JP2008109572A - On-vehicle navigation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption by powering on a receiving means for acquiring road traffic information, particularly, only when acquiring the road traffic information in an on-vehicle navigation system which guides route, on the basis of the acquired road traffic information. <P>SOLUTION: An on-vehicle navigation system 10 comprises a receiving means 14 for receiving VICS, a reception completion detecting means 15 and a reception interval detecting means, and in a reception interval measuring mode, the reception interval detecting means 16 measures an interval of receiving VICS multiple times to discriminate whether the interval is fixed. If it is decided that the interval is fixed, the reception interval detecting means 16 sets the predetermined time for the measurement and shifts to a power saving mode and when the completion of reception is detected by the reception completion detecting means 15; and a power supply control means 199 stops supplying power to the receiving means 14. After the lapse of the predetermined time, power supply is restarted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an in-vehicle navigation device that provides route guidance based on acquired road traffic information, and in particular, consumes a receiving means for acquiring road traffic information by turning on the power only when road traffic information is acquired. The present invention relates to an in-vehicle navigation device that reduces electric power.

  2. Description of the Related Art Conventionally, an in-vehicle navigation device that acquires road traffic information from an information center via a communication infrastructure and notifies a driver of an optimal route from a current location to a destination using the acquired information is known.

  As a traffic information providing system used in such an in-vehicle navigation device, VICS (registered trademark) (Vehicle Information and Communication) that provides road traffic information using FM multiplex broadcasting or optical beacons or radio beacons provided on the roadside. System) is widely used. VICS (Registered Trademark) transmits road traffic information such as traffic jams and traffic regulations edited and processed in the information center in real time, and the navigation device receives this road traffic information with a receiving antenna or the like and receives the received signal. It is an information communication system that provides real-time road traffic information to a user by demodulating and displaying characters and figures on a display means or displaying them superimposed on a map.

  Furthermore, when the navigation device receives road traffic information, it can be reflected in the route search function to provide route guidance. In other words, the navigation device has a road network database and searches for a route by referring to the road network database. This road network data is composed of nodes and links connecting the nodes, and the link cost is accumulated. Search for the route with the lowest link cost and provide route guidance. The road traffic information includes, for example, traffic jam information, which is adjusted by adding it to the link cost as a cost factor, and a route search is performed using the adjusted road network data.

  And many of the current on-vehicle navigation devices are equipped with road traffic information acquisition means so that road traffic information can be acquired. For example, if an optical beacon is used to acquire road traffic information, an optical signal is transmitted. A photodiode or the like is provided as a light receiving element for receiving. Also, if the road traffic information is transmitted in a specific frequency band of FM broadcast and transmitted in audio broadcast, the road traffic information can be obtained using an FM tuner equipped with a normal vehicle. Is getting.

  These road traffic information receiving means generally maintain a standby state so that signals can be received at all times in order to provide users with real-time information in response to the update of road traffic information. However, if the standby state is maintained, there is a problem that the power consumption increases and the load on the battery is large.

Accordingly, as an invention made in view of such a point, an “in-vehicle wireless device” is disclosed in the following Patent Document 1 (Japanese Patent Laid-Open No. 2004-310402). In the normal state, the invention of the in-vehicle wireless device disclosed in Patent Document 1 supplies power to only the ETC receiver, the VICS receiver, and the signal strength detector, and the signal strength detector detects an ETC signal. Supplies power to the ETC transmission unit, signal processing unit, control unit, and display unit of the ETC receiver, and communicates with the roadside wireless device of the ETC. When the signal intensity detection unit detects a VICS signal, power is also supplied to the signal processing unit and the display unit of the VICS receiver, and the VICS is received from the radio beacon. By doing so, in the in-vehicle wireless device having the ETC mechanism and the VICS mechanism, the ETC signal is received where the ETC signal is received, the power supply to the VICS mechanism is cut off, and the power Reduction can be achieved.
JP 2004-310402 A (summary)

  However, according to the above configuration, it is necessary to separately provide a signal strength detection unit for determining whether or not a VICS or ETC signal can be received, and there is a concern that the structure becomes complicated and the cost increases. In addition, since this signal intensity detection unit needs to operate constantly, it is not possible to expect a significant reduction in power consumption. In addition, even though many vehicles have a radio tuner as standard equipment, there are not many that have a radio beacon reception mechanism, and many in-vehicle navigation devices use a radio tuner for road traffic. Currently, information is acquired. That is, the above-described invention cannot be applied to a vehicle in which the vehicle-mounted navigation device and the ETC are separately mounted, and such a vehicle-mounted navigation device is required to reduce power.

  By the way, in the case of a type that acquires road traffic information from FM multiplex broadcasting, the FM tuner receives a specific frequency band and outputs a voice broadcast from a speaker, and at the same time, receives road traffic information and performs display processing. It is common.

  The road traffic information is normally updated and transmitted at intervals of 5 minutes, but the navigation device on the receiving side always maintains a standby state in order to receive the latest road traffic information. On the other hand, the road traffic information is not updated in real time, but only updated every 5 minutes. In the case of using FM multiplex broadcasting, road traffic information is transmitted from the base station at a cycle of 2 times every 5 minutes, and this is automatically received by the navigation device. Since the update is performed every 5 minutes, information having the same content as the previous transmission is transmitted once out of the two transmissions of road traffic information. Nevertheless, the usual navigation apparatus always keeps the power of the receiving means on, and the power consumed during that time is wasted.

  Accordingly, the inventors of the present application have made various studies to solve the above problems, and as a result, paying attention to the fact that the road traffic information is a system that is updated at a constant cycle, the road traffic information is transmitted or the update information is not updated. The present invention has been completed by conceiving that the above problem can be solved by reducing the power consumption by repeating the power on / off of the receiving means in accordance with the transmission timing. It has come to be.

  That is, an object of the present invention is to solve the above-described problems, and an object thereof is to provide an in-vehicle navigation device capable of reducing power by controlling a power source of a receiving unit.

In order to solve the above problems, the invention according to claim 1 of the present application is
In a vehicle-mounted navigation device comprising: receiving means for receiving road traffic information; and power supply control means for controlling supply of power to the receiving means.
The in-vehicle navigation device further includes reception interval detection means,
When the reception means completes the reception of road traffic information, the reception interval detection means starts measuring a predetermined time, and the power control means stops supplying power to the reception means, and the reception interval detection means When it is determined that a predetermined time has passed, the power control means starts supplying power to the receiving means.

Furthermore, the invention according to claim 2 of the present application is the invention according to claim 1,
The predetermined time is set in accordance with a cycle in which road traffic information is transmitted or a cycle in which update information is transmitted.

Furthermore, the invention according to claim 3 of the present application is the invention according to claim 1,
The in-vehicle navigation device further includes reception interval detection means,
The reception interval detecting means measures a plurality of times from when the receiving means starts receiving road traffic information until it starts receiving road traffic information to be transmitted next, and all the measured times are predetermined. A predetermined time to be measured by the reception interval detecting means is set when it is within the range.

Furthermore, the invention according to claim 4 of the present application is the invention according to claim 1,
The receiving means is an FM tuner that receives FM multiplex broadcasting.

  The present invention provides the following excellent effects by having the above-described configuration. That is, according to the first aspect of the present invention, the in-vehicle navigation apparatus stops the supply of power to the receiving means by the power control means when the receiving means completes the reception of the road traffic information, Since the supply is resumed, power is not consumed while the road traffic information is not received, and the power consumption can be reduced.

  According to the invention according to claim 2 of the present application, the predetermined time in claim 1 is set in accordance with the cycle in which road traffic information is transmitted or the cycle in which update information is transmitted. Information can be acquired in a timely manner, reducing power consumption and preventing information from being missed.

  According to the invention of claim 3 of the present application, the in-vehicle navigation apparatus measures the reception interval a plurality of times, and sets the predetermined time measured by the reception interval detection means when it is determined that the reception interval is constant. When the cycle in which road traffic information is transmitted is not stable, the power supply to the receiving means can be maintained, and processing according to the situation becomes possible.

  Furthermore, according to the invention according to claim 4 of the present application, since the FM tuner is used as the receiving means, it is possible to periodically acquire road traffic information, the timing at which the road traffic information is transmitted, or the update information It becomes easy to control on / off of the power supply to the receiving means in accordance with the timing of transmission.

  Hereinafter, the best embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies an in-vehicle navigation device for embodying the technical idea of the present invention, and is not intended to specify the present invention as this in-vehicle navigation device. Other embodiments within the scope of the claims are equally applicable.

  FIG. 1 is a block diagram showing a configuration of an in-vehicle navigation device according to an embodiment of the present invention. The in-vehicle navigation device 10 includes a position detection unit 201, a route search unit 202, and a map database 203, and map data and roads stored in the map database 203 according to the position information of the departure point and destination set by the input unit 12 With reference to the data, an optimum route having the shortest distance or required time between two points is searched, and the optimum route is displayed on the display means 13 together with the map image. The position detection means 201 includes positioning means such as GPS, and calculates the current position by receiving GPS satellite signals via the antenna 21.

  Map data and road data are structured as follows. For example, when there are a plurality of roads A, B, and C, the end points, intersections, and inflection points of the roads A, B, and C are used as nodes, the roads connecting the nodes are represented by directional links, and node data ( Node latitude / longitude), link data (link number), and link cost data using link cost (link distance or time required for traveling the link) of each link as data. Then, the link connected from the node at the departure point to the node at the destination is traced, the link cost is accumulated, and a route that minimizes the accumulated link cost is searched and guided. This method is performed by, for example, a known method called a Dijkstra method or a label determination method. As described above, the VICS is reflected in the road data and map data, information such as traffic congestion is added to the link cost, the cumulative link cost is adjusted, and the route search result is displayed on the display means 13.

  Although not shown, the control unit 11 is a microprocessor having a processor, and controls the operation of each unit by a control program stored in the ROM 17. The input means 12 includes numbers, alphabets, other function keys, selection keys, and the like, and includes a remote control unit provided in the in-vehicle navigation device 10 and operation keys provided in the device body.

  The display unit 13 is an output unit including a display panel such as a liquid crystal display, a speaker, and the like, and displays a result of the route search searched by the route search unit 202 and a guidance map obtained by referring to the map database 203. . Furthermore, the VICS receiving unit 14 also functions when the VICS received and processed is displayed as an image or guided by voice. The display unit 13 may be a touch panel or the like. In this case, the display unit 13 also functions as a part of the input unit 12.

  The VICS receiving unit 14 is an interface for acquiring the VICS, and may be any device that can acquire the VICS from any of a radio wave beacon, an optical beacon, and FM multiplex broadcasting. In addition, if a normal vehicle has an FM tuner as a standard equipment or uses FM multiplex broadcasting, for example, VICS does not travel on a specific road equipped with a beacon according to a certain cycle. Since FM can be automatically acquired, the form using FM multiplex broadcasting is preferable. In the following, an example in which VICS is received using FM multiplex broadcasting will be described.

  The VICS reception completion detection means 15 is for detecting whether or not the reception of the VICS is completed, and the VICS reception interval detection means 16 is for detecting an interval for receiving this VICS when the VICS is received a plurality of times. belongs to. Further, the power control means 19 is for controlling the supply of power to the VICS receiving means 14 and is connected to the VICS receiving means 14. The power supply control means 19 normally operates to supply power to the VICS reception means 14, but when the VICS reception interval detection means 16 measures the VICS reception interval and determines that reception is possible at a fixed period, the next time It operates so as to turn off the power of the VICS receiving means 14 until reception of VICS. This point will be described later.

  Hereinafter, the operation of the entire navigation apparatus will be described with reference to FIGS. 2 and 3 are flowcharts showing the operation of the navigation device according to the embodiment. FIG. 2 shows the operation at the stage of measuring the reception interval for periodically receiving the VICS. FIG. 3 shows the VICS receiving means periodically after determining that the interval is constant as a result of measuring the reception interval. The operation at the stage of turning on / off the power is shown. Hereinafter, the operation routine in FIG. 2 is referred to as a reception interval measurement mode, and the operation routine in FIG. 3 is referred to as a power saving mode.

  The navigation apparatus 10 main body is turned on, or an operation for acquiring the VICS is performed by the input means 12 in a state where the main body is activated to start the operation. In step S21, when starting the reception interval measurement mode, timer information stored in the memory is initialized. This makes it possible to determine whether or not the reception interval is constant without being affected by the previously stored reception interval measurement result.

  When the process proceeds to step S22, the VICS receiving unit 14 receives the VICS. The VICS receiving means 14 is provided with an FM tuner, and the frequency band received by the FM tuner is set to 76 to 90 MHz. When reception is started, the VICS reception interval detection means 16 starts measuring the reception interval in the process of step S23. The reception interval here means an interval from the time when the navigation apparatus side starts to receive the VICS transmitted at a frequency of twice every 5 minutes by FM multiplex broadcasting until the next reception starts. .

  In step S24, the VICS reception completion detection unit 15 determines whether or not the reception of the VICS is completed. Completion of reception is handled as reception completion when reception of radio waves is completed. If it is determined that the reception of VICS is not completed, the process returns to step S22 to receive the VICS again. If it is determined that reception is completed, the process proceeds to step S25.

  In step S25, it is determined whether or not the reception interval measurement started in step S23 has finished a predetermined number of times (for example, five times). If it is determined that the predetermined number of times is not satisfied, the process returns to step S22 to receive the VICS again and measure the reception interval. This is repeated until a predetermined number of times, and for example, the latest five times are accumulated and stored in the RAM 18.

  When it is determined that the predetermined number of measurements have been completed, the process proceeds to step S26, and it is detected whether the reception interval is constant. That is, since the transmission of VICS by FM multiplex broadcasting is supposed to be performed twice every about 5 minutes, the VICS is transmitted once every 2 minutes 30 seconds. The present invention uses this to reduce the power consumption by turning on / off the power supply of the tuner in accordance with the timing at which the VICS is transmitted. However, in actuality, the VICS is not always transmitted without a one-second error, and a deviation may occur in the cycle. For example, the reception interval between the first reception and the second reception is 2 minutes 30 seconds, but the reception interval between the second reception and the third reception is 2 minutes 40 seconds. Has an error of 10 seconds from the original period. The invention of the present application is meaningful in that the power supply is repeatedly turned on and off in a timely manner in accordance with the VICS transmission period. Thus, when the VICS reception interval is irregular, the power supply is repeatedly turned on and off. It is meaningless. For example, even if the power is turned on later than when the VICS is transmitted, the VICS cannot be received. Conversely, even if it is too early, it is necessary to wait until the VICS is transmitted, resulting in unnecessary waiting time. The power consumption cannot be reduced.

  Therefore, in this embodiment, the standby state of the VICS receiving unit 14 is maintained until it is determined that the reception interval is constant, and the power supply is turned on / off repeatedly after the reception interval is determined to be constant. Configured to migrate. Note that whether or not the reception interval is constant is determined in units of seconds, but it is preferable to determine that the reception interval is constant if it is within a range of about 2 minutes 30 seconds ± 1 second. This is because if it is judged too strict, the reception of radio waves may be affected by the driving state of the car, which may impair practicality. In addition, whether or not it is constant is determined by detecting reception intervals of multiple times (4 intervals if received 5 times), and the intervals are constant when all measurement results are around 2 minutes 30 seconds. If it is determined that there is, the VICS can be received stably.

  When the above operation is finished, the navigation device 10 shifts to the power saving mode. The operation after shifting to the power saving mode will be described below with reference to FIG. First, in step S31, the power control unit 19 turns off the power of the VICS receiving unit 14. However, the power supply of the navigation apparatus 10 main body remains on, and the timer and the like continue to operate. In step S32, the timer detects whether or not a predetermined time has elapsed since the previous VICS reception, and repeats this process until it is determined that the timer has elapsed. As described above, the VICS is transmitted twice in 5 minutes, but one of them transmits a VICS having the same contents as the first time, so there is no need to receive it. Therefore, after shifting to the power saving mode, if 5 minutes is set as the predetermined time, the VICS having the same contents is not acquired and the power consumption can be further suppressed. The information of the reception interval stored in the RAM 18 as the predetermined time may be read and set as the predetermined time.

  If it is determined that the predetermined time has elapsed, the power supply control means 19 turns on the power supply of the VICS receiving means 14 in the process of step S33, and the process proceeds to step S34 where the VICS receiving means 14 acquires the VICS.

  In the process of step S35, it is determined whether or not the VICS reception completion detecting means 15 has received the VICS. If it is determined that the signal has been received, the process returns to step S31, and thereafter, this operation is repeated. If the VICS could not be received, it is possible that there was a gap in the transmission period of the VICS. After that, even if the power supply is repeatedly turned on and off in the same period, the gap may become even larger. is expected. Therefore, in such a case, the routine for turning on / off the power supply is interrupted, the process returns to the reception interval measurement mode, and the reception interval is measured until the VICS can be stably received.

  Although the present invention is configured to acquire VICS using FM multiplex broadcasting, it is not appropriate to turn off the FM tuner according to the present invention until the FM radio broadcasting audio is being output. It is preferable that this function is not activated in a radio broadcast audio output state.

  As described above, according to the present invention, since the power of the receiving means is turned on / off in accordance with the cycle in which the VICS is transmitted, it is possible to suppress power consumption compared to the case where the receiving means is always in a standby state. In addition, a navigation device that reduces battery load can be provided.

It is a block diagram which shows the structure of this invention. It is a flowchart which shows the operation | movement in the step which measures the receiving interval of this invention. It is a flowchart which shows the operation | movement in the step which repeats on / off of the power supply of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Navigation apparatus 11 ... Control means 12 ... Input means 13 ... Display means 14 ... Reception means 15 ... Reception completion detection means 16 ... Reception interval detection means 17 ... ROM
18 ... RAM
19 ... Power supply control means

Claims (4)

In a vehicle-mounted navigation device comprising: receiving means for receiving road traffic information; and power supply control means for controlling supply of power to the receiving means.
The in-vehicle navigation device further includes reception interval detection means,
When the reception means completes the reception of road traffic information, the reception interval detection means starts measuring a predetermined time, and the power control means stops supplying power to the reception means, and the reception interval detection means When it is determined that a predetermined time has elapsed, the power supply control means starts supplying power to the receiving means.   The in-vehicle navigation device according to claim 1, wherein the predetermined time is set in accordance with a cycle in which road traffic information is transmitted or a cycle in which update information is transmitted.   The reception interval detecting means measures a plurality of times from when the receiving means starts receiving road traffic information until it starts receiving road traffic information to be transmitted next, and all the measured times are predetermined. The vehicle-mounted navigation device according to claim 1, wherein the measured time is set as the predetermined time when the time is within the range.   The in-vehicle navigation device according to claim 1, wherein the receiving means is an FM tuner that receives FM multiplex broadcasting.

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