JP5058105B2 - Optical signal transceiver - Google Patents

Description

  The present invention relates to an optical signal transmitter / receiver suitable for use in detecting an object or judging approach based on the presence / absence or intensity of light.

  2. Description of the Related Art Conventionally, an optical signal transmitter / receiver whose main part is shown in FIG. 25 is used as an apparatus for determining whether an object is detected or approached based on the presence or absence of light or intensity (see, for example, Patent Document 1). In the figure, 1 is a light emitting element (transmitter), 2 is a light receiving element (receiver), 3 is an input circuit (current / voltage converter), 4 is a low frequency component detection circuit, and 5 is a variable current source.

  In this optical signal transceiver, the light emitting element 1 periodically emits pulsed light. The light receiving element 2 receives the pulsed light from the light emitting element 1 and converts the received pulsed light into a current to generate a photocurrent. The input circuit 3 converts the photocurrent converted by the light receiving element 2 into a voltage and outputs the voltage. The low frequency component detection circuit 4 receives the output of the input circuit 3 and detects a low frequency component included in the photocurrent. The variable current source 5 changes the value of the canceling current to the light receiving element 2 according to the level of the low frequency component detected by the low frequency component detection circuit 4.

In this optical signal transmitter / receiver, when light from sunlight or an incandescent lamp is input to the light receiving element 2, this light is added to the pulsed light (transmission signal A) from the light emitting element 1 as DC disturbance light. Thus, the light receiving element 2, as shown in FIG. 26 (a), generates a photocurrent I _PD corresponding to the incident level a combination of the transmission signal A and DC disturbance light. The input circuit 3 converts the photocurrent _IPD generated by the light receiving element 2 into a voltage, and outputs a voltage Vo having a waveform as shown in FIG.

The low frequency component detection circuit 4 receives the voltage Vo output from the input circuit 3, and detects the low frequency component included in the photocurrent _IPD by averaging the voltage Vo. Variable current source 5, according to the level of the low frequency component detected by the low-frequency component detector 4, changing the value of offset current I _DC to the light receiving element 2.

As a result, the current I _DC corresponding to the level of the low frequency component detected by the low frequency component detection circuit 4 is subtracted from the photocurrent _IPD generated by the light receiving element 2, and the influence of the DC disturbance light acting on the light receiving element 2 is obtained. Can be removed.

US Pat. No. 6,644,489B1

However, in the conventional optical signal transmitter / receiver described above, the low-frequency component detection circuit 4 averages up to the component of the transmission signal A included in the voltage Vo output from the input circuit 3. offset current I _DC it will contain an error component due to the transmission signal a (see FIG. 26 (c)), there is a possibility that malfunction occurs.

  In addition, in the conventional optical signal transmitter / receiver described above, when another optical signal transmitter / receiver is connected in the vicinity, a malfunction may occur due to receiving pulsed light from a light emitting element in the other optical signal transmitter / receiver. Becomes higher.

FIG. 27 shows a state where pulse light (transmission signal B) from a light emitting element (not shown) in another optical signal transmitter / receiver acts on the light receiving element 2 as AC disturbance light. In this case, the light receiving element 2, as shown in FIG. 28 (a), generates a photocurrent I _PD corresponding to the incident level a combination of the transmission and DC ambient light signal A and AC disturbance light B. The input circuit 3 converts the photocurrent _IPD generated by the light receiving element 2 into a voltage, and outputs a voltage Vo having a waveform as shown in FIG.

The low frequency component detection circuit 4 receives the voltage Vo output from the input circuit 3, and detects the low frequency component included in the photocurrent _IPD by averaging the voltage Vo. Here, the voltage Vo output from the input circuit 3 includes a component of the transmission signal A (voltage component V _OA ) and a component of AC disturbance light B (voltage component V _OB ). Therefore, not only the component of the transmission signal A cancellation current I _DC to the light receiving element 2, will also include an error component due to the AC disturbance light B (see FIG. 28 (c)), a possibility that malfunction occurs becomes high .

  The present invention has been made to solve such a problem, and an object of the present invention is to provide an optical signal transmitter / receiver capable of detecting an object and judging an approach without malfunctioning. There is to do.

In order to achieve such an object, the present invention (the invention according to claim 1) includes a light emitting element that periodically emits pulsed light, and a light receiving device that converts the pulsed light from the light emitting element into a current to generate a photocurrent. An input circuit that converts the photocurrent converted by the light receiving element into a voltage; a low-frequency component detection circuit that detects a low-frequency component contained in the photocurrent using the output of the input circuit; and In an optical signal transmitter / receiver equipped with a variable current source that passes the current corresponding to the low frequency component detected by the component detection circuit as a canceling current to the light receiving element, the input to the low frequency component detection circuit is cut off for a predetermined period Thus, an error component reducing means for reducing an error component included in the low frequency component detected by the low frequency component detection circuit is provided.
According to the present invention, the error component included in the low frequency component detected by the low frequency component detection circuit is reduced, and the current error included in the canceling current to the light receiving element is reduced.

For example, in the present invention, the input to the low frequency component detection circuit is cut off at least while the light receiving element receives the pulsed light from the light emitting element.
In this way, the transmission signal component while the light receiving element is receiving the pulsed light from the light emitting element is removed from the input to the low frequency component detection circuit, and the low frequency component detected by the low frequency component detection circuit is removed. The error component included is reduced, and the current error included in the canceling current to the light receiving element is reduced.

According to the present invention, the output of the input circuit is reset for a predetermined period after the light receiving element receives the pulsed light from the light emitting element.
In this way, the transmission signal component after the light receiving element receives the pulsed light from the light emitting element is removed from the input to the low frequency component detection circuit and is included in the low frequency component detected by the low frequency component detection circuit. The error component is reduced, and the current error included in the canceling current to the light receiving element is reduced.

  Further, in the present invention, at least while the light receiving element receives the pulsed light from the light emitting element, the input to the low frequency component detection circuit is cut off, and the predetermined light after the light receiving element receives the pulsed light from the light emitting element. The output of the input circuit is reset during the period (claim 4).

  For example, as a first example, a first switch is provided between the input line and the output line of the input circuit, and a second switch is provided between the output line of the input circuit and the input line of the low frequency component detection circuit. The second switch is turned off at least while the light receiving element receives the pulsed light from the light emitting element, and the first switch is turned on for a predetermined period after the light receiving element receives the pulsed light from the light emitting element. (Claim 5).

  For example, as a second example, a first switch is provided between the output line of the input circuit and the ground line, and a second switch is provided between the output line of the input circuit and the input line of the low frequency component detection circuit. The second switch is turned off at least while the light receiving element receives the pulsed light from the light emitting element, and the first switch is turned on for a predetermined period after the light receiving element receives the pulsed light from the light emitting element. (Claim 6).

  In this way, after the light receiving element receives the pulsed light from the light emitting element, the transmission signal component is removed from the input to the low frequency component detection circuit, and the light receiving element receives the pulsed light from the light emitting element. Transmission signal component is removed from the input to the low frequency component detection circuit, the error component included in the low frequency component detected by the low frequency component detection circuit is reduced, and the current error included in the canceling current to the light receiving element is reduced. Get smaller.

In the present invention, at least while the light receiving element receives the pulsed light from the light emitting element and receives the pulsed light from a different light source, the input to the low frequency component detection circuit is cut off. (Claim 7).
In this way, the transmission signal component while the light receiving element is receiving the pulsed light from the light emitting element and the AC disturbance light component while receiving the pulsed light from a different light source are sent to the low frequency component detection circuit. The error component included in the low frequency component detected by the low frequency component detection circuit is reduced, and the current error included in the canceling current to the light receiving element is reduced.

According to the present invention, the output of the input circuit is reset at least during a predetermined period after the light receiving element receives the pulsed light from the light emitting element and during the period of receiving the pulsed light from a different light emitting source. Item 8).
In this way, the transmission signal component after the light receiving element receives the pulsed light from the light emitting element and all components of the AC disturbance light when the pulsed light from the different light source is received are input to the low frequency component detection circuit. The error component included in the low-frequency component detected by the low-frequency component detection circuit is reduced, and the current error included in the canceling current to the light receiving element is reduced.
In this case, since all components of the AC disturbance light when the light receiving element receives pulsed light from different light sources are not generated in the output of the input circuit, the component of the AC disturbance light does not overlap the component of the transmission signal. The error component due to AC disturbance light is also removed from the output of the input circuit.

  Further, in the present invention, at least while the light receiving element receives the pulsed light from the light emitting element and while receiving the pulsed light from a different light emitting source, the input to the low frequency component detection circuit is cut off, and at least The output of the input circuit is reset for a predetermined period after the light receiving element receives the pulsed light from the light emitting element and while receiving the pulsed light from a different light emitting source.

  For example, as a first example, a first switch is provided between the input line and the output line of the input circuit, and a second switch is provided between the output line of the input circuit and the input line of the low frequency component detection circuit. The second switch is turned off at least while the light receiving element receives the pulsed light from the light emitting element and while receiving the pulsed light from a different light emitting source, and at least the light receiving element receives a pulse from the light emitting element. The first switch is turned on for a predetermined period after receiving light and while receiving pulsed light from a different light source.

  For example, as a second example, a first switch is provided between the output line of the input circuit and the ground line, and a second switch is provided between the output line of the input circuit and the input line of the low frequency component detection circuit. The second switch is turned off at least while the light receiving element receives the pulsed light from the light emitting element and while receiving the pulsed light from a different light emitting source, and at least the light receiving element receives a pulse from the light emitting element. The first switch is turned on for a predetermined period after receiving light and while receiving pulsed light from a different light source.

In this way, all components of the transmission signal when the light receiving element receives pulsed light from the light emitting element and all components of AC disturbance light when the light receiving element receives pulsed light from a different light source are low frequency components. The error component included in the low-frequency component that is removed from the input to the detection circuit and detected in the low-frequency component detection circuit is reduced, and the current error included in the canceling current to the light receiving element is reduced.
In this case, an AC disturbance light component due to pulsed light from a different light source does not occur in the output of the input circuit, so that the AC disturbance light component does not overlap the transmission signal component, and the AC disturbance light is also output from the input circuit output. The error component due to is removed.

Further, in the present invention, a light emitting element that periodically emits pulsed light, a light receiving element that converts the pulsed light from the light emitting element into a current to generate a photocurrent, and a photocurrent converted by the light receiving element as a voltage. An input circuit for conversion, a signal extracted from the flow path of the current flowing through the light receiving element, and a low frequency component detection circuit for detecting a low frequency component included in the photocurrent, and the low frequency component detection circuit Low-frequency component detection circuit in an optical signal transmitter / receiver having a variable current source that flows a current corresponding to a low-frequency component as a canceling current to the light-receiving element, at least while the light-receiving element receives pulsed light from the light-emitting element By cutting off the input to the low frequency component, the error component contained in the low frequency component detected by the low frequency component detection circuit is reduced (claim 10).
In this way, the transmission signal component while the light receiving element is receiving the pulsed light from the light emitting element is removed from the input to the low frequency component detection circuit, and the low frequency component detected by the low frequency component detection circuit is removed. The error component included is reduced, and the current error included in the canceling current to the light receiving element is reduced.

  According to the present invention, while the light receiving element receives the pulsed light from the light emitting element, the input to the low frequency component detection circuit is blocked, or after the light receiving element receives the pulsed light from the light emitting element. For example, reset the output of the input circuit for a predetermined period of time to reduce the error component included in the low-frequency component detected by the low-frequency component detection circuit. Etc. can be performed.

Hereinafter, the present invention will be described in detail with reference to the drawings.
[Embodiment 1A]
FIG. 1 is a block diagram showing a main part of an embodiment (Embodiment 1A) of an optical signal transceiver according to the present invention. 25, the same reference numerals as those in FIG. 25 denote the same or equivalent components as those described with reference to FIG. 25, and description thereof will be omitted.

  In this embodiment 1A, a switch SW is provided between the output line of the input circuit 3 and the input line of the low frequency component detection circuit 4, and on / off of the switch SW is controlled by the switch control circuit 6A. Yes.

  In this example, the switch control circuit 6A has a function of turning off the switch SW while the light receiving element 2 receives the pulsed light from the light emitting element 1. This switch control circuit 6A corresponds to the error component reducing means in the present invention.

In this optical signal transceiver, when light from sunlight or an incandescent lamp is input to the light receiving element 2, this light is added to the transmission signal A from the light emitting element 1 as DC disturbance light. Thus, the light receiving element 2, as shown in FIG. 2 (a), generates a photocurrent I _PD corresponding to the incident level a combination of the transmission signal A and DC disturbance light. The input circuit 3 converts the photocurrent _IPD generated by the light receiving element 2 into a voltage, and outputs a voltage Vo having a waveform as shown in FIG.

  The switch control circuit 6A turns off the switch SW while the light receiving element 2 receives the pulsed light from the light emitting element 1 (FIG. 2B). As a result, the voltage Vo output from the input circuit 3 is input to the low frequency component detection circuit 4 except during the period in which the light receiving element 2 receives the pulsed light from the light emitting element 1.

Figure 2 (d) shows the waveform of the voltage Vo is input to the low-frequency component detecting circuit 4 through the switch SW as the voltage V _F. Low frequency component detection circuit 4, by averaging the voltage V _F to be input, to detect the low-frequency components contained in the photocurrent I _PD.

Variable current source 5, according to the level of the low frequency component detected by the low-frequency component detector 4, changing the value of offset current I _DC to the light receiving element 2. Thus, a current I _DC corresponding to the level of the low-frequency component detected from the optical current I _PD light-receiving element 2 is produced by the low-frequency component detecting circuit 4 is subtracted.

In embodiments 1A of this embodiment, the voltage V _F which is input to the low-frequency component detecting circuit 4, the components of the transmission signal A between the light receiving element 2 is received pulsed light from the light emitting element 1 is removed Yes. Accordingly, the error component contained in the low-frequency component detected by the low-frequency component detecting circuit 4 is reduced, a current error contained in the offset current I _DC to the light receiving element 2 is decreased (Fig. 2 (e)).

  In this embodiment 1A, the period during which the switch SW is turned off may include the period in which the light receiving element 2 receives the pulsed light from the light emitting element 1, and the width may be wider than this period. . In the first embodiment, the output of the low frequency component detection circuit 4 is held during a period when no input signal is input.

[Embodiment 1B]
FIG. 3 shows, as Embodiment 1B, a modification of Embodiment 1A in the case where a transmission signal B from a light emitting element in another connected optical signal transceiver acts on the light receiving element 2 as AC disturbance light.

  In this embodiment 1B, the switch control circuit 6B is used while the light receiving element 2 receives the pulsed light from the light emitting element 1 and while receiving the pulsed light from the light emitting element in another optical signal transceiver. The switch SW is turned off.

  In this optical signal transceiver, when light from sunlight or an incandescent lamp is input to the light receiving element 2, this light is added to the transmission signal A from the light emitting element 1 as DC disturbance light. Further, when the transmission signal B from the light emitting element in another optical signal transmitter / receiver is input to the light receiving element 2, this is added to the transmission signal A from the light emitting element 1 as AC disturbance light.

Thus, the light receiving element 2, as shown in FIG. 4 (a), generates a photocurrent I _PD corresponding to the incident level a combination of the transmission and DC ambient light signal A and AC disturbance light B. The input circuit 3 converts the photocurrent _IPD generated by the light receiving element 2 into a voltage, and outputs a voltage Vo having a waveform as shown in FIG.

  The switch control circuit 6B turns off the switch SW while the light receiving element 2 receives the pulsed light from the light emitting element 1 and while receiving the pulsed light from the light emitting element in another optical signal transceiver. (FIG. 4B). Thus, the voltage Vo output from the input circuit 3 receives the pulsed light from the light emitting element in the period during which the light receiving element 2 receives the pulsed light from the light emitting element 1 and other optical signal transceivers. It is input to the low frequency component detection circuit 4 except for the period.

Figure shows 4 waveforms of the voltage Vo input to the low-frequency component detecting circuit 4 through the switch SW in (d) of the voltage V _F. Low frequency component detection circuit 4, by averaging the voltage V _F to be input, to detect the low-frequency components contained in the photocurrent I _PD.

Variable current source 5, according to the level of the low frequency component detected by the low-frequency component detector 4, changing the value of offset current I _DC to the light receiving element 2. Thus, a current I _DC corresponding to the level of the low-frequency component detected from the optical current I _PD light-receiving element 2 is produced by the low-frequency component detecting circuit 4 is subtracted.

In this embodiment 1B, from the voltage V _F inputted to the low frequency component detection circuit 4, the transmission signal A and the AC disturbance light B while the light receiving element 2 receives the pulsed light from the light emitting element 1. The components of AC disturbance light B and transmission signal A during the reception of the pulse light from the light emitting element in the component and other optical signal transceivers are removed. Accordingly, the error component contained in the low-frequency component detected by the low-frequency component detecting circuit 4 is reduced, a current error contained in the offset current I _DC to the light receiving element 2 is decreased (Fig. 4 (e)).

  In the embodiment 1B, the period during which the switch SW is turned off includes the period in which the light receiving element 2 receives the pulsed light from the light emitting element 1 and the pulse from the light emitting element in the other optical signal transceiver. The period during which light is received may be included, and the width may be wider than this period. In the first embodiment, the output of the low frequency component detection circuit 4 is held during a period when no input signal is input.

[Embodiment 2A]
FIG. 5 is a block diagram showing a main part of another embodiment (Embodiment 2A) of the optical signal transceiver according to the present invention. In this embodiment 2A, a switch SW is provided between the input line and the output line of the input circuit 3, and ON / OFF of the switch SW is controlled by the switch control circuit 7A.

  In this example, the switch control circuit 7A has a function of turning on the switch SW for a predetermined period immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1 and for a predetermined period immediately after receiving the light. This switch control circuit 7A corresponds to the error component reducing means in the present invention.

In this optical signal transceiver, when light from sunlight or an incandescent lamp is input to the light receiving element 2, this light is added to the transmission signal A from the light emitting element 1 as DC disturbance light. Thus, the light receiving element 2, as shown in FIG. 6 (a), generates a photocurrent I _PD corresponding to the incident level a combination of the transmission signal A and DC disturbance light.

  The switch control circuit 7A turns on the switch SW for a predetermined period immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1 and for a predetermined period immediately after receiving the light (FIG. 6B). When the switch SW is turned on, the output of the input circuit 3 is reset. FIG. 6C shows the waveform of the voltage Vo output from the input circuit 3.

The input circuit 3 converts the photocurrent _IPD generated by the pulsed light into the voltage Vo while the light receiving element 2 receives the pulsed light from the light emitting element 1. In this case, the output of the input circuit 3 is reset immediately after the light receiving element 2 receives the pulsed light from the light emitting element 1, so that a time spread occurs in the waveform of the voltage Vo corresponding to the pulsed light from the light emitting element 1. There is nothing. The voltage Vo output from the input circuit 3 is input as a voltage V _F to a low-frequency component detector 4.

Low frequency component detection circuit 4, by averaging the voltage V _F to be input, to detect the low-frequency components contained in the photocurrent I _PD. Variable current source 5, according to the level of the low frequency component detected by the low-frequency component detector 4, changing the value of offset current I _DC to the light receiving element 2. Thus, a current I _DC corresponding to the level of the low-frequency component detected from the optical current I _PD light-receiving element 2 is produced by the low-frequency component detecting circuit 4 is subtracted.

In the embodiment 2A, the component of the transmission signal A after the light receiving element 2 receives the pulsed light from the light emitting element 1 is removed from the voltage V _F input to the low frequency component detection circuit 4. Accordingly, the error component contained in the low-frequency component detected by the low-frequency component detecting circuit 4 is reduced, a current error contained in the offset current I _DC to the light receiving element 2 is decreased (Fig. 6 (d)).

  In Embodiment 2A, the output of the input circuit 3 is reset immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1. However, as shown in the time chart of FIG. The output of the input circuit 3 may be reset only immediately after the element 2 receives the pulsed light from the light emitting element 1.

  In Embodiment 2A, the output of the input circuit 3 is reset immediately after the light receiving element 2 receives the pulsed light from the light emitting element 1, but the light receiving element 2 is not necessarily the pulsed light from the light emitting element 1. May not be immediately after receiving the light, and there may be a slight time delay.

[Embodiment 2B]
FIG. 8 shows a modified example of the embodiment 2A in the case where the transmission signal B from the light emitting element in the other optical signal transmitter / receiver connected acts as the AC disturbance light on the light receiving element 2 as the embodiment 2B.

  In this embodiment 2B, the switch control circuit 7B has a function of turning on the switch SW for a predetermined period immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1 and a predetermined period immediately after receiving the light, and the light receiving element 2 has a function of turning on the switch SW while receiving pulsed light from a light emitting element in another optical signal transceiver.

In this optical signal transceiver, when light from sunlight or an incandescent lamp is input to the light receiving element 2, this light is added to the transmission signal A from the light emitting element 1 as DC disturbance light. Further, when the transmission signal B from the light emitting element in another optical signal transmitter / receiver is input to the light receiving element 2, this is added to the transmission signal A from the light emitting element 1 as AC disturbance light. Thus, the light receiving element 2, as shown in FIG. 9 (a), generates a photocurrent I _PD corresponding to the incident level a combination of the transmission and DC ambient light signal A and AC disturbance light B.

  The switch control circuit 7B turns on the switch SW for a predetermined period immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1 and for a predetermined period immediately after receiving the light. Further, the switch SW is turned on while the light receiving element 2 receives the pulsed light from the light emitting element in the other optical signal transceiver (FIG. 9B). When the switch SW is turned on, the output of the input circuit 3 is reset. FIG. 9C shows the waveform of the voltage Vo output from the input circuit 3.

The input circuit 3 converts the photocurrent _IPD generated by the pulsed light into the voltage Vo while the light receiving element 2 receives the pulsed light from the light emitting element 1. In this case, the output of the input circuit 3 is reset immediately after the light receiving element 2 receives the pulsed light from the light emitting element 1, so that a time spread occurs in the waveform of the voltage Vo corresponding to the pulsed light from the light emitting element 1. There is nothing. Further, the output of the input circuit 3 is reset while the light receiving element 2 receives the pulsed light from the light emitting element in the other optical signal transmitter / receiver. A corresponding waveform does not occur in the voltage Vo. The voltage Vo output from the input circuit 3 is input as a voltage V _F to a low-frequency component detector 4.

Low frequency component detection circuit 4, by averaging the voltage V _F to be input, to detect the low-frequency components contained in the photocurrent I _PD. Variable current source 5, according to the level of the low frequency component detected by the low-frequency component detector 4, changing the value of offset current I _DC to the light receiving element 2. Thus, a current I _DC corresponding to the level of the low-frequency component detected from the optical current I _PD light-receiving element 2 is produced by the low-frequency component detecting circuit 4 is subtracted.

In this embodiment 2B, from the voltage V _F inputted to the low frequency component detection circuit 4, the component of the transmission signal A immediately after the light receiving element 2 receives the pulsed light from the light emitting element 1 and other optical signal transmission / reception. All components of the AC disturbance light B when the pulsed light from the light emitting element in the vessel is received are removed. Accordingly, the error component contained in the low-frequency component detected by the low-frequency component detecting circuit 4 is reduced, a current error contained in the offset current I _DC to the light receiving element 2 is decreased (Fig. 9 (d)).

  Further, in this embodiment 2B, all components of AC disturbance light when the light receiving element 2 receives the pulsed light from the light emitting element in another optical signal transceiver are not generated in the output of the input circuit 3, so this AC The disturbance light component does not overlap the component of the transmission signal A, and the error component due to the AC disturbance light is also removed from the output of the input circuit 3.

That is, for example, in Embodiment 1B, as shown in FIG. 4C, the waveform of the voltage Vo output from the input circuit 3 is the voltage component V _OA of the transmission signal A and the voltage component V of the AC disturbance light B. _The waveform is a combination of _OB and an error component due to the AC disturbance light B occurs in the waveform of the voltage Vo when the transmission signal A is received. In contrast, in Embodiment 2B, the voltage components V _OB of AC disturbance light B does not occur, and that the error component due to the AC disturbance light B on the waveform of the voltage Vo at the time of reception of the transmission signal A does not occur.

  In this embodiment 2B, the output of the input circuit 3 is reset immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1. However, as shown in the time chart of FIG. The output of the input circuit 3 may be reset only immediately after the element 2 receives the pulsed light from the light emitting element 1.

  In Embodiment 2B, the output of the input circuit 3 is reset immediately after the light receiving element 2 receives the pulsed light from the light emitting element 1. However, the light receiving element 2 is not necessarily pulsed from the light emitting element 1. May not be immediately after receiving the light, and there may be a slight time delay.

  In Embodiment 2B, when the light receiving element 2 is receiving pulsed light from the light emitting element in another optical signal transmitter / receiver, the light receiving element 2 transmits / receives another optical signal during the period in which the switch SW is turned on. A period for receiving the pulsed light from the light emitting element in the device may be included, and the width may be wider than this period.

[Embodiment 3A]
FIG. 11 is a block diagram showing a main part of another embodiment (embodiment 3A) of the optical signal transceiver according to the present invention. In this embodiment 3A, a switch SW1 is provided between the input line and the output line of the input circuit 3, and a switch SW2 is provided between the output line of the input circuit 3 and the input line of the low frequency component detection circuit 4, The on / off of the switches SW1 and SW2 is controlled by the switch control circuit 8A.

  In this example, the switch control circuit 8A has a function of turning on the switch SW1 for a predetermined period immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1 and a predetermined period immediately after receiving the light, and the light receiving element 2 emits light. It has a function of turning off the switch SW2 for a predetermined period including a period in which pulse light from the element 1 is received (in this example, a wide period including an ON period before and after the switch SW1). This switch control circuit 8A corresponds to the error component reducing means in the present invention.

In this optical signal transceiver, when light from sunlight or an incandescent lamp is input to the light receiving element 2, this light is added to the transmission signal A from the light emitting element 1 as DC disturbance light. Thus, the light receiving element 2, as shown in FIG. 12 (a), generates a photocurrent I _PD corresponding to the incident level a combination of the DC disturbance light and the transmission signal A.

  The switch control circuit 8A turns on the switch SW1 for a predetermined period immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1 and for a predetermined period immediately after receiving the light (FIG. 12B). When the switch SW1 is turned on, the output of the input circuit 3 is reset. FIG. 12C shows the waveform of the voltage Vo output from the input circuit 3.

The input circuit 3 converts the photocurrent _IPD generated by the pulsed light into the voltage Vo while the light receiving element 2 receives the pulsed light from the light emitting element 1. In this case, the output of the input circuit 3 is reset immediately after the light receiving element 2 receives the pulsed light from the light emitting element 1, so that a time spread occurs in the waveform of the voltage Vo corresponding to the pulsed light from the light emitting element 1. There is nothing.

The switch control circuit 8A turns off the switch SW2 for a predetermined period including the period in which the light receiving element 2 receives the pulsed light from the light emitting element 1 (FIG. 12C). Thereby, the voltage Vo output from the input circuit 3 is input to the low frequency component detection circuit 4 except for a predetermined period including a period in which the light receiving element 2 receives the pulsed light from the light emitting element 1. Figure 12 to the low-frequency component detector 4 (e) shows the waveform of the voltage V _F which is input via the switch SW2.

Low frequency component detection circuit 4, by averaging the voltage V _F to be input, to detect the low-frequency components contained in the photocurrent I _PD. Variable current source 5, according to the level of the low frequency component detected by the low-frequency component detector 4, changing the value of offset current I _DC to the light receiving element 2. Thus, a current I _DC corresponding to the level of the low-frequency component detected from the optical current I _PD light-receiving element 2 is produced by the low-frequency component detecting circuit 4 is subtracted.

In Embodiment 3A, all components of the transmission signal A when the light receiving element 2 receives the pulsed light from the light emitting element 1 are removed from the voltage V _F input to the low frequency component detection circuit 4. . Accordingly, the error component contained in the low-frequency component detected by the low-frequency component detecting circuit 4 is substantially zero, and the current error contained in the offset current I _DC to the light receiving element 2 is decreased (FIG. 12 (f)) .

  In Embodiment 3A, the output of the input circuit 3 is reset immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1. However, as shown in the time chart of FIG. The output of the input circuit 3 may be reset only immediately after the element 2 receives the pulsed light from the light emitting element 1.

  In Embodiment 3A, the output of the input circuit 3 is reset immediately after the light receiving element 2 receives the pulsed light from the light emitting element 1. However, the light receiving element 2 does not necessarily receive the pulsed light from the light emitting element 1. May not be immediately after receiving the light, and there may be a slight time delay.

  In Embodiment 3A, the period during which the switch SW2 is turned off may include the period during which the light receiving element 2 receives the pulsed light from the light emitting element 1, and the width thereof may be further reduced. In the embodiment 3A, the output of the low frequency component detection circuit 4 is held during a period when no input signal is input.

[Embodiment 3B]
FIG. 14 shows, as Embodiment 3B, a modification of Embodiment 3A in the case where a transmission signal B from a light emitting element in another connected optical signal transceiver acts on the light receiving element 2 as AC disturbance light.

  In this embodiment 3B, the switch control circuit 8B has a function of turning on the switch SW1 for a predetermined period immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1 and for a predetermined period immediately after receiving the light. 2 includes a function of turning on the switch SW1 while receiving pulsed light from the light emitting element in another optical signal transceiver, and a period during which the light receiving element 2 receives pulsed light from the light emitting element 1. For a predetermined period (in this example, a wide period including the on period before and after the switch SW1), the function of turning off the switch SW2, and the light receiving element 2 receives pulsed light from the light emitting element in another optical signal transceiver The switch SW2 is turned off for a predetermined period including a certain period.

In this optical signal transceiver, when light from sunlight or an incandescent lamp is input to the light receiving element 2, this light is added to the transmission signal A from the light emitting element 1 as DC disturbance light. Further, when the transmission signal B from the light emitting element in another optical signal transmitter / receiver is input to the light receiving element 2, this is added to the transmission signal A from the light emitting element 1 as AC disturbance light. Thus, the light receiving element 2, as shown in FIG. 15 (a), generates a photocurrent I _PD corresponding to the incident level a combination of the transmission and DC ambient light signal A and AC disturbance light B.

  The switch control circuit 8B turns on the switch SW1 for a predetermined period immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1 and for a predetermined period immediately after receiving the light. Further, the switch SW1 is turned on while the light receiving element 2 receives the pulsed light from the light emitting element in the other optical signal transceiver (FIG. 15B). When the switch SW1 is turned on, the output of the input circuit 3 is reset. FIG. 15D shows the waveform of the voltage Vo output from the input circuit 3.

The input circuit 3 converts the photocurrent _IPD generated by the pulsed light into the voltage Vo while the light receiving element 2 receives the pulsed light from the light emitting element 1. In this case, the output of the input circuit 3 is reset immediately after the light receiving element 2 receives the pulsed light from the light emitting element 1, so that a time spread occurs in the waveform of the voltage Vo corresponding to the pulsed light from the light emitting element 1. There is nothing. Further, the output of the input circuit 3 is reset while the light receiving element 2 receives the pulsed light from the light emitting element in the other optical signal transmitter / receiver. A corresponding waveform does not occur in the voltage Vo.

The switch control circuit 8B turns off the switch SW2 for a predetermined period including a period in which the light receiving element 2 receives the pulsed light from the light emitting element 1. Further, the switch SW2 is turned off for a predetermined period including a period in which the light receiving element 2 receives the pulsed light from the light emitting element in another optical signal transceiver (FIG. 15C). Thereby, the voltage Vo output from the input circuit 3 is a predetermined period including a period in which the light receiving element 2 receives the pulsed light from the light emitting element 1 and the light receiving element 2 from the light emitting element in another optical signal transceiver. Is input to the low frequency component detection circuit 4 except for a predetermined period including a period in which the pulse light is received. 15 to the low-frequency component detector 4 (e) through the switch SW2 shows the waveform of the voltage V _F to be input.

Low frequency component detection circuit 4, by averaging the voltage V _F to be input, to detect the low-frequency components contained in the photocurrent I _PD. Variable current source 5, according to the level of the low frequency component detected by the low-frequency component detector 4, changing the value of offset current I _DC to the light receiving element 2. Thus, a current I _DC corresponding to the level of the low-frequency component detected from the optical current I _PD light-receiving element 2 is produced by the low-frequency component detecting circuit 4 is subtracted.

In the embodiment 3B, all components of the transmission signal A when the light receiving element 2 receives the pulsed light from the light emitting element 1 are removed from the voltage V _F input to the low frequency component detection circuit 4. . Further, all components of the AC disturbance light B when the light receiving element 2 receives the pulsed light from the light emitting element in another optical signal transceiver are removed. Thus, substantially becomes zero error component contained in the low-frequency component detected by the low-frequency component detecting circuit 4, a current error contained in the offset current I _DC to the light receiving element 2 from the variable current source 5 is decreased ( FIG. 15 (f)).

  In the embodiment 3B, all components of AC disturbance light when the light receiving element 2 receives pulsed light from the light emitting element in another optical signal transceiver are not generated in the output of the input circuit 3. The disturbance light component does not overlap the component of the transmission signal A, and the error component due to the AC disturbance light is also removed from the output of the input circuit 3.

  In this embodiment 3B, the output of the input circuit 3 is reset immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1. However, as shown in the time chart of FIG. The output of the input circuit 3 may be reset only immediately after the element 2 receives the pulsed light from the light emitting element 1.

  Further, in Embodiment 3B, the light receiving element 2 resets the output of the input circuit 3 immediately after receiving the pulsed light from the light emitting element 1, but the light receiving element 2 does not necessarily receive the pulsed light from the light emitting element 1. May not be immediately after receiving the light, and there may be a slight time delay.

  In Embodiment 3B, when the light receiving element 2 is receiving pulsed light from a light emitting element in another optical signal transmitter / receiver, the light receiving element 2 transmits / receives another optical signal during the period in which the switch SW1 is turned on. A period for receiving the pulsed light from the light emitting element in the device may be included, and the width may be wider than this period.

  In the embodiment 3B, the period during which the switch SW2 is turned off is the period in which the light receiving element 2 receives the pulsed light from the light emitting element 1 and the pulse light from the light emitting element in another optical signal transceiver. The period during which light is received may be included, and the width may be further narrowed. In Embodiment 3B, the output of the low frequency component detection circuit 4 is held during a period when no input signal is input.

[Embodiment 4A]
FIG. 17 is a block diagram showing the main part of another embodiment (Embodiment 4A) of the optical signal transceiver according to the present invention. In this embodiment 4A, a switch SW1 is provided between the output line of the input circuit 3 and the ground line, and a switch SW2 is provided between the output line of the input circuit 3 and the input line of the low frequency component detection circuit 4, The on / off of the switches SW1 and SW2 is controlled by the switch control circuit 9A.

  In the embodiment 4A, the switch control circuit 9A has a function of turning on the switch SW1 for a predetermined period immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1 and a predetermined period immediately after receiving the light, and the light receiving element 2 has a function of turning off the switch SW2 for a predetermined period (in this example, a wide period including an on period before and after the switch SW1) including a period in which pulse light from the light emitting element 1 is received. This switch control circuit 9A corresponds to the error component reducing means in the present invention.

  Also in the fourth embodiment, when the switch SW1 is turned on, the output of the input circuit 3 is reset, and the same operation as the third embodiment described with reference to the time chart of FIG. 12 is performed.

[Embodiment 4B]
FIG. 18 shows, as Embodiment 4B, a modification of Embodiment 4A in the case where the transmission signal B from the light emitting element in another optical signal transmitter / receiver connected to the light receiving element 2 acts as AC disturbance light.

  In this embodiment 4B, the switch control circuit 9B turns on the switch SW1 for a predetermined period immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1 and for a predetermined period immediately after receiving the light, as in the embodiment 3B. And the function of turning on the switch SW1 while the light receiving element 2 receives the pulsed light from the light emitting element in the other optical signal transceiver, and the light receiving element 2 receives the pulsed light from the light emitting element 1. A predetermined period including a light receiving period (in this example, a wide period including an ON period before and after the switch SW1), a function of turning off the switch SW2, and the light receiving element 2 from a light emitting element in another optical signal transceiver The switch SW2 is turned off for a predetermined period including the period in which the pulse light is received.

  Also in the fourth embodiment, when the switch SW1 is turned on, the output of the input circuit 3 is reset, and the same operation as the third embodiment described with reference to the time chart of FIG. 15 is performed.

[Embodiment 5A]
FIG. 19 is a block diagram showing the main part of another embodiment (Embodiment 5A) of the optical signal transceiver according to the present invention.

  In this embodiment 5A, a signal generated at a connection point P1 between the light receiving element 2 and the variable current source 5 is used as an input to the input circuit 3, and a switch SW1 is provided on the input line from the connection point P1 to the input circuit 3. The signal generated at the connection point P2 between the light receiving element 2 and the variable current source 5 is used as an input to the low frequency component detection circuit 4, and the switch SW2 is connected to the input line from the connection point P2 to the low frequency component detection circuit 4. The switches SW1, SW2 are turned on / off by the switch control circuit 10A.

  In this example, the switch control circuit 10A has a function of turning on the switch SW1 while the light receiving element 2 receives the pulsed light from the light emitting element 1, and the light receiving element 2 receives the pulsed light from the light emitting element 1. During this time, the switch SW2 is turned off. This switch control circuit 10A corresponds to the error component reducing means in the present invention.

In this optical signal transceiver, when light from sunlight or an incandescent lamp is input to the light receiving element 2, this light is added to the transmission signal A from the light emitting element 1 as DC disturbance light. Thus, the light receiving element 2, as shown in FIG. 20 (a), generates a photocurrent I _PD corresponding to the incident level a combination of the transmission signal A and DC disturbance light.

The switch control circuit 10A turns on the switch SW1 while the light receiving element 2 receives the pulsed light from the light emitting element 1 (FIG. 20B), and the connection point P1 between the light receiving element 2 and the variable current source 5 is turned on. Is sent to the input circuit 3. Thus, the input circuit 3 inputs the photocurrent I _PD generated by the light receiving element 2, and outputs a voltage Vo of the waveform as shown in FIG. 20 (d).

The switch control circuit 10A turns off the switch SW2 while the light receiving element 2 receives the pulsed light from the light emitting element 1 (FIG. 20C), and connects the light receiving element 2 and the variable current source 5 to each other. The point P2 is separated from the low frequency component detection circuit 4. Thus, the low-frequency component of the transmission signal A in component detector 4 from the low-frequency component to be detected is removed, substantially becomes zero error component, the current error contained in the offset current I _DC to the light receiving element 2 is reduced (FIG. 20 (e)).

  Further, in the embodiment 5A, the switch SW1 is turned on only while the light receiving element 2 receives the pulsed light from the light emitting element 1, so that light components other than this period are sent to the input circuit 3. Of course, the error component is also removed from the output of the input circuit 3.

  In Embodiment 5A, the period during which the switch SW2 is turned off may include a period in which the light receiving element 2 receives the pulsed light from the light emitting element 1, and the width may be wider than this period. The period during which the switch SW1 is turned on may include a period in which the light receiving element 2 receives the pulsed light from the light emitting element 1, and the width may be wider than this period. Further, the switch SW1 is not necessarily provided. In the embodiment 5A, the output of the low frequency component detection circuit 4 is held during a period when no input signal is input.

[Embodiment 5B]
FIG. 21 shows, as Embodiment 5B, a modification of Embodiment 5A in the case where the transmission signal B from the light emitting element in another optical signal transmitter / receiver connected to the light receiving element 2 acts as AC disturbance light.

  In this embodiment 5B, the switch control circuit 10B has a function of turning on the switch SW1 while the light receiving element 2 is receiving the pulsed light from the light emitting element 1, and the light receiving element 2 is a pulse from the light emitting element 1. It has a function of turning off the switch SW2 while receiving light and while receiving pulsed light from a light emitting element in another optical signal transceiver.

In this optical signal transceiver, when light from sunlight or an incandescent lamp is input to the light receiving element 2, this light is added to the transmission signal A from the light emitting element 1 as DC disturbance light. Further, when the transmission signal B from the light emitting element in another optical signal transmitter / receiver is input to the light receiving element 2, this is added to the transmission signal A from the light emitting element 1 as AC disturbance light. Thus, the light receiving element 2, as shown in FIG. 22 (a), generates a photocurrent I _PD corresponding to the incident level a combination of the transmission and DC ambient light signal A and AC disturbance light B.

The switch control circuit 10B turns on the switch SW1 while the light receiving element 2 receives the pulsed light from the light emitting element 1 (FIG. 22B), and the connection point P1 between the light receiving element 2 and the variable current source 5 is turned on. Is sent to the input circuit 3. Thus, the input circuit 3 inputs the photocurrent I _PD generated by the light receiving element 2, and outputs a voltage Vo of the waveform as shown in FIG. 22 (d).

The switch control circuit 10B turns off the switch SW2 while the light receiving element 2 receives the pulsed light from the light emitting element 1 and while receiving the pulsed light from the light emitting element in another optical signal transceiver. (FIG. 22C), the connection point P2 between the light receiving element 2 and the variable current source 5 is disconnected from the low frequency component detection circuit 4. As a result, the transmission signal A and the component of the transmission signal B from the light emitting element in the other optical signal transmitter / receiver are removed from the low frequency component detected by the low frequency component detection circuit 4, and the error component becomes substantially zero. current error contained in the offset current I _DC to the 2 decreases (FIG. 22 (e)).

  In the embodiment 5B, the switch SW1 is turned on only while the light receiving element 2 receives the pulsed light from the light emitting element 1, so that the light receiving element 2 is connected to the light emitting element in another optical signal transceiver. The component of the AC disturbance light when receiving the pulsed light is not sent to the input circuit 3, and the error component due to the AC disturbance light is also removed from the output of the input circuit 3.

  In the embodiment 5B, the period during which the switch SW2 is turned off includes a period in which the light receiving element 2 receives the pulsed light from the light emitting element 1 and a period in which the light receiving element in the other optical signal transceiver receives the pulsed light. It may be included, and the width may be wider than this period. The period during which the switch SW1 is turned on may include a period in which the light receiving element 2 receives the pulsed light from the light emitting element 1, and the width may be wider than this period. In the embodiment 5B, the output of the low frequency component detection circuit 4 is held during a period when no input signal is input.

[Embodiment 6]
FIG. 23 is a block diagram showing a main part of another embodiment (sixth embodiment) of the optical signal transceiver according to the present invention.

  In the figure, reference numeral 100 denotes a first integration circuit, 200 denotes a second integration circuit, the first integration circuit 100 includes an input circuit 3, and the second integration circuit 200 includes a low frequency component detection circuit 4. .

The first integration circuit 100 includes an operational amplifier A1, a capacitor C _INT, and a switch S _INT . The capacitor C _INT is connected between the inverting input terminal and the output terminal of the operational amplifier A1, and a reference voltage VR is applied to the non-inverting input terminal of the operational amplifier A1. A switch S _INT is connected in parallel with the capacitor C _INT between the inverting input terminal and the output terminal of the operational amplifier A1.

The second integration circuit 200 includes an operational amplifier A2, capacitors C1 and C2, switches S1 (S1 ₁ and S1 ₂ ), and switches S2 (S2 ₁ and S2 ₂ ). The capacitor C2 is connected between the inverting input terminal and the output terminal of the operational amplifier A2, and a reference voltage VR is applied to the non-inverting input terminal of the operational amplifier A2. A capacitor C1 is connected between the inverting input terminal of the operational amplifier A2 and the output terminal of the operational amplifier A1 in the first integrating circuit 100.

In the second integration circuit 200, to a connection line between the output terminal and the capacitor C1 of the operational amplifier A1 is switched S1 ₁ is provided, on the connecting line between the inverting input and the capacitor C1 of the operational amplifier A2 switches S1 ₂ is Is provided. Further, a reference voltage VR is applied to the connection point between the capacitor C1 and the switch S1 ₁ via the switch S2 _1, and a reference voltage VR is applied to the connection point between the capacitor C1 and the switch S1 ₂ via the switch S2 _2. It is supposed to be.

In the optical signal transceiver, the variable current source 5 is constituted by a MOS transistor M _P1, the connection point of the drain and the light receiving element 2 of the MOS transistor M _P1 the inverting input terminal of the operational amplifier A1 in the first integrating circuit 100 It is connected to the. The gate of the MOS transistor M _P1 is connected to the output terminal of the operational amplifier A2 in the second integration circuit 200.

In this optical signal transmitter / receiver, the switch control circuit 11 controls on / off of the switch S _INT , the switch S1 (S1 ₁ , S1 ₂ ), and the switch S2 (S2 ₁ , S2 ₂ ). In this example, the switch control circuit 11 has a function of turning on the switch _SINT for a predetermined period immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1 and a predetermined period immediately after receiving the light, and the light receiving element 2 A function including a function of turning on the switch _SINT while receiving pulsed light from the light emitting element in another optical signal transmitter / receiver and a period during which the light receiving element 2 receives pulsed light from the light emitting element 1 period (in this example, a wide period including before and after the oN period of the switch S _INT), and includes a function of turning off the switch S1, the function of the switch S2 for a predetermined period on the off period of the switch S1. This switch control circuit 11 corresponds to the error component reducing means in the present invention.

In this optical signal transceiver, when light from sunlight or an incandescent lamp is input to the light receiving element 2, this light is added to the transmission signal A from the light emitting element 1 as DC disturbance light. Further, when the transmission signal B from the light emitting element in another optical signal transmitter / receiver is input to the light receiving element 2, this is added to the transmission signal A from the light emitting element 1 as AC disturbance light. Thus, the light receiving element 2, as shown in FIG. 24 (a), generates a photocurrent I _PD corresponding to the incident level a combination of the transmission and DC ambient light signal A and AC disturbance light B.

The switch control circuit 11 turns on the switch _SINT for a predetermined period immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1 and for a predetermined period immediately after receiving the light. Further, the switch _SINT is turned on while the light receiving element 2 receives the pulsed light from the light emitting element in the other optical signal transceiver (FIG. 24B). When the switch _SINT is turned on, the output of the operational amplifier A1 (output of the input circuit 3) is reset. FIG. _24E shows a waveform of the voltage V _INT output from the operational amplifier A1.

The operational amplifier A1 converts the photocurrent _IPD generated by the light receiving element 2 while receiving the pulsed light from the light emitting element 1 into the voltage V _INT . In this case, since the output of the operational amplifier A1 is reset immediately after the light receiving element 2 receives the pulsed light from the light emitting element 1, a time spread occurs in the waveform of the voltage V _INT corresponding to the pulsed light from the light emitting element 1. There is nothing. Further, the output of the operational amplifier A1 is reset while the light receiving element 2 receives the pulsed light from the light emitting element in the other optical signal transceiver, so that it responds to the pulsed light from the light emitting element in the other optical signal transceiver. The waveform does not occur at the voltage V _INT .

The switch control circuit 11 turns off the switches S1 (S1 ₁ , S1 ₂ ) for a predetermined period including a period in which the light receiving element 2 receives the pulsed light from the light emitting element 1. Further, the switch S1 (S1 ₁ , S1 ₂ ) is turned off for a predetermined period including a period in which the light receiving element 2 receives the pulsed light from the light emitting element in another optical signal transceiver (FIG. 24C). . Further, the switch S2 (S2 ₁ , S2 ₂ ) is turned on for a predetermined period during the off period of the switch S1 (S1 ₁ , S1 ₂ ) (FIG. 24 (d)).

As a result, the voltage V _INT output from the operational amplifier A1 is a predetermined period including the period in which the light receiving element 2 receives the pulsed light from the light emitting element 1 and the light receiving element 2 from the light emitting element in another optical signal transceiver. Are input to the operational amplifier A2 except for a predetermined period including a period during which the pulse light is received. FIG. 24F shows the waveform of the voltage V _F input to the operational amplifier A2 via the switch S1 (S1 ₁ , S1 ₂ ).

Operational amplifier A2, by integrating the voltage V _F to be input, to detect the low-frequency components contained in the photocurrent I _PD. The output of the operational amplifier A2 is given to the gate of the MOS transistor _MP1 . MOS transistor M _P1, in response to the output level of the operational amplifier A2, the drain - to adjust the magnitude of the current flowing between the source, changing the value of offset current I _DC to the light receiving element 2. Thus, a current I _DC corresponding to the level of the low-frequency component detected from the optical current I _PD light-receiving element 2 is produced by the low-frequency component detecting circuit 4 is subtracted.

In the sixth embodiment, all components of the transmission signal A when the light receiving element 2 receives the pulsed light from the light emitting element 1 are removed from the voltage V _F input to the operational amplifier A2. Further, all components of the AC disturbance light B when the light receiving element 2 receives the pulsed light from the light emitting element in another optical signal transceiver are removed. Thus, the error component contained in the low-frequency component detected by the operational amplifier A2 is substantially zero, and the current error contained in the offset current I _DC to the light receiving element 2 from the MOS transistors M _P1 decreases (FIG. 24 (g )).

  In the sixth embodiment, since all components of the AC disturbance light are not generated in the output of the operational amplifier A1 when the light receiving element 2 receives the pulsed light from the light emitting element in another optical signal transmitter / receiver, this AC disturbance is not generated. The light component does not overlap the component of the transmission signal A, and the error component due to the AC disturbance light is removed from the output of the operational amplifier A1.

  In the sixth embodiment, the output of the operational amplifier A1 is reset immediately before the light receiving element 2 receives the pulsed light from the light emitting element 1, but the light receiving element 2 receives the pulsed light from the light emitting element 1. The output of the operational amplifier A1 may be reset only immediately after.

  In Embodiment 6, the output of the operational amplifier A1 is reset immediately after the light receiving element 2 receives the pulsed light from the light emitting element 1. However, the light receiving element 2 does not necessarily receive the pulsed light from the light emitting element 1. It may not be immediately after receiving light, and there may be some time delay.

Further, in the sixth embodiment, when the light receiving element 2 receives the pulsed light from the light emitting element in another optical signal transmitter / receiver, the light receiving element 2 receives another optical signal during the period when the switch _SINT is turned on. A period for receiving pulsed light from the light emitting element in the transceiver may be included, and the width may be wider than this period.

In the sixth embodiment, the period during which the switch S1 (S1 ₁ , S1 ₂ ) is turned off is the period during which the light receiving element 2 receives the pulsed light from the light emitting element 1 and other optical signal transceivers. The period during which the pulsed light from the light emitting element is received may be included, and the width thereof may be further narrowed.

  Further, in Embodiments 1B, 2B, 3B, 4B, 5B and Embodiment 6 described above, the number of other optical signal transmitters / receivers connected is one, but a plurality of other optical signal transmitters / receivers are connected in series. In the same manner, the error component included in the low frequency component detected by the low frequency component detection circuit 4 is reduced, or the error component due to AC disturbance light included in the output from the input circuit 3 is removed. It is possible to

It is a block diagram which shows the principal part of one Embodiment (Embodiment 1A) of the optical signal transmitter / receiver which concerns on this invention. 5 is a time chart for explaining the operation of the optical signal transceiver according to Embodiment 1A. It is a figure which shows the modification (Embodiment 1B) of Embodiment 1A in case the transmission signal B from the light emitting element in the other optical signal transmitter / receiver connected acts on the light receiving element as AC disturbance light. 6 is a time chart for explaining the operation of the optical signal transceiver according to Embodiment 1B. It is a block diagram which shows the principal part of other embodiment (Embodiment 2A) of the optical signal transmitter-receiver which concerns on this invention. 6 is a time chart for explaining the operation of the optical signal transceiver according to Embodiment 2A. 4 is a time chart in a case where the output of the input circuit is reset only immediately after the light receiving element receives the pulsed light from the light emitting element in the optical signal transmitter and receiver of Embodiment 2A. It is a figure which shows the modification (Embodiment 2B) of Embodiment 2A in case the transmission signal B from the light emitting element in the other optical signal transmitter / receiver connected acts on a light receiving element as AC disturbance light. 6 is a time chart for explaining the operation of the optical signal transceiver according to Embodiment 2B. 4 is a time chart when the output of the input circuit is reset only immediately after the light receiving element receives pulsed light from the light emitting element in the optical signal transceiver according to Embodiment 2B. It is a block diagram which shows the principal part of other embodiment (Embodiment 3A) of the optical signal transmitter-receiver which concerns on this invention. 4 is a time chart for explaining the operation of the optical signal transceiver according to Embodiment 3A. 6 is a time chart when the output of the input circuit is reset only immediately after the light receiving element receives the pulsed light from the light emitting element in the optical signal transmitter and receiver of Embodiment 3A. It is a figure which shows the modification (Embodiment 3B) of Embodiment 3A in case the transmission signal B from the light emitting element in the other optical signal transmitter / receiver connected acts on the light receiving element as AC disturbance light. 6 is a time chart for explaining the operation of the optical signal transceiver according to Embodiment 3B. 6 is a time chart when the output of the input circuit is reset only immediately after the light receiving element receives pulsed light from the light emitting element in the optical signal transceiver of Embodiment 3B. It is a block diagram which shows the principal part of other embodiment (Embodiment 4A) of the optical signal transmitter-receiver which concerns on this invention. It is a figure which shows the modification (Embodiment 4B) of Embodiment 4A in case the transmission signal B from the light emitting element in the other optical signal transmitter / receiver connected acts on a light receiving element as AC disturbance light. It is a block diagram which shows the principal part of other embodiment (Embodiment 5A) of the optical signal transmitter-receiver which concerns on this invention. It is a time chart for demonstrating operation | movement of the optical signal transmitter-receiver of Embodiment 5A. It is a figure which shows the modification (Embodiment 5B) of Embodiment 5A in case the transmission signal B from the light emitting element in the other optical signal transmitter / receiver connected acts on a light receiving element as AC disturbance light. 6 is a time chart for explaining the operation of the optical signal transceiver according to Embodiment 5B. It is a block diagram which shows the principal part of other embodiment (Embodiment 6) of the optical signal transmitter-receiver which concerns on this invention. 10 is a time chart for explaining the operation of the optical signal transceiver according to the sixth embodiment. It is a block diagram which shows the principal part of the conventional optical signal transmitter / receiver. It is a time chart for demonstrating operation | movement of the conventional optical signal transmitter / receiver. It is a figure which shows the state in which the pulse light from the light emitting element in another optical signal transmitter / receiver is acting as AC disturbance light on the light receiving element in the conventional optical signal transmitter / receiver. It is a time chart for demonstrating the error component which arises when AC disturbance light is acting on the light receiving element in the conventional optical signal transceiver.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light emitting element, 2 ... Light receiving element, 3 ... Input circuit, 4 ... Low frequency component detection circuit, 5 ... Variable current source, 6A, 6B, 7A, 7B, 8A, 8B, 9A, 9B, 10A, 10B ... Switch Control circuit, SW, SW1, SW2 ... switch, 100 ... first integration circuit, 200 ... second integration circuit, A1, A2 ... operational amplifier, _CINT , C1, C2 ... capacitor, _SINT , S1 (S1 ₁ , S1 ₂ ), S2 (S2 ₁ , S2 ₂ )... Switch, M _P1 ... MOS transistor, 11.

Claims (10)

A light emitting element that periodically emits pulsed light, a light receiving element that converts the pulsed light from the light emitting element into a current to be a photocurrent, an input circuit that converts the photocurrent converted by the light receiving element into a voltage, A low-frequency component detection circuit for detecting a low-frequency component included in the photocurrent using an output of the input circuit as an input, and a current corresponding to the low-frequency component detected by the low-frequency component detection circuit as a canceling current In an optical signal transmitter / receiver provided with a variable current source flowing in the element,
Error component reducing means is provided for reducing an error component included in the low frequency component detected by the low frequency component detection circuit by cutting off the input to the low frequency component detection circuit during a predetermined period. An optical signal transceiver. The optical signal transceiver according to claim 1.
The error component reducing means is
The optical signal transmitter / receiver characterized in that the input to the low frequency component detection circuit is cut off at least while the light receiving element receives the pulsed light from the light emitting element. The optical signal transceiver according to claim 1.
The error component reducing means is
An optical signal transmitter / receiver, wherein the output of the input circuit is reset for a predetermined period after the light receiving element receives pulsed light from the light emitting element. The optical signal transceiver according to claim 1.
The error component reducing means is
At least while the light receiving element receives the pulsed light from the light emitting element, the input to the low frequency component detection circuit is cut off, and a predetermined period after the light receiving element receives the pulsed light from the light emitting element An optical signal transceiver characterized by resetting the output of the input circuit. The optical signal transceiver according to claim 4,
A first switch is provided between an input line and an output line of the input circuit;
A second switch is provided between the output line of the input circuit and the input line of the low-frequency component detection circuit;
The error component reducing means is
The second switch is turned off at least while the light receiving element receives the pulsed light from the light emitting element, and the first light is received for a predetermined period after the light receiving element receives the pulsed light from the light emitting element. An optical signal transceiver characterized by turning on the switch. The optical signal transceiver according to claim 4,
A first switch is provided between an output line of the input circuit and a ground line;
A second switch is provided between the output line of the input circuit and the input line of the low-frequency component detection circuit;
The error component reducing means is
The second switch is turned off at least while the light receiving element receives the pulsed light from the light emitting element, and the first light is received for a predetermined period after the light receiving element receives the pulsed light from the light emitting element. An optical signal transceiver characterized by turning on the switch. The optical signal transceiver according to claim 1.
The error component reducing means is
The input to the low frequency component detection circuit is cut off at least while the light receiving element is receiving pulsed light from the light emitting element and while receiving pulsed light from a light source different from the light emitting element. An optical signal transmitter / receiver. The optical signal transceiver according to claim 1.
The error component reducing means is
The output of the input circuit is reset at least during a predetermined period after the light receiving element receives pulsed light from the light emitting element and during reception of pulsed light from a light source different from the light emitting element. An optical signal transceiver. The optical signal transceiver according to claim 1.
The error component reducing means is
At least while the light receiving element is receiving pulsed light from the light emitting element and while receiving pulsed light from a light source different from the light emitting element, the input to the low frequency component detection circuit is cut off. Resetting the output of the input circuit at least during a predetermined period after the light receiving element receives the pulsed light from the light emitting element and while receiving the pulsed light from a light emitting source different from the light emitting element. An optical signal transmitter / receiver. A light emitting element that periodically emits pulsed light, a light receiving element that converts the pulsed light from the light emitting element into a current to be a photocurrent, an input circuit that converts the photocurrent converted by the light receiving element into a voltage, A low frequency component detection circuit that detects a low frequency component included in the photocurrent and a low frequency component detected by the low frequency component detection circuit using a signal extracted from a flow path of a current flowing through the light receiving element as an input. In an optical signal transmitter / receiver provided with a variable current source that flows a current corresponding to the light receiving element as a canceling current,
It is included in the low frequency component detected by the low frequency component detection circuit by cutting off the input to the low frequency component detection circuit at least while the light receiving element receives the pulsed light from the light emitting element. An optical signal transmitter / receiver comprising error component reducing means for reducing an error component.

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