Clock and time synchronization system

Abstract

It reduces power consumption and adjusts the time even in areas where standard radio waves are difficult to receive. [Solution] The wall clock 5 includes a light receiving unit 50 that receives an optical signal representing standard time information, a photoelectric conversion unit 51 that converts the optical signal received by the light receiving unit 50 into an electrical signal, a standard time information acquisition unit 52 that acquires standard time information from the electrical signal, and a time synchronization unit 53 that synchronizes the time measured by the time measurement unit 54 based on the standard time information.

Description

Technical Field

[0001] The present invention relates to a clock and a time synchronization system for synchronizing time based on standard time information.

Background Art

[0002] Currently, if standard time information is obtained by wireless communication such as Bluetooth (registered trademark) or Wi-Fi (registered trademark), the time can be easily adjusted. Therefore, a time adjustment clock corresponding to wireless communication (hereinafter, "wireless communication clock") is known (for example, Non-Patent Document 1).

[0003] There is also known a radio clock that can adjust time using standard radio waves (for example, Non-Patent Document 2). Standard radio waves are information representing frequency and time generated by an ultra-high-precision atomic clock. A radio clock is a clock that can receive standard radio waves and adjust time based on the received standard radio waves.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, wireless communication watches have the problem of consuming a lot of power to send and receive wireless signals. In particular, there is a strong demand to reduce power consumption in battery-powered watches. For example, Bluetooth-enabled watches are equipped with many AA batteries (for example, 6), and Wi-Fi-enabled watches are equipped with many C batteries (for example, 6), to ensure a battery life of 5 years.

[0006] Radio-controlled clocks do not transmit wireless signals, so they consume less power than wireless communication clocks. For example, a radio-controlled clock can keep time for a long period of time using only one AA battery. However, radio-controlled clocks have a problem in that it is difficult to adjust the time in places where standard radio waves cannot easily reach (for example, indoors away from windows).

[0007] Therefore, the object of the present invention is to provide a clock and a time synchronization system that can reduce power consumption and adjust the time even in places where standard radio waves are difficult to reach. [Means for solving the problem]

[0008] To solve the aforementioned problems, the present invention provides a clock that synchronizes the time based on standard time information generated by a time server, comprising: a light receiving unit that receives an optical signal representing standard time information; a photoelectric conversion unit that converts the optical signal received by the light receiving unit into an electrical signal; a standard time information acquisition unit that acquires standard time information from the electrical signal converted by the photoelectric conversion unit; a time measurement unit that measures the time difference; and a time synchronization unit that synchronizes the time measured by the time measurement unit based on the standard time information acquired by the standard time information acquisition unit.

[0009] With this configuration, the clock receives standard time information as an optical signal, eliminating the need to send and receive wireless signals and thus reducing power consumption. Furthermore, the clock can adjust the time even in places where standard radio waves are difficult to reach, such as indoors, as long as lighting can be installed.

[0010] Furthermore, the present invention can also be realized as a time synchronization system comprising the aforementioned clock and lighting that converts standard time information generated by a time server into an optical signal and outputs it as illumination light. [Effects of the Invention]

[0011] According to the present invention, power consumption is reduced, and the time can be adjusted even in places where standard radio waves are difficult to receive. [Brief explanation of the drawing]

[0012] [Figure 1] This is a block diagram showing the configuration of the time synchronization system according to the first embodiment. [Figure 2] This is a flowchart showing the operation of the time synchronization system according to the first embodiment. [Figure 3] This block diagram shows the configuration of the time synchronization system according to the second embodiment. [Figure 4] This is a block diagram showing the configuration of the time synchronization system according to Modification Example 1. [Figure 5] Modification Example 1 is an explanatory diagram illustrating a method by which a wristwatch receives light signals from a mobile device. [Modes for carrying out the invention]

[0013] The embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below are intended to embody the technical concept of the present invention, and unless otherwise specified, the present invention is not limited to these embodiments. In addition, the same reference numerals are used for the same means, and their descriptions may be omitted.

[0014] (First Embodiment) [Overview of the Time Synchronization System] Referring to Figure 1, the time synchronization system 1 according to the first embodiment will be described. The time synchronization system 1 synchronizes the time of the wall clock (clock) 5 based on the standard time information from a time server (not shown). As shown in FIG. 1, the time synchronization system 1 includes a wireless router 2, a mobile terminal 3, a lighting fixture 4 with a communication function, and a wall clock 5.

[0015] Note that a time server is a server that distributes standard time information on a network such as the Internet. For example, as a time server, an NTP (Network Time Protocol) server that uses NTP can be mentioned. Also, standard time information is information that represents the time that serves as a standard during time synchronization. For example, in Japan, standard time information represents Japan Standard Time.

[0016] The wireless router 2 is a router for performing wireless communication such as Wi-Fi. In this embodiment, the wireless router 2 connects the mobile terminal 3 and the lighting fixture 4 with a communication function to the network.

[0017] The mobile terminal 3 connects to the lighting fixture 4 with a communication function via the wireless router 2 and performs settings for the lighting fixture 4 with a communication function. Specifically, the mobile terminal 3 performs network settings and time zone settings related to DHCP (Dynamic Host Configuration Protocol) and Wi-Fi. For example, as the mobile terminal 3, a smartphone or a tablet terminal can be mentioned.

[0018] The lighting fixture 4 with a communication function is a lighting fixture having a wireless communication function such as Wi-Fi. For example, the lighting fixture 4 with a communication function is an LED (Light Emitting Diode) lighting fixture installed on the indoor ceiling. Also, the lighting fixture 4 with a communication function is connected to an AC power supply, and it is assumed that the power consumption is not limited. Note that the light source type and installation location of the lighting fixture 4 with a communication function are not limited to the above examples.

[0019] The lighting device 4 with communication function converts the standard time information generated by the time server into an optical signal and outputs it as illumination light. In this embodiment, the lighting device 4 with communication function is capable of wireless communication according to the network settings by the mobile terminal 3. Therefore, the lighting device 4 with communication function can receive the standard time information from the time server via the wireless router 2. Then, the lighting device 4 with communication function converts the received standard time information into an optical signal and outputs it as illumination light. Here, the lighting device 4 with communication function can output an optical signal according to a newly defined protocol or a known protocol such as Li-Fi.

[0020] Here, the intensity modulation of the illumination light by the lighting device 4 with communication function will be described. The lighting device 4 with communication function intensity-modulates the illumination light according to the standard time information. For example, the lighting device 4 with communication function intensity-modulates the illumination light at the maximum intensity or the minimum intensity (turning off the light). In this case, the brightness and darkness of the illumination light may be perceived by humans. Therefore, the lighting device 4 with communication function may perform intensity modulation at a high speed (for example, 200 times or more per second) so that the brightness and darkness of the illumination light are not perceived by humans.

[0021] Furthermore, the lighting device 4 with communication function may intensity-modulate at the maximum intensity of the illumination light or at an intensity decreased by an amount that humans cannot perceive (for example, 5%) from the maximum intensity. Thereby, it is possible to prevent the brightness and darkness of the illumination light from being perceived by people.

[0022] The wall clock 5 synchronizes the time based on the standard time information generated by the time server. In this embodiment, it is assumed that the wall clock 5 is a wall-mounted clock fixed to an indoor wall. Also, it is assumed that the wall clock 5 is arranged within the range where the illumination light from the lighting device 4 with communication function can reach. For example, the wall clock 5 is arranged in the same indoor space as the lighting device 4 with communication function.

[0023] [Configuration of Wall Clock] Referring to FIG. 1, the configuration of the wall clock 5 will be described. As shown in Figure 1, the wall clock 5 comprises a light receiving unit 50, a photoelectric conversion unit 51, a standard time information acquisition unit 52, a time synchronization unit 53, and a time measurement unit 54. The general functions of the clock are not described or illustrated.

[0024] The light receiving unit 50 receives an optical signal representing standard time information. In this embodiment, the light receiving unit 50 receives illumination light from the communication-enabled lighting 4 as an optical signal. For example, a general-purpose light sensor can be used as the light receiving unit 50. The light receiving unit 50 outputs the received optical signal to the photoelectric conversion unit 51.

[0025] The photoelectric conversion unit 51 converts the optical signal received by the light receiving unit 50 into an electrical signal. In this embodiment, the photoelectric conversion unit 51 photoelectrically converts the optical signal input from the light receiving unit 50 into an electrical signal. For example, the photoelectric conversion unit 51 can be a general-purpose photoelectric conversion element. The photoelectric conversion unit 51 outputs the converted electrical signal to the standard time information acquisition unit 52.

[0026] The standard time information acquisition unit 52 acquires standard time information from the electrical signal converted by the photoelectric conversion unit 51. In this embodiment, the standard time information acquisition unit 52 extracts standard time information from the electrical signal input from the photoelectric conversion unit 51. The standard time information acquisition unit 52 outputs the acquired standard time information to the time synchronization unit 53.

[0027] The time synchronization unit 53 synchronizes the time measured by the time measurement unit 54 based on the standard time information acquired by the standard time information acquisition unit 52. In this embodiment, the time synchronization unit 53 outputs a command to the time measurement unit 54 to adjust the time so that it synchronizes with the standard time indicated by the standard time information.

[0028] The time measurement unit 54 measures the time (time difference). The time measurement unit 54 also adjusts the measured time according to commands input from the time synchronization unit 53. For example, the time measurement unit 54 is composed of a quartz crystal oscillator and a drive circuit, similar to a typical quartz clock.

[0029] [Operation of the time synchronization system] Referring to Figure 2, the operation of the time synchronization system 1 will be explained. As shown in Figure 2, in step S1, the communication-enabled lighting 4 receives standard time information from the time server via the wireless router 2. In step S2, the communication-enabled lighting 4 converts the received standard time information into an optical signal and outputs it as illumination light.

[0030] In step S3, the light receiving unit 50 receives the illumination light from the communication-enabled lighting 4 as an optical signal. In step S4, the photoelectric conversion unit 51 converts the optical signal received by the light receiving unit 50 into an electrical signal.

[0031] In step S5, the standard time information acquisition unit 52 acquires standard time information from the electrical signal converted by the photoelectric conversion unit 51. In step S6, the time synchronization unit 53 synchronizes the time of the time measurement unit 54 based on the standard time information acquired by the standard time information acquisition unit 52.

[0032] [effect] As described above, the wall clock 5 according to the first embodiment receives standard time information as an optical signal, eliminating the need to transmit and receive wireless signals and thus reducing power consumption. For example, by using an optical receiver with low power consumption as the optical receiving unit 50, the wall clock 5 can operate for several years on a single AA battery. Furthermore, the wall clock 5 can adjust the time even in places where standard radio waves are difficult to reach, such as indoors, as long as a communication-enabled light 4 can be installed.

[0033] Here, Wall Clock 5 establishes a de facto standard for the protocol that outputs standard time information, enabling time synchronization regardless of the country. In particular, since Wall Clock 5 uses optical signals, it does not need to comply with the radio wave regulations of each country, and can be used in various countries with the same configuration.

[0034] (Second Embodiment) [Overview of the Time Synchronization System] Referring to Figure 3, the differences between the time synchronization system 1B according to the second embodiment and the first embodiment will be explained. In the second embodiment, the time synchronization system 1B differs from the first embodiment in that it includes a wristwatch (clock) 5B.

[0035] As shown in Figure 3, the time synchronization system 1B comprises a wireless router 2, a mobile terminal 3, a communication-enabled light 4, and a wristwatch 5B. Note that, except for the wristwatch 5B, the components are the same as in the first embodiment and therefore their description is omitted.

[0036] The wristwatch 5B synchronizes its time based on standard time information generated by a time server. In this embodiment, the wristwatch 5B is a wristwatch worn on a person's wrist. For example, the wristwatch 5B can adjust its time when facing the communication-enabled light 4.

[0037] [Wristwatch Components] Referring to Figure 3, the configuration of the wristwatch 5B will be explained. As shown in Figure 3, the wristwatch 5B comprises a light receiving unit 50B, a photoelectric conversion unit 51, a standard time information acquisition unit 52, a time synchronization unit 53, and a time measurement unit 54. Note that, except for the light receiving unit 50B, the components are the same as in the first embodiment and therefore their description is omitted.

[0038] The light-receiving unit 50B is preferably a solar cell built into the wristwatch 5B. If the wristwatch 5B has a built-in solar cell for charging, this solar cell can receive illumination light from the communication-enabled light 4. In this case, the wristwatch 5B can use its built-in solar cell as the light-receiving unit 50B.

[0039] [effect] As described above, the wristwatch 5B according to the second embodiment, like the first embodiment, consumes less power and allows time adjustment even in places where standard radio waves are difficult to receive. Furthermore, since the 5B watch utilizes its built-in solar cell as the light-receiving unit 50B, the addition of a time-setting function does not increase its thickness. Currently available radio-controlled watches with automatic time setting capabilities are 6mm or thicker due to the inclusion of an antenna and battery. In contrast, the 5B watch can be made thinner, with a thickness of less than 6mm, while still offering automatic time setting capabilities.

[0040] (Variation 1) Referring to Figure 4, the differences between the time synchronization system 1C according to Modification 1 and the second embodiment will be explained. In this modified version, the wristwatch 5B receives an optical signal from the mobile terminal 3, which is different from the second embodiment.

[0041] As shown in Figure 4, the time synchronization system 1C comprises a wireless router 2, a mobile terminal 3C, and a wristwatch 5B. In other words, the time synchronization system 1C does not include a communication-enabled light 4 (Figure 3).

[0042] Since the mobile terminal 3C is often equipped with a light 30 (Figure 5), this is used as a communication-enabled light 4. In other words, the mobile terminal 3C receives standard time information from a time server via the wireless router 2. Then, like the communication-enabled light 4, the mobile terminal 3C converts the received standard time information into an optical signal and outputs it to the wristwatch 5B. Note that the method and protocol used by the wristwatch 5B for intensity modulation are the same as those used for the communication-enabled light 4, so an explanation is omitted.

[0043] In the wristwatch 5B, the light receiving unit 50B receives light from the mobile terminal 3C as an optical signal. The configuration of the wristwatch 5B is the same as in the second embodiment, so its description is omitted.

[0044] Referring to Figure 5, the method by which the wristwatch 5B receives the optical signal from the mobile terminal 3C will be explained. As shown in Figure 5, the mobile terminal holder 6 is designed to hold the mobile terminal 3C on its top surface. The mobile terminal holder 6 has an internal space in which the main body 55 of the wristwatch 5B can be positioned so that the light receiving unit 50B is shielded from ambient light. The mobile terminal holder 6 also has a hole on its top surface with a larger diameter than the light 30 so that light from the mobile terminal 3C can reach the light receiving unit 50B.

[0045] The mobile terminal 3C is placed on the top surface of the mobile terminal holder 6 with the light 30 facing downwards. The wristwatch 5B is positioned in the internal space of the mobile terminal holder 6 with its main body 55 facing the light receiving unit 50B. This prevents other light from shining on the wristwatch 5B when it receives the light signal from the mobile terminal 3C. For example, one can place the wristwatch 5B in the mobile terminal holder 6 and adjust the time before going to sleep.

[0046] In this modified example, for the sake of clarity, the time synchronization system 1C is omitted from the communication-enabled lighting 4, but it may also be equipped with the communication-enabled lighting 4, as in the second embodiment. In this case, the mobile terminal 3C can receive optical signals through two paths: the mobile terminal 3C and the communication-enabled lighting 4.

[0047] Furthermore, although it was explained that the wristwatch 5B uses the mobile terminal holder 6 when receiving optical signals, it is not limited to this. In other words, the wristwatch 5B can receive optical signals from the mobile terminal 3C even without using the mobile terminal holder 6.

[0048] (Other variations) Although each embodiment has been described in detail above, the present invention is not limited to the embodiments described above, and includes design changes and the like that that do not depart from the spirit of the present invention. In the embodiments described above, the clock was described as either a wall clock or a wristwatch, but the clock is not limited to these types. For example, the clock may be a desk clock.

[0049] In the first embodiment described above, the lighting with communication function was explained as having a light source that outputs an optical signal, but it is not limited to this. In addition to the light source that emits illumination light, a light source of invisible light (e.g., infrared light) for outputting an optical signal of standard time information may also be provided. In this case, the light receiving unit should be one that corresponds to invisible light (e.g., an infrared sensor). This prevents the brightness of the illumination light from being perceived by a person. [Explanation of symbols]

[0050] 1,1B,1C Time Synchronization System 2 Wireless router 3.3C mobile devices 4. Lighting with communication function 5. Wall Clocks (Clocks) 5B Wristwatch (Watch) 6. Mobile device holder 50,50B Light receiving part 51 Photoelectric conversion unit 52 Standard time information acquisition section 53 Time Synchronization Section 54 Time Measurement Unit

Claims

1. A clock that synchronizes its time based on standard time information generated by a time server, A light receiving unit that receives an optical signal representing the standard time information, The photoelectric conversion unit converts the optical signal received by the light receiving unit into an electrical signal, A standard time information acquisition unit that acquires the standard time information from the electrical signal converted by the photoelectric conversion unit, A time measuring unit for measuring the aforementioned time, A time synchronization unit synchronizes the time measured by the time measurement unit based on the standard time information acquired by the standard time information acquisition unit, A watch characterized by having the following features.

2. The light receiving unit is characterized in that it receives illumination light from the lighting as the optical signal, as described in claim 1.

3. The watch according to claim 1, characterized in that the light receiving unit is a solar cell built into the watch.

4. The watch according to claim 1, characterized in that it is a wristwatch.

5. The watch according to claim 4, characterized in that the light receiving unit receives light from a mobile terminal as the optical signal.

6. The clock according to claim 1, characterized in that it is a wall clock or a desk clock.

7. The clock according to claim 1, A lighting system that converts standard time information generated by a time server into an optical signal and outputs it as illumination light, A time synchronization system characterized by comprising the following features.

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