timing 321 is output to the light emission block switching circuit 103 after 1 microsecond has elapsed, and the light emitting element 104 corresponding to the next sensor number is switched.
The sensor data write timing 114 occurs 8 microseconds after the start of the sensor scan. The on / off information determined by the on / off determination unit 115 triggered by the sensor data write timing 114 is extracted and stored in the storage unit 116. The sensor data write timing 114 is negative logic, and notifies the storage unit 116 of an opportunity to read the on / off data 117 at the falling edge of the signal.

In this embodiment, the sensor scan time 20 has been described as 10 microseconds, but is not limited thereto, and may be, for example, 5 microseconds, 20 microseconds, or the like.
As described above, in the second embodiment, the light emission block selector 120 and the light receiving sensor selector 119 are separated, and the light emission block switching signal 109 is sent to the light emission block switching circuit 103 4 microseconds before the sensor scan is started. By outputting, the on / off determination unit 115 can determine a stable select sensor output signal 111 after 9 microseconds from the time when the light emission current 102 is passed through the light emitting element 104. The effect that the accuracy can be improved is obtained.

Further, since the sensor scan time 20 which is a time for controlling the sensor is not increased, the effect that the resolution is not lowered can be obtained.
FIG. 5 is a block diagram of an optical sensor circuit showing a third embodiment, and FIG. 6 is a block diagram of a light emitting element and a light receiving element switching portion of the optical sensor circuit showing the third embodiment. Note that parts similar to those of the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

In FIG. 5, reference numeral 530 denotes a base current clamp circuit whose output terminal is connected to the light emission current 102. The base current clamp circuit 530 supplies a base current 531 having a predetermined current value from an output terminal to the light emitting element 104 connected to the light emitting current 102 to light the light emitting element 104 in advance.
Note that this base current 531 shortens the time until the light emitting element 104 reaches the maximum light emission amount, and has a current value smaller than the light emission current 102 that can be determined on / off by the on / off determination unit 115. Good.

In FIG. 6, the base current 531 output from the base current clamp circuit 530 is connected to the light emission current 102 connected to each light emission block.
The operation of the above configuration will be described with reference to a time chart showing the operation of the optical sensor circuit of the third embodiment shown in FIG.
In FIG. 7, the sensor scan time 20 is the total time for reading the select sensor output signal 111 output from one light receiving element 105, and is 10 microseconds. The sensor scan time 20 is synchronized with a pulse signal generated by the basic clock 118 every 10 microseconds.

  The sensor lead timing 113 is generated 5 microseconds after the start of the sensor scan which is the center of 10 microseconds of the total sensor scan time. In response to this sensor read timing 113, the on / off determination unit 115 determines whether the object is on or off from the select sensor output signal 111 and stores it. The sensor read timing 113 is negative logic, and informs the on / off determination unit 115 of the timing for reading the select sensor output signal 111 and determining on / off at the falling edge of the signal.

  The sensor data write timing 114 occurs 8 microseconds after the start of the sensor scan. The on / off information determined by the on / off determination unit 115 triggered by the sensor data write timing 114 is extracted and stored in the storage unit 116. The sensor data write timing 114 is negative logic, and notifies the storage unit 116 of an opportunity to read the on / off data 117 at the falling edge of the signal.

Since a predetermined current is already flowing in the light emission current 102, the select sensor output signal 111 is stable after 5 microseconds from the start of the sensor scan.
Further, the basic clock 118 may be output every 8 microseconds. The operation in this case will be described with reference to a time chart showing the operation of the optical sensor circuit of the third embodiment shown in FIG.

In FIG. 8, the sensor scan time 20 is the total time for reading the select sensor output signal 111 output from one light receiving element 105, and is 8 microseconds. The sensor scan time 20 is synchronized with a pulse signal generated by the basic clock 118 every 8 microseconds.
The sensor read timing 113 is generated 2 microseconds after the start of the sensor scan, and the on / off determination unit 115 determines whether the object is on or off from the select sensor output signal 111.

In this embodiment, the sensor scan time 20 has been described as 10 microseconds, but is not limited thereto, and may be, for example, 5 microseconds, 20 microseconds, or the like.
As described above, in the third embodiment, since the light emitting element 104 is turned on in advance by supplying the base current 531 to the light emitting current 102, 2 microseconds after the start of the sensor scan. Even after microseconds, the stable select sensor output signal 111 can be determined by the on / off determination unit 115, so that the effect of improving the detection accuracy of the presence or absence of an object can be obtained.

In addition, the sensor scan time 20 which is a time for controlling one sensor is shortened, so that the resolution can be improved.
FIG. 9 is a block diagram of the light emitting element and light receiving element switching unit of the optical sensor circuit showing the fourth embodiment. Note that parts similar to those of the third embodiment described above are denoted by the same reference numerals and description thereof is omitted.

In FIG. 9, the base current 531 output from the base current clamp circuit 530 is connected to the light emission current 102 connected to a specific light emission block that requires more time than a predetermined time until sufficient light emission is performed.
In this embodiment, the sensor blocks (1), (9), (17), (25), (33), (41), (49), (57) and the light emission blocks (2), (10), A base current 531 is connected to the light emitting blocks of (18), (26), (34), (42), (50), and (58).

  As described above, in the fourth embodiment, by limiting the light-emitting blocks that supply the base current 531, in addition to the effects of the third embodiment, an effect that power consumption can be reduced is obtained.

Block diagram of the optical sensor circuit showing the first embodiment Time chart showing the operation of the optical sensor circuit of the first embodiment Block diagram of an optical sensor circuit showing a second embodiment. Time chart showing the operation of the optical sensor circuit showing the second embodiment Block diagram of an optical sensor circuit showing a third embodiment. Block diagram of light emitting element and light receiving element switching unit of optical sensor circuit showing third embodiment Time chart showing the operation of the optical sensor circuit of the third embodiment Time chart showing the operation of the optical sensor circuit of the third embodiment Block diagram of light emitting element and light receiving element switching unit of optical sensor circuit showing fourth embodiment Block diagram of a conventional optical sensor circuit Block diagram of light emitting element and light receiving element switching unit of conventional optical sensor circuit Time chart showing the operation of a conventional optical sensor circuit

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical sensor circuit 101 Light emission current switching circuit 102 Light emission current 103 Light emission block switching circuit 104 Light emitting element 105 Light receiving element 106 Light receiving sensor switching circuit 107 Sensor control circuit 108 Sensor select signal 109 Light emitting block switching signal 110 Sensor output signal 111 Select sensor output signal 112 timing generation unit 113 sensor data read timing 114 sensor data write timing 115 on / off determination unit 116 storage unit 117 on / off data 118 basic clock 119 light reception sensor selection unit 120 light emission block selection unit 121 light emission block switching signal / light reception sensor selection Signal 130 Light emission block / light emission sensor selection unit 321 Light emission current switching timing 530 Base current clamp circuit 531 Base current

Claims (5)

The light emission current switching circuit supplies the light emission current to the light emitting element selected by the light emission block switching circuit, the light receiving element that receives the light emitted from the light emitting element is selected by the light receiving sensor switching circuit, and the current output by the selected light receiving element In an optical sensor circuit that detects the presence or absence of an object by detecting the on / off determination unit,
A light emission block selector for outputting a light emission block switching signal for selecting a light emitting element in synchronization with the light emission current switching timing generated by the timing generator;
An optical sensor circuit comprising: a light receiving sensor selection unit that outputs a sensor select signal for selecting a light receiving element in synchronization with a basic clock generated by a timing generation unit to a light receiving sensor switching circuit. The optical sensor circuit of claim 1,
An optical sensor circuit characterized in that the light emission current switching timing is synchronized with a sensor data write timing in which a current output from a light receiving element is determined by an on / off determination unit and the determination result is read. The optical sensor circuit of claim 1,
An optical sensor circuit, wherein the light emission current switching timing is output after a lapse of a certain time from the output of a sensor lead timing at which a current output from a light receiving element is detected by an on / off determination unit. The light emission current switching circuit supplies the light emission current to the light emitting element selected by the light emission block switching circuit, the light receiving element that receives the light emitted from the light emitting element is selected by the light receiving sensor switching circuit, and the current output by the selected light receiving element In an optical sensor circuit that detects the presence or absence of an object by detecting the on / off determination unit,
An optical sensor circuit comprising a base current clamp circuit for supplying a base current to the light emission current. The optical sensor circuit of claim 1, claim 2 or claim 3,
An optical sensor circuit comprising a base current clamp circuit for supplying a base current to the light emission current.

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