JP2002098568A - Gas meter and optical radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas meter enabling identification of errors in display means. SOLUTION: This system is provided with a measuring mechanism 34 measuring flow rate or flow velocity of gas, an integrating flow rate counter 20 showing gas utility rate value calculated from the value of flow rate or flow velocity, a microcomputer 317 determining whether the reasons for cut-off/warning with decision standard preset has generated or not, a shutoff valve 33 blocking gas supply if any cut-off reason occurs, and LCD315 displaying data on a reason generated when the reason for either cut-off or warning occurs or displaying normal state data showing normal state when no reason for cut-off nor warning occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas meter for monitoring a gas use state and shutting off gas supply when an abnormality is detected, and an optical wireless communication device for transmitting and / or receiving information to and from the gas meter. About.

[0002]

2. Description of the Related Art At present, gas meters already in practical use have a built-in meter control device having a microcomputer. This gas meter calculates the amount of gas used by the customer and constantly monitors the gas flow rate, saying that a large amount of gas different from the normal use state flows out or that the gas flows out continuously for a long time. It monitors abnormalities in gas pipes, such as abnormal use of gas and minute flow rates that continue to flow for a long time.

[0003] In addition, a built-in seismic sensor for detecting an earthquake and a pressure switch for detecting a decrease in gas pressure are provided, and a microcomputer judges the occurrence of an earthquake or a decrease in gas pressure. Shut off or warn. The interruption is
The gas control device controls the gas shut-off device incorporated in the gas meter.

[0004] When the interruption or alarm is generated, the reason for interruption is displayed on a display device incorporated in the meter control device to notify the reason for the interruption or alarm to the outside. When the shutoff occurs, the customer normally releases the shutoff by the return device by himself and the gas can be used. However, if shutoffs occur frequently, the gas company is contacted, and gas company workers go to the site and take appropriate measures in accordance with the grounds for the shutoff, so that consumers can safely refuel. Can be used.

[0005] In addition, when an alarm is generated, a meter reader checks the alarm display at the time of monthly meter reading, and when an alarm is issued, contacts a sales office and takes appropriate measures.

[0006]

However, as described above, when the interruption or alarm is generated, the reason for the interruption is displayed on the liquid crystal display (LCD) of the gas meter. The interruption reason will not be displayed. For this reason, it is impossible to distinguish between a case where this interruption reason is not displayed and a case where the LCD of the gas meter is turned off due to a failure or the like. as a result,
There is a possibility that a problem of not being aware of an abnormality due to a failure of the LCD or the like may occur.

[0007] If a segment of the LCD of the gas meter fails and the segment is turned off, the display is different from the original display. Therefore, the operator cannot take corrective measures.

Further, when the LCD driver fails, L
If the CD does not light up at all, the alarm is not displayed even if an alarm is generated, so that a problem arises that the meter reader does not notice the alarm.

It is an object of the present invention to provide a gas meter capable of determining a failure of a display means. Another object of the present invention is to provide an optical wireless communication device capable of confirming the display content of the display unit even when the display unit of the gas meter breaks down.

[0010]

The gas meter according to the present invention comprises:
Measuring means for measuring the flow rate or flow rate of gas, gas usage display means for displaying the value of gas usage calculated from the value of the flow rate or flow rate, and interruption / warning reasons for which predetermined criteria are set Determining means for determining whether or not the occurrence has occurred;
A shutoff means for shutting off the gas supply when the shutoff event occurs, and information of the event that occurred when the shutoff event or alarm event occurred, and when the shutoff event or alarm event did not occur. Display means for displaying normal state information indicating a normal state.

According to the gas meter of the present invention, the display means displays the information of the event that occurred when the interruption event or the alarm event occurred, so that the occurrence of the interruption or the alarm can be recognized. Since normal state information indicating a normal state is displayed when no error occurs, the failure of the display means can be determined based on the presence or absence of the normal state information.

The gas meter has a measuring means for measuring a gas flow rate or a gas flow rate, a gas use quantity display means for displaying a gas use quantity value calculated from the flow rate or the flow rate value, and a criterion set in advance. Transmitting and / or transmitting information to and from an external optical wireless communication device, an interrupting means for detecting the occurrence of the shutoff / alarm event, and shutting off the gas supply, a display means comprising a plurality of segments; Optical wireless communication means for receiving, the display means, when the optical wireless communication means receives an optical signal of a display command transmitted from the optical wireless communication device, lights all the segments of the plurality of segments It is characterized by making it.

According to the gas meter of the present invention, when the optical wireless communication means receives the optical signal of the display command transmitted from the optical wireless communication device, the display means turns on all the segments. Failure of the means can be determined.

The optical wireless communication device is an optical wireless communication device that transmits and / or receives information to and from a gas meter that calculates a gas usage value based on a measured value of a gas flow rate or a gas flow rate. Transmitting means for transmitting an optical signal of a read command for reading the display content of the display means provided in the gas meter to the gas meter when the power is turned on, and when the gas meter receives the optical signal of the read command. Receiving means for receiving the optical signal of the display content transmitted from the gas meter, and display means for displaying the display content received by the receiving means.

According to the optical wireless communication apparatus of the present invention, when the power is turned on, the transmitting means transmits an optical signal of the read command to the gas meter, and when the gas meter receives the optical signal of the read command, the receiving means operates the gas meter. Since the optical signal of the display content transmitted from is received and the received display content is displayed on the display means, the display content of the display means of the gas meter can be confirmed even when the display means on the gas meter side is out of order.

Further, the optical wireless communication device is an optical wireless communication device for transmitting and / or receiving information to and from a gas meter which calculates a gas usage value based on a measured value of a gas flow rate or a gas flow rate. Transmitting a light signal of a command for turning on all the segments of the display means including a plurality of segments provided to the gas meter to the gas meter when the power is turned on or the operation unit is operated. It is characterized by comprising means.

According to the optical wireless communication apparatus of the present invention, when the power is turned on or the operating section is operated, the transmitting means is connected to all the segments of the display means comprising a plurality of segments provided in the gas meter. Is transmitted to the gas meter, so that all segments of the display means can be lit on the gas meter side based on the optical signal of the command.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a gas meter and a handy terminal according to an embodiment of the present invention. In FIG. 1, a handy terminal 12, which is an optical wireless communication device, transmits and / or receives information to and from a gas meter 11 that calculates a value of a gas usage based on a measured value of a gas flow rate or a gas flow rate. That is, bidirectional optical wireless communication using infrared rays is performed between the gas meter 11 and the handy terminal 12.

The gas meter 11 has a function of displaying the reason for the interruption and the alarm on the LCD when the interruption and the alarm occur, and the gas meter 11 always determines the failure of the LCD.
A function to display a specific pattern on D, a function to automatically read the display of the gas meter by the handy terminal and display it on the handy terminal side, and a function to turn on all the segments of the gas meter LCD by communication from the handy terminal to display the gas meter LCD And a function capable of judging a failure.

FIG. 2 is a detailed view of the upper case of the gas meter. In the upper case portion of the gas meter 11, an integrated flow rate counter 20 (gas usage display means) for measuring a gas flow rate or a gas flow rate and displaying a value of a gas usage obtained by integrating the gas flow rate or a gas flow rate, and a shutdown and alarm reason. Information is transmitted and / or transmitted by optical wireless communication between the LCD display window 21 for the LCD 315 for displaying characters and numerals and the handy terminal 12.
Or a window 22 for a light emitting element and a light receiving element for reception
And a return switch 23 for opening a shut-off valve 33 (cut-off means) for shutting off gas supply when the gas meter 11 shuts off.

FIG. 3 is a block diagram showing the configuration of the gas meter. Inside the upper case portion of the gas meter 11, a meter control unit 31 for controlling the gas meter, a pressure switch 32 for detecting a pressure drop of the gas, and a shutoff valve 3 for shutting off the gas supply are provided.
3 are provided. In the lower case of the gas meter,
A measuring mechanism 34 (measuring means) for measuring the flow rate or flow rate of the gas is provided.

The meter controller 31 includes a flow rate pulse detector 311 for detecting a signal from a metering mechanism 34 provided in a lower case of the gas meter, and a seismic sensor 312 for detecting an earthquake.
A pressure signal input circuit 313 for inputting a signal from the pressure switch 32, and a shutoff valve 33 when a shutoff event occurs.
Valve driving circuit 314 for driving the LCD, an LCD 315 (display means) for displaying a shut-off and alarm event, and a light-emitting element for transmitting and / or receiving information by optical communication between the handy terminal 12 and a light-receiving element. An optical communication unit 316 (optical wireless communication means) composed of elements, a microcomputer 317, a power supply unit 318 for driving these units, information on occurrence of interruption / warning events, and various settings shown in the list of FIG. Storage unit 319 for storing the information of rewritably
It is comprised including.

Microcomputer 317 (judgment means)
Is a process of calculating a gas flow rate from a signal of the flow rate pulse detection unit 311 and determining abnormal use of gas based on the value of the gas flow rate, a process of determining occurrence of an earthquake based on a signal from the seismic sensor 312, and a pressure switch 32. A process for judging a decrease in gas pressure based on a signal from the controller, a process for displaying a shut-off or alarm reason on the LCD 315 when an abnormality occurs by these judgment processes, a drive of the shut-off valve 33, and a process between the hand-held terminal 12 Processing for controlling optical wireless communication is performed.

The microcomputer 317 constantly monitors the usage state of the gas, the minute flow rate leak, the earthquake, the gas pressure drop, the battery voltage drop, and the failure of the shut-off valve 33 to determine whether or not a shut-off or alarm event has occurred. If the judgment is made and a cutoff or alarm event occurs, a cutoff or alarm is performed, and control is performed so that the cutoff or alarm reason is displayed on the LCD 315.

There are various interruption / warning reasons as shown in the table of FIG. By displaying a display pattern defined using characters and numerals on the display screen of the LCD 315 in association with each of the interruption / warning reasons (display reasons), an example of which is shown in FIG. Express occurrence. For example, the interruption / warning reason of “pressure drop interruption” is “pressure drop”.
The first letter "P" is displayed.

The English characters expressing the interruption / warning reason are shown in FIG.
LCD composed of 16 segments as shown in
315 is displayed on the display screen. Blocked by this English character
You can intuitively recognize the alarm reason. In the case of the normal mode, the display pattern is lit. When the interruption / warning reason overlaps, it is displayed alternately. At the time of alternate display, the display pattern of each event is switched every second.

When no interruption or alarm event occurs, that is, when the microcomputer 317 is in a normal state, the microcomputer 317 displays a specific pattern on the LCD 315 to indicate that it is normal. For example, as shown in FIG. 4, “*” is lit on the LCD 315 during normal operation. This makes it possible to visually determine a failure due to the non-lighting of the LCD 315.

When the optical communication unit 316 receives the optical signal of the cutoff / alarm display reason request message, which is a read command transmitted from the handy terminal 12, the microcomputer 317 changes the display contents of the LCD 315 based on the message. The information on the occurrence of a certain interruption / warning event is read out, and the optical communication unit 316 converts the information into a signal and transmits an optical signal based on the signal.

The microcomputer 317 turns on all the segments of the plurality of segments of the LCD 315 when the optical communication unit 316 receives the optical signal of the LCD check request message which is a display command transmitted from the handy terminal 12. Control to be performed.

FIG. 6 is a schematic structural view of the handy terminal. The handy terminal 12 has an LCD 61 for displaying a menu for executing various functions, and an operation switch unit 62 used for transmitting a read command.
And an optical communication unit 63 in which a light emitting element and a light receiving element for transmitting and / or receiving information by optical communication with the gas meter 11 are provided.

FIG. 7 is a block diagram showing the configuration of the handy terminal 12. As shown in FIG. The handy terminal 12 has an LCD 6
1 (display means) and an LCD for driving the LCD 61
Drive circuit section 72, operation switch section 62, optical communication section 6
3 (a transmitting unit and a receiving unit), a microcomputer 75 for controlling these units, a power supply unit 76 composed of a lithium battery, and a storage unit 77 for storing various information.

The optical communication unit 63 transmits an optical signal of a cutoff / alarm display reason request message, which is a read command for reading the display content of the LCD 315 provided in the gas meter 11 when the power supply unit 76 is turned on, to the gas meter. , Gas meter 1
When 1 receives the optical signal of the message for requesting the interruption / warning display reason, the optical signal of the display content transmitted from the gas meter 11 is received. The LCD 61 displays the display content of the LCD 315 of the gas meter 11 received from the gas meter 11.

The optical communication unit 63 turns on all the segments of the LCD 315 provided in the gas meter 11 when the power supply unit 76 is turned on or the operation switch unit 62 is operated. An optical signal of an LCD check request message, which is a command for the operation, is transmitted to the gas meter 11.

The handy terminal 12 has a function of performing various settings and readings on the gas meter 11 by optical wireless communication. The information transmitted by the handy terminal 12 by optical wireless communication includes information in which an instruction to be displayed on the LCD is signalized, information in which various setting instructions relating to the function of the gas meter 11 are signalized, information of the setting content, and the like. Specific items of various settings are the items shown in the list of FIG.

FIG. 11 is a diagram showing an example of an LCD check request message in optical wireless communication. The LCD check request message transmitted from the handy terminal 12 to the gas meter 11 is STX, identification code, message type, ETX, B
It is composed of CC.

FIG. 9 is a flowchart showing an operation in which the handy terminal reads out the interruption / warning display reason displayed on the gas meter and displays it on the LCD of the handy terminal. FIG. 10 is a flowchart showing an operation in which the gas meter transmits a shutdown / alarm display reason response message in which the shutdown / alarm reason is written to the handy terminal in response to the shutdown / alarm display reason request message from the handy terminal.

First, the operation of the handy terminal will be described with reference to the flowchart of FIG. It is determined whether the power switch (power SW) is turned on (step S).
1) When the power switch is turned on, a message for requesting a shutdown / alarm display reason is transmitted to the gas meter 11 (step S).
2).

Next, it is in a state of waiting for reception of a response message from the gas meter 11 for shutoff / alarm display (step S).
3). When the shutdown / alarm display reason response message is received from the gas meter 11 (step S4), the display reasons 1 to 10 of the shutdown / alarm display reason response message are displayed on the LCD 61 (step S5).

Next, the operation of the gas meter 11 will be described with reference to the flowchart of FIG. The system is in a state of waiting for reception of the message for requesting the interruption / warning display reason (step S11). When the cutoff / alarm display reason request message is received (step S12), the cutoff / alarm display reason response message display reason 1 is displayed.
Then, the display reason is written to the handy terminal 12 (step S13), and the shutdown / alarm display reason response message in which the display reason is written is transmitted to the handy terminal 12 (step S14).

As described above, when the handy terminal 12 transmits the message for requesting the interruption / alarm display reason to the gas meter 11, the gas meter 11 displays the interruption / alarm display reason displayed on the gas meter 11 as a display of the response message for the interruption / alarm display. Write the reason 1 to 10 and send it to the handy terminal 12. When the handy terminal 12 receives the cutoff / alarm display reason response message, the handy terminal 12 displays the cutoff / alarm display reason written in the display reason 1 to 10 of the cutoff / alarm display reason response message on the LCD 61 of the handy terminal 12.

For example, in the display example of FIG.
When "P" is displayed on the LCD 315 of the
It is assumed that one segment is turned off and “F” is displayed. In this case, "P" is displayed on the LCD 61 of the handy terminal 12. Therefore, the handy terminal 12
By comparing the display on the LCD 315 of the gas meter 11 with the display on the LCD 61 of the handy terminal 12, the operator can determine the failure of the LCD 315 of the gas meter 11. This allows the operator to take correct measures.

Further, when the power supply unit 76 of the handy terminal 12 is turned on, an interruption / alarm reason request message is automatically transmitted, so that the operator can use the handy terminal 12.
This eliminates the hassle of selecting a menu by using the operation switch section 62 and the LCD 61 and transmitting a cutoff / alarm reason request message.

FIG. 12 is a flowchart showing the operation of transmitting a LCD check request message by the handy terminal. FIG. 13 shows that the gas meter responds to the LCD check request message from the handy terminal and displays the gas meter LC.
It is a flowchart which shows operation | movement which turns on all the segments of D.

First, the operation of the handy terminal is shown in FIG.
This will be described with reference to the flowchart of FIG. It is determined whether the power switch has been turned on (step S21). If the power switch has been turned on, an LCD check request message is transmitted to the gas meter 11 (step S22).

The operation of the gas meter 11 will be described with reference to the flowchart of FIG. It is in a state of waiting for reception of an LCD check request message (step S31). If an LCD check request message has been received (step S32), L
All segments of the CD 315 are lit and displayed (Step S)
33). Then, it is determined whether or not one second has elapsed since all the segments of the LCD 315 were turned on (step S3).
4) If one second has elapsed since the lighting, the LCD 315
Are turned off (step S35).

As described above, when the handy terminal 12 is
When a CD check request message is transmitted to the gas meter 11,
The gas meter 11 lights all the segments of the LCD 315 of the gas meter 11 for a certain period of time, for example, one second, based on the received LCD check request message.

Accordingly, the operator of the handy terminal 12 can determine that the LCD 315 of the gas meter 11 has failed by turning on all the segments of the LCD 315 of the gas meter 11.

Further, when the power supply section 76 of the handy terminal 12 is turned on, an LCD check request message is automatically transmitted, so that the operator selects a menu by the operation switch section 62 of the handy terminal 12 and the LCD 61 and displays the LCD. The trouble of transmitting a check request message is eliminated.

As described above, in the gas meter 11 for displaying the reason for the interruption on the LCD 315 of the gas meter when the interruption or the alarm is generated, when a part of the LCD is turned off due to a failure, the original operation is stopped. The display is different from the display, and the problem that the operator cannot take corrective measures does not occur. Further, when the LCD is completely turned off due to the failure of the LCD driver, no display is made even if an alarm is generated, so that the problem that the meter reader does not notice the alarm can be solved.

[0050]

According to the gas meter of the first aspect of the present invention,
The display means displays the information of the event that occurred when the interruption reason or the alarm event occurred, so that the occurrence of the interruption or the alarm is known, and it is in a normal state when the interruption event or the alarm has not occurred. Since the normal state information is displayed, it is possible to determine the failure of the display means based on the presence or absence of the normal state information.

According to the gas meter of the present invention, when the optical wireless communication means receives the optical signal of the display command transmitted from the optical wireless communication device, the display means turns on all the segments. Failure of the display means of the gas meter can be determined.

According to the optical wireless communication apparatus of the third aspect, when the power is turned on, the transmitting means transmits the optical signal of the read command to the gas meter, and receives the signal when the gas meter receives the optical signal of the read command. The means receives the optical signal of the display content transmitted from the gas meter and displays the received display content on the display means, so that even if the display means on the gas meter side is out of order, the display content on the display means of the gas meter can be confirmed. .

According to the optical wireless communication apparatus of the fourth aspect, when the power is turned on or the operation unit is operated,
The transmitting means transmits to the gas meter an optical signal of a command for turning on all the segments of the display means comprising a plurality of segments provided on the gas meter, so that the gas meter displays based on the optical signal of the command. All segments of the means can be turned on.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a gas meter and a handy terminal according to an embodiment of the present invention.

FIG. 2 is a detailed view of an upper case portion of the gas meter.

FIG. 3 is a configuration block diagram of a gas meter.

FIG. 4 is a diagram showing a shutdown of a gas meter, an alarm generation reason, and an example of an LCD display pattern.

FIG. 5 is a diagram showing an example of a display pattern on an LCD display unit of the gas meter.

FIG. 6 is a schematic structural view of a handy terminal.

FIG. 7 is a configuration block diagram of a handy terminal.

FIG. 8 is a diagram showing an example of setting / reading items of a handy terminal.

FIG. 9 is a flowchart showing an operation in which the handy terminal reads out the interruption / alarm display reason displayed on the gas meter and displays the reason on the LCD of the handy terminal.

FIG. 10 is a flowchart showing an operation in which the gas meter transmits a shutdown / alarm display reason response message in which the shutdown / alarm reason is written to the handy terminal in response to the shutdown / alarm display reason request message from the handy terminal.

FIG. 11 is a diagram showing an example of an LCD check request message in optical wireless communication.

FIG. 12 is a flowchart showing an operation in which the handy terminal transmits an LCD check request message.

FIG. 13: Gas meter is LC from handy terminal
It is a flowchart which shows the operation | movement which turns on all the segments of LCD of a gas meter in response to the D check request message.

[Explanation of symbols]

11 gas meter, 12 handy terminal, 21
LCD display window, 22 window for light emitting element and light receiving element, 23
Return switch, 31 Meter control unit, 32 Pressure switch, 33 Shutoff valve, 34 Metering mechanism, 61, 315 L
CD, 62 operation switch section, 63, 316 optical communication section,
72 LCD drive circuit section, 75,317 microcomputer, 76,318 power supply section, 311 flow pulse detection section, 312 seismic section, 313 pressure signal input section, 3
14 Shut-off valve drive circuit.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G08B 21/00 G08B 21/00 5K067 21/16 21/16 25/10 25/10 C G08C 23/04 H04B 7/24 D H04B 7/24 G08C 23/00 A (72) Inventor Mamoru Suzuki 1-5-20 Kaigan, Minato-ku, Tokyo Inside Tokyo Gas Co., Ltd. (72) Mitsuhiro Nakamura 1-5-20 Kaigan, Minato-ku, Tokyo No. Tokyo Gas Co., Ltd. (72) Hitoshi Hayashi, Inventor Hitoshi Hayashi No. 1-5-20, Kaigan, Minato-ku, Tokyo Tokyo Gas Co., Ltd. (72) Inventor Ikuo Maeda 70 Yanagicho, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Toshiba Yanagicho Business Co., Ltd. Office (72) Inventor Toshihiro Hirasawa 70 Yanagicho, Yukicho, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Yanagicho Business Office (72) ) 2F030 CB01 CC13 CE09 CE22 CE25 CE27 CE32 CF05 CF11 CF20 2F031 AA01 AB01 AE09 AF04 AF10 2F073 AA08 AA33 AB01 BB01 BC04 CC03 CC05 CC06 CC08 DD01 EE11 EF09 FG01 FG02 GG01 GG04 GG08 GG09 5C086 AA02 AA60 DA08 DA40 FA18 GA09 5C087 AA02 AA10 AA25 BB19 BB74 CC02 CC22 DD07 EE05 EE08 FF01 GG27 FF01 GG03 GG66

Claims (4)

[Claims] 1. A measuring means for measuring a flow rate or a flow rate of a gas; a gas usage quantity display means for displaying a value of a gas usage quantity calculated from the value of the flow rate or a flow rate; Determining means for determining whether an event / alarm event has occurred; interrupting means for shutting off gas supply when the interrupting event has occurred; and determining the event occurring when the interrupting event or the alarm event has occurred. Display means for displaying information and displaying normal state information indicating a normal state when the interruption reason or the alarm reason does not occur. 2. A measuring means for measuring a gas flow rate or a gas flow rate; a gas usage quantity display means for displaying a gas usage quantity value calculated from the flow rate or flow rate value; A shutoff means for detecting the occurrence of an event or alarm event to shut off gas supply; a display means comprising a plurality of segments; and a light for transmitting and / or receiving information between an external optical wireless communication device. Wireless communication means, the display means, when the optical wireless communication means receives an optical signal of a display command transmitted from the optical wireless communication device, to light all the segments of the plurality of segments. Characteristic gas meter. 3. An optical wireless communication device for transmitting and / or receiving information to and from a gas meter which calculates a gas usage value based on a measured value of a gas flow rate or a gas flow rate, when a power supply is turned on. Transmitting means for transmitting to the gas meter an optical signal of a read command for reading the display content of the display means provided in the gas meter, and transmitted from the gas meter when the gas meter receives the optical signal of the read command. An optical wireless communication apparatus comprising: a receiving unit that receives the optical signal of the display content; and a display unit that displays the display content received by the receiving unit. 4. An optical wireless communication device for transmitting and / or receiving information to and from a gas meter for calculating a gas usage value based on a measured value of a gas flow rate or a gas flow rate, when a power supply is turned on. Or, when the operation unit is operated, the gas meter is provided with transmitting means for transmitting to the gas meter an optical signal of a command for turning on all segments of the display means composed of a plurality of segments provided on the gas meter. Optical wireless communication device.