JP2016080397A - User detection method, user detection device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a user detection method and a user detection device, capable of detecting the existence of a detection object on the basis of the size of the pulse width of a reception pulse, even when the detection object exists in a close range.SOLUTION: The user detection method includes a transmission process for transmitting a pulse signal by a transmitter, a reception process for receiving the pulse signal by a receiver, an arithmetic process for deciding a distance up to the detection object reflecting the pulse signal, a storage process for holding the distance, and a user determination process for determining whether or not the detection object is a user on the basis of the time change of the distance. In the arithmetic process, when the pulse width of the pulse signal received by the receiver is a predetermined value or less, the distance up to the detection object is decided on the basis of the propagation time and propagation velocity of the pulse signal and when the pulse width is larger than the predetermined value, a predetermined distance is decided as the distance up to the detection object.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a user detection method, a user detection device, and an image forming apparatus. In particular, the present invention relates to a user detection method, a user detection apparatus, and an image forming apparatus that detect a person or an object around the apparatus and detect whether the person or object is a user.

  Conventionally, in a device such as a smartphone, a tablet terminal, a personal computer (PC), or an image forming apparatus, a function (hereinafter referred to as “power consumption”) of the device by shifting from the normal mode to the energy saving mode (or eco mode) under a certain condition. , Called “energy saving function”).

  Here, the energy saving mode means that the power supply to the CPU is stopped when an operation such as key input to the device has not been performed for a certain period of time, thereby reducing the power consumption compared to the normal mode in which the device is operating. A mode that can be suppressed.

  An apparatus having such an energy saving function switches between the normal mode and the energy saving mode based on the detection result of a human sensor such as an infrared sensor, an optical sensor, or an ultrasonic sensor that detects the presence of a human body. For example, when measuring the distance to the detection target using an ultrasonic sensor, an ultrasonic pulse signal is transmitted from the transmission unit of the ultrasonic sensor, and the ultrasonic pulse signal reflected from the detection target existing around the apparatus is transmitted. Received by the receiver of the ultrasonic sensor. And based on the propagation time and propagation speed of an ultrasonic pulse signal, the distance to a detection target is calculated | required, and it is determined whether the said detection target is a user based on the time change.

  After the user is detected in this way, when the user moves away from the device, the device is shifted from the normal mode to the energy saving mode. Conversely, when the user approaches the device, the device is shifted to the automatic preheating mode. To reduce power consumption.

  By the way, the reception pulse received by the receiver includes the reception pulse reflected from the detection target and the reception pulse directly received by the receiver from the transmitter without passing through the detection target (hereinafter referred to as “direct arrival pulse”). It is known that there is. In particular, when the detection target enters the short-range area, the received pulse waveform reflected from the detection target and the direct arrival pulse waveform may overlap, and the detection time of the received pulse may not be known. Sometimes distance was not required.

  In order to solve such a problem, the reflected wave including the wraparound wave (direct arrival pulse) is received, and the reference voltage is varied by the comparison means, so that the reflected wave from the short distance object is compared with a high reference voltage. Moreover, the invention of a distance detection sensor that can accurately detect an object from a close distance to a long distance by comparing reflected waves from a long distance object with a low reference voltage is disclosed (for example, (See Patent Document 1).

JP-A-7-174842

  However, when the waveform of the received pulse reflected from the detection target overlaps with the waveform of the direct arrival pulse so that the detection target exists at a short distance, it is reflected from the detection target even if the reference voltage is changed. Since the contribution of the received pulse cannot be extracted, the presence of the detection target may not be detected.

  The present invention has been made in consideration of the above circumstances, and its purpose is to detect the waveform so that the waveform of the received pulse reflected from the detection object overlaps with the waveform of the direct arrival pulse and becomes integrated. The present invention provides a user detection method and a user detection device that detect the presence of a detection target even when the user exists at a short distance.

The present invention includes a transmission step in which a transmitter transmits a pulse signal, a reception step in which the receiver receives the pulse signal, a calculation step to determine a distance to a detection target that reflects the pulse signal, and the distance A storing step for holding, and a user determining step for determining whether or not the detection target is a user based on a time change of the distance, and the pulse of the pulse signal received by the receiver in the calculating step When the width is equal to or less than a predetermined value, the distance to the detection target is determined based on the propagation time and propagation speed of the pulse signal propagated to the receiver through the detection target, while the pulse width is When the value is larger than a predetermined value, the pulse signal propagated to the receiver through the detection target is directly transmitted to the receiver without passing through the detection target. As being the detection target is located in the overlapping distance, there is provided a user detection method characterized by determining the predetermined distance as the distance to the detection target.
The present invention also includes a transmitter that transmits a pulse signal, a receiver that receives the pulse signal, a calculation unit that determines a distance to a detection target that reflects the pulse signal, and a memory that holds the distance. A user determination unit that determines whether or not the detection target is a user based on a time change of the distance, and a control unit that controls the transmitter, the receiver, the calculation unit, the memory, and the user determination unit The control unit includes a propagation time of the pulse signal propagated to the receiver via the detection target when a pulse width of the pulse signal received by the receiver is equal to or less than a predetermined value, and Based on the propagation speed, let the computing unit determine the distance to the detection target, while when the pulse width is larger than a predetermined value, before propagating to the receiver through the detection target It is determined that the detection target is located at a distance where the pulse signal overlaps with the pulse signal directly propagated to the receiver without passing through the detection target, and a predetermined distance is set as the distance to the detection target. The present invention provides a user detection device characterized in that a calculation unit is determined.

  According to the present invention, even when the detection target exists at a short distance so that the waveform of the reception pulse reflected from the detection target overlaps and integrates directly with the waveform of the arrival pulse, the pulse width of the reception pulse is reduced. A user detection method and a user detection device for detecting the presence of a detection target based on the size are realized.

It is a block diagram which shows schematic structure of the user detection apparatus of this invention. (Embodiment 1) It is a timing chart of the user detection apparatus of this invention. (Embodiment 1) It is a flowchart which shows the process of the user detection apparatus of this invention. (Embodiment 1) It is an Example of the user detection apparatus of this invention. FIG. 3A shows the waveforms of the transmission pulse and the reception pulse of the ultrasonic pulse signal when the detection target is at a medium distance or a long distance from the apparatus, and FIG. 3B shows the detection target at a short distance from the apparatus. The waveforms of the transmission pulse and the reception pulse of the ultrasonic pulse signal at the time are shown in FIG. (Embodiment 1) It is a flowchart which shows the process of the user detection apparatus of this invention. (Embodiment 2) It is an example of the graph which shows the correspondence of the pulse width of a 1st receiving pulse, and the distance from a user detection apparatus to a detection target. (Embodiment 2)

  Hereinafter, the present invention will be described in more detail with reference to the drawings. In addition, the following description is an illustration in all the points, Comprising: It should not be interpreted as limiting this invention.

Embodiment 1
<Configuration of User Detection Device 1>
Hereinafter, based on FIGS. 1-4, the user detection apparatus 1 which concerns on Embodiment 1 of this invention is demonstrated.
FIG. 1 is a block diagram showing a schematic configuration of a user detection device 1 of the present invention. FIG. 2 is a timing chart of the user detection device 1 of the present invention. FIG. 3 is a flowchart showing processing of the user detection device 1 of the present invention. FIG. 4 shows an embodiment of the user detection device 1 of the present invention. FIG. 4A shows the waveforms of the transmission pulse 501 and the reception pulse (first reception pulse 601 and second reception pulse 602) of the ultrasonic pulse signal when the detection target 100 is at a medium distance or a long distance from the apparatus. FIG. 4B shows waveforms of the transmission pulse 501 and the reception pulse (the first reception pulse 601 and the second reception pulse 602) of the ultrasonic pulse signal when the detection target 100 is at a short distance from the apparatus.

The user detection device 1 transmits an ultrasonic wave to the external detection target 100 and detects the reflected wave, thereby measuring the distance LN to the detection target 100 and its change over time, and whether the detection target 100 is a user. It is a device that detects whether or not.
As shown in FIG. 1, the user detection device 1 includes a calculation unit 10, a memory 20, a timing generation unit 30, a transmission driver 40, a transmitter 50, a receiver 60, an amplifier / comparator 70, and a user / non-user determination unit 80. Prepare.

Hereinafter, each component shown in FIG. 1 will be described.
The calculation unit 10 is a part that controls the operation of each component of the user detection device 1 and is mainly realized by a microcomputer including a CPU, a ROM, a RAM, an I / O controller, a timer, and the like. The arithmetic unit 10 operates each hardware organically based on a control program stored in advance in the memory 20 and executes a distance determination process of the present invention as described later.

  The memory 20 is a part for storing information necessary for realizing various functions of the user detection device 1, control programs, display data, valid keys, various set times, and the like, semiconductor elements such as RAM and ROM, and hard disks A storage medium such as a flash memory is used.

The timing generation unit 30 is a part that drives a pulse of a signal having a constant frequency and adjusts the generation timing of the ultrasonic pulse signal.
As shown in FIG. 2A, the timing generator 30 drives the signal at a constant frequency. At this time, for example, when the transmission signal is pulse-driven at a frequency of 40 kHz, one pulse is generated every 25 μs.

The transmission driver 40 is a driver that generates a burst signal in synchronization with the timing signal from the timing generation unit 30 and transmits the burst signal to the transmitter 50.
The transmission driver 40 transmits a burst signal for each of a plurality of pulses as shown in FIG. For example, when 8 pulses are transmitted in a burst at a frequency of 40 kHz, the burst width is 200 μs. If the burst interval BI is 40 ms, 8 pulses are transmitted in bursts every 40 ms.

The transmitter 50 is a device that vibrates an ultrasonic transducer by a high voltage pulse from the transmission driver 40, generates an ultrasonic pulse signal, and transmits the ultrasonic pulse signal to the outside.
The ultrasonic vibrator is driven at a frequency unique to the vibrator. In the first embodiment, a vibrator driven at a frequency of 40 kHz is used.
In addition, since the transmission and reception have the maximum sensitivity when the duty ratio is 50%, the duty ratio is set to 50% in the first embodiment.
Regarding the number of pulses, the detection distance increases as the number of pulses increases, but the number of pulses saturates at about 10, and if the number of pulses is too large, the power consumption is high and the response time is delayed. It is desirable to determine the number of pulses in a balanced manner.

The receiver 60 is a device that receives the ultrasonic pulse signal transmitted from the transmitter 50.
As shown in FIG. 2C, the ultrasonic pulse signal received by the receiver 60 includes a reception pulse (direct arrival pulse) directly received by the receiver 60 without passing through the detection target 100 and a detection target 100. There are two types of received pulses received by the receiver 60.

  The transmitter 50 and the receiver 60 are determined in advance to determine the arrival time of the direct arrival pulse and to determine the correspondence between the pulse width PW of the first reception pulse 601 and the distance LN to the detection target 100, which will be described later. Keep the distance apart.

The amplifier / comparator 70 is a device that converts a signal exceeding a predetermined threshold among received pulses received by the receiver 60 into an active digital signal, and amplifies the signal with an operational amplifier or the like.
As shown in FIG. 2D, the amplifier / comparator 70 performs envelope detection of the received pulse received by the receiver 60 and converts it into a digital signal. Then, as shown in FIG. Is amplified and inverted.

  The user / non-user determining unit 80 is a part that obtains the distance LN to the detection target 100 and determines whether or not the detection target 100 is a user based on the change over time.

  The detection target 100 is a target to be detected by the user detection apparatus 1 and is a person or an object having a reflectance that reflects the ultrasonic pulse signal. A detection target 100 within a predetermined distance (for example, 0 m to 2 m) from the user detection device 1 is a detection target.

  In the first embodiment, the “transmission step” of the present invention is realized by the cooperation of the timing generator 30, the transmission driver 40, and the transmitter 50. The “reception process” of the present invention is realized by the receiver 60. The “calculation process” of the present invention is realized by the cooperation of the amplifier / comparator 70 and the calculation unit 10. The “storage process” of the present invention is realized by the memory 20. Further, the “user determination step” of the present invention is realized by the user / non-user determination unit 80.

<Processing Procedure of User Detection Device 1>
Next, based on FIG. 3, the process procedure of the user detection apparatus 1 of this invention is demonstrated.

  In step S1 of FIG. 3, the arithmetic unit 10 stores the counter N = 1 in the memory 20 (step S1).

  Next, in step S2, the Nth transmission pulse 501 is transmitted from the transmitter 50 to the outside, and the transmission start time T1 is stored in the memory 20 (step S2).

  Next, in step S3, the arithmetic unit 10 measures the pulse width PW of the first received pulse 601 received by the receiver 60 (step S3).

  As a specific measuring method of the pulse width PW, the pulse width of a digital signal obtained by digitizing the first received pulse 601 received by the receiver 60 by the amplifier / comparator 70 is measured.

Next, in step S4, the arithmetic unit 10 determines whether or not the pulse width PW of the first reception pulse 601 is greater than or equal to a predetermined value (step S4).
When the pulse width PW of the first reception pulse 601 is greater than or equal to a predetermined value (when the determination in step S4 is Yes), the calculation unit 10 has the detection target 100 near the user detection device 1 in step S5. The predetermined distance (for example, 30 cm) is stored in the memory 20 (step S5). Then, the calculating part 10 performs the process of step S11 (step S11).
On the other hand, when the pulse width PW of the first reception pulse 601 is not equal to or greater than a predetermined value (when the determination in step S4 is No), the arithmetic unit 10 determines that the receiver 60 receives the second reception pulse 602 in step S6. It is determined whether or not it has been received (step S6).

  Next, when the receiver 60 receives the second received pulse 602 in Step S6 (when the determination in Step S6 is Yes), the arithmetic unit 10 receives the second reception pulse 602 at the reception start time T2 in Step S7. Is stored in the memory 20 (step S7).

  Subsequently, in step S8, the calculation unit 10 detects the detection target 100 from the user detection device 1 based on the transmission start time T1 of the transmission pulse 501, the reception start time T2 of the second reception pulse 602, and the propagation speed of the ultrasonic pulse signal. Is obtained and stored in the memory 20 (step S8). Then, the calculating part 10 performs the process of step S11 (step S11).

  The distance obtained by the first transmission pulse 501 is L1, the distance obtained by the second transmission pulse 501 is L2, and the distance obtained by the Nth transmission pulse 501 is LN. save.

On the other hand, when the receiver 60 has not received the second received pulse 602 in Step S6 (when the determination in Step S6 is No), the calculation unit 10 has determined whether or not the time predetermined in Step S9 has elapsed. Is determined (step S9).
When the predetermined time has elapsed (when the determination in step S9 is Yes), the calculation unit 10 determines in step S10 that the detection target 100 is not within the detection range of the user detection device 1, and is determined in advance. The measured limit distance is stored in the memory 20 (step S10).
Then, the calculating part 10 performs the process of step S11 (step S11).

The measurement limit distance is a maximum distance determined in advance to confirm the presence of the user within the detection range of the user detection device 1, and is set to a value between 1 m50 cm and 2 m, for example.
The predetermined time standard is, for example, the time required for the ultrasonic pulse signal to reciprocate the measurement limit distance.

  On the other hand, when the predetermined time has not elapsed in Step S9 (when the determination in Step S9 is No), the arithmetic unit 10 performs the determination in Step S6 (Step S6).

  Finally, in step S11, the arithmetic unit 10 inputs N + 1 to the counter N and stores it in the memory 20 (step S11). Then, the process of step S2 is performed (step S2).

  In this way, the arithmetic unit 10 transmits the transmission pulse 501 for each burst interval BI, and stores the distance LN from the detection target 100 in the memory 20 when the Nth transmission pulse 501 is transmitted. And the calculating part 10 determines whether the detection target 100 is a user based on the time change of the distance LN.

Example 1
Next, based on FIG. 4, the result when the transmission pulse 501 is transmitted to the detection target 100 separated from the user detection device 1 to some extent will be described.
4A and 4B, the horizontal axis indicates time (milliseconds), and the vertical axis indicates transmission pulses, reception pulses, and amplitudes (arbitrary units) of digital signals.

In FIG. 4A, a transmission pulse 501 indicates a waveform of a pulse signal generated by the transmission driver 40, and is not an actual waveform of an ultrasonic pulse signal transmitted from the transmitter 50. The transmission pulse 501 is a waveform that electrically drives the transmitter 50, and is converted from an electrical signal to an ultrasonic signal by an ultrasonic transducer and output from the transmitter 50 to the outside.
In the first embodiment, the transmission pulse 501 is composed of 8 pulses, and the frequency of the carrier wave is 40 kHz. The transmission pulse 501 is output from the transmitter 50 at every burst interval BI (= 25 ms).

The first reception pulse 601 is a reception pulse directly received by the receiver 60 without using the detection target 100.
The second reception pulse 602 is a reception pulse received by the receiver 60 via the detection target 100.

  Note that neither the first reception pulse 601 nor the second reception pulse 602 is an actual waveform of the ultrasonic pulse signal received by the receiver 60. The first reception pulse 601 and the second reception pulse 602 are converted into weak electric signals by the ultrasonic transducer again after being converted into weak electric signals by the receiver 60, and then digitized and amplified by the amplifier / comparator 70. It is the waveform of the electric signal.

  4A and 4B, the duration of the first reception pulse 601 and the second reception pulse 602 is longer than the duration of the transmission pulse 501 from the transmitter 50 through the detection target 100 to the receiver 60. This is thought to be because there are many routes to reach.

In addition, a plurality of vibration waveforms with small amplitudes appearing after 4 ms after the second reception pulse 602 are received pulses after multiple reflection with the detection target 100 or detection objects 100 such as walls farther from the detection target 100. The received pulse reflected by.
As described above, the amplitude of the reception pulse reflected by the far detection target 100 is smaller than the amplitude of the reception pulse reflected by the near detection target 100.

The digital signals 701 to 703 are digital signals output by activating the first reception pulse 601 and the second reception pulse 602 with an electric signal exceeding a predetermined threshold by the amplifier / comparator 70.
In FIG. 4A, the digital signal 701 corresponds to the first reception pulse 601 and the digital signal 702 corresponds to the second reception pulse 602.

  In this embodiment, the threshold is set so as to ignore the contribution of the received pulse reflected by the distant detection target 100.

  As shown in FIG. 4B, the round trip time RTT from the transmission start time T1 of the transmission pulse 501 to the reception start time T2 of the second reception pulse 602 (corresponding to the pulse edge of the second reception pulse 602) is measured. Thus, the distance LN to the detection target 100 can be calculated.

  The round-trip time RTT is the time for the ultrasonic wave to reciprocate between the user detection device 1 and the detection target 100. Since the ultrasonic wave propagates in the air at a constant speed (about 340 m / s), the detection target 100 The distance LN can be obtained from LN = (340 m / s × round trip time RTT) ÷ 2.

  The distance L obtained in this way is stored in the memory 20 for each burst interval BI (= 25 ms) of the transmission pulse 501, thereby obtaining the time change of the distance LN to the detection target 100, that is, the velocity data of the detection target 100. be able to.

  Based on the speed data obtained as described above, it is determined whether or not the detection target 100 is a user.

  For example, when the detection target 100 is approaching the user detection device 1 at a human walking speed from a change in the distance LN from the user detection device 1 to the detection target 100, it can be detected that the detection target 100 is a user.

  By the way, when the detection target 100 is near the user detection device 1, as the detection target 100 approaches the user detection device 1, the round-trip time RTT in which the ultrasonic waves reciprocate between the user detection device 1 and the detection target 100 is calculated. Since it becomes shorter, the second reception pulse 602 in FIG. 4A approaches the first reception pulse 601.

  Then, when the detection target 100 enters within a certain distance from the user detection device 1, as shown in FIG. 4B, the first reception pulse 601 and the second reception pulse 602 are overlapped and integrated. As a result, a series of first reception pulses 601 having a large pulse width PW are formed.

  When such superposition of the received pulses 601 and 602 occurs, the receiver 60 detects only the first received pulse 601 and cannot detect the second received pulse 602, and therefore cannot obtain the round trip time RTT. Thus, the distance LN to the detection target 100, and hence the speed of the detection target 100 cannot be obtained.

  Therefore, when the pulse width PW of the first reception pulse 601 is larger than a predetermined value (for example, 2000 μs), the user detection is increased as the reception pulse related to the direct arrival pulse overlaps the reception pulse related to the reflection of the detection target 100. It is assumed that the detection target 100 is near the device 1, a predetermined distance is determined as the distance LN to the detection target 100, and the second reception pulse 602 is not detected.

  Depending on the distance between the transmitter 50 and the receiver 60, the number of transmission pulses and the frequency of the carrier wave, and the size and reflectance of the detection target 100, the distance LN from the user detection device 1 to the detection target 100 is approximately When the distance is 20 to 30 cm, the first reception pulse 601 and the second reception pulse 602 are superimposed.

In the example of FIG. 4A, when the falling edge of the second reception pulse 602 reaches about 1.4 ms, it overlaps with the end of the first reception pulse 601. At this time, the distance LN from the user detection device 1 to the detection target 100 is about 24 cm.
Therefore, the predetermined distance is set to 24 cm, for example.

  Since the value of the pulse width PW varies greatly depending on the voltage value of the transmission pulse 501, the number of pulses, the frequency, and the like, the example given here is merely an example.

  Thus, even when the detection target 100 is present at a short distance such that the waveform of the reception pulse reflected from the detection target 100 directly overlaps with the waveform of the arrival pulse, the first reception pulse 601 is present. By measuring the pulse width PW, the user detection device 1 that detects the presence of the detection target 100 can be realized.

[Embodiment 2]
Next, based on FIG. 5 and FIG. 6, the user detection apparatus 1 which concerns on Embodiment 2 of this invention is demonstrated.
FIG. 5 is a flowchart showing processing of the user detection device 1 according to the second embodiment of the present invention. FIG. 6 is an example of a graph showing a correspondence relationship between the pulse width PW of the first reception pulse 601 and the distance LN from the user detection device 1 to the detection target 100.

Note that the processes in steps S21 to S24 and S26 to S31 in FIG. 5 are the same as the processes in steps S1 to S4 and S6 to S11 in FIG.
Here, the process of step S25 not described in FIG. 4 will be described.

  In step S25 of FIG. 5, the calculation unit 10 refers to the graph shown in FIG. 6 (described later), obtains the distance LN to the detection target 100 based on the pulse width PW of the first reception pulse 601 and stores it in the memory 20. To do.

The vertical axis of the graph in FIG. 6 indicates the pulse width PW (μs) of the first reception pulse 601, and the horizontal axis indicates the distance LN (cm) from the user detection device 1 to the detection target 100.
For example, when the pulse width PW of the first reception pulse 601 is 3000 μs, it can be estimated from the graph of FIG. 6 that the distance LN from the user detection device 1 to the detection target 100 is 15 cm.

Data indicating the relationship between the pulse width shown in FIG. 6 and the distance LN from the user detection device 1 to the detection target 100 is stored in the memory 20 in advance.
Note that since the pulse width PW of the first reception pulse 601 varies depending on the voltage value, burst width, frequency, and the like of the transmission pulse 501, the correspondence relationship in FIG. 6 is merely an example.

  In this way, when the waveform of the second reception pulse 602 reflected from the detection target 100 overlaps with the waveform of the first reception pulse 601 (direct arrival pulse) and becomes integrated, the detection target 100 exists at a short distance. Even so, the user detection device 1 that estimates the distance LN from the user detection device 1 to the detection target 100 can be realized by measuring the pulse width PW of the first reception pulse 601.

(Other embodiments)
1. In the first embodiment, the detection distance may be varied by changing the voltage value or the number of pulses of the transmission pulse 501. (Embodiment 3)

  In general, the higher the voltage value of the transmission pulse 501 and the greater the number of pulses, the farther the detection distance can be extended, but the pulse widths PW of the first reception pulse 601 and the second reception pulse become larger. As a result, the first reception pulse 601 easily overlaps with the second reception pulse 602, so that the voltage value of the transmission pulse 501 is low and measurement at a short distance becomes more difficult than when the number of pulses is small.

  However, measurement of the pulse width PW of the first reception pulse 601 can realize the user detection device 1 that can freely adjust the detection distance without sacrificing the accuracy of detection of the detection target 100 at a short distance.

2. In the second embodiment, when the voltage value and the number of pulses of the transmission pulse 501 are variously changed, the pulse width PW of the first reception pulse 601 corresponding to each voltage value and the number of pulses and the detection target from the user detection device 1 A plurality of graphs showing the correspondence with the distance LN up to 100 may be held in the memory 20, and the graph to be referred to may be switched according to changes in the voltage value and the number of pulses of the transmission pulse 501. . (Embodiment 4)

  In this way, the setting for long-distance measurement with a large voltage value of the transmission pulse 501 and a large number of pulses and the setting for short-distance measurement with a small voltage value of the transmission pulse 501 and a small number of pulses are temporally alternated. By switching to, it is possible to realize the user detection device 1 that enables measurement at various distances without sacrificing the accuracy of determining the distance of the detection target 100 at a short distance.

3. In the first to fourth embodiments, an image forming apparatus including the user detection device 1 may be used. (Embodiment 5)

  In this way, in the image forming apparatus having a user detection function, the waveform of the second reception pulse 602 reflected from the detection target 100 overlaps with the waveform of the first reception pulse 601 (direct arrival pulse) and is integrated. Even when the detection target 100 is present at a short distance, the image forming apparatus detects the presence of the detection target 100 or the distance LN to the detection target 100 based on the pulse width PW of the first reception pulse 601. Can be realized.

As mentioned above,
(I) In the user detection method of the present invention, a transmission step in which a transmitter transmits a pulse signal, a reception step in which the receiver receives the pulse signal, and a distance to a detection target that reflects the pulse signal are determined. A calculation step; a storage step for holding the distance; and a user determination step for determining whether or not the detection target is a user based on a temporal change in the distance. In the calculation step, the receiver When the pulse width of the received pulse signal is equal to or less than a predetermined value, the distance to the detection target is determined based on the propagation time and propagation speed of the pulse signal propagated to the receiver through the detection target. On the other hand, when the pulse width is larger than a predetermined value, the pulse signal propagated to the receiver through the detection target is directly transmitted to the receiver without passing through the detection target. Assuming that the detection target is located at a distance overlapping with the propagated pulse signal, a predetermined distance is determined as the distance to the detection target.
Further, the user detection device of the present invention includes a transmitter that transmits a pulse signal, a receiver that receives the pulse signal, a calculation unit that determines a distance to a detection target that reflects the pulse signal, and the distance. A memory to hold, a user determination unit that determines whether or not the detection target is a user based on a time change of the distance, the transmitter, the receiver, the arithmetic unit, the memory, and the user determination unit A control unit that controls the pulse signal propagated to the receiver via the detection target when a pulse width of the pulse signal received by the receiver is equal to or less than a predetermined value. The calculation unit determines the distance to the detection target based on the propagation time and the propagation speed of the signal, and when the pulse width is larger than a predetermined value, the reception is performed via the detection target. It is determined that the detection target is located at a distance where the pulse signal propagated to the machine overlaps with the pulse signal directly propagated to the receiver without passing through the detection target, and a predetermined distance is determined as the detection target. The calculation unit is determined as the distance up to.

In the present invention, the “user detection device” and the “user detection method” transmit a pulse signal such as an ultrasonic wave to an external detection target and detect the reflected wave, thereby changing the distance to the detection target and its time change. The “predetermined distance” is an apparatus and method for detecting whether or not the detection target is a user. The “predetermined distance” varies greatly depending on the voltage value of the transmission pulse, the number of pulses, the frequency, etc. Set to a distance of ~ 30 cm.
The “propagation speed” does not necessarily need to be detected, and a known propagation speed value may be used. For example, when the pulse signal is an ultrasonic signal, a value (about 340 m / s) at which the ultrasonic signal propagates in the air is used as a known value.

Furthermore, the preferable aspect of this invention is demonstrated.
(Ii) In the user detection method according to the present invention, the pulse signal may be an ultrasonic pulse signal.

  In this way, even when an ultrasonic pulse signal is used, a user detection method for detecting the presence of a detection target can be realized based on the magnitude of the pulse width of the received pulse.

  (Iii) In the user detection method according to the present invention, in the calculation step, when the pulse width of the pulse signal received by the receiver is larger than a predetermined value, the pulse width and the distance to the detection target The distance from the pulse width to the detection target may be determined by referring to data indicating the corresponding relationship.

  In this way, since the distance from the pulse width to the detection target can be measured, an inexpensive and highly accurate user detection method can be realized.

  (Iv) Moreover, the user detection apparatus using the said user detection method may be sufficient.

  In this way, even if the detection target is present at a short distance so that the waveform of the reception pulse reflected from the detection target overlaps and integrates directly with the waveform of the arrival pulse, the pulse of the first reception pulse is obtained. A user detection device that detects the presence of a detection target or a distance to the detection target based on the width can be realized.

  (V) In the user detection device according to the present invention, the pulse signal may be an ultrasonic pulse signal.

  In this way, even when an ultrasonic pulse signal is used, a user detection device that detects the presence of a detection target can be realized based on the magnitude of the pulse width of the received pulse.

  (Vi) In the user detection device according to the present invention, the memory previously stores data indicating a correspondence relationship between the pulse width and the distance to the detection target, and the calculation unit is configured to determine the pulse width based on the data. The distance from the detection target to the detection target may be determined.

  In this way, since the distance from the pulse width to the detection target can be measured, an inexpensive and highly accurate user detection device can be realized.

  (Vii) The image forming apparatus may include the user detection device.

  In the image forming apparatus having a user detection function, even if the detection target exists at a short distance so that the waveform of the reception pulse reflected from the detection target overlaps and integrates directly with the waveform of the arrival pulse, the first An image forming apparatus that detects the presence of the detection target or the distance to the detection target based on the pulse width of the reception pulse can be realized.

  An “image forming device” is a copier or multifunction device having a copying (copying function) function such as a printer using an electrophotographic method for image formation with toner, or an MFP (Multifunction Peripheral) including functions other than copying. A device that forms and outputs an image.

Preferred embodiments of the present invention include combinations of any of the above-described plurality of embodiments.
In addition to the above-described embodiments, there can be various modifications of the present invention. These modifications should not be construed as not belonging to the scope of the present invention. The present invention should include the meaning equivalent to the scope of the claims and all modifications within the scope.

DESCRIPTION OF SYMBOLS 1: User detection apparatus, 10: Operation part, 20: Memory, 30: Timing generation part, 40: Transmission driver, 50: Transmitter, 60: Receiver, 70: Amplifier / comparator, 80: User / non-user determination part , 100: detection target, 501: transmission pulse, 601: first reception pulse, 602: second reception pulse, 701, 702, 703: digital signal, BI: burst interval, L1, L2, LN: distance, N: counter , PW: Pulse width, RTT: Round trip time, T1: Transmission start time, T2: Reception start time

Claims (8)

A transmitting step in which a transmitter transmits a pulse signal, a receiving step in which the receiver receives the pulse signal, a calculating step for determining a distance to a detection target reflecting the pulse signal, and a storing step for holding the distance And a user determination step of determining whether or not the detection target is a user based on the time change of the distance,
In the calculation step, when the pulse width of the pulse signal received by the receiver is equal to or smaller than a predetermined value, based on the propagation time and propagation speed of the pulse signal propagated to the receiver through the detection target Determine the distance to the detection object;
On the other hand, when the pulse width is larger than a predetermined value, the pulse signal propagated to the receiver through the detection target is directly transmitted to the receiver without passing through the detection target. A user detection method, wherein a predetermined distance is determined as a distance to the detection target, assuming that the detection target is located at a distance overlapping with the detection target.   The user detection method according to claim 1, wherein the pulse signal is an ultrasonic pulse signal.   In the calculation step, when the pulse width of the pulse signal received by the receiver is larger than a predetermined value, referring to data indicating a correspondence relationship between the pulse width and the distance to the detection target, The user detection method according to claim 1, wherein a distance from the pulse width to the detection target is determined.   The user detection apparatus using the user detection method as described in any one of Claims 1-3. A transmitter for transmitting a pulse signal; a receiver for receiving the pulse signal; a calculation unit for determining a distance to a detection target reflecting the pulse signal; a memory for holding the distance; and a time variation of the distance A user determination unit that determines whether or not the detection target is a user, and a control unit that controls the transmitter, the receiver, the arithmetic unit, the memory, and the user determination unit,
When the pulse width of the pulse signal received by the receiver is equal to or less than a predetermined value, the control unit is based on a propagation time and a propagation speed of the pulse signal propagated to the receiver through the detection target. Let the calculation unit determine the distance to the detection target,
On the other hand, when the pulse width is larger than a predetermined value, the pulse signal propagated to the receiver through the detection target is directly transmitted to the receiver without passing through the detection target. The user detection device is characterized in that the detection target is determined to be located at a distance that overlaps with the calculation target, and the calculation unit determines a predetermined distance as a distance to the detection target.   The user detection device according to claim 5, wherein the pulse signal is an ultrasonic pulse signal.   The memory previously stores data indicating a correspondence relationship between the pulse width and a distance to the detection target, and the calculation unit determines a distance from the pulse width to the detection target based on the data. Item 5. The user detection device according to Item 5 or 6.   An image forming apparatus comprising the user detection device according to claim 4.