System and Program

Abstract

To make it possible to extract warning targets that are likely to actually become warning targets.SOLUTION: A system includes: a GPS receiver 8 that detects a position of a vehicle: a database 19 that stores position information of a warning target and road network information; and a control unit 18 that controls notifications to a display unit 5 or the like when the position information of the warning target and a current position of the vehicle have a predetermined proximity relation. The control unit uses the road network information to determine a recommended route from an own vehicle position to a warning target existing in the periphery, and determines whether or not there is the proximity relation based on a travel distance when the vehicle travels along the determined recommended route.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a system and a program for notifying information regarding an approach when a current position comes into a predetermined approach relationship with an alarm target.

Background Art

[0002] In recent years, a large number of vehicle speed measurement devices for measuring the speed of automobiles have been installed on the roadside and the like. As an example of a vehicle speed measurement device, microwaves in a predetermined frequency band are emitted toward a vehicle, and the reflected wave is received to measure the traveling speed of the vehicle.

[0003] In order to detect the presence of such a vehicle speed measurement device, a microwave detector configured to detect microwaves emitted from the vehicle speed measurement device and output an alarm has been conventionally known.

[0004] In addition, some vehicle speed measurement devices cannot be detected by conventional microwave detectors. For example, as called a loop type, a loop-shaped coil is embedded in the ground, and when a vehicle passes over the coil, the vehicle speed is detected and determined. There are also devices that detect the speed of a vehicle using light other than microwaves. Therefore, the installation position information of the vehicle speed measurement device is stored in advance, and when the current position acquired by GPS (Global Positioning System) or the like approaches the stored installation position (when it comes into a predetermined approach relationship), there is an in-vehicle electronic device such as a radar detector that issues an alarm regardless of the detection of microwaves (Patent Document 1). Since these various vehicle speed measurement devices are installed at locations where traffic accidents frequently occur or where it is easy to exceed the speed and induce traffic accidents, by notifying the driver of those locations in advance, it is possible to encourage safe driving while complying with traffic rules especially at particularly dangerous locations.

[0005] Specific methods of notification include, for example, outputting audio information from a speaker that indicates relative locations, such as "Highway H system 1km ahead to the left" or "General road N system immediately ahead," or displaying characters or images representing these on a display unit.

[0006] Furthermore, the system can alert on a variety of things, including fixed vehicle speed measuring devices, N-systems (automatic license plate recognition systems), accident-prone areas, various enforcement areas, checkpoint areas, etc., and the system can select which items to alert on through its settings.

[0007] Incidentally, one of the conditions for a registered alarm target to actually trigger an alarm is that the current location and the location of the alarm target must be in a predetermined proximity relationship. Specifically, this proximity relationship is determined by calculating the straight-line distance between the current location and the location of the alarm target, and ensuring that this straight-line distance is less than or equal to a set reference value r (for example, 2km, 1km, etc.). As a result, alarm targets located within a circle of radius r centered on the current location are extracted as targets to be actually alarmed.

[0008] In this situation, there are often multiple warning targets in the vicinity of the current location. In such cases, one warning target that meets predetermined conditions is designated as the target object, and warning information indicating the relative positional relationship, etc., as described above, is provided for that target object. Furthermore, if a display unit is provided, an object representing the vehicle is drawn at a predetermined position on the display screen, and if a warning target exists within the space displayed on the screen, the object of that warning target is drawn at the corresponding position on the screen. In this case, at the position of the target warning target, an object with a different appearance from other warning target objects is drawn so that it can be seen as the target object. By changing the drawing style of the object in this way, the driver can recognize the presence of the designated warning target among the multiple warning targets (objects) drawn on the display screen and know its relative positional relationship with the vehicle's position. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2008-64588 [Overview of the project] [Problems that the invention aims to solve]

[0010] One of the conditions for extracting warning targets is proximity, which is determined based on the straight-line distance between the current position and the location of the warning target. Therefore, for example, if a warning target installed on a different road than the one the vehicle is currently traveling on is within a certain straight-line distance from the current position, the system may issue a warning. However, since the reported warning target is not installed on the road the vehicle is currently traveling on, the vehicle will not pass in front of it even if it continues driving. In other words, this warning is unnecessary. Receiving such an unnecessary warning causes the driver unnecessary worry. Furthermore, because the vehicle will not pass in front of the warning target, it may not be possible to actually find and confirm the presence of the warning target, potentially leading to continued anxiety. In addition, if the different road in question is parallel to the road the vehicle is currently traveling on and relatively close, and if objects are drawn on the display screen at the vehicle's position and the location of the warning target, the object of the warning target will be drawn ahead in the direction of travel, potentially leading to the misconception that the warning target is on the road the vehicle is currently traveling on. This risk of misconception is particularly high on small display screens.

[0011] Furthermore, for example, if the road ahead has a sharp curve and the warning target is located beyond that curve, and the display screen shows objects representing the vehicle's position and the warning target's position, the warning target object will be drawn far from the direction of travel. This could lead the driver to mistakenly believe, at first glance, that it is on a different road than the one they are currently traveling on. Conversely, if the road is currently straight with a curve ahead, and the warning target is located on a different road that lies on the extension of the straight road, and the display screen shows objects representing the vehicle's position and the warning target's position, the warning target object will be drawn ahead in the direction of travel. This could lead to the driver mistakenly believing that the warning target is located further down the road they are currently traveling on. This problem of misrecognition is particularly pronounced with inexpensive products that do not store map information, as they cannot display a map when storing and displaying the location information of the warning target point.

[0012] Furthermore, some warning systems include a function that notifies the remaining distance to the warning target. This remaining distance is based on the straight-line distance mentioned above. However, when a vehicle is actually traveling, it may encounter curves in the road, or change lanes by turning right or left at intersections. Therefore, the warning target is often not on the extension of the direction the vehicle is currently traveling, and the rate at which the remaining distance decreases differs from the actual distance traveled, creating a sense of incongruity in how the remaining distance decreases.

[0013] Furthermore, the distance traveled to actually reach the warning target is naturally longer than the straight-line distance. And, as mentioned above, the difference can be very large if the driver has to make multiple turns, navigate sharp curves, or follow road network conditions, one-way streets, or other traffic regulations from their current location to the warning target. As a result, it takes a long time to travel a long distance from the time the warning is initially issued until actually reaching the warning target. Consequently, even if a warning is issued, the driver may have difficulty visually confirming the warning target, potentially leading to suspicion of the warning, or even causing a situation where the driver mistakenly concludes the warning was false before reaching the target. Moreover, warning targets that require multiple turns to reach are often not actually visited, resulting in unnecessary warnings, which is undesirable.

[0014] On the other hand, increasing the number of alarm targets registered in the database also increases the number of alarm targets around the current location. Displaying all of them results in a cluttered display of alarm targets, making it difficult to identify the target object. To reduce the number of alarm targets, measures are taken such as pre-registering the types of alarms to be issued or designating targets as those located in a sector-shaped area at a predetermined angle ahead of the direction of travel.

[0015] However, in the former case, if the alarm types are narrowed down more than necessary, it becomes impossible to notify about the various alarm targets that have been registered. In the latter case, alarm targets located at the end of a sharp curve in the road or after turning at an intersection may be located outside the fan shape, making it impossible to issue an alarm.

[0016] Thus, conventional in-vehicle electronic devices of this type have the problem of not being able to adequately extract warning targets in the surrounding area and issue warnings. Furthermore, when multiple warning targets exist and detailed warning information is provided for a specific warning target (object), there is a need to make it easy for the driver to understand which warning target is being warned about. [Means for solving the problem]

[0017] To achieve the above-mentioned objectives, the in-vehicle electronic device according to the present invention is a system comprising: (1) a position acquisition means for acquiring the current position of a vehicle; and a control means for performing notification control to a notification means when the current position of the vehicle acquired by the position acquisition means and the position information of a warning target acquired by accessing a position storage means for storing the position information of a warning target have a predetermined proximity relationship, wherein the control means uses the road network information acquired by accessing a map data storage means for storing road network information to determine a route from the current position of the vehicle to the warning target, and determines whether or not the proximity relationship exists based on the determined route.

[0018] In the embodiment, the position acquisition means corresponds to a GPS receiver 8. The position acquisition means of the present invention includes not only those that acquire the current position by a position detection means that detects the current position, such as the GPS receiver in the embodiment, but also those that have a function to acquire position information about the current position of the vehicle from external devices and equipment. Examples of such external devices and equipment include electronic devices equipped with a position detection function (GPS receiver), such as a car navigation system, and GPS antenna units.

[0019] In this embodiment, the map data storage means corresponds to the database 19. Thus, the information may be built into the device, or some or all of the information may be stored on an external device such as a server, and the necessary information may be retrieved by accessing that server via communication.

[0020] In this embodiment, the route corresponds to a recommended route. This recommended route may be one commonly used in car navigation systems, and it is determined from among several routes from the current location to the destination that has the shortest travel distance or can be reached in the shortest time. At this time, the type of road to be traveled (priority road / general road) may be specified and a route that meets the conditions may be determined. In this invention, such car navigation technology can be used, or the route to the warning target may be determined based on other conditions.

[0021] Conventional proximity determinations were based on the straight-line distance between the current location and the alert target, but this invention determines proximity based on a route determined using road network information. Route-based determination should be based on conditions and situations that are more relevant to actual driving, such as whether the alert target is located ahead on the road being driven on or on a different road, or whether it is easy to reach the alert target from the current location. In this way, even if there are many registered alert targets around the vehicle, the one that is most relevant to actual driving will be determined to have a "predetermined proximity relationship." Therefore, the user can identify the most appropriate alert target from among the many alert targets around their vehicle.

[0022] (2) The control means may determine the distance traveled along the route and determine whether or not there is an approach relationship based on that distance. Depending on the road network conditions, such as whether it is a straight road or a curved road, the location of intersections, and traffic rules such as one-way streets and no right turns, the straight-line distance from the current location to the warning target and the distance traveled along the route to reach the warning target (travel distance) will differ. The travel distance will be longer than the straight-line distance, but the difference will vary greatly depending on the situation. Even if there is a warning target that is close in a straight line, it may take a long time to reach it if a detour or other means is required, so there is little need to issue a warning immediately, and the possibility of actually going to the location of the warning target is also low. On the other hand, for warning targets that are a short distance away along the route, there is a possibility of reaching them relatively quickly, so it is preferable to issue a warning. In this way, by determining the approach relationship based on the distance traveled to reach the warning target via the route and controlling the warning, it is possible to appropriately extract and notify warning targets that should be warned.

[0023] (3) The control means may determine the time required to travel along the route and determine whether or not there is an approach relationship based on that time. The time may be calculated using, for example, probe information on traffic congestion obtained by VICS or communication. If it takes a long time to reach the warning target, the urgency to issue a warning is low, and conversely, if the time is short, the urgency to issue a warning is high. Therefore, it is good to determine whether or not there is an approach relationship based on time.

[0024] (4) The control means may be configured to determine the number of intersections where a turn is made when traveling along the route, and determine the presence or absence of the approaching relationship based on that number. In the route from the current position to the warning target, the more intersections where a turn (right or left turn) is made, the more complex the route to reach that warning target. Therefore, it can be said that the possibility of actually reaching the location of the warning target is lower for a more complex route. That is, if the possibility of actually reaching the location of the warning target is low, even if the straight-line distance or the like is short, it can be said that in terms of the driving situation at that time, it is not approaching (the approaching relationship is low or non-existent). By determining the approaching relationship based on the number of intersections where a turn is made and controlling the warning in this way, it is possible to extract and notify the warning target to which a warning should be appropriately issued.

[0025] (5) In the invention of (4), it is preferable that the control means does not give a normal warning to a warning target where the number of intersections where a turn is made is two or more. For example, when a warning target exists on another road parallel (substantially parallel or non-intersecting) to the road currently being traveled, in order to travel on such another road, it is necessary to turn once at an intersection on the currently traveled road to deviate from the currently traveled road, and further, to enter the other road, it is necessary to turn once at an intersection of the other road. Therefore, in order to travel on such another road, it is necessary to turn at intersections at least twice. In other words, when there is a relationship of turning at intersections two or more times before reaching the warning target, it means that the warning target exists on another parallel road or passes through a complex route, and the possibility of reaching such a warning target is low. Therefore, by doing as in the present invention, even if the distance to the warning target (straight-line distance and / or distance when traveling along the route) is short, it is possible to effectively exclude warning targets existing on other parallel roads or the like. Not giving a normal warning includes not only not giving a warning, but also cases where a warning is given but the level is lowered. Lowering the level means, for example, drawing an object in a less conspicuous manner compared to a normal warning target at the position of the warning target, or not outputting detailed warning information associated with the warning target even if an object is drawn at the position of the warning target.

[0026] (6) The control means may extract, as warning target candidates, warning targets existing in a circular or sector-shaped area with a set predetermined distance radius centered on the current position from the current position and the position information of the warning target, obtain the path to the extracted warning target candidates, and determine the warning target to be notified by the notification means based on the obtained path. By narrowing down the target for which the path is obtained, the load on the control means can be reduced. The sector-shaped area serving as the criterion for extracting warning target candidates may be a sector-shaped area with a radius r and a central angle θ with respect to the traveling direction of the vehicle.

[0027] (7) The predetermined distance may be set to be not more than the distance at which the presence of the approaching relationship is determined based on the distance when traveling on the path. The distance when assuming traveling along the road of the path from the current position to the warning target is equal to or longer than the straight-line distance from the current position to the warning target. Therefore, by setting the predetermined distance to the distance at which the approaching relationship is determined to exist, it is possible to prevent extracting as warning target candidates those that cannot be warning targets for which an alarm should be issued. Furthermore, the traveling distance and the straight-line distance are equal when the warning target is connected to the current position of the vehicle by a single straight road, and in many cases, the straight-line distance is shorter. Therefore, by setting the predetermined distance shorter than the distance at which the approaching relationship is determined to exist, the number of candidates extracted as warning target candidates can be appropriately reduced.

[0028] (8) In the case of a warning target for which it is better to issue a warning when the warning target approaches from a specific direction, direction information indicating the specific direction is registered in a predetermined storage means in association with the warning target, and the control means determines whether to issue a normal warning based on the traveling direction of the vehicle when traveling on the path and on the road where the warning target is installed and the direction information.

[0029] When a vehicle approaches a warning target, there are some targets that should be warned regardless of the direction from which the vehicle approaches, and others that should be warned only when the vehicle approaches from a specific direction. For example, targets that should be warned regardless of the direction from which the vehicle approaches include locations where drowsy driving accidents occur, parking violation monitoring areas, intersection monitoring points, accident-prone areas, and car break-in-prone areas. In contrast, in the case of vehicle monitoring devices and systems such as vehicle speed measuring devices and N-systems, there is a monitoring area and a monitoring lane (uphill lane / downhill lane), and if the vehicle approaches from the opposite direction, it will not pass through the monitoring area or lane, so there is little need to issue a warning. Similarly, speed limit change points are points where the speed limit changes to the lower side, and are usually set on either the uphill or downhill lane, so there is little need to issue a warning if the vehicle is traveling in the opposite lane and approaching the warning target. In this way, if the decision to issue an alarm depends on the direction in which the vehicle approaches the alarm target, registering direction information to identify the direction of approach in association with the alarm target allows the system to prevent the normal alarm from being issued if, upon reaching the alarm target via the designated route, the vehicle's direction of travel at that time does not match the desired relationship with the direction identified by the direction information registered with the alarm target.

[0030] In other words, when direction information is registered, what is important is not the relationship between the vehicle's direction of travel at its current location, but ultimately the vehicle's direction of travel immediately before the target of the warning. In this invention, since road network information is available and the vehicle's direction of travel immediately before the target of the warning is known, it is possible to determine in advance whether the direction identified by the direction information of the target of the warning and the vehicle's direction of travel immediately before are in an appropriate relationship, and thus a correct warning can be issued.

[0031] The storage means for registering this directional information may be the same as (partially incorporated into) the position storage means, or it may be separate. Furthermore, this storage means may be located within the device equipped with the control means, or it may be implemented as a storage device such as a server outside the device. In this embodiment, this specific direction corresponds to the installation direction. That is, since the specific direction is set based on the orientation in which the device is installed (the direction that identifies the monitoring area), in this embodiment, the installation direction is used as the basis for assuming that the alarm target is a device, but this does not preclude defining the specific direction for alarm targets other than devices.

[0032] (9) In the case of a warning target that should be warned when it approaches from a specific direction, direction information indicating that specific direction should be registered in a predetermined storage means in association with the warning target, and the route should be selected such that, on roads where a warning target for which direction information has been set exists, the route proceeds toward the direction in which the warning target is located. In this way, routes that approach the warning target from a direction different from the originally specified direction can be eliminated.

[0033] (10) The control means controls the alarm according to the remaining distance to a predetermined alarm target, and the remaining distance should be set to be less than or equal to the distance traveled from the current position to the predetermined alarm target along the aforementioned route. In this type of system, the remaining distance to the alarm target is displayed numerically or by an indicator, the background color of the display unit is changed, or the remaining distance is announced by voice. In this case, by using the travel distance, an alarm based on the remaining distance can be issued at an appropriate timing that more closely matches the actual situation.

[0034] (11) The notification means includes a display unit, and the control means draws a road map based on the road network information on the display unit, and draws objects on the road map corresponding to the current position and the location of the warning target, and draws a guide line connecting the object representing the vehicle drawn at the current position and the object representing the warning target, along the determined route. Since the guide line is drawn along the road, the driver can understand at a glance whether the route to the warning target is the road they are about to travel on, and can intuitively understand whether it is a warning target that requires attention. Furthermore, it would be better to draw the guide line with an animation, for example, gradually extending from the vehicle's position along the road and finally reaching the object representing the warning target, to make it more noticeable. Also, the guide line only needs to show the positional relationship between the current position and the warning target, and the tip of the guide line does not need to be directly connected to the object representing the vehicle and the object representing the warning target, respectively.

[0035] (12) The notification means includes a display unit, and the control means draws a display board on the display unit that displays information about the alarm target, and if there are multiple alarm targets, it is preferable to draw the display boards for each of the multiple alarm targets so that the one with the highest priority is at the front. This is preferable because the existence of multiple alarm targets and their order can be understood at a glance.

[0036] (13) The program of the present invention is a program for a computer to realize the functions of the control means in the in-vehicle electronic device described in any of (1) to (12) above. [Effects of the Invention]

[0037] According to the present invention, it is possible to extract alarm targets that are highly likely to actually trigger an alarm, appropriately narrow down the surrounding alarm targets to be warned about, and issue alarms for those narrowed-down alarm targets. By narrowing down the alarm targets to be warned about, for example, even when the location of alarm targets is shown on the display, the number of displayed targets is small, making it easier for the driver to confirm each alarm target. Furthermore, by improving the rendering, when detailed alarm information about a predetermined alarm target (object) is reported, the driver can easily understand which alarm target is being warned about. [Brief explanation of the drawing]

[0038] [Figure 1] This is a diagram showing the configuration of a radar detector, which is a preferred embodiment of the present invention. [Figure 2] This is a block diagram of a radar detector. [Figure 3] This diagram shows examples of the standby screen, radar scope, and GPS warning displays. [Figure 4] This figure shows an example of the display of the warning screen in the radar wave warning function. [Figure 5] This diagram shows the vehicle's position and an example of a warning target in its surroundings. [Figure 6] This figure shows the search results for recommended routes to each potential alarm target. [Figure 7] This diagram shows the relationship between the installation direction set for the alarm target and the direction of vehicle travel. [Figure 8] This figure shows an example of a display screen. [Figure 9] This figure shows an example of a display screen. [Figure 10] This is a diagram explaining the function. [Figure 11] This figure shows an example of a display screen. [Modes for carrying out the invention]

[0039] Figures 1 and 2 show the configuration of a radar detector, which is a suitable embodiment of the electronic equipment constituting the system of the present invention. This radar detector is usually mounted on the dashboard. As shown in Figure 1, this radar detector has a solar panel 2 and a switch unit 3 on the top surface of the case body 1, and a microwave receiver 4 for detecting microwaves in the frequency band emitted by a speed measuring device is placed inside the front side of the case body 1. On the other hand, a display unit 5, a warning lamp 6, an infrared communication device 7, and a remote control receiver 16 are placed on the rear side of the case body 1 (the side facing the rear of the vehicle (driver's side)). A GPS receiver 8 is also placed on the top side inside the case body 1. Furthermore, an adapter jack 9 is placed on one side of the case body 1, and a power switch 10 and a DC jack (not shown) are placed on the other side. A speaker 20 is also built into the case body 1.

[0040] In this embodiment, the display unit 5 is a 2.4-inch small liquid crystal display, and the rear side of the case body 1 (the side positioned towards the rear of the vehicle (driver's side)) serves as the display surface. The height H of the rear side of the case body 1 on which the display unit 5 is mounted is greater than the height H0 of the other parts.

[0041] As shown in Figure 2, the infrared communication device 7 transmits and receives data with a communication device that has a built-in infrared communication device, such as a mobile phone 12. The adapter jack 9 is a terminal for connecting the memory card reader 13. By connecting the memory card reader 13 to the adapter jack 9, data stored on the memory card 14 inserted into the memory card reader 13 can be taken into the device, or the contents of the database 19 and the memory of the control unit 18 can be written to the memory card 14. More specifically, if the data stored on the memory card 14 contains updated information such as alarm target information, which is information about new targets or other alarm targets, the control unit 18 stores (downloads) that updated information in the database 19 built into the device and updates the data in the database 19. The function of the memory card reader 13 may also be configured to be built into the main unit case 1.

[0042] The database 19 is a non-volatile memory (such as an EEPROM) located within the microcontroller of the control unit 18 or attached externally to the microcontroller. The database 19 contains alarm target information, which is information about certain alarm targets, at the time of shipment, and data for alarm targets added thereafter can be updated as described above. Data updates can also be performed via the infrared communication device 7.

[0043] The DC jack is for connecting a cigarette lighter plug cord (not shown), which connects to the vehicle's cigarette lighter socket to receive power. The wireless receiver 15 receives incoming radio waves of a predetermined frequency. The remote control receiver 16 communicates with the remote control (portable unit: slave unit) 17 via infrared light to perform various settings on the device. The switch unit 3 is also connected to the control unit 18 (not shown), allowing it to perform the same settings as the remote control 17. The remote control 17 is equipped with a play button, a standby switch button, a setting button, a select button, a cancel button, a confirm button, and a directional pad for up, down, left, and right.

[0044] Furthermore, the control unit 18 is a microcontroller equipped with a CPU, ROM, RAM, non-volatile memory, I / O, etc., and as shown in Figure 2, it is connected to the above-mentioned parts and executes predetermined processing based on the information input from the above-mentioned parts, and controls the above-mentioned parts to output predetermined alarm messages and information. Note that these basic configurations can basically be the same as those of conventional systems.

[0045] The functions of the radar detector in this embodiment are implemented by the computer in the control unit 18 executing a program stored in the EEPROM of the control unit 18. The functions implemented by the computer in the control unit 18 include a GPS log function, a standby screen display function, a radar scope display function, a GPS warning function, a radar wave warning function, and a wireless warning function.

[0046] The GPS logging function is a function in which the control unit 18 stores the current location detected by the GPS receiver 8 every second as a location history in the memory card 14, associated with the time of detection and speed (vehicle speed). This location history is recorded in, for example, NMEA format. The standby screen display function, as shown in Figure 3(a), displays the vehicle's speed, latitude, longitude, and altitude detected by the GPS receiver 8 on the display unit 5.

[0047] The radar scope display function, as shown in Figure 3(b), searches for warning targets (also called targets, etc.) within a predetermined range (for example, within a range of about 1 km) from the current position detected by the GPS receiver 8 using location information stored in the database 19, and displays the relative positional relationship between the vehicle's position and the warning target's position on the display unit 5. In Figure 3(b), the "W" on the left indicates west, the "E" on the right indicates east, and the "N" at the top indicates north. The icon at the intersection of the horizontal line connecting "W" and "E" and the vertical line extending downward from "N" indicates the vehicle's position. Icons with letters such as "L," "RD," "P," and "N" indicate the type and location (existence point) of the warning target.

[0048] If the standby screen display function shown in Figure 3(a) is activated and the standby switching button on the remote control 17 is pressed, the system switches to the radar scope display function shown in Figure 3(b).

[0049] The control unit 18 executes processing to implement various functions such as GPS warning function, radar wave warning function, and wireless warning function in response to events that occur while the standby screen display function or radar scope display function (hereinafter these functions are collectively referred to as standby functions) is being executed.

[0050] The radar wave warning function is a warning function that, when the microwave receiver 4 detects a signal corresponding to microwaves in a frequency band emitted from a speed measuring device (mobile radar, etc. (hereinafter simply referred to as "radar")), displays a warning screen on the display unit 5 and outputs a warning sound from the speaker 20. For example, when the microwave receiver 4 detects microwaves in a frequency band emitted by a radar, as shown in Figure 4, a schematic diagram or photograph of the radar stored in the database 19 is displayed on the display unit 5 as a warning screen, and audio data stored in the database 19 is read out and the voice "Radar. Be careful of speed" is output from the speaker 20. The warning lamp 6 is illuminated while the voice is being output.

[0051] The wireless warning function is a function that, when the wireless receiver 15 receives radio waves emitted by emergency vehicles, etc., issues a warning to prevent interference with their driving. The wireless warning function scans frequencies such as speed enforcement radio, car location radio, digital radio, low-power radio, police station activity radio, police telephone, police activity radio, tow truck radio, helicopter telemetry radio, fire helicopter telemetry radio, fire radio, ambulance radio, highway radio, and security radio. When a radio signal is received on a scanned frequency, a schematic diagram indicating that a radio signal corresponding to that frequency has been received, stored in the database 19 for each radio signal type, is displayed on the display unit 5 as a warning screen. At the same time, audio data stored in the database 19 for each radio signal type is read out and an alarm sound indicating the type of radio signal is output from the speaker 20. For example, when a speed enforcement radio signal is received, an audio message such as "Speed ​​enforcement radio. Be careful of speed" is output. The warning lamp 6 is illuminated while the audio is being output.

[0052] The GPS warning function is a process that is executed at predetermined time intervals (1-second intervals) in response to an event from a timer in the control unit 18 while the standby screen display function in Figure 3(a) or the radar scope display function in Figure 3(b) is being executed. This function determines whether or not a warning condition (a predetermined proximity relationship) is met using the current location detected by the GPS receiver 8 and the warning target information stored in the database 19, and issues a warning if the condition is met.

[0053] To begin with, here are some examples of the types of locations that trigger warnings: locations where drivers fall asleep at the wheel, vehicle speed measuring devices (radar type / H system / loop coil / LH system), mobile vehicle speed measuring areas, speed limit change points, enforcement areas, checkpoint areas, parking violation monitoring areas, N systems, traffic monitoring systems, intersection monitoring points, red light violation prevention systems, police stations, accident-prone areas, car break-in-prone areas, sharp / consecutive curves (expressways), junction / merging points (expressways), ETC lane advance notice (expressways), service areas (expressways), parking areas (expressways), highway oases (expressways), smart interchanges (expressways), gas stations within PA / SA (expressways), tunnels (expressways), highway radio reception areas (expressways), prefectural border notices, roadside stations, viewpoint parking areas, and many other diverse types.

[0054] The alarm target information stored in the database 19 is information about individual alarm targets, including location information such as longitude and latitude to identify the location of the alarm target, and alarm target identification information that helps the driver identify the alarm target. In this embodiment, the location information is absolute location information using longitude and latitude. This is preferable because it makes it easy to determine the relative positional relationship with the current position detected by the GPS receiver 8.

[0055] Information used to identify alarm targets includes type information indicating the type of alarm target, text information indicating the location of the alarm target, audio information indicating the alarm target, and image information indicating the alarm target. If the audio information or image information indicating the alarm target corresponds to the type information of the alarm target, it can be stored separately as common information in a predetermined storage area, rather than being stored as alarm target information for each individual alarm target. When issuing an alarm, the control unit 18 reads the type information stored as alarm target information, obtains the corresponding image information or audio information from that type of alarm target, and can output an alarm.

[0056] Common image information includes schematic diagrams and other image data that make it easy to understand the type of warning target. These schematic diagrams are also marks that allow the type of warning target to be understood intuitively from a visual perspective. For example, they include 3D images of vehicle speed devices, police cars, and police officers. These schematic diagrams are displayed on the display unit 5 when a warning is issued, allowing the driver to intuitively understand the type and content of the warning target currently being issued. Furthermore, as will be described later, it is preferable to draw a vehicle icon at the vehicle's position on the display area of ​​the display unit 5 and draw the schematic diagram at the location of the warning target, so that the driver can intuitively understand where and what kind of warning target is located.

[0057] Furthermore, the voice information is data for outputting from speaker 20 as voice information, such as relative positional relationships, the type of warning target, and such as "Highway H system 1km ahead to the left" or "General road N system just ahead." In the example above, voice data indicating the relative positional relationship between the vehicle's current position and the warning target, such as "to the left," "1km ahead," and "just ahead," and voice data specifying the type and content of the warning target, such as "General road N system" or "Highway H system," are managed and stored separately, and the control unit 18 combines and outputs the respective voice data when issuing a notification.

[0058] By separately managing fixed audio information (audio data, etc.) according to the type of alarm target, it becomes unnecessary to register the same information as the alarm target information for each individual alarm target, thereby reducing memory usage.

[0059] For example, while the standby screen display function in Figure 3(a) or the radar scope function in Figure 3(b) is being executed, the system periodically accesses the database 19 based on the current location. If the distance between the loop coil to be warned and the vehicle reaches one of the proximity warning distances stored in the database 19 (2km, 1km, or 500m), the system reads a schematic diagram or photograph of the loop coil to be warned from the database 19 and displays it on the display unit 5. At the same time, it reads audio data stored in the database 19 and outputs an alarm sound from the speaker 20 to provide proximity warning. For example, when approaching 500m, as shown in Figure 3(c), the system displays a radar scope screen on the right side of the screen similar to that in Figure 3(b) to show the positional relationship between the loop coil to be warned and the vehicle. It also reads a schematic diagram or photograph of the loop coil to be warned from the database 19 and displays it on the display unit 5, and reads audio data saying "Loop coil 500m ahead, be careful of speed" from the database 19 and outputs it from the speaker 20. Additionally, the alarm lamp 6 will illuminate while the alarm sound is being output.

[0060] Furthermore, database 19 stores map data including road network information. This road network information is necessary when searching for recommended routes in car navigation systems, and includes information such as the road network (road layout) and traffic regulations such as one-way streets. In addition, this road network information stores the location information (latitude and longitude) of each node, with road intersections or inflection points as nodes, and also stores information indicating the connection relationships between each node and the other nodes it is connected to. Based on this information indicating the connection relationships of each node, adjacent nodes are connected, and the connections between these nodes form road links. It should be noted that, unlike car navigation systems that provide guidance to a destination, this system does not contain detailed data such as display data for facilities and houses, and the data is simplified.

[0061] In this embodiment, the condition for issuing a proximity warning is whether the distance between the current location and the location of the warning target has reached the proximity warning distance. However, this distance is not the straight-line distance, but rather the distance (travel distance) calculated assuming that the vehicle traveled along the route to the warning target based on road data. Specifically, the control unit 18 executes the following processes (1) to (3).

[0062] (1) The control unit 18 first extracts alarm targets that are within a radius r (e.g., 1km, 2km) from the vehicle's position (current position) (Condition 1). This can be performed using the same algorithm as the conventional process of extracting alarm targets that are within a circle of radius r around the current position based on straight-line distance, and the extracted alarm targets are designated as alarm target candidates. Here, r should be set to be less than or equal to the predetermined proximity distance in (3) below. Assuming that the vehicle travels along an actual road from the current position to the alarm target, the travel distance will be equal to or longer than the straight-line distance from the current position to the alarm target. By setting r to the proximity distance, it is possible to avoid extracting alarm target candidates that cannot be alarm targets that should issue an alarm. The case where the travel distance and the straight-line distance are equal is when the vehicle's current position and the alarm target are connected by a single straight road, and in most cases the straight-line distance is shorter. Therefore, by setting r shorter than the predetermined proximity distance in (3), the number of alarm target candidates extracted will be reduced, and the load on the processing from (2) onward will be reduced.

[0063] (2) Next, the control unit 18 performs a route search from the current location to each of the potential warning targets. This is done using the technology of recommended route search in a car navigation system. That is, each potential warning target is considered a destination in the navigation system, the location information of each potential warning target is set sequentially as the location information of the destination, and the recommended route from the current location to the destination is determined based on the road network information stored in the database 19. The database 19 contains road network information, including location information of nodes such as intersections and information indicating the connection relationships between each node. Therefore, the control unit 18 finds candidate routes from the current location to the location of the potential warning target set as the destination, passing through adjacent nodes in sequence, and determines one route that meets the conditions as the recommended route. The conditions for the recommended route are that the route with the shortest distance is selected as the recommended route. Alternatively, the route that takes the shortest time to reach the destination may be selected as the recommended route, rather than the shortest distance. Furthermore, various conditions may be added when searching for a route, such as prioritizing general roads or prioritizing toll roads. For calculating this recommended route, known methods such as Dijkstra's algorithm can be used. Furthermore, the control unit 18 determines the distance traveled when traveling from the current position to the candidate for alarm along the determined recommended route. In this embodiment, the route with the shortest travel distance to the candidate for alarm is determined as the recommended route, so the travel distance obtained during this determination is used.

[0064] (3) The control unit 18 determines that a warning should be issued for a vehicle whose travel distance to reach a candidate for warning via the recommended route is within a predetermined proximity distance (for example, 2 km) (Condition 2). Furthermore, if an installation direction (monitoring direction) is registered for a vehicle to be warned, the control unit 18 extracts vehicles to be warned that meet the warning conditions, such as those whose travel distance is within the predetermined proximity distance and whose direction of travel just before reaching the candidate for warning via the recommended route and the installation direction of the vehicle to be warned, and determines that such vehicles to be warned (Condition 3).

[0065] For example, if the alarm target is a vehicle speed measuring device, there is a monitoring area where the vehicle's speed is measured. If the vehicle speed measuring device uses microwaves, this monitoring area is within a predetermined angular range to the left and right of the direction the microwave-emitting antenna is facing, and within a certain distance from the vehicle speed measuring device. Therefore, if a vehicle approaches the vehicle speed measuring device from the opposite direction of installation, there is little need to issue an alarm about the presence of that vehicle speed measuring device. Thus, by registering the direction of the vehicle speed measuring device (antenna) as the installation direction, it is possible to determine whether an alarm is necessary even if the distance to the potential alarm target is short, based on the relationship with the direction of travel of the vehicle. In this way, the installation direction of the alarm target can specify the monitoring area, but it is not limited to the range from which microwaves are emitted as described above. For example, if there is an alarm target that monitors only one of the uphill or downhill lanes of a road, it is appropriate to set the direction in which either the uphill or downhill lane extends as the installation direction.

[0066] Next, we will explain the determination based on the above processes (1) to (3) with a concrete example. For example, as shown in Figure 5, suppose there are four registered alarm targets (satisfying condition 1) that exist around the current position of the vehicle G (within radius r). Then, by executing process (1), the control unit 18 extracts these four alarm targets as alarm target candidates K1 to K4. Next, the control unit 18 executes process (2) and performs a route search for each alarm target candidate K1 to K4. That is, the control unit 18 sets alarm target candidate K1 as the destination and searches for a recommended route from the vehicle's position. Then, for example, as shown in Figure 6(a), the control unit 18 determines route R1, which involves turning left at the first T-junction and then turning left again at the next intersection, as the recommended route.

[0067] The control unit 18 then sets the alarm target candidate K2 as the destination and searches for a recommended route from the vehicle's current position. For example, as shown in Figure 6(b), it determines route R2, which involves turning left at the first T-junction and then going straight, as the recommended route. Similarly, the control unit 18 sets the alarm target candidate K3 as the destination and searches for a recommended route from the vehicle's current position. For example, it determines route R3, as shown in Figure 6(c), as the recommended route. Since alarm target candidate K3 is set on a highway, a vehicle traveling on a general road will take a route that goes to an interchange and then enters the highway. Furthermore, the control unit 18 then sets the alarm target candidate K4 as the destination and searches for a recommended route from the vehicle's current position. For example, it determines route R4, as shown in Figure 6(d), as the recommended route.

[0068] Subsequently, the control unit 18 executes the process in (3) and extracts alarm target candidates that satisfy condition 2 or condition 3. First, in the determination based on the distance traveled to reach the alarm target candidate via the recommended route common to conditions 2 and 3, the alarm target candidate K3, which is located on a highway, is excluded from the alarm targets because the distance traveled is much greater than the straight-line distance and is greater than the approach distance. In this way, if the road type of the road currently being traveled and the road on which the alarm target is installed are different, in many cases the alarm target can be excluded without determining whether the road types match or not.

[0069] In other words, with this type of radar detector, the target of the alerts can be switched via settings, such as highways, general roads, or both. If "both" is selected, it can be annoying to receive alerts about highway targets when driving only on general roads. In this case, one can simply select "general roads" as the alert target, but switching such settings is complicated and there is a risk of incorrect settings. Similarly, it can be annoying to receive alerts about alert targets installed on parallel general roads while driving on a highway. In this case, one can simply select "highways" as the alert target, but switching such settings is complicated and there is a risk of incorrect settings. Furthermore, for example, if an alert target is set at a point on a general road relatively close to a highway exit, and the alert target is set to only highways, the driver will only become aware of the existence of the alert target after exiting the highway and entering the general road. In other words, a drawback arises in that the driver will not be aware of the existence of that alert target near the highway exit.

[0070] In contrast, as in this embodiment, if the alarm is issued only when the distance traveled to reach the alarm target candidate via the recommended route is less than or equal to the approach distance, then, as shown in Figure 5, the distance traveled from vehicle G, which is traveling on a general road, to alarm target candidate K3 on the expressway is far, so an alarm can be avoided. Also, if a vehicle is located at the position of alarm target candidate K3 (while traveling on an expressway), although alarm target candidates K2 and K4 are very close in a straight line from the vehicle's position, actually reaching the positions of alarm target candidates K2 and K4 would require exiting onto a general road at a distant interchange exit, traveling on the general road, and then returning, resulting in a very long travel distance. Therefore, in such cases, alarm target candidates K2 and K4 can also be excluded from the targets for which an alarm is issued. On the other hand, although specific illustrations are omitted, if a vehicle is traveling near an expressway exit, the distance traveled to the alarm target located on the road furthest from that exit is relatively short because the vehicle can simply exit at that exit, and it can be set as an alarm target for which an alarm is issued. Therefore, by making a decision based on the distance traveled to reach a potential warning target via the recommended route, it is possible to normally avoid issuing warnings for warning targets located on different road types while driving on general roads or expressways. Conversely, warnings can be issued for warning targets located on general roads near expressway exits while driving on expressways, or vice versa, for warning targets located near expressway entrances while driving on general roads near expressway entrances.

[0071] Furthermore, in the example described above, since the installation direction is registered for all four alarm target candidates K1 to K4 (monitoring the direction of the arrows in the figure), the control unit 18 determines whether or not condition 3 is satisfied. If the vehicle is moving in the direction of installation, it will enter the monitoring area of ​​the alarm target and be monitored if it continues moving. For example, if the alarm target is a vehicle speed measuring device, the vehicle's speed will be measured, and if the alarm target is an N system, the vehicle's license plate will be photographed.

[0072] In other words, as shown in Figure 7(a), if the direction of travel of the vehicle and the installation direction (monitoring direction) of the alarm target are opposite (the angle between them is 180 degrees), it can be determined that the alarm target is located ahead of the direction of travel of the vehicle, and that if the vehicle continues on, it will enter the monitoring area of ​​the alarm target. In contrast, as shown in Figure 7(b), if the angle between the direction of travel of the vehicle and the installation direction (monitoring direction) of the monitoring target is 0 degrees, it means that the vehicle is either moving in the opposite direction to the alarm target, or even if it is moving towards the alarm target, the monitoring direction is different, and therefore it is not an alarm target that should issue an alarm. Furthermore, in this embodiment, in the example shown in Figure 7, if it is within a range of ± a predetermined angle (for example, ±90 degrees) centered on 180 degrees, it is determined that it is an alarm target that should issue an alarm. Of course, the angle range is not limited to 90 degrees and can be set arbitrarily. The specific algorithm for determining whether the installation direction of the alarm target and the direction of travel of the vehicle are in a predetermined angle relationship can be implemented using, for example, the technology disclosed in Japanese Patent Application Publication No. 2002-228741.

[0073] What is important in this embodiment is the relationship between the direction of travel of the vehicle and the direction of monitoring of the warning target when the vehicle is traveling on the road where the warning target is installed. In other words, for example, if we focus on the candidate warning target K4, the current direction of travel of the vehicle and the direction in which the candidate warning target K4 is installed are almost the same, so based on the direction of travel of the vehicle at the current position, it is determined that it is not a warning target that should issue a warning. However, when the vehicle actually reaches the candidate warning target K4 and passes in front of it, as shown by route R4 in Figure 6(d), it will be traveling in the direction in which the warning target is installed, and it will become a warning target that should issue a warning.

[0074] Furthermore, focusing on the potential alarm target K1, the current direction of travel of the vehicle and the direction in which the potential alarm target K1 is installed are almost opposite. Based on the direction of travel of the vehicle at its current position, it is determined that it is an alarm target that should issue a warning. However, when the vehicle actually reaches the potential alarm target K1 and passes in front of it, as shown by route R1 in Figure 6(a), it will be traveling in the same direction as the installation direction of the alarm target, and it will no longer be an alarm target that should issue a warning.

[0075] As a result, in relation to the direction of the vehicle's movement and the installation direction of the alarm target, alarm target candidates K2 and K4 become the targets for which an alarm will be issued, while alarm target candidates K1 and K3 do not. Therefore, the control unit 18 extracts alarm target candidates K2 and K4 as alarm targets that satisfy condition 3.

[0076] Of course, even in the conventional method disclosed in, for example, Japanese Patent Publication No. 2002-228741, an alarm can be issued when the vehicle approaches the alarm target candidate K4 because the direction of travel of the vehicle and the direction in which the alarm target is installed are opposite. However, in this embodiment, an alarm can be issued from a more distant position prior to that. Furthermore, in the conventional method described above, the alarm target candidate K1 is initially identified as an object that should be alarmed, and an alarm is issued. However, as the vehicle progresses, it moves out of a predetermined angular range in front of the vehicle's position, so the alarm is never issued until the end. In contrast, in this embodiment, no alarm is issued from the beginning, thus preventing unnecessary alarms and notifications from being issued to the driver.

[0077] Furthermore, the control unit 18 notifies the candidates for alarm targets K2 and K4, which have been extracted in this manner, using alarm output means such as the display unit 5, lamp 6, and speaker 20. In this case, the notification can be basically the same as that known conventionally.

[0078] In other words, Figure 8 represents an example of an alarm screen based on the example shown in Figure 5. Here, two potential alarm targets, K2 and K4, are used as actual alarm targets, and predetermined polygons are drawn on the map at the corresponding locations according to the alarm types registered for them.

[0079] First, the screen area layout adopts a configuration in which a strip-shaped icon display area E2 is placed above the rectangular main display area E1, which occupies the majority of the screen area. Of course, this icon display area E2 may be placed at an appropriate position on the bottom or left or right, or it may not be placed at all. The icon display area E2 may contain icons that indicate the operating status of the device, such as the icon I1 that indicates GPS reception, or icons I2 that notify the type of alarm target. Such displays are controlled by the control unit 18. Furthermore, the remaining distance to the alarm target is drawn at the right edge of the icon display area E2. To make this remaining distance more prominent, it may be drawn in a separate window at an appropriate position, such as the lower right of the main display area E1. In that case, the right edge of the icon display area E2 may display the current time, date, or other information. Also, this remaining distance may be the straight-line distance as in the conventional method, but preferably it should be the distance traveled by following the recommended route from the current location to the alarm target. This way, the remaining distance value decreases (approaches) to match the actual distance traveled, eliminating any sense of incongruity.

[0080] Furthermore, the main display area E1 primarily shows the positional relationship between the warning target and the vehicle, and is an area for displaying objects of predetermined shapes at their respective positions. This display unit 5 is divided into multiple layers, each rendering images and other elements. Specifically, the bottom layer renders the background color. This background color is rendered using a gradient so that it becomes brighter towards the foreground (vehicle side: bottom of the screen), or it is rendered as a single color. In addition, the color is varied depending on the positional relationship with the warning target. That is, if the warning target exists but is more than a certain distance away (for example, more than 500m), green is used as the base color, and when the distance to the warning target approaches less than a certain distance, the base color is changed to a different color (for example, "yellow"). Furthermore, when approaching, the base color is changed to red, and by changing the color as appropriate, the driver can easily understand that they are approaching.

[0081] The remaining distance to the warning target, which serves as the basis for changing the color, may be based on the straight-line distance between the two, as in the past, but it is preferable to use the distance traveled by taking the recommended route from the current location to the warning target. By changing the color based on the distance traveled, even if the straight-line distance is very close, such as when the locations are on adjacent roads, if the distance traveled to reach the potential warning target via the recommended route is considerable, a green base color can be used to let the driver know that arrival will not be immediate.

[0082] The control unit 18 retrieves the corresponding map data for the displayed space and draws that map data (a rough road map) on a layer above the background color layer. Then, the control unit 18 draws various objects on layers above the map data drawing layer. An object indicating the vehicle's position (hereinafter referred to as the "vehicle object") Gob is drawn at a predetermined position below the main display area R1. In the figure, it is drawn as a two-dimensional mark with an arrow indicating the direction of travel drawn inside a circle, but it is preferable to make the vehicle object Gob more three-dimensional by constructing it from a triangular or square pyramidal polygon. In that case, when the control unit 18 draws the vehicle object Gob, it is preferable to draw it so that the vertices of the triangular or square pyramidal pyramid face forward in the direction of travel of the vehicle, and so that it appears to be floating in mid-air (by drawing a shadow below it). In the following description, unless otherwise specified, the control unit 18 is responsible for drawing each object and other images on the display screen of the display unit 5.

[0083] Furthermore, if there is an object that should be alerted within the displayed space, the object of that object is drawn at the corresponding position on the screen. In this case, there are often multiple objects registered in the database 19 that should be alerted in the surrounding area. In this case, one that satisfies the conditions is designated as the actual object to be alerted (the object of the alarm), and the object to be alerted, Kob, is drawn at the position on the display screen corresponding to the location where that object exists. For other objects that could potentially be alerted, the control unit 18 draws an object corresponding to the type of object detected as a POI (Point of Interest) object, Iob, at the corresponding position.

[0084] In the diagram, both the alert target object Kob and the POI object Iob are represented as two-dimensional marks with a symbol indicating the type of alert target inside a circle. The alert target object Kob is also indicated by a pair of triangular indicator marks so that its presence can be easily identified. Furthermore, if the installation direction is registered for the alert target object Kob, that direction is also indicated by an arrow. This allows drivers to see at a glance whether or not there are alert targets on the road they plan to travel on.

[0085] Furthermore, the alert target object Kob and the POI object Iob may also be rendered as three-dimensional polygons, similar to the vehicle object. In that case, it is preferable that the display of the alert target object Kob be a three-dimensional shape that mimics something related to the actual alert target, as this makes its type more intuitively understandable.

[0086] Furthermore, in order to draw more attention to the presence of the warning target object Kob, it is advisable to draw a "guide line" connecting the vehicle object Gob to the warning target object Kob. This guide line should have both ends touching or being close to the vehicle object Gob and the warning target object Kob, and should also be drawn along the road or beside the road that leads from the vehicle object Gob to the warning target object Kob.

[0087] In particular, when there are many POI objects (Iobs), it can be difficult to spot the object to be warned at a glance. As shown in Figure 8, simply adding a triangular indicator mark or making it blink may not differentiate it from other POI objects (Iobs), and this difficulty is even more pronounced in radar detectors, which have a smaller display area compared to car navigation systems. Therefore, it is advisable to connect the two with guide lines made of dotted lines or different colors. Then, the driver can easily find the object to be warned by following these guide lines.

[0088] Furthermore, in that case, for example, as shown in Figures 9(a) to (c), if a guide line S is animated as a dotted line flowing from the vehicle object Gob to the warning target object Kob, and its tip eventually reaches the warning target object Kob, the driver can easily understand the presence of the warning target object Kob by watching the animation. In addition, since the animated guide line S extends along the road, the driver can easily understand whether or not it is the road they are about to travel on, and can intuitively understand whether it is a warning target that requires attention or something unrelated. [Other methods for determining recommended routes]

[0089] In the embodiment described above, in process (2), when determining a recommended route to use as a basis for calculating the travel distance, the control unit 18 selects the shortest route from among multiple routes from the current location to the candidate for alarm target as the recommended route. When determining this recommended route, the installation direction used in condition 3 may also be taken into consideration. That is, a typical recommended route is selected from among many routes from the current location to the destination that have the shortest travel distance or can be reached in the shortest time. However, as a condition for selecting this route, if there is a candidate for alarm target on a road where an installation direction has been set, the recommended route is one that proceeds in the direction of the installation direction as the direction of approaching the alarm target.

[0090] Furthermore, since the installation direction is already taken into account when determining the recommended route, the determination of whether or not an item should be alarmed, as performed in the above-mentioned process (3), is made based on whether or not condition 2 is satisfied. In other words, the control unit 18 determines that items that travel a certain distance (for example, 2 km) from the recommended route to the candidate item should be alarmed.

[0091] For example, as shown in Figure 6(a), the recommended route for potential warning target K1 is the route from the left side, not the route from the right side. In other words, in Figure 6(a), the distance traveled to the potential warning target is calculated assuming a route going in the opposite direction of the current travel (clockwise), and if that distance is 2km or more, it is not considered a potential warning target.

[0092] [Determine whether or not to issue a warning based on the number of right and left turns] In the embodiments and modifications described above, the algorithm for determining whether or not a vehicle should be subject to a warning using road network information was determined based on the distance traveled when following the recommended route. However, the present invention is not limited to this, and various methods can be used. For example, the following (1), (2), and (3)' are implemented.

[0093] (1) The control unit 18 first extracts alarm targets that are located within a radius r (for example, 1km, 2km) from the vehicle's current position (condition 1). This can be done using the same algorithm as the conventional process of extracting alarm targets around the current position based on straight-line distance, and the extracted alarm targets are designated as alarm target candidates.

[0094] (2) Next, the control unit 18 performs a route search from the current location to each candidate for alerting. This involves sequentially setting the location information of each candidate for alerting as the location information of the destination, and determining the recommended route from the current location to the destination based on the road network information stored in the database 19. For example, a known method such as Dijkstra's algorithm can be used to calculate this recommended route.

[0095] Detailed explanations of the processes up to (1) and (2) are omitted, but they are the same as those described above. In addition, when determining the recommended path in process (2), the installation direction of condition 3 may be taken into account, as in the modified example described above.

[0096] (3)′ Next, the number of intersections to which a driver must turn right or left if they proceed along the recommended route from their current location to the candidate for a warning is determined. Candidates for warnings with n or more such intersections (the number of intersections passed by going straight is not counted) are not designated as warning targets for which a warning should be issued. In other words, candidates for warnings with fewer than n intersections are designated as warning targets for which a warning should be issued. That is, in cases where a driver is traveling on a complex route that requires turning right or left at n or more intersections to reach a warning target, it is highly likely that they will not actually travel on the road where the warning target is installed. In particular, in cases where it is necessary to turn at many intersections to get there even if the straight-line distance is short, it is highly likely that the driver will not go to the location where the warning target is installed. Therefore, since notifying such warning targets may result in an unnecessary warning for the driver, they are not designated as warning targets for which a warning should be issued.

[0097] This allows the system to extract warning targets that are relatively easy to reach (highly likely to reach) from among the warning targets present within a certain distance in a straight line, and issue warnings accordingly. In other words, by not issuing warnings for warning targets that are unlikely to actually be reached, the number of warning targets to be issued for can be effectively reduced, and the system can appropriately notify the driver of what is necessary. Of course, even if the number of warnings is less than n, if the direction in which a warning target is installed is set, a function may be provided to discriminate whether or not to issue a warning based on the angular relationship with the direction of travel on the road immediately preceding it.

[0098] Furthermore, setting n to 2 is preferable because it prevents warning targets installed on other roads parallel to or adjacent to the road being traveled on from being designated as warning targets. That is, for example, as shown in Figure 10(a), suppose a vehicle G is traveling on the road on the left, and a warning target K is installed on the road on the right that is parallel to it. In this case, if the vehicle continues straight on the road on the left, it will not reach the warning target K on the road on the right. Therefore, for the driver currently traveling straight on the left-hand road, the warning about the warning target K is unnecessary and may even be perceived as a nuisance.

[0099] As is clear from Figure 10(a), in order for vehicle G to travel along the recommended route and reach the warning target K, it needs to make two turns: a right turn at intersection A and a left turn at intersection B. This example is not limited to this case, but when there are two roads that are roughly parallel (not intersecting), in order for a vehicle traveling on one road to reach the other road, it needs to change direction (turn right / left) at an intersection on the road it is currently traveling on in order to leave the road it is currently traveling on, and then turn right or left at an intersection on the other road in order to enter the other road. In this case, the vehicle will change course at least twice at intersections. On the other hand, as illustrated in the above embodiment, for example, if the warning target exists on a road that intersects with the road the vehicle is traveling on, simply making one turn at an intersection on the road the vehicle is traveling on could result in the vehicle coming into contact with the warning target.

[0100] Therefore, by setting n=2, it becomes possible to know about warning targets installed around a turn at an intersection, etc., before turning, while warning targets installed on other parallel roads, etc., do not receive notifications.

[0101] In the case shown in Figure 10(a), if the vehicle turns right at intersection A, as shown in Figure 10(b), the recommended route from the vehicle G's current position to the warning target K is to turn left once at intersection B to reach the warning target K, and therefore the warning will be issued at that point.

[0102] Furthermore, as shown in Figure 10(a), if a warning target exists on the left-hand road while driving, and the distance to that warning target is longer than the distance to the warning target K installed on the right side, the control unit 18 will issue a warning for the warning target installed on the left-hand road because it is necessary to make two turns to reach the warning target K.

[0103] Regarding how the display unit issues warnings, if there are multiple warning targets in the vicinity, it is best to sort them in order of the number of turns required, prioritizing those with fewer turns required. If the number of turns is the same, the vehicle with the shortest driving distance to the warning target should have a higher priority. Of course, you can also consider the priority given to the type of warning target to further prioritize them.

[0104] [Time-based determination] Another algorithm for determining whether or not a vehicle should be subject to a warning can be used, which is the estimated time to reach the vehicle. That is, the control unit 18 determines a recommended route using the methods shown in each embodiment and its modifications described above. The control unit 18 then determines the estimated time to reach the vehicle when traveling along the determined recommended route, and if that estimated time is less than or equal to a preset threshold value, it determines that the vehicle should be subject to a warning. The estimated time can be calculated using, for example, probe information on traffic congestion obtained through VICS or communication.

[0105] [Alarm behavior for the display unit] As shown in Figure 11, for alarm targets in the surrounding area that satisfy condition 2 or condition 3, the alarm information for each should be drawn on a virtual sign 51 and then drawn overlapping in the front-to-back direction to create a sense of depth. The alarm information written on the virtual sign 51 here includes the type of alarm target, information identifying the installation location, and the remaining distance, but it should not interfere with the display of other information. For example, when driving on a straight road, the view should be similar to that of multiple intersection guide signs installed from the near side to the far side, and the virtual signs 51 should be drawn smaller towards the far side to create a sense of depth. This makes it easy to see the priority levels at a glance. Also, as the route changes while driving, the priority of each alarm target will change, so in such cases, it is good practice to rearrange the front-to-back order of the virtual signs 51 according to the priority.

[0106] Furthermore, in the embodiments and modifications described above, items that do not satisfy the conditions are not drawn on the display unit 5 as alarm targets for which an alarm should not be issued. However, the present invention is not limited to this, and the display mode may be changed to draw them. That is, items that do not satisfy the conditions should not become alarm target objects Kob (which notify detailed alarm information). It is also preferable that they not become POI (Point of Interest) objects Iob. For alarm targets that satisfy condition 1 and are candidates for alarm targets but do not satisfy conditions 2 and 3, a simple object (such as a simple shape like a circle, or a circle with a smaller radius) is drawn at the corresponding position. This allows the driver to know that there is some kind of alarm, even if it does not fall under the category of alarm targets for which an alarm should be issued.

[0107] The embodiments and modifications described above show examples of application to a radar detector as an electronic device, but the present invention is not limited to this, and may be incorporated as a function of a car navigation system or other electronic device.

[0108] Furthermore, in the embodiments and modifications described above, the device is equipped with a database 19 that stores various types of information, and the control unit 18 accesses the database 19 to read the necessary information and perform various processes. However, the present invention is not limited to this. That is, some or all of the information to be registered in the database 19 is registered in a server. The radar detector and other electronic devices and equipment are equipped with a function to communicate with the server, and the control unit 18 may be configured to access the server as appropriate, obtain the necessary information, and perform processing. [Explanation of symbols]

[0109] 1 Case body 2 Solar Panels 4. Microwave receiver 5 Display section 6 lamps 7. Infrared communication device 8 GPS receiver 9 Adapter jacks 10 Power switch 11 Mobile phones 12. Memory card reader 14 Memory Cards 15 Wireless receiver 16 Remote control receiver 17 Remote control 18 Control Unit 19 Databases 20 speakers

Claims

1. A function to obtain the vehicle's current location, A function that displays the warning targets around the aforementioned vehicle on a map, A function to display an arrow on the map indicating the installation direction or monitoring direction of the alarm target, Equipped with, When there are multiple items that require a warning, the function prioritizes the items in descending order of the number of turns the vehicle makes to reach the item, and if the number of turns is the same, the priority is given to the items with the shortest travel distance the vehicle would have to travel to reach the item. A function to display the multiple alarm targets so that the priority can be recognized, A system characterized by comprising the following features.

2. A program for a computer to implement the functions of the system described in claim 1.

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