Detection device

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 irradiated by a laser-type speed measuring device.

Background Art

[0002] When a vehicle approaches a speed measuring device or receives a radar wave from the speed measuring device, the detector notifies information that directly or indirectly encourages speed compliance. This detector is performed by receiving the radar wave transmitted from the speed measuring device with an antenna. In addition, the detector also has a function of detecting that the position of the own vehicle specified by GPS has approached a predetermined distance from the position of a speed measuring device registered in advance and notifying warning information.

[0003] In recent years, speed measuring devices are becoming less radar-based, such as loop coil type and photoelectric tube type. Among such a trend of non-radarization, a laser light type speed measuring device has been developed. The laser light type speed measuring device irradiates a traveling vehicle with laser light by scanning in a predetermined range with laser light, and detects the speed by detecting the reflected laser light. There are a fixed type with a fixed installation position and a movable type that can be easily installed and removed. The laser light is transmitted continuously for a predetermined transmission time at a predetermined transmission interval.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Conventional detectors do not have the function of detecting laser light. Therefore, for a laser light type speed measurement device, it could not be detected unless the installation location was known. Thus, the development of detectors capable of detecting laser light has been progressing. However, since laser light has a characteristic that radar waves do not have, namely high directivity, there was a risk that the timing of notifying the reception of laser light would be delayed.

[0006] That is, since radar waves have high diffusivity, the sensor can receive radar waves even if the sensor of the detector is not located on the irradiation axis of the radar waves. In contrast, since laser light has high directivity, the sensor of the detector must be located on the optical axis of the laser light irradiated by the speed measurement device, reducing the chance of receiving the laser light.

[0007] Therefore, when the vehicle is far from the speed measurement device, a situation may occur where the first laser light is received successfully but the next laser light is not received. Also, when there is an obstacle between the vehicle and the speed measurement device, a situation may occur where the first laser light is received successfully but the next laser light is not received. There is also an idea to give a notification to prompt speed compliance upon receiving the first laser light, but in this case, false alarms will increase.

[0008] The present invention has been proposed to solve the problems of the prior art as described above, and its object is to provide a detector that quickly notifies the reception of laser light irradiated by a speed measurement device and suppresses false alarms.

Means for Solving the Problem

[0009] In order to achieve the above object, a detector according to the present invention is a detector installed in a vehicle, and includes an optical sensor that receives light in a wavelength band including the wavelength of the laser light irradiated by a speed measuring device and outputs a detection signal based on the light reception time and light reception interval of the light; a determination unit that determines whether the detection signal output by the optical sensor matches a determination condition; and a notification unit that notifies predetermined information when the determination unit determines that the detection signal satisfies the determination condition. The determination condition includes a pulse interval condition that the pulse interval of the detection signal is an integer multiple including 1 times the transmission interval of the laser light. The determination unit is characterized by determining the pulse interval condition.

[0010] The determination condition includes a first NOT condition that the pulse interval of the detection signal is also an integer multiple including 1 times a predetermined pulse interval different from the transmission interval of the laser light. In addition to the pulse interval condition, the determination unit may be configured to determine the first NOT condition.

[0011] The determination condition includes a second NOT condition 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. In addition to the pulse interval condition, the determination unit may be configured to determine the second NOT condition.

[0012] The determination condition includes an AND condition that the pulse width of the detection signal falls within a predetermined range including the transmission time of the laser light. In addition to the pulse interval condition, the determination unit may be configured to determine the AND condition.

[0013] The detector further includes a distance calculation unit that calculates the distance between the vehicle and the speed measuring device. The determination unit changes the determination condition based on the distance calculated by the distance calculation unit. If the distance calculated by the distance calculation unit is within a predetermined distance, the determination condition is to determine a pulse width condition that the pulse width of the detection signal falls within a predetermined range including the transmission time of the laser light. If the distance calculated by the distance calculation unit is not within the predetermined distance, the determination condition may include an AND condition of the pulse interval condition and the pulse width condition for determination.

[0014] The determination unit may have a condition achievement counter and determine whether the determination condition is satisfied a predetermined number of times or more.

[0015] The determination condition includes one or more AND conditions including the pulse width condition and a predetermined NOT condition. The determination unit has a condition achievement counter and determines whether the determination condition is satisfied a predetermined number of consecutive times or more. When the light corresponds to the predetermined NOT condition, the value of the condition achievement counter may be maintained.

[0016] The determination condition includes a first NOT condition in which the pulse interval of the detection signal is an integer multiple including one time of a predetermined pulse interval different from the transmission interval of the laser light. The determination condition further includes a second NOT condition in which the pulse interval of the detection signal is the interval between the reception of the laser light and the noise appearing immediately after the reception of the laser light. The determination unit has a condition achievement counter and determines whether the determination condition is satisfied a predetermined number of consecutive times or more. When the light corresponds to the first NOT condition or the second NOT condition, the value of the condition achievement counter may be maintained.

[0017] The optical sensor may have an optical filter that restricts the wavelength of light to a predetermined wavelength band, and the predetermined wavelength band may include the wavelengths of light transmitted on the road and along the road in addition to the laser light of the speed measurement device.

Advantages of the Invention

[0018] According to the present invention, even if it is not possible to continuously receive all the laser light, it is possible to give a notification that encourages compliance with the speed, and since the notification is given by receiving the laser light two or more times, false alarms can also be suppressed.

Brief Description of the Drawings

[0019]

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Embodiments for Carrying Out the Invention

[0020] (Configuration) The detector according to the embodiment of the present invention will be described in detail with reference to the drawings. The detector 1 is installed in vehicles such as automobiles, motorcycles, trucks, and buses. This detector 1 notifies information for promoting speed compliance by direct or indirect content on the occasion of an event for which speed compliance should be promoted. The detector 1 is typically installed on the dashboard and is powered from the vehicle side via an OBD-II connector or a cigarette socket, etc. The dashboard is an example of a place where it is easy to receive radar waves and laser light irradiated by the speed measuring device and where information can be notified to the driver. Radar waves and laser light are collectively referred to as electromagnetic waves.

[0021] Examples of speed measurement devices include radar types that irradiate radar waves, non-radar types that have loop coils or phototubes, and laser light types that irradiate laser light. The radar type and the laser light type include fixed and mobile types. The events for which speed compliance should be promoted are when a vehicle reaches within a predetermined distance from a speed measurement device with a known installation location, and when an electromagnetic wave irradiated by the speed measurement device is received. Examples of the information to be notified include the presence of the speed measurement device, the type of the speed measurement device, the reception and type of the electromagnetic wave irradiated by the speed measurement device, or a reminder of speed compliance, or a plurality of these.

[0022] As shown in FIGS. 1 and 2, this detector 1 includes a screen 14, a speaker 15, and a lamp 16 on the outer surface of the housing 10. The screen 14 is a liquid crystal display, an organic EL display, or the like, and is arranged on the front surface 12 of the detector 1, and displays notification information in a form that appeals to the vision such as characters, pictures, and symbols. The speaker 15 outputs the notification information as sound. The lamp 16 notifies the notification information by regular light emission such as color, blinking, and lighting interval. Note that the front surface 12 faces the inside of the vehicle and is a surface visible to the driver. On the contrary, the back surface 11 faces the outside of the vehicle through the windshield.

[0023] The back surface 11 of the detector 1 is a reception area 13. That is, as shown in FIG. 3, a radio wave sensor 2, a positioning signal reception unit 3, and an optical sensor 4 are housed and arranged inside the housing 10 on the back surface 11. The radio wave sensor 2 has an antenna and a demodulator such as a superheterodyne method, and receives and detects radar waves in the X-band and K-band wavelength bands irradiated by a radar type speed measurement device. When the radio wave sensor 2 receives the radar wave of the speed measurement device, it outputs a detection signal. The positioning signal reception unit 3 has an antenna, a demodulator, and a processor capable of receiving radio signals of positioning satellites, receives and demodulates the positioning signals of GNSS (Global Navigation Satellite System), and calculates the vehicle position composed 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 receiving light. The detection signal is a voltage signal having a pulse width corresponding to the light reception time of the light, and is output at a pulse interval corresponding to the light reception interval.

[0025] This optical filter 41 is preferably made of a material that easily transmits light even when incident obliquely, for example, made of an acrylic resin. Thereby, even when the speed measurement device is installed along the road and the filter surface of the optical filter 41 is obliquely intersecting with respect to the optical axis of the laser light irradiated by the speed measurement device, reception leakage can be suppressed. However, the optical filter 41 is not limited to being made of an acrylic resin, and known materials can be widely used.

[0026] Also, this optical filter 41 is a filter that transmits a wavelength band including the wavelength of the laser light irradiated by the speed measurement device. This wavelength band may include, for example, the wavelengths of light irradiated by VICS (registered trademark), N system, in-vehicle distance measurement sensors, other roadside facilities, and vehicles in motion. For example, the light emitted by the electro-optical display board mounted on the vehicle may be included in the wavelength band transmitted by the optical filter 41.

[0027] The light-receiving element 42 is a detector that responds including the wavelength band transmitted by the optical filter 41 and allows current to flow when receiving light. This light-receiving element 42 is installed behind the optical filter 41 and receives the light transmitted 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 includes, for example, an operational amplifier. When receiving a current signal from the light receiving element 42, it starts from the reference voltage and outputs an Lo signal, and when the current signal from the light receiving element 42 is interrupted, it starts up and returns to the reference voltage. That is, the optical sensor 4 lowers the voltage to the Lo level at the timing that matches the start of light reception, and maintains the Lo level of the voltage in accordance 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] As shown in FIG. 3, the detector 1 further includes a control unit 5 and a notification 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 including a processor such as a CPU, FPGA, or microcomputer, a storage for storing programs and data, and a work memory.

[0030] This control unit 5 determines whether the radio wave sensor 2 and the optical sensor 4 have received the electromagnetic wave of the speed measuring device. The control unit 5 also determines the distance between the position of the host vehicle output by the positioning signal receiving unit 3 and the speed measuring device whose installation location is known, and the position where the speed measuring device has been installed in the past (hereinafter, generally 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 includes a screen 14, a speaker 15, a lamp 16, or a plurality of these arranged on the outer surface of the housing 10.

[0031] As shown in FIG. 4, this 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 by program processing by a processor or the like. When the detection signal of the radio wave sensor 2 is input to the control unit 5, the radar wave processing unit 51 performs an interrupt process and causes the notification unit 6 to notify information for prompting speed compliance. In particular, it is desirable that the radar wave processing unit 51 causes the notification unit 6 to notify information for notifying the presence of a radar type speed measuring device and the reception of radar waves irradiated by the speed measuring device.

[0032] The memory unit 53 is composed of a storage device provided in the detection device 1 or a portable memory medium such as an SD card, and stores the latitude and longitude of the registration 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 registration speed measurement device stored in the memory unit 53.

[0033] Furthermore, the distance calculation unit 52 has a threshold value in advance and compares the calculation result with the threshold value. If the calculation result is less than or equal to the threshold value, that is, if the vehicle position is within a predetermined distance from the registration speed measurement device, the distance calculation unit 52 controls the notification unit 6 to notify the information. In particular, it is desirable that the distance calculation unit 52 causes the notification unit 6 to notify information about the presence and type of the registration speed measurement device, and the distance between the registration 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 the laser light of the speed measurement device. This laser light determination unit 54 has determination conditions, determines the coincidence between the detection signal output by the optical sensor 4 and the determination conditions, and as a result, determines whether the laser light has been received.

[0035] When the detection signal output by the optical sensor 4 matches the determination conditions, the laser light determination unit 54 controls the notification unit 6 to notify the information. In particular, it is desirable that the laser light determination unit 54 causes the notification unit 6 to notify information about the presence of the laser type speed measurement device and the reception of the laser light irradiated by the speed measurement device.

[0036] (Example 1 of determination of received light wave) 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 the delay associated with the determination process, so as to quickly notify that the laser light of the speed measurement 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 less than or equal to a predetermined pulse width A (step S01). The pulse width is obtained, for example, by sampling the voltage at a sampling rate based on the clock frequency, and counting the number of times the Lo-level voltage is sampled, or converting this number into time. The predetermined pulse width A is pre-stored 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 light of several other known light emission sources from the laser light of the speed measurement device. This predetermined pulse width A has a value greater than or equal to the transmission time when the speed measurement device emits laser light once, and also has a value less than the transmission time of the light emitted by other light emission sources such as the N system at one time. And less than or equal to the predetermined pulse width A is a range including the transmission time of the laser light of the speed measurement device. However, less than or equal to the predetermined pulse width A includes the transmission times of unknown or known light emission sources that cannot be distinguished by the predetermined pulse width A because their transmission times are similar to that of the speed measurement device.

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

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

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

[0042] Therefore, if the position of the host vehicle is within the distance B from the registered speed measurement device (step S02, Yes), 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 position of the host vehicle exists at a known location where it is highly likely to receive the laser light of the speed measurement device, the laser light determination unit 54 performs the notification process only based on the pulse width of the detection signal. As a result, this detector 1 can perform the notification at a rapid timing of only receiving one pulse.

[0044] In addition, although the mode of determining whether the position of the host vehicle exists within the distance B after receiving light having a pulse width of the predetermined pulse width A or less has been described, each time the distance calculation unit 52 calculates the distance, the laser light determination unit 54 compares the calculation result with the distance B, and if the optical sensor 4 receives light and the detection signal has a pulse width of A or less, the notification process may be immediately performed. In this case, since the distance determination after reception is omitted, the notification can be performed at a more rapid timing.

[0045] Here, if the position of the host vehicle is not within the distance B from the registered speed measurement device (step S02, No), since high reliability cannot be obtained only with the pulse width A, the laser light determination unit 54 determines whether it is the laser light of the speed measurement device based on the determination conditions with other conditions added (steps S03 and subsequent). That is, the determination conditions are changed depending on whether the position of the host vehicle is within the distance B from the registered speed measurement device.

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

[0047] The pulse interval is the time from the end of the previous detection signal, that is, the timing when the voltage rises to the Hi level, to the end of the latest detection signal. The pulse interval is obtained, for example, by sampling the voltage at a sampling rate based on the clock frequency, and counting the number of times the Hi-level voltage is sampled, or converting that number to time.

[0048] The condition achievement counter is the number of consecutive light receptions that satisfy the determination condition. The condition achievement counter being zero means that the light reception having a pulse width equal to or less than the predetermined pulse width A is the first time. That is, it means that the first pulse of the laser light that satisfies the conditions of the speed measuring device has been received. Also, the predetermined pulse interval C is an interval that can be regarded as the reception of the first pulse of the laser light that satisfies the conditions of the speed measuring device because it is too long compared to the interval during which the laser light of the speed measuring device can be received, even considering the failure to receive the highly directional laser light.

[0049] If the condition achievement counter is zero (Yes in step S03) and the pulse interval is equal to or greater than the predetermined pulse interval C (Yes in step S04), the laser light determination unit 54 sets the condition achievement counter to "1" as the first possible light reception of the laser light of the speed measuring device (step S05). Note that the initial value of the condition achievement counter is zero.

[0050] If the condition achievement counter is not zero (step S03, No) and the pulse interval is not greater than or equal to the predetermined pulse interval C (step S04, NO), it indicates that the first possible reception of the laser light of the speed measurement device has 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 pre-stored in the laser light determination unit 54.

[0051] The predetermined pulse interval D is the transmission interval of the laser light of the speed measurement device. Here, due to the high directivity of the laser light, 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 the presence of a shielding object such as a truck in front of the vehicle. In particular, since the speed measurement device scans a predetermined range on the road, when the vehicle is far from the speed measurement device, the timing when the optical sensor 4 exists on the optical path of the laser light decreases, and the timing when the optical sensor 4 cannot receive light is likely to occur.

[0052] If it is determined that it is not laser light because it does not match the predetermined pulse interval D when there is a timing when the optical sensor 4 cannot receive light, the host vehicle must approach the speed measurement device to a position where the laser light can be surely received, and the notification will be delayed. However, the laser light determination unit 54 compares with an integer multiple of the predetermined pulse interval D, takes into account the existence of the timing when reception is impossible, and enhances the promptness of notification.

[0053] If the pulse interval is an integer multiple of the predetermined pulse interval D (step S06, Yes), the condition achievement counter is incremented by 1 (step S07). Note that the integer multiple of the predetermined pulse interval D includes 1 times. 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 the laser light of the speed measurement device becomes low, the condition achievement counter is initialized to zero (step S10), and the determination process ends. In this way, the incremented condition achievement counter indicates the number of consecutive receptions of the laser light of the speed measurement device with a high possibility.

[0054] When the condition achievement counter is incremented by 1 (step S07), the laser light determination unit 54 determines whether the condition achievement counter has reached the threshold value N (step S08). The threshold value N is pre-stored in the laser light determination unit 54. The laser light determination unit 54 compares the magnitude of the condition achievement counter with the threshold value N.

[0055] When the condition achievement counter has reached the threshold value N (step S08, Yes), the laser light determination unit 54 performs notification processing (step S09), resets the condition achievement counter to zero which is the initial value (step S10), and ends the determination processing. When the condition achievement counter is less than the threshold value N (step S08, No), the value of the condition achievement counter remains as it is and the determination processing ends.

[0056] FIG. 6 is a schematic diagram showing the operation based on the first operation example of this laser light determination unit 54. Assume that the threshold value N of the condition achievement counter is 3. At this time, in the first light reception, when the pulse width is less than or equal to the predetermined pulse width A and the position of the host vehicle is within the distance B from the registered speed measurement device, notification is quickly performed in the first light reception.

[0057] When the position of the host vehicle is not within the distance B from the registered speed measurement device, in the second light reception, since the pulse width is less than or equal to the predetermined pulse width A and it is 1 times the predetermined pulse interval D, the condition achievement counter is set to 2. Even if the third light reception fails, in the fourth light reception, since the pulse width is less than or equal to the predetermined pulse width A and the pulse interval is 2 times the predetermined pulse interval D based on the second light reception, the condition achievement counter can be set to 3 in the fourth light reception. Then, since the condition achievement counter has reached 3, notification is performed.

[0058] In addition, since the optical filter 41 easily transmits oblique light, the possibility of light reception failure is suppressed. Therefore, comparing with an integer multiple of the predetermined pulse interval D, in combination with this optical filter 41, even for a highly directional laser light, it increases the possibility of performing notification more quickly.

[0059] Here, the condition achievement counter only needs to be 2 or more. If the condition achievement counter is 2, it can be notified at the second light reception. In order to ensure high reliability, when setting the condition achievement counter to 2, other AND conditions that can be determined for the second light reception may be added.

[0060] Also, after the second light reception, only the condition of a pulse width of a predetermined pulse width A or less may be determined. However, by including a different perspective from the pulse width, such as the pulse interval, as a condition, the risk of false alarms caused by other light emission sources with similar pulse widths can be further reduced.

[0061] In this way, if the vehicle position is not within the distance B from the registered speed measurement device, the laser light determination unit 54 changes the determination condition, and a detection signal with a pulse width of a predetermined pulse width A or less is continuously obtained N times at intervals that are integer multiples of a predetermined pulse interval D, thereby obtaining a high reliability that it is the laser light of the speed measurement device and performing the notification process. Also, the laser light determination unit 54 compares the integer multiple of the predetermined pulse interval D with the pulse interval of the detection signal output by the optical sensor 4, so that even if it does not approach the speed measurement device to a distance where light reception is surely possible, or even if an obstacle temporarily exists, it notifies the reception of the laser light from the speed measurement device.

[0062] (Example of determination of received light wave 2) 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, in order to more quickly notify the irradiation of the laser light from the speed measurement device by comparison with an integer multiple of a predetermined pulse width D, etc., this laser light determination unit 54 incorporates countermeasures against false alarms. However, this laser light determination unit 54 does not initialize the value of the condition achievement counter to zero for a predetermined condition, but maintains the value, thereby achieving both countermeasures against false alarms and rapid notification.

[0063] 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 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 also has a value less than the pulse width of the light irradiated by another light source such as an N system. If the pulse width of the detection signal is not 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 position of the host vehicle is within a distance B from the registered speed measurement device (step S22). The distance B is the distance at which highly directional laser light can reach the vehicle. If the position of the host vehicle is within the 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 the laser light (step S31).

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

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

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

[0068] If the pulse interval of the detection signal is less than the predetermined pulse interval E (step S26, Yes), the process ends while maintaining the value of the condition satisfaction counter. That is, detection signals with a pulse interval less than the predetermined pulse interval E are ignored.

[0069] Regarding cases where the pulse interval is less than the predetermined pulse interval E, when the vehicle approaches the speed measurement device, it has been found that noise may enter at a very short interval from the reception of the laser light. The pulse interval less than the predetermined pulse interval E is a threshold for separating this noise and is a NOT condition for determining whether it is the interval between the reception of the laser light and the noise. However, if the presence of noise causes the condition satisfaction counter to be initialized to zero (step S32), the notification will be delayed. Therefore, when the detection signals are very close to each other, since it is noise, the laser light determination unit 54 does not increase the condition satisfaction counter as a countermeasure against false alarms, nor does it initialize it to zero, and maintains the value of the condition satisfaction counter from the perspective of the promptness of 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 a 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 determination process ends. On the other hand, if the pulse interval is an integer multiple of the predetermined pulse interval D (step S27, Yes), the laser light determination unit 54 further determines whether the pulse interval is an integer multiple of the predetermined pulse interval F (step S28). The predetermined pulse interval F is pre-stored in the laser light determination 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 process ends while maintaining the value of the condition fulfillment counter. That is, when either the condition of being less than the predetermined pulse interval E or the condition of being an integer multiple of both the predetermined pulse interval D and the predetermined pulse interval F is satisfied, the detection signal is ignored.

[0073] The integer multiple of the predetermined pulse interval F is the transmission interval of a light source different from the speed measurement device, such as the light irradiated by the N system. Therefore, a pulse interval that is an integer multiple of both the predetermined pulse interval D and the predetermined pulse interval F raises doubts about the possibility of being the laser light of the speed measurement device. On the other hand, it may also be the laser light of the speed measurement device. Thus, the laser light determination unit 54 takes measures against false alarms by not incrementing the value of the condition fulfillment counter and ensures the 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 a notification process (step S31), returns the condition fulfillment counter to zero, which is the initial value (step 32), and ends the determination process. If the condition fulfillment counter is less than the threshold value N (step S30, No), the value of the condition fulfillment counter remains as it is and the determination process ends.

[0075] FIG. 8 is a schematic diagram showing the operation based on the second operation example of the laser light determination unit 54. Assume that the threshold value N of the condition achievement counter is 3. After receiving the first laser light irradiated by the speed measurement device, the detection signal generated within a time less than the predetermined pulse interval E is noise. Therefore, the laser light determination unit 54 ignores this detection signal. That is, the condition achievement counter is maintained at "1".

[0076] If the condition achievement counter is reset to zero triggered by this detection signal which is noise because it is not an integer multiple of the predetermined pulse interval D, the notification will be delayed by at least the predetermined pulse interval D. However, since the condition achievement counter is maintained for this detection signal which is noise, false alarms are suppressed while maintaining the promptness of the notification.

[0077] Assume that the third and fourth laser lights emitted by the speed measurement device cannot be received, and the fifth laser light can be received. At this time, a detection signal is generated at a pulse interval three times the predetermined pulse interval D. However, assume that the pulse interval three times the predetermined pulse interval D is equal to one time the predetermined pulse interval F. Then, there is a possibility that the second and fifth detection signals are based on the light irradiated by a light source other than the speed measurement device. Therefore, the laser light determination unit 54 ignores the detection signal based on the fifth laser light emitted by the speed measurement device. That is, the condition achievement counter is maintained at "2". And at the sixth time, the condition achievement counter can reach 3, and since the condition achievement counter reaches 3, a notification is made.

[0078] Actually, there is no mistake in the fifth laser light of the speed measurement device, and the notification is delayed by one tempo. However, it is possible to suppress notifying a light source other than the speed measurement device, and since the condition achievement counter is maintained, false alarms are suppressed while maintaining a certain degree of promptness of the notification.

[0079] In this way, when the pulse interval is an integer multiple of the predetermined pulse interval F and the pulse interval is less than the predetermined pulse interval E, the laser light determination unit 54 does not determine whether it is the laser light of the speed measurement device or not, and ignores the detection signal. Thereby, both false alarm countermeasures and the promptness of notification are achieved.

[0080] (Determination Example 3 of Received Light Wave) 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. In this operation example, the determination as to whether the position of the host vehicle is at a distance B from the registered speed measurement device is omitted, but this determination may be added or excluded.

[0081] For example, when the laser light determination unit 54 cannot determine whether it is the laser light of the speed measurement device or not, when it is suspected that the laser light of the speed measurement device is received but the light from other light sources is also received, and when it is noise, the value of the condition achievement counter is maintained, achieving both false alarm suppression and the promptness of notification. On the other hand, there may be a case where it is highly likely that it is not the laser light of the speed measurement device. When it is highly likely that it is not the laser light of the speed measurement device, the laser light determination unit 54 does not increase the condition achievement counter even if there is a reception that may be the laser light of the speed measurement device, and increases the level of false alarm countermeasures within the range where the 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 it is the laser light of the speed measurement device (step S41). This condition is, for example, that the pulse width is less than or equal to the predetermined pulse width A, the pulse interval is an integer multiple of the predetermined pulse interval D, the pulse interval is greater than or equal to the predetermined pulse interval E, the pulse interval is not an integer multiple of the predetermined pulse interval F, or a combination thereof.

[0083] The detection signal output by the optical sensor 4 does not match the conditions of the laser light of the speed measurement device (step S41, No). If the reason for the mismatch is that the pulse interval is less than the predetermined pulse interval E (step S42, Yes), or if the pulse interval is an integer multiple of the predetermined pulse interval D but at the same time is also an integer multiple of the predetermined pulse interval E (step S43, Yes), the detection signal is ignored and the determination process ends. On the other hand, if the condition for the mismatch 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 not an integer multiple of the predetermined pulse interval E at the same time (step S43, No), the laser light determination 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 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 determination 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 of receiving light that is not the laser light of the speed measurement device, and it is a period during which the condition fulfillment counter is not incremented except for exceptions even when receiving light that may be the laser light of the speed measurement device. That is, once the laser light determination unit 54 has a possibility of receiving light that is not the laser light of the speed measurement device, it raises the level of false alarm suppression. The false alarm prevention counter is incremented when receiving light that may be the laser light of the speed measurement device during the invalid period, and adjusts the false alarm suppression level during the invalid period.

[0086] Then, when the laser light determination unit 54 determines that the detection signal output by the optical sensor 4 matches the conditions of the laser light of the speed measurement device (step S41, Yes), it determines whether it is an invalid period (step S47). If it is not the invalid period (step S47, No), it increments the condition achievement counter (step S50). If the condition achievement counter has reached the threshold value N (step S51, Yes), it performs a notification process (step S52), resets the condition achievement counter to zero (step S46), and ends the determination process.

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

[0088] After the laser light determination unit 54 increments the false alarm prevention counter, it determines whether the false alarm prevention counter has reached the threshold value M (step S49). The threshold value M is stored in advance by the laser light determination unit 54. The laser light determination unit 54 compares the magnitude of the false alarm prevention counter and the threshold value M.

[0089] If the false alarm prevention counter has reached the threshold value M (step S49, Yes), the laser light determination unit 54 increments the condition achievement counter by 1 (step S50). However, if the false alarm 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 conditions of the laser light of the speed measurement device (step S41, Yes), the value of the condition achievement counter remains unchanged, and the determination process ends.

[0090] That is, during the invalid period, the laser light determination unit 54 does not increment the condition fulfillment counter as long as the detection signal output by the optical sensor 4 matches the conditions of the laser light of the speed measurement device for only the consecutive number of minutes until the false alarm prevention counter reaches the threshold value M, or until the invalid period ends. This increases the level of false alarm suppression in case there is a possibility of receiving light that is not the laser light of the speed measurement device.

[0091] FIG. 10 is a schematic diagram showing the operation based on the third operation example of this laser light determination unit 54. Assume that the threshold value N of the condition fulfillment counter is 3 and the threshold value M of the false alarm prevention counter is 2.

[0092] Since the first detection signal has a pulse width equal to or less than the predetermined pulse width A, the condition fulfillment counter increases to "1". Since the second detection signal has a pulse width equal to or less than the predetermined pulse width A and reaches at a pulse interval that is 1 times the predetermined pulse interval D, the condition fulfillment counter increases to "2". However, since the third detection signal has a pulse width exceeding the predetermined pulse width A, the condition fulfillment counter is reset to zero. Furthermore, since the third detection signal that does not match the conditions has occurred, an invalid period is set and the false alarm prevention counter is reset to zero.

[0093] The fourth detection signal reaches at a pulse width equal to or less than the predetermined pulse width A and at a pulse interval that is 1 times the predetermined pulse interval D. However, since it is during the invalid period, the condition fulfillment counter maintains its value and the false alarm prevention counter increases to "1". The fifth detection signal has a pulse width equal to or less than the predetermined pulse width A but reaches at a pulse interval less than the predetermined pulse interval E. Therefore, the fifth detection signal is ignored and neither the condition fulfillment counter nor the false alarm prevention counter fluctuates. Note that even if the detection signal reaches at a pulse interval that is an integer multiple of the predetermined pulse interval D, the detection signal is ignored and neither the condition fulfillment counter nor the false alarm prevention counter fluctuates.

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

[0095] The eighth detection signal arrives at a pulse width equal to or less than the predetermined pulse width A and at a pulse interval that is 1 times the predetermined pulse interval D. Therefore, since it is within the invalid period, the false alarm prevention counter increases to "2". Here, since the false alarm prevention counter has reached "2" during the invalid period, for the eighth detection signal, the condition fulfillment counter increases by 1 and its value becomes "1". Furthermore, the ninth detection signal arrives at a pulse width equal to or less than the predetermined pulse width A and at a pulse interval that is 1 times the predetermined pulse interval D. Since the false alarm prevention counter remains "2" or more even if it is incremented, the condition fulfillment counter increases by 1 and its value becomes "2".

[0096] Then, the tenth detection signal arrives at a pulse width equal to or less than the predetermined pulse width A and at a pulse interval that is 1 times 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 increases by 1 and its value becomes "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 prompts speed compliance.

[0097] In this way, when there is a high possibility that the laser light of the speed measuring device is not the laser light, the laser light determination unit 54 sets an invalid period. And during the invalid period, the laser light determination unit 54 does not increase the condition fulfillment counter unless a predetermined number of consecutive lights that may be the laser light of the speed measuring device are received. That is, when the laser light determination unit 54 receives light that is highly likely not to be the laser light of the speed measuring device, it raises the false alarm suppression level.

[0098] (Example of determination of received light wave 4) A typical operation example integrating the above various determination processes will be described based on FIGS. 11 to 13. FIGS. 11 to 13 are flowcharts showing typical operation examples 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 a predetermined pulse width A (FIG. 11: step S61, Yes), and if the position of the host vehicle is within a distance B from the registered speed measurement device (FIG. 11: step S62, Yes), the notification unit 6 is controlled to notify information such as reception of laser light (FIG. 12: step S63). Further, 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.

[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 the 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 position of the host vehicle is not within a distance B from the registered speed measurement device (FIG. 11: step S62, No), it is determined whether the pulse interval of the detection signal is equal to or greater than a predetermined pulse interval C (FIG. 11: step S66). The case where the detection signal has not been received and thus the pulse interval cannot be calculated is also included in the case of being equal to or greater than the predetermined pulse interval C.

[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 determination 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 achievement counter to "1" (step S65), and ends the determination process.

[0103] If the pulse interval of the detection signal is not greater than a 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 a 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 alarm prevention counter is not less than a threshold value M (Fig. 11: step S72). If the false alarm prevention counter is not less 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 a predetermined pulse interval F (Fig. 11: step S73).

[0106] If the pulse interval 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 alarm prevention counter by 1 (Fig. 11: step S74) and compares the false alarm prevention counter with the threshold value M again. If the false alarm prevention counter is not less 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 M or more (Fig. 11: step S75, No), and if it is not the invalid period (Fig. 11: step S76, No), the laser light determination unit 54 increments the condition achievement counter by 1 (Fig. 11: step S77). However, if it is the invalid period (Fig. 11: step S76, Yes), the invalid period is reset (Fig. 13: step S71), and the condition achievement counter is set 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). If the condition achievement counter has not reached the threshold value N (Fig. 12: step S78, No), the determination process ends. If the condition achievement counter has reached the threshold value N (Fig. 12: step S78, Yes), the notification unit 6 is controlled to notify information such as the reception of the laser light (Fig. 12: step S63). Further, 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, this detector 1 is provided with 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 irradiated 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 the coincidence between the determination condition and the detection signal based on the detection signal output by the optical sensor 4. The notification unit 6 notifies predetermined information when the detection signal is determined to satisfy the determination condition by the laser light determination unit 54. Then, 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 that the pulse interval of the detection signal is an integer multiple including 1 times the transmission interval of the laser light.

[0110] As a result, reception failure due to the highly directional laser light or reception failure due to the presence of an obstacle may occur. Even if all the laser light cannot be continuously received, the promptness of notification can be enhanced. On the other hand, since notification is performed by receiving the laser light two or more times, false alarms can also be suppressed.

[0111] In addition, as the laser light determination unit 54, regardless of whether the distance calculated by the distance calculation unit 52 is within a predetermined distance B, comparison between a predetermined pulse width A that defines a threshold value in a predetermined range including the transmission time of the laser light and the pulse width of the detection signal may be omitted. Even in this aspect, the promptness of notification can be enhanced with respect to reception failure due to the highly directional laser light or reception failure due to the presence of an obstacle.

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

[0113] If the distance calculated by the distance calculation unit 52 is not within the predetermined distance B, the laser light determination unit 54 compares the pulse width and the pulse interval of the detection signal with the predetermined pulse width A and the predetermined pulse interval D. That is, if the distance calculated by the distance calculation unit 52 is not within the predetermined distance B, as a determination condition, a pulse width condition that the pulse width of the detection signal is the transmission time of the laser light and a pulse interval condition that the pulse interval of the detection signal is an integral multiple including 1 times the transmission interval of the laser light are included as an AND condition. Thereby, when the own vehicle position exists at a known location where there is a high possibility of receiving the laser light of the speed measurement device, notification can be performed at a prompt timing of only one reception.

[0114] In addition, the determination condition includes a NOT condition in which the pulse interval of the detection signal is an integral multiple including one time of a predetermined pulse interval F that is different from the transmission interval of the laser beam. The laser beam determination unit 54 is configured to determine this NOT condition in addition to the pulse interval condition in which the pulse interval of the detection signal is an integral multiple including one time of the transmission interval of the laser beam. Thereby, while ensuring the promptness of notification regarding the laser beam type speed measurement device, false alarms due to the presence of an optical signal source different from the speed measurement device can be suppressed.

[0115] In addition, the determination condition includes a NOT condition of less than a predetermined pulse interval E, that is, a NOT condition in which the pulse interval of the detection signal is the interval between the reception of the laser beam and the noise that appears immediately after the laser beam. The laser beam determination unit 54 is configured to determine this NOT condition as well. Thereby, while ensuring the promptness of notification regarding the laser beam type speed measurement device, false alarms due to noise mixed in the detection signal can be suppressed.

[0116] The laser beam determination unit 54 has a condition fulfillment counter and is configured to determine whether the determination condition is satisfied a predetermined number of times or more. Thereby, while ensuring the promptness of notification regarding the laser beam type speed measurement device, false alarms can be further suppressed.

[0117] In addition, the determination condition includes one or more AND conditions including a pulse interval condition in which the pulse interval of the detection signal is an integral multiple including one time of the transmission interval D of the laser beam and a predetermined NOT condition. The laser beam determination unit 54 has a condition fulfillment counter and is configured to determine whether the determination condition is satisfied a predetermined continuous number of times or more. Then, when the detection signal output by the optical sensor 4 corresponds to the predetermined NOT condition, the laser beam determination unit 54 is configured to maintain the value of the condition fulfillment counter. The predetermined NOT condition is a case where there is doubt about receiving the laser beam, but there is still a sufficient possibility of receiving the laser beam. This detection device 1 can achieve both the promptness of notification and the suppression of false alarms.

[0118] For example, it is one of the predetermined NOT conditions that the pulse interval of the detection signal is an integral multiple including one time of a predetermined pulse interval F different from the transmission interval of the laser beam. Also, it is another one of the predetermined NOT conditions that 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.

[0119] As described above, the laser beam determination unit 54 compares various pulse intervals such as the predetermined pulse intervals C, D, E, and F. However, the detection signal output from the optical sensor 4 does not necessarily exactly match the comparison target pulse interval. That is, typically, the laser beam determination unit 54 determines whether the detection signal output from the optical sensor 4 is within the range of a predetermined pulse interval before and after various pulse intervals, greater than or exceeding the range, or less than or below the range. That is, when the pulse interval of the detection signal is an integral multiple including one time of the pulse interval of the laser beam, a predetermined error is allowed. When the pulse interval of the detection signal is also an integral multiple including one time of a predetermined pulse interval different from the transmission interval of the laser beam, a predetermined error is allowed.

[0120] Also, the predetermined pulse interval E caused by noise has a short pulse interval. Therefore, when allowing a predetermined error in the comparison of the pulse intervals, the pulse interval for the next 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 also an integral multiple of a predetermined pulse interval F different from the transmission interval of the laser beam, the end of the detection signal that meets this condition may be used as the start period, or the end of the detection signal immediately before it may be used as the start period.

[0121] Such a detector 1 is particularly useful when using an optical filter 41 that also transmits the wavelength of light transmitted on the road. Generally, the narrower the transmissible wavelength band of the optical filter 41, the more difficult it is to reduce the reflectance of light incident obliquely. However, since the optical filter 41 transmits a wide wavelength band, it is easy to reduce the reflectance from an oblique direction, and the probability that the light receiving element 42 receives the laser light increases. Therefore, the speed of notification is further improved. On the other hand, various false alarm countermeasures by the laser light determination unit 54 achieve both the speed of notification and the suppression of false alarms.

[0122] (Other embodiments) Although the embodiments of the present invention have been described as above, various omissions, replacements, and changes can be made without departing from the gist of the invention. And this embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

[0123] For example, the information to be notified may include information indicating how many times the pulse interval of the detection signal is with respect to 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 notified. Considering that it is more difficult to receive the laser light as the distance between the host vehicle and the speed measurement device is farther, the distance between the host vehicle and the speed measurement device and the integer part of this quotient are in a proportional relationship as a rough guide. Therefore, this detector 1 can notify the approximate distance between the speed measurement device and the host vehicle. Incidentally, the detector 1 may classify the integer part of the quotient into categories such as "strong laser" or "weak laser" and notify it.

Explanation of reference numerals

[0124] 1 Detector 10 Housing 11 Rear surface 12 Front surface 13 Reception area 14 Screen 15 Speaker 16 Lamp 2 Radio wave sensor 3 Positioning signal reception unit 4 Optical sensor 41 Optical filter 42 Light receiving element 43 Conversion unit 5 Control unit 51 Radar wave processing unit 52 Distance calculation unit 53 Memory unit 54 Laser light determination unit 6 Notification unit

Claims

1. A detector installed in a vehicle, comprising: an optical sensor that receives light in a wavelength band including the wavelength of the laser light irradiated by the speed measurement device and outputs a detection signal of a pulse width and a pulse interval reflecting the light reception time and the light reception interval of the light; a determination unit that determines whether the detection signal satisfies a determination condition based on the detection signal output by the optical sensor; an alert unit that alerts predetermined information when the determination unit determines that the detection signal satisfies the determination condition; a distance calculation unit that calculates the distance between the vehicle and the speed measurement device; The determination unit: changes the determination condition based on the distance calculated by the distance calculation unit, has a threshold value that is equal to or greater than a predetermined transmission time of the laser light and less than a transmission time of at least one known light source different from the speed measurement device, and if the distance calculated by the distance calculation unit is within a predetermined distance, determines, as the determination condition, a pulse width condition that the pulse width of the detection signal is less than or equal to the threshold value, and if the distance calculated by the distance calculation unit is not within the predetermined distance, determines whether the detection signal satisfies a determination condition including a logical product of a pulse interval condition that the pulse interval of the detection signal is one of each integer multiple including 1 times the transmission interval of the laser light and the pulse width condition. A detector characterized by the above.

2. The determination unit has a condition achievement counter that is the number of consecutive light receptions that satisfy the determination condition, and if the distance calculated by the distance calculation unit is not within the predetermined distance, when the detection signal satisfies the determination condition, the condition achievement counter is incremented, and it is further determined whether the determination condition is satisfied for a predetermined number of consecutive times of 2 or more by the condition achievement counter. The alert unit alerts predetermined information when the determination unit determines, by the condition achievement counter, that the determination condition is satisfied for the predetermined number of consecutive times if the distance calculated by the distance calculation unit is not within the predetermined distance. The detector according to claim 1, characterized by the above.

3. The determination unit: if the distance calculated by the distance calculation unit is not within the predetermined distance, further determines whether the detection signal output by the optical sensor satisfies another condition different from the determination condition, has a condition achievement counter that is the number of consecutive light receptions that satisfy the determination condition, increments the condition achievement counter when the detection signal satisfies the determination condition, and further determines whether the determination condition is satisfied for a predetermined number of consecutive times of 2 or more by the condition achievement counter. ​ When the other another condition is also satisfied, even if the detection signal satisfies the determination condition, the value of the condition achievement counter is maintained without incrementing, When the determination unit determines by the condition achievement counter that the determination condition is satisfied for the predetermined consecutive number of times, the notification unit notifies predetermined information. The detection device according to claim 1, characterized in that.

4. The other another condition includes a first another condition that the pulse interval of the detection signal is an integral multiple including one time of a predetermined pulse interval different from the transmission interval of the laser beam, and a second another condition that the pulse interval of the detection signal is less than a predetermined pulse interval indicating the interval between the reception of the laser beam and the noise appearing immediately after the reception of the laser beam, is included, When the determination unit also satisfies the first another condition or the second another condition, even if the detection signal satisfies the determination condition, the value of the condition achievement counter is maintained without incrementing. The detection device according to claim 3, characterized in that.

5. The optical sensor has an optical filter that restricts the wavelength of light to a predetermined wavelength band, The predetermined wavelength band includes the wavelengths of light transmitted by VICS (registered trademark), N system, in-vehicle distance measurement sensors, or a plurality of these in addition to the laser beam of the speed measurement device. The detection device according to any one of claims 1 to 4, characterized in that.

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