Detection Machine

Abstract

To provide a detector capable of quickly notifying reception of laser light radiated by a speed measurement device while suppressing false alarms.SOLUTION: A laser light determination unit 54 of a detector 1 provided herein uses light received by a photosensor 4 to determine if the light matches determination conditions. The laser light determination unit 54 compares a pulse interval of a detection signal with an integer multiple of a predetermined pulse interval D. In other words, the determination conditions include a pulse interval condition that the pulse interval of the detection signal should be an integer multiple, including 1x, of a laser light emission interval.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a detector capable of receiving laser light emitted by a laser type speed measurement device. [Background technology]

[0002] When a vehicle approaches a speed measuring device or receives radar waves from the speed measuring device, the detector issues information directly or indirectly encouraging compliance with the speed limit. This detector does this by receiving radar waves emitted from the speed measuring device with an antenna. The detector also has a function of notifying a warning when it detects that the vehicle's position, determined by GPS, has come within a certain distance from the position of a previously registered speed measuring device.

[0003] In recent years, speed measuring devices have been moving towards non-radar types, such as loop coil types and photocell types. In line with this trend towards non-radar, laser light type speed measuring devices have been developed. Laser light type speed measuring devices detect the speed of a vehicle by scanning a specified range with a laser light, irradiating the vehicle with the laser light and detecting the reflected laser light. There are fixed types that are installed in a fixed location, and mobile types that are easy to install and remove. The laser light is emitted continuously for a specified transmission time at a specified transmission interval. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6161429 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional detectors do not have the function to detect laser light, so they cannot detect laser light-based speed measuring devices unless the installation location is known. Therefore, the development of detectors that can detect laser light has progressed, but because laser light has a characteristic that radar waves do not have, namely high directivity, there is a risk that the timing of reporting that laser light has been delayed.

[0006] In other words, because radar waves are highly diffusive, the detector sensor can receive the radar waves even if it is not positioned on the axis of irradiation of the radar waves. In contrast, because laser light is highly directional, the detector sensor must be positioned on the optical axis of the laser light emitted by the speed measurement device, which reduces the opportunities to receive the laser light.

[0007] Therefore, when the vehicle is far from the speed measurement device, a situation may occur in which the first laser light is successfully received but the second laser light is unsuccessful. Also, when an obstruction is present between the vehicle and the speed measurement device, a situation may occur in which the first laser light is successfully received but the second laser light is unsuccessful. There is also a concept of issuing a warning to encourage compliance with the speed limit when the first laser light is received, but this would increase the number of false alarms.

[0008] The present invention has been proposed to solve the problems of the conventional technology as described above, and its object is to provide a detector that quickly reports the reception of laser light emitted by a speed measuring device while reducing false alarms. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, a detector of the present invention is a detector installed in a vehicle, and comprises an optical sensor that receives light in a wavelength band that includes the wavelength of laser light emitted by a speed measurement device, and outputs a detection signal based on the light-receiving time and light-receiving interval of the light, a judgment unit that judges whether the detection signal matches a judgment condition based on the detection signal output by the optical sensor, and a notification unit that notifies predetermined information when the judgment unit judges that the detection signal satisfies the judgment condition, wherein the judgment conditions include a pulse interval condition in which the pulse interval of the detection signal is an integer multiple including 1 time the transmission interval of the laser light, and the judgment unit judges the pulse interval condition.

[0010] The judgment conditions may include a first NOT condition in which the pulse interval of the detection signal is an integer multiple including 1 time of a predetermined pulse interval that is different from the transmission interval of the laser light, and the judgment unit may be configured to judge the first NOT condition in addition to the pulse interval condition.

[0011] The judgment conditions may include a second NOT condition in which the pulse interval of the detection signal is the interval between the reception of the laser light and a noise appearing immediately after the reception of the laser light, and the judgment unit may be configured to judge the second NOT condition in addition to the pulse interval condition.

[0012] The judgment condition may include an AND condition that a pulse width of the detection signal falls within a predetermined range including an emission time of the laser light, and the judgment unit may judge the AND condition in addition to the pulse interval condition.

[0013] The vehicle may be provided with a distance calculation unit that calculates a distance between the vehicle and the speed measurement device, and the judgment unit may change the judgment condition based on the distance calculated by the distance calculation unit, and if the distance calculated by the distance calculation unit is within a predetermined distance, judge the judgment condition to be a pulse width condition in which the pulse width of the detection signal falls within a predetermined range including the transmission time of the laser light, and if the distance calculated by the distance calculation unit is not within the predetermined distance, judge the judgment condition to include an AND condition of the pulse interval condition and the pulse width condition.

[0014] The determination unit may have a condition fulfillment counter and determine whether the determination condition is fulfilled a predetermined number of times, which is equal to or greater than two.

[0015] The judgment condition may include one or more AND conditions including the pulse width condition and a predetermined NOT condition, and the judgment unit may have a condition fulfillment counter and judge whether the judgment condition is satisfied a predetermined consecutive number of times that is two or more, and if the light corresponds to the predetermined NOT condition, the value of the condition fulfillment counter may be maintained.

[0016] The judgment conditions may include a first NOT condition in which the pulse interval of the detection signal is an integer multiple including one of a predetermined pulse interval different from the transmission interval of the laser light, and further include a second NOT condition in which the pulse interval of the detection signal is the interval between the reception of the laser light and a noise appearing immediately after the reception of the laser light, and the judgment unit may have a condition fulfillment counter and judge whether the judgment condition is satisfied a predetermined number of times or more, and maintain a value of the condition fulfillment counter when the light corresponds to the first NOT condition or the second NOT condition.

[0017] The optical sensor may have an optical filter that limits the wavelength of light to a predetermined wavelength band, and the predetermined wavelength band may include, in addition to the laser light of the speed measuring device, the wavelengths of light emitted on roads and along roads. Effect of the Invention

[0018] According to the present invention, even if all of the laser light cannot be received continuously, a notification urging the driver to observe the speed limit can be given. In addition, since a notification is given when the laser light is received two or more times, false notifications can also be suppressed. [Brief description of the drawings]

[0019] [Figure 1] 1 is a perspective view showing the surface of the detector facing outside the vehicle. [Diagram 2] FIG. 2 is a perspective view showing the surface of the detector facing the interior of the vehicle. [Diagram 3]FIG. 2 is a block diagram showing the internal configuration of the detector. [Figure 4] 2 is a block diagram showing the configuration of a control unit of the detector. FIG. [Diagram 5] 13 is a flowchart showing a first operation example of an optical signal determination unit. [Figure 6] 11 is a schematic diagram showing an effect based on a first operation example. FIG. [Figure 7] 13 is a flowchart showing a second operation example of the optical signal determination unit. [Figure 8] 13 is a schematic diagram showing an effect based on a second operation example. FIG. [Figure 9] 13 is a flowchart showing a third operation example of the optical signal determination unit. [Figure 10] 13 is a schematic diagram showing an effect based on the third operation example. FIG. [Figure 11] 11 is a first flowchart showing an example of the overall operation of an optical signal determination unit. [Figure 12] 13 is a second flowchart showing an example of the overall operation of the optical signal determination unit. [Figure 13] 13 is a third flowchart showing an example of the overall operation of the optical signal determination unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] (composition) A detector according to an embodiment of the present invention will be described in detail with reference to the drawings. The detector 1 is installed in a vehicle such as an automobile, a motorcycle, a truck, or a bus. This detector 1 notifies the driver of information encouraging the driver to observe the speed limit by direct or indirect content when an event that should encourage the driver to observe the speed limit occurs. The detector 1 is typically installed on the dashboard and is powered from the vehicle side via an OBD-II connector or a cigarette lighter socket. The dashboard is an example of a place that is easy to receive radar waves and laser light emitted by a speed measurement device and can notify the driver of information. Radar waves and laser light are collectively called electromagnetic waves.

[0021] Speed ​​measuring devices include radar types that emit radar waves, non-radar types that have loop coils or photocells, and laser light types that emit laser light, and the radar and laser light types are available in both fixed and mobile types. Events that should encourage speeding are when a vehicle arrives within a specified distance of a speed measuring device whose installation location is known, and when electromagnetic waves emitted by the speed measuring device are received. Examples of information to be notified include the presence of the speed measuring device, the type of the speed measuring device, the reception and type of electromagnetic waves emitted by the speed measuring device, or a warning to observe the speed limit, or a combination of these.

[0022] As shown in Figures 1 and 2, the detector 1 is equipped with a screen 14, a speaker 15, and a lamp 16 on the outer surface of a housing 10. The screen 14 is a liquid crystal display or an organic EL display, etc., and is arranged on the front surface 12 of the detector 1, and displays the notification information in a visually appealing format such as letters, pictures, and symbols. The speaker 15 outputs the notification information as audio. The lamp 16 notifies the user of the notification information by regular emission of light such as colors, flashing, and lighting intervals. The front surface 12 faces the interior of the vehicle and is visible to the driver, while the rear surface 11 faces the exterior of the vehicle via the windshield.

[0023] The rear surface 11 of the detector 1 is a receiving area 13. That is, as shown in FIG. 3, the radio wave sensor 2, the positioning signal receiving unit 3, and the optical sensor 4 are arranged inside a housing 10 on the rear surface 11. The radio wave sensor 2 has an antenna and a demodulator such as a superheterodyne type demodulator, and receives and detects radar waves in the wavelength bands of X-band and K-band irradiated by a radar-type speed measuring device. When the radio wave sensor 2 receives the radar waves from the speed measuring device, it outputs a detection signal. The positioning signal receiving unit 3 has an antenna, demodulator, and processor capable of receiving radio signals from a positioning satellite, receives and demodulates the positioning signal of a GNSS (Global Navigation Satellite System), and calculates the vehicle position consisting of the latitude and longitude of the current position.

[0024] The optical sensor 4 includes an optical filter 41, a light receiving element 42, and a conversion unit 43, and outputs a detection signal when it receives light. The detection signal is a voltage signal having a pulse width that matches the light receiving time, and is output at pulse intervals that match the light receiving interval.

[0025] This optical filter 41 is preferably made of a material that easily transmits light even from an oblique angle, for example, acrylic resin. This makes it possible to suppress reception leakage even when the filter surface of the optical filter 41 is obliquely intersecting with the optical axis of the laser light emitted by the speed measurement device when the speed measurement device is installed along a road. However, the optical filter 41 is not limited to being made of acrylic resin, and a wide variety of known materials can be used.

[0026] Moreover, the optical filter 41 is a filter that transmits a wavelength band including the wavelength of the laser light emitted by the speed measurement device. This wavelength band may include, for example, the wavelengths of light emitted by VICS (registered trademark), N system, an in-vehicle distance measurement sensor, other facilities on the road, and vehicles in motion. For example, the wavelength band transmitted by the optical filter 41 may include light emitted by an electronic scoreboard mounted on a vehicle.

[0027] The light receiving element 42 is a detector that responds to light including the wavelength band transmitted by the optical filter 41 and passes a current when it receives light. The light receiving element 42 is placed behind the optical filter 41 and receives light that has passed through the optical filter 41. The light receiving element 42 is, for example, a phototransistor or a photodiode.

[0028] The conversion unit 43 converts the current signal output by the light receiving element 42 into a voltage signal and outputs it as a detection signal. This conversion unit 43 is configured to include, for example, an operational amplifier, and when it receives a current signal from the light receiving element 42, it drops the voltage from the reference voltage and outputs a Lo signal, and when the current signal from the light receiving element 42 stops, it raises it back to the reference voltage. That is, the optical sensor 4 drops the voltage to the Lo level at a timing that coincides with the start of light reception, and maintains the voltage at the Lo level to coincide with the light reception time. The period during which this voltage is at the Lo level is called a detection signal. However, the logic of the voltage level including the reference voltage may be reversed.

[0029] 3, the detector 1 further includes a control unit 5 and an alarm unit 6. The radio wave sensor 2, the positioning signal receiving unit 3, and the optical sensor 4 input signals to the control unit 5. This control unit 5 is a so-called computer that includes a processor such as a CPU, FPGA, or microcomputer, storage for storing programs and data, and a work memory.

[0030] The control unit 5 determines whether the radio wave sensor 2 and the optical sensor 4 have received electromagnetic waves from a speed measuring device. The control unit 5 also determines the distance between the vehicle position output by the positioning signal receiving unit 3 and a speed measuring device whose installation location is known, and a location where a speed measuring device has been installed in the past (hereinafter collectively referred to as a registered speed measuring device). Then, the control unit 5 causes the notification unit 6 to notify information according to the determination result. The notification unit 6 is a screen 14, a speaker 15, a lamp 16, or a combination of these, which are arranged on the outer surface of the housing 10.

[0031] 4, the control unit 5 includes a radar wave processing unit 51, a distance calculation unit 52, a storage unit 53, and a laser light determination unit 54, which are implemented by program processing by a processor, etc. When a detection signal from the radio wave sensor 2 is input to the control unit 5, the radar wave processing unit 51 performs interrupt processing and causes the notification unit 6 to notify information encouraging compliance with the speed limit. In particular, it is desirable for the radar wave processing unit 51 to notify the notification unit 6 of information notifying the presence of a radar-type speed measurement device and the reception of radar waves emitted by the speed measurement device.

[0032] The memory unit 53 is configured with a storage provided in the detector 1 or a portable storage medium such as an SD card, and stores the latitude and longitude of the registered speed measurement device. The distance calculation unit 52 calculates the distance between the vehicle position output by the positioning signal receiving unit 3 and the registered speed measurement device stored in the memory unit 53.

[0033] Furthermore, the distance calculation unit 52 has a preset threshold value and compares the calculation result with the threshold value. If the calculation result is equal to or less than the threshold value, that is, if the vehicle position is within a predetermined distance from a registered speed measurement device, the distance calculation unit 52 controls the notification unit 6 to notify the information. In particular, it is desirable for the distance calculation unit 52 to cause the notification unit 6 to notify the presence and type of a registered speed measurement device, as well as information notifying the distance between the registered speed measurement device and the vehicle position.

[0034] When the detection signal of the optical sensor 4 is input to the control unit 5, the laser light determination unit 54 performs an interrupt process and determines whether the optical sensor 4 has received laser light from a speed measuring device. The laser light determination unit 54 has a determination condition, and determines whether the detection signal output by the optical sensor 4 matches the determination condition, and as a result, determines whether laser light has been received.

[0035] When the detection signal output by the optical sensor 4 matches the judgment condition, the laser light judgment unit 54 controls the notification unit 6 to notify the information. In particular, it is desirable for the laser light judgment unit 54 to cause the notification unit 6 to notify the presence of a laser type speed measuring device and the reception of laser light emitted by the speed measuring device.

[0036] (Example 1 of receiving light wave judgment) A first example of the determination process of the laser light determination unit 54 will be described with reference to Fig. 5. Fig. 5 is a flowchart showing a first operation example of the laser light determination unit 54. This laser light determination unit 54 changes the determination conditions according to the situation and suppresses delays associated with the determination process, thereby quickly reporting that a laser light from a speed measuring device has been received.

[0037] That is, the laser light determination unit 54 determines whether the pulse width of the detection signal output by the optical sensor 4 is equal to or less than a predetermined pulse width A (step S01). The pulse width is obtained by sampling the voltage at a sampling rate based on the clock frequency, for example, and calculating the number of sampled Lo-level voltages, or by converting this number into time. The predetermined pulse width A is stored in advance in the laser light determination unit 54, and the laser light determination unit 54 compares the obtained pulse width with the predetermined pulse width A.

[0038] This predetermined pulse width A is a threshold value for distinguishing the laser light of the speed measuring device from the light of several other known light emitting sources. This predetermined pulse width A has a value equal to or greater than the transmission time of the laser light emitted by the speed measuring device at one time, and has a value less than the transmission time of light emitted by other light emitting sources such as an N system at one time. The range below the predetermined pulse width A includes the transmission time of the laser light of the speed measuring device. However, the range below the predetermined pulse width A includes the transmission time of unknown or known light emitting sources that cannot be distinguished by the predetermined pulse width A because their transmission times are similar to those of the speed measuring device.

[0039] If the pulse width of the detection signal is not equal to or less than the predetermined pulse width A (step S01, No), it is unlikely that the optical sensor 4 has received the laser light of the speed measuring device, and the interrupt process ends. In other words, the notification process (step S09) is not executed.

[0040] If the pulse width of the detection signal is equal to or less than predetermined pulse width A (step S01, Yes), laser light determination unit 54 determines whether the vehicle position is within distance B from the registered speed measurement device (step S02). Distance B is stored in advance in laser light determination unit 54. The distance between the vehicle position and the registered speed measurement device is calculated by distance calculation unit 52 in response to an interrupt from positioning signal receiving unit 3, or is calculated periodically, and laser light determination unit 54 compares the calculation result of distance calculation unit 52 with distance B.

[0041] This distance B is the distance at which highly directional laser light can reach the vehicle. In other words, if the vehicle is located within the distance B and the optical sensor 4 outputs a detection signal with a predetermined pulse width A or less, the optical sensor 4 is more likely to have received the laser light of the speed measuring device, rather than receiving light from an unidentified light emitting source or a known light emitting source that irradiates light with a transmission time similar to that of the laser light of the speed measuring device.

[0042] Therefore, if the vehicle position is within distance B from the registered speed measuring device (Yes in step S02), the laser light determination unit 54 controls the notification unit 6 to notify information such as the reception of the laser light (step S09).

[0043] In this way, when the vehicle is located in a known location that is highly likely to receive the laser light from the speed measuring device, the laser light determination unit 54 performs notification processing using only the pulse width of the detection signal. As a result, the detector 1 can issue a notification with rapid timing, receiving only one pulse of light.

[0044] Although the embodiment has been described in which it is determined whether the vehicle position is within distance B after receiving light having a pulse width equal to or less than the predetermined pulse width A, the laser light determination unit 54 may compare the calculation result with distance B every time the distance calculation unit 52 calculates the distance, and may immediately perform notification processing when the optical sensor 4 receives light and the detection signal is equal to or less than the pulse width A. In this case, since the distance determination after light reception is omitted, notification can be performed at an even more rapid timing.

[0045] Here, if the vehicle position is not within distance B from the registered speed measuring device (step S02, No), high reliability cannot be obtained with only pulse width A, so the laser light determination unit 54 determines whether the light is from a speed measuring device based on a determination condition that includes other conditions (steps S03~). That is, the determination condition is changed depending on whether the vehicle position is within distance B from the registered speed measuring device.

[0046] If the vehicle position is not within distance B from the registered speed measuring device (step S02, No), the laser light determination unit 54 judges whether the condition fulfillment counter is zero (step S03). Even if the condition fulfillment counter is not zero (step S03, No), it determines whether the pulse interval of the detection signal is equal to or greater than a predetermined pulse interval C (step S04). The condition fulfillment counter is stored in the laser light determination unit 54 as a changeable variable, and the predetermined pulse interval C is stored in advance in the laser light determination unit 54.

[0047] The pulse interval is the time from the end of the previous detection signal, i.e., the time when the voltage rises to Hi level, to the end of the latest detection signal. The pulse interval is obtained by sampling the voltage at a sampling rate based on the clock frequency, for example, and calculating the number of Hi level voltage samples, or by converting this number into time.

[0048] The condition fulfillment counter is the number of consecutive light receptions that satisfy the judgment condition. When the condition fulfillment counter is zero, it means that the light reception having a pulse width equal to or less than the predetermined pulse width A is the first. In other words, it means that the first pulse that satisfies the condition of the laser light of the speed measuring device has been received. Furthermore, the predetermined pulse interval C is too long compared to the interval at which the laser light of the speed measuring device can be received, even taking into account failure to receive highly directional laser light, so it is an interval that can be regarded as the reception of the first pulse that satisfies the condition of the laser light of the speed measuring device.

[0049] If the condition fulfillment counter is zero (Yes in step S03) or if the pulse interval is equal to or greater than the predetermined pulse interval C (Yes in step S04), this is the first reception of light that may be a laser beam from a speed measuring device, and the laser beam determination unit 54 sets the condition fulfillment counter to "1" (step S05). The initial value of the condition fulfillment counter is zero.

[0050] If the condition fulfillment counter is not zero (step S03, No) and the pulse interval is not equal to or greater than the predetermined pulse interval C (step S04, No), this indicates that a first light that may be a laser light from a speed measuring device has already been received. At this time, the laser light determination unit 54 determines whether the pulse interval is an integer multiple of the predetermined pulse interval D (step S06). The predetermined pulse interval D is stored in advance in the laser light determination unit 54.

[0051] The predetermined pulse interval D is the transmission interval of the laser light of the speed measuring device. Here, since the laser light has high directivity, the optical sensor 4 may not receive all of the laser light, or the optical sensor 4 may not receive all of the laser light due to an obstruction such as a truck in front of the vehicle. In particular, since the speed measuring device scans a predetermined range on the road, if the vehicle is far away from the speed measuring device, there are fewer times when the optical sensor 4 is on the optical path of the laser light, and it is easy for times when the optical sensor 4 cannot receive the light to occur.

[0052] If there is a timing when the optical sensor 4 cannot receive the light, and it is determined that the light is not laser light because it does not match the predetermined pulse interval D, the vehicle must approach the speed measurement device to a position where the laser light can be received reliably, which will delay the notification. However, the laser light determination unit 54 takes into account the existence of timings when the light cannot be received by comparing with an integer multiple of the predetermined pulse interval D, thereby improving the promptness of the notification.

[0053] If the pulse interval is an integer multiple of the predetermined pulse interval D (step S06, Yes), the condition fulfillment counter is incremented by 1 (step S07). Note that the integer multiple of the predetermined pulse interval D also includes 1. On the other hand, if the pulse interval is not an integer multiple of the predetermined pulse interval D (step S06, No), the possibility of receiving laser light from a speed measuring device becomes low, so the condition fulfillment counter is initialized to zero (step S10) and the judgment process ends. In this way, the incremented condition fulfillment counter indicates the number of consecutive times that light that is likely to be laser light from a speed measuring device has been received.

[0054] When the condition fulfillment counter is incremented by 1 (step S07), the laser light determination unit 54 determines whether the condition fulfillment counter has reached a threshold value N (step S08). The threshold value N is stored in advance in the laser light determination unit 54. The laser light determination unit 54 compares the condition fulfillment counter with the threshold value N to determine which is larger.

[0055] If the condition fulfillment counter has reached the threshold value N (step S08, Yes), the laser light determination unit 54 performs a notification process (step S09), resets the condition fulfillment counter to its initial value of zero (step S10), and ends the determination process. If the condition fulfillment counter has not yet reached the threshold value N (step S08, No), the value of the condition fulfillment counter is left as it is and the determination process ends.

[0056] 6 is a schematic diagram showing the action based on the first operation example of the laser light determination unit 54. The threshold value N of the condition fulfillment counter is assumed to be 3. At this time, when the pulse width is equal to or less than the predetermined pulse width A at the first light reception and the vehicle position is within the distance B from the registered speed measurement device, a prompt notification is issued at the first light reception.

[0057] If the vehicle position is not within distance B from the registered speed measuring device, the second light reception is less than the specified pulse width A and is one time the specified pulse interval D, so the condition fulfillment counter is set to 2. Even if the third light reception is unsuccessful, the fourth light reception is less than the specified pulse width A and the pulse interval based on the second light reception is twice the specified pulse interval D, so the condition fulfillment counter can be set to 3 by the fourth light reception. Then, since the condition fulfillment counter has reached 3, an alert is issued.

[0058] In addition, since the optical filter 41 easily transmits oblique light, the possibility of failure to receive light is suppressed. Therefore, the comparison with an integer multiple of the predetermined pulse interval D, in combination with the optical filter 41, increases the possibility of more quickly reporting even if the laser light has high directivity.

[0059] Here, the condition fulfillment counter only needs to be 2 or more, and if the condition fulfillment counter is 2, a notification can be made upon the second reception of light. In order to ensure high reliability, when the condition fulfillment counter is set to 2, further AND conditions that can be determined upon the second reception of light may be added.

[0060] Furthermore, from the second reception onwards, only the condition of the pulse width being equal to or less than the predetermined pulse width A may be judged. However, by including a viewpoint different from the pulse width, namely the pulse interval, in the conditions, it is possible to further reduce the risk of a false alarm being generated due to another light emission source with a similar pulse width.

[0061] In this way, if the vehicle position is not within distance B from a registered speed measuring device, the laser light determination unit 54 changes the determination condition and performs notification processing with high reliability that the laser light is from a speed measuring device when a detection signal having a predetermined pulse width A or less is obtained N times in succession at an interval that is an integer multiple of a predetermined pulse interval D. Also, by comparing an integer multiple of the predetermined pulse interval D with the pulse interval of the detection signal output by the optical sensor 4, the laser light determination unit 54 notifies of reception of laser light from a speed measuring device even if the vehicle is not close enough to the speed measuring device to reliably receive the laser light or if an obstruction is temporarily present.

[0062] (Example 2 of judging received light waves) A second example of the determination process of the laser light determination unit 54 will be described with reference to Fig. 7. Fig. 7 is a flowchart showing a second operation example of the laser light determination unit 54. For example, the laser light determination unit 54 incorporates a countermeasure against false alarms in order to more quickly notify the laser light irradiation from the speed measuring device by comparing with an integer multiple of a predetermined pulse width D. However, the laser light determination unit 54 does not initialize the value of a condition fulfillment counter to zero for a predetermined condition, but maintains the value, thereby achieving both a countermeasure against false alarms and quick notification.

[0063] That is, the laser light determination unit 54 judges whether the pulse width of the detection signal output by the optical sensor 4 is equal to or less than a predetermined pulse width A (step S21). The predetermined pulse width A has a value equal to or greater than the pulse width of the laser light of the speed measurement device, and has a value less than the pulse width of light emitted by another light emission source such as an N system. If the pulse width of the detection signal is not equal to or less than the predetermined pulse width A (step S21, No), the interrupt process ends. That is, the notification process (step S31) is not executed.

[0064] If the pulse width of the detection signal is equal to or less than the predetermined pulse width A (step S21, Yes), the laser light determination unit 54 determines whether the vehicle position is within distance B from the registered speed measurement device (step S22). Distance B is the distance at which highly directional laser light can reach the vehicle. If the vehicle position is within distance B from the registered speed measurement device (step S22, Yes), the laser light determination unit 54 controls the notification unit 6 to notify information such as the reception of laser light (step S31).

[0065] If the vehicle position is not within distance B from the registered speed measuring device (step S22, No), the laser light judgment unit 54 judges whether the condition fulfillment counter is zero (step S23). If the condition fulfillment counter is not zero (step S23, No), it judges whether the pulse interval of the detection signal is equal to or greater than a predetermined pulse interval C (step S24). The condition fulfillment counter is the number of consecutive receptions of the laser light of the speed measuring device that satisfy the condition. The predetermined pulse interval C is too long compared to the interval at which the laser light of the speed measuring device can be received, and is therefore an interval that can be regarded as the reception of the first pulse that satisfies the condition of the laser light of the speed measuring device.

[0066] If the condition fulfillment counter is zero (Yes in step S23), or if the pulse interval is equal to or greater than the predetermined pulse interval C (Yes in step S24), the laser light determination unit 54 sets the condition fulfillment counter to "1" (Step S25).

[0067] If the condition fulfillment counter is not zero (step S23, No) and the pulse interval is not equal to or greater than the predetermined pulse interval C (step S24, No), the laser light determination unit 54 determines whether the pulse interval is less than the predetermined pulse interval E (step S26). The predetermined pulse interval E is stored in advance in the laser light determination unit 54. The laser light determination unit 54 compares the obtained pulse interval with the predetermined pulse interval E to determine which is larger.

[0068] If the pulse interval of the detection signal is less than the predetermined pulse interval E (Yes in step S26), the process ends while maintaining the value of the condition fulfillment counter. In other words, the detection signal having a pulse interval less than the predetermined pulse interval E is ignored.

[0069] With regard to the pulse interval less than the predetermined pulse interval E, it was found that when a vehicle approaches the speed measuring device, noise may be introduced at an interval very close to the reception of the laser light. The pulse interval less than the predetermined pulse interval E is a threshold value for distinguishing this noise, and is a NOT condition for determining whether the interval is between the reception of the laser light and the noise. However, if the condition fulfillment counter is initialized to zero due to the presence of noise (step S32), the notification will be delayed. Therefore, when the detection signals are very close to each other, it is noise, so the laser light determination unit 54 does not increase the condition fulfillment counter as a countermeasure against false alarms, nor does it initialize it to zero, but maintains the value of the condition fulfillment counter from the viewpoint of prompt notification.

[0070] If the pulse interval of the detection signal is not less than the predetermined pulse interval E (step S26, No), the laser light determination unit 54 determines whether the pulse interval is an integer multiple of the predetermined pulse interval D (step S27). The predetermined pulse interval D is the pulse interval of the laser light of the speed measurement device.

[0071] If the pulse interval is not an integer multiple of the predetermined pulse interval D (step S27, No), the condition fulfillment counter is initialized to zero (step S32) and the judgment process is terminated. On the other hand, if the pulse interval is an integer multiple of the predetermined pulse interval D (step S27, Yes), the laser light judgment unit 54 further judges whether the pulse interval is an integer multiple of the predetermined pulse interval F (step S28). The predetermined pulse interval F is stored in advance in the laser light judgment unit 54.

[0072] If the pulse interval of the detection signal is not an integer multiple of the predetermined pulse interval F (step S28, No), the condition fulfillment counter is incremented by 1 (step S29). On the other hand, if the pulse interval of the detection signal is an integer multiple of the predetermined pulse interval F (step S28, Yes), the value of the condition fulfillment counter is maintained and the process is terminated. That is, the detection signal is ignored when either the condition that the pulse interval is less than the predetermined pulse interval E or the condition that the pulse interval is either an integer multiple of the predetermined pulse interval D or an integer multiple of the predetermined pulse interval F is satisfied.

[0073] An integer multiple of the predetermined pulse interval F is an emission interval of a light emission source different from the speed measuring device, such as light emitted by the N system. Therefore, there is doubt as to whether an integer multiple of the predetermined pulse interval D and an integer multiple of the predetermined pulse interval F are the laser light of the speed measuring device. On the other hand, there is a possibility that they are the laser light of the speed measuring device. Therefore, the laser light determination unit 54 takes measures against false alarms by not increasing the value of the condition fulfillment counter, and ensures promptness of notification by maintaining the value of the condition fulfillment counter without initializing it to zero.

[0074] When the condition fulfillment counter is incremented by 1 (step S29), the laser light determination unit 54 determines whether the condition fulfillment counter has reached the threshold value N (step S30). If the condition fulfillment counter has reached the threshold value N (step S30, Yes), the laser light determination unit 54 performs notification processing (step S31), resets the condition fulfillment counter to its initial value of zero (step S32), and ends the determination processing. If the condition fulfillment counter has not reached the threshold value N (step S30, No), the value of the condition fulfillment counter is left as it is and the determination processing ends.

[0075] Fig. 8 is a schematic diagram showing the action based on the second operation example of the laser light determination unit 54. The threshold value N of the condition fulfillment counter is assumed to be 3. After receiving the first laser light irradiated by the speed measurement device, a detection signal occurring within a predetermined pulse interval E is noise. Therefore, the laser light determination unit 54 ignores this detection signal. In other words, the condition fulfillment counter is maintained at "1".

[0076] Since this is not an integer multiple of the predetermined pulse interval D, if the condition fulfillment counter is reset to zero in response to this noise detection signal, the notification will be delayed by at least the predetermined pulse interval D. However, since the condition fulfillment counter is maintained for this noise detection signal, false notifications are suppressed while the prompt notification is maintained.

[0077] Assume that the third and fourth laser beams emitted by the speed measuring device cannot be received, but the fifth laser beam can be received. At this time, a detection signal is generated at a pulse interval three times the predetermined pulse interval D. However, the pulse interval three times the predetermined pulse interval D is equal to one time the predetermined pulse interval F. In this case, there is a possibility that the second and fifth detection signals are based on light emitted by a light source other than the speed measuring device. Therefore, the laser beam determining unit 54 ignores the detection signal based on the fifth laser beam emitted by the speed measuring device. In other words, the condition fulfillment counter is maintained at "2". Then, the condition fulfillment counter can be set to 3 at the sixth time, and since the condition fulfillment counter has reached 3, an alert is issued.

[0078] In reality, there is no mistake in the fifth laser light from the speed measuring device, and although the notification is delayed by one beat, it is possible to prevent notification to light sources other than the speed measuring device, and since a condition fulfillment counter is maintained, false alarms are suppressed while a certain degree of promptness in notification is maintained.

[0079] In this way, the laser light determination unit 54 does not determine whether the light is a laser light of a speed measuring device or not and ignores the detection signal when the pulse interval is an integer multiple of the predetermined pulse interval F or is less than the predetermined pulse interval E. This achieves both a countermeasure against false alarms and quick notification.

[0080] (Received light wave judgment example 3) A third example of the determination process of the laser light determination unit 54 will be described with reference to Fig. 9. Fig. 9 is a flowchart showing a third operation example of the laser light determination unit 54. Note that in this operation example, the determination of whether or not the vehicle position is at a distance B from a registered speed measurement device is omitted, but this determination may be added or removed.

[0081] For example, when the laser light determination unit 54 cannot determine whether the light is a laser light from a speed measuring device or not, when the laser light from a speed measuring device is received but light from another light source is suspected to be received, or when the light is noise, the value of the condition fulfillment counter is maintained, thereby achieving both suppression of false alarms and prompt notification. On the other hand, there are cases where the light is highly likely not to be a laser light from a speed measuring device. When the light is highly likely not to be a laser light from a speed measuring device, the laser light determination unit 54 does not increase the condition fulfillment counter even if light that may be a laser light from a speed measuring device is received, thereby increasing the level of false alarm counter measures to the extent that notification is not delayed.

[0082] That is, the laser light determination unit 54 determines whether the detection signal output by the optical sensor 4 matches the condition that the signal is a laser light of a speed measuring device (step S41). This condition is, for example, that the pulse width is equal to or smaller than a predetermined pulse width A, that the pulse interval is an integer multiple of a predetermined pulse interval D, that the pulse interval is equal to or larger than a predetermined pulse interval E, that the pulse interval is not an integer multiple of a predetermined pulse interval F, or a combination of these.

[0083] If the detection signal output by the optical sensor 4 does not match the laser light conditions of the speed measuring device (step S41, No), and the reason for the mismatch is that the pulse interval is less than the predetermined pulse interval E (step S42, Yes), or the pulse interval is an integer multiple of the predetermined pulse interval D but is also an integer multiple of the predetermined pulse interval E (step S43, Yes), the detection signal is ignored and the judgment process is terminated. On the other hand, if the mismatched condition is other than the pulse interval being less than the predetermined pulse interval E (step S42, No), and the pulse interval is an integer multiple of the predetermined pulse interval D but is not also an integer multiple of the predetermined pulse interval E (step S43, No), the laser light judgment unit 54 sets an invalid period (step S44) and resets the false alarm prevention counter (step S45).

[0084] That is, for example, if the pulse width is not equal to or less than the predetermined pulse width A, or the pulse interval is not an integer multiple of the predetermined pulse interval D, the laser light judgment unit 54 sets an invalid period (step S44), resets the false alarm prevention counter (step S45), and also resets the condition fulfillment counter to zero (step S46).

[0085] The invalid period is set when there is a possibility that light other than the laser light of a speed measuring device has been received, and is a period during which the condition fulfillment counter is not incremented, except in exceptional cases, even if light that may be the laser light of a speed measuring device has been received. That is, the laser light determination unit 54 increases the false alarm suppression level once there is a possibility that light other than the laser light of a speed measuring device has been received. The false alarm prevention counter is counted up when light that may be the laser light of a speed measuring device has been received during the invalid period, and the false alarm suppression level during the invalid period is adjusted.

[0086] If the detection signal output by the optical sensor 4 matches the laser light condition of the speed measuring device (step S41, Yes), the laser light determination unit 54 determines whether it is an invalid period (step S47). If it is not an invalid period (step S47, No), the condition fulfillment counter is incremented (step S50), and if the condition fulfillment counter has reached the threshold value N (step S51, Yes), a notification process is performed (step S52), the condition fulfillment counter is reset to zero (step S46), and the determination process is terminated.

[0087] If it is an invalid period (step S47, Yes), the laser light determination unit 54 increments the false report prevention counter by 1 (step S48). The false report prevention counter is stored as a changeable variable in the laser light determination unit 54. Note that, if the detection signal output by the optical sensor 4 does not match the laser light conditions of the speed measurement device, the laser light determination unit 54 resets the false report prevention counter to zero.

[0088] After incrementing the false alarm prevention counter, the laser light determination unit 54 determines whether the false alarm prevention counter has reached a threshold value M (step S49). The threshold value M is stored in advance in the laser light determination unit 54. The laser light determination unit 54 compares the false alarm prevention counter with the threshold value M.

[0089] If the false report prevention counter has reached the threshold value M (step S49, Yes), the laser light determination unit 54 increments the condition fulfillment counter by 1 (step S50). However, if the false report prevention counter has not reached the threshold value M (step S49, No), even if the detection signal output by the optical sensor 4 matches the laser light condition of the speed measuring device (step S41, Yes), the value of the condition fulfillment counter is not changed and the determination process is terminated.

[0090] That is, during the invalid period, the laser light determination unit 54 does not count up the condition fulfillment counter for the consecutive number of times that the false alarm prevention counter reaches the threshold value M, unless the detection signal output by the optical sensor 4 matches the condition for the laser light of the speed measuring device or the invalid period ends. In this way, when there is a possibility that light other than the laser light of the speed measuring device has been received, the false alarm suppression level is increased.

[0091] 10 is a schematic diagram showing the action based on the third operation example of the laser light determination unit 54. It is assumed that the threshold value N of the condition achievement counter is three, and the threshold value M of the false alarm prevention counter is two.

[0092] The first detection signal has a pulse width less than the specified pulse width A, so the condition fulfillment counter is incremented to "1", and the second detection signal has a pulse width less than the specified pulse width A and arrives at a pulse interval 1x the specified pulse interval D, so the condition fulfillment counter is incremented to "2". However, the third detection signal has a pulse width greater than the specified pulse width A, so the condition fulfillment counter is reset to zero. Furthermore, because a third detection signal has occurred that does not meet the condition, an invalid period is set and the false alarm prevention counter is reset to zero.

[0093] The fourth detection signal arrives with a pulse width less than the specified pulse width A, and with a pulse interval one time the specified pulse interval D. However, since it is during an invalid period, the condition fulfillment counter maintains its value and the false alarm prevention counter increments to "1". The fifth detection signal arrives with a pulse width less than the specified pulse width A, but with a pulse interval less than the specified pulse interval E. Therefore, the fifth detection signal is ignored, and neither the condition fulfillment counter nor the false alarm prevention counter changes. Incidentally, even if it arrives with a pulse interval that is an integer multiple of the specified pulse interval D, the detection signal is ignored, and neither the condition fulfillment counter nor the false alarm prevention counter changes.

[0094] The sixth detection signal has a pulse width less than the specified pulse width A, but arrives at a pulse interval that is not an integer multiple of the specified pulse interval D. Therefore, both the condition fulfillment counter and the false alarm prevention counter are reset to zero, and the invalid period is reset. The next seventh detection signal arrives with a pulse width less than the specified pulse width A, and at a pulse interval that is 1 time the specified pulse interval D. However, since it is within the invalid period, the condition fulfillment counter maintains its value and the false alarm prevention counter is incremented to "1".

[0095] The eighth detection signal arrives with a pulse width less than the specified pulse width A, and with a pulse interval 1x the specified pulse interval D. Therefore, since it is during the invalid period, the false alarm prevention counter increases to "2". Here, since the false alarm prevention counter reached "2" during the invalid period, the condition fulfillment counter is incremented by 1 for the eighth detection signal, and its value becomes "1". Furthermore, the ninth detection signal arrives with a pulse width less than the specified pulse width A, and with a pulse interval 1x the specified pulse interval D. Since the false alarm prevention counter is still greater than "2" even after it has been incremented, the condition fulfillment counter is incremented by 1, and its value becomes "2".

[0096] The tenth detection signal arrives with a pulse width equal to or less than the predetermined pulse width A, and with a pulse interval equal to one time the predetermined pulse interval D. Moreover, since the invalid period has ended, regardless of the value of the false alarm prevention counter, the condition fulfillment counter is incremented by one, becoming "3". Since the condition fulfillment counter has reached "3", the laser light determination unit 54 controls the notification unit 6 to cause the notification unit 6 to notify information that directly or indirectly urges compliance with the speed limit.

[0097] In this way, the laser light determination unit 54 sets an invalid period when there is a high possibility that the light is not laser light from a speed measuring device. During the invalid period, the laser light determination unit 54 does not increment the condition fulfillment counter unless it receives a predetermined number of consecutive light beams that may be laser light from a speed measuring device. In other words, when the laser light determination unit 54 receives light that is likely not laser light from a speed measuring device, it increases the level of false alarm suppression.

[0098] (Received light wave judgment example 4) A typical operation example in which the above-mentioned various types of determination processing are integrated will be described with reference to Figures 11 to 13. Figures 11 to 13 are flowcharts showing a typical operation example of the laser light determination unit 54.

[0099] If the pulse width of the detection signal output by the optical sensor 4 is equal to or less than the predetermined pulse width A (FIG. 11: step S61, Yes) and the vehicle position is within distance B from the registered speed measuring device (FIG. 11: step S62, Yes), the laser light determination unit 54 controls the notification unit 6 to notify information such as the reception of the laser light (FIG. 12: step S63).The laser light determination unit 54 also initializes the invalid period to zero (FIG. 12: step S64), initializes the condition fulfillment counter to "1" (step S65), and ends the determination process.

[0100] If the pulse width of the detection signal is not equal to or less than the predetermined pulse width A (FIG. 11: step S61, No), the laser light determination unit 54 resets the false alarm prevention counter to zero (FIG. 13: step S70) and sets an invalid period (FIG. 13: step S71).

[0101] If the pulse width of the detection signal output by the optical sensor 4 is equal to or less than the predetermined pulse width A (FIG. 11: step S61, Yes) but the vehicle position is not within distance B from the registered speed measuring device (FIG. 11: step S62, No), the laser light determination unit 54 determines whether the pulse interval of the detection signal is equal to or more than a predetermined pulse interval C (FIG. 11: step S66). The case where the detection signal is not received and therefore the pulse interval cannot be calculated is also included in the case where the detection signal is not received and therefore the pulse interval cannot be calculated.

[0102] If the pulse interval of the detection signal is equal to or greater than the predetermined pulse interval C (FIG. 11: step S66, Yes), the laser light judgment unit 54 resets the false alarm prevention counter to zero (FIG. 12: step S67), initializes the invalid period to zero (FIG. 12: step S64), initializes the condition fulfillment counter to "1" (step S65), and terminates the judgment process.

[0103] If the pulse interval of the detection signal is not equal to or greater than the predetermined pulse interval C (FIG. 11: step S66, No), the laser light determination unit 54 determines whether the pulse interval of the detection signal is less than the predetermined pulse interval E (FIG. 11: step S68). If the pulse interval of the detection signal is less than the predetermined pulse interval E (FIG. 11: step S68, Yes), the laser light determination unit 54 ignores the detection signal and ends the determination (FIG. 12).

[0104] If the pulse interval of the detection signal is not less than the predetermined pulse interval E (FIG. 11: step S68, No), the laser light determination unit 54 determines whether the pulse interval of the detection signal is an integer multiple of D (FIG. 11: step S69). If the pulse interval of the detection signal is not an integer multiple of D (FIG. 11: step S69, No), the laser light determination unit 54 resets the false alarm prevention counter to zero (FIG. 13: step S70) and sets an invalid period (FIG. 13: step S71).

[0105] On the other hand, if the pulse interval of the detection signal is an integer multiple of D (FIG. 11: step S69, Yes), the laser light determination unit 54 determines whether the false report prevention counter is equal to or greater than the threshold value M (FIG. 11: step S72). If the false report prevention counter is not equal to or greater than the threshold value M (FIG. 11: step S72, No), the laser light determination unit 54 determines whether the pulse interval of the detection signal is an integer multiple of the predetermined pulse interval F (FIG. 11: step S73).

[0106] If the count is not an integer multiple of the predetermined pulse interval F (FIG. 11: step S73, No), the laser light determination unit 54 increments the false report prevention counter by 1 (FIG. 11: step S74) and again compares the false report prevention counter with the threshold value M. If the false report prevention counter is equal to or greater than the threshold value M (FIG. 11: step S75, Yes), the laser light determination unit 54 increments the condition fulfillment counter by 1 (FIG. 11: step S77).

[0107] On the other hand, even if the false alarm prevention counter is not equal to or greater than M (FIG. 11: step S75, No), and if the period is not an invalid period (FIG. 11: step S76, No), the laser light determination unit 54 increments the condition fulfillment counter by 1 (FIG. 11: step S77). However, if the period is an invalid period (FIG. 11: step S76, Yes), the laser light determination unit 54 resets the invalid period (FIG. 13: step S71) and sets the condition fulfillment counter to "1" (FIG. 12: step S65).

[0108] After incrementing the condition achievement counter by 1 (FIG. 11: step S77), the laser light determination unit 54 determines whether the condition achievement counter has reached the threshold value N (FIG. 12: step S78), and if the condition achievement counter has not reached the threshold value N (FIG. 12: step S78, No), ends the determination process. If the condition achievement counter has reached the threshold value N (FIG. 12: step S78, Yes), the laser light determination unit 54 controls the notification unit 6 to notify information such as the reception of the laser light (FIG. 12: step S63). In addition, the laser light determination unit 54 initializes the invalid period to zero (FIG. 12: step S64), initializes the condition achievement counter to "1" (step S65), and ends the determination process.

[0109] (effect) As described above, the detector 1 includes the optical sensor 4, the laser light determination unit 54, and the notification unit 6. The optical sensor 4 receives light in a wavelength band including the wavelength of the laser light emitted by the speed measuring device, and outputs a detection signal based on the light reception time and the light reception interval of the light. The laser light determination unit 54 determines whether the detection signal matches the determination condition based on the detection signal output by the optical sensor 4. The notification unit 6 notifies predetermined information when the laser light determination unit 54 determines that the detection signal satisfies the determination condition. The laser light determination unit 54 compares the pulse interval of the detection signal with an integer multiple of the predetermined pulse interval D, so that the determination condition includes a pulse interval condition in which the pulse interval of the detection signal is an integer multiple including one time the transmission interval of the laser light.

[0110] This makes it possible to improve the promptness of the notification even if the laser beam cannot be continuously received due to a failure in reception caused by the high directivity of the laser beam or a failure in reception caused by an obstruction. On the other hand, since the notification is made by receiving the laser beam two or more times, false alarms can also be suppressed.

[0111] Furthermore, the laser light determination unit 54 may omit the comparison between the predetermined pulse width A, which defines a threshold value of a predetermined range including the transmission time of the laser light, and the pulse width of the detection signal, regardless of whether the distance calculated by the distance calculation unit 52 is within the predetermined distance B. Even in this embodiment, it is possible to increase the promptness of notification even in the case of a failure to receive light due to the laser light having high directionality or a failure to receive light due to the presence of an obstruction.

[0112] However, in this detector 1, if the distance calculated by distance calculation unit 52 is within predetermined distance B, laser light determination unit 54 compares the pulse width of the detection signal with predetermined pulse width A. In other words, if the distance calculated by distance calculation unit 52 is within predetermined distance B, the determination condition is that the pulse width of the detection signal falls within a predetermined range that includes the emission time of the laser light.

[0113] If the distance calculated by distance calculation unit 52 is not within predetermined distance B, laser light determination unit 54 compares the pulse width and pulse interval of the detection signal with a predetermined pulse width A and a predetermined pulse interval D. In other words, if the distance calculated by distance calculation unit 52 is not within predetermined distance B, the determination conditions include, as AND conditions, a pulse width condition where the pulse width of the detection signal is the transmission time of the laser light and a pulse interval condition where the pulse interval of the detection signal is an integer multiple including one time the transmission interval of the laser light. This makes it possible to issue a prompt notification with only one reception of light when the vehicle is located in a known location that is likely to receive laser light from a speed measuring device.

[0114] The judgment conditions also include a NOT condition where the pulse interval of the detection signal is an integer multiple including 1 of a predetermined pulse interval F that is different from the transmission interval of the laser light, and the laser light judgment unit 54 judges this NOT condition in addition to the pulse interval condition where the pulse interval of the detection signal is an integer multiple including 1 of the transmission interval of the laser light. This makes it possible to suppress false alarms due to the presence of a light emission source other than the speed measuring device while ensuring the promptness of notification regarding the laser light type speed measuring device.

[0115] The judgment conditions also include a NOT condition that the pulse interval is less than a predetermined pulse interval E, i.e., the pulse interval of the detection signal is the interval between the reception of the laser beam and the noise appearing immediately after the laser beam, and the laser beam judgment unit 54 judges this NOT condition as well. This makes it possible to ensure the promptness of the notification regarding the laser beam speed measuring device while suppressing false alarms due to noise mixed in with the detection signal.

[0116] The laser light determination unit 54 has a condition fulfillment counter and determines whether the determination condition is satisfied a predetermined number of times, which is equal to or greater than 2. This makes it possible to further reduce false alarms while ensuring the promptness of notification regarding the laser light type speed measurement device.

[0117] The judgment conditions include one or more AND conditions including a pulse interval condition where the pulse interval of the detection signal is an integer multiple including 1 time of the transmission interval D of the laser light, and a predetermined NOT condition, and the laser light judgment unit 54 has a condition fulfillment counter and judges whether the judgment condition is satisfied a predetermined number of times or more in succession. When the detection signal output by the optical sensor 4 corresponds to the predetermined NOT condition, the laser light judgment unit 54 maintains the value of the condition fulfillment counter. The predetermined NOT condition is when there is doubt as to whether the laser light has been received, but there is still a sufficient possibility that the laser light has been received, and this detector 1 can achieve both rapid reporting and suppression of false reports.

[0118] For example, one of the specified NOT conditions is that the pulse interval of the detection signal is an integer multiple including 1 of a specified pulse interval F that is different from the transmission interval of the laser light, and another of the specified NOT conditions is that the pulse interval of the detection signal is the interval between the reception of the laser light and the noise that appears immediately after the reception of the laser light.

[0119] As described above, the laser light determination unit 54 compares various pulse intervals such as the predetermined pulse intervals C, D, E, and F, but the detection signal output by the optical sensor 4 does not need to strictly match the pulse interval to be compared. That is, typically, the laser light determination unit 54 only needs to determine whether the detection signal output by the optical sensor 4 is before or after various pulse intervals, within a predetermined pulse interval range, above or beyond the range, or below or below the range. That is, the pulse interval of the detection signal being an integer multiple including 1x the pulse interval of the laser light allows for a predetermined error. The pulse interval of the detection signal being an integer multiple including 1x the predetermined pulse interval that is different from the transmission interval of the laser light allows for a predetermined error.

[0120] Furthermore, the predetermined pulse interval E caused by noise is a short pulse interval. Therefore, when a predetermined error is allowed in the comparison of pulse intervals, the pulse interval for the next light reception may start from the end of the noise, or from the end of the detection signal immediately before the noise. When the pulse interval of the detection signal is an integer multiple of the predetermined pulse interval F that is different from the emission interval of the laser light, the end of the detection signal that meets this condition may be used as the start, or from the end of the detection signal immediately before that.

[0121] Such a detector 1 is particularly useful when using an optical filter 41 that also transmits the wavelengths of light emitted on the road. Generally, the more the transmittable wavelength band of the optical filter 41 is narrowed, the more difficult it becomes to reduce the reflectance of light incident at an angle. However, since the optical filter 41 transmits a wide wavelength band, it is easy to reduce the reflectance from an angle, and the probability that the light receiving element 42 will receive the laser light increases. This further improves the promptness of the notification. Meanwhile, various measures against false alarms taken by the laser light determination unit 54 allow both promptness of the notification and suppression of false alarms to be achieved at the same time.

[0122] (Other embodiments) Although the embodiment of the present invention has been described above, various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The embodiment and modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims.

[0123] For example, the information to be reported may include information indicating how many times the pulse interval of the detection signal is compared with the transmission interval of the laser light. That is, the pulse interval of the detection signal may be divided by a predetermined pulse interval D, and the integer part of the quotient may be reported. Considering that the greater the distance between the vehicle and the speed measuring device, the more difficult it is to receive the laser light, the distance between the vehicle and the speed measuring device and the integer part of the quotient are roughly proportional to each other as a guide. Therefore, the detector 1 can report the approximate distance between the speed measuring device and the vehicle. The detector 1 may report the integer part of the quotient by classifying it into a category such as "strong laser" or "weak laser". [Explanation of symbols]

[0124] 1 detector 10. Chassis 11 Back 12 Front 13 Reception area 14 screens 15 Speaker 16 Lamp 2. Radio wave sensor 3 Positioning signal receiver 4. Light Sensor 41 Optical Filters 42 Photodetector 43 Conversion section 5. Control section 51 Radar wave processing section 52 Distance calculation unit 53 Memory section 54 Laser light judgment unit 6. Notification Department

Claims

1. A detector installed in a vehicle, an optical sensor that receives light in a wavelength band that includes the wavelength of the laser light emitted by the speed measurement device and outputs a detection signal of a pulse width and a pulse interval that reflect a light reception time and a light reception interval of the light; a determination unit that determines the detection signal output by the optical sensor based on a determination condition; A notification unit that notifies predetermined information; Equipped with the determination condition includes a pulse interval condition that the pulse interval of the detection signal is one of integer multiples including 1 time of the transmission interval of the laser light, The determination unit is determining whether a first condition is satisfied, the first condition being different from the determination condition and being an integer multiple including 1 time of a predetermined pulse interval different from the transmission interval of the laser light; determining whether a second condition is satisfied, the second condition being different from the determination condition, the second condition being that the pulse interval of the detection signal is less than a predetermined pulse interval indicating the interval between the reception of the laser light and a noise appearing immediately after the reception of the laser light; a condition fulfillment counter that counts the number of consecutive light receptions that satisfy the judgment condition, and when the detection signal satisfies the judgment condition, the condition fulfillment counter is counted up, and it is further judged whether the judgment condition is satisfied a predetermined number of times that is equal to or greater than two by the condition fulfillment counter; When the first other condition or the second other condition is also satisfied, even if the detection signal satisfies the judgment condition, the value of the condition fulfillment counter is maintained without being counted up, the notification unit notifies the predetermined information when the determination unit determines based on the condition fulfillment counter that the determination condition has been satisfied the predetermined number of consecutive times; A detector characterized by:

2. The optical sensor has an optical filter that limits the wavelength of light to a predetermined wavelength band, The predetermined wavelength band includes wavelengths of light emitted by VICS (registered trademark), N system, an in-vehicle distance measuring sensor, or a combination of these, in addition to the laser light of the speed measuring device; 2. The detector according to claim 1,

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