JP5194958B2 - AC power supply detection device and circuit protection device - Google Patents

Description

  The present invention relates to an AC power supply detection device that detects that an AC power supply such as a commercial power supply is mixed in a line, and a circuit protection device including the AC power supply detection device.

  In recent years, there has been a remarkable spread of multi-function products (hereinafter referred to as MFPs) in homes and offices. This is because the MFP can realize various services such as a printer function, a copy function, and a facsimile function with a single device in place of the conventional single-function devices such as a printer, a copier, a scanner, and a facsimile. .

  This MFP is equipped with a system controller, an image processing unit, a facsimile controller, a line control (I / F) unit, an AC control unit, and the like, and a direct current obtained by switching by rectifying alternating current from a commercial power source with a rectifier. The voltage is applied as a DC power source to the facsimile controller, line control (I / F) unit, and system controller.

  In order to execute the copy function, the image processing unit is provided with an image sensor, which reads an image and converts it into electronic data. The image data is not only digitized by the image sensor, but also inputted through communication from a telephone line. The MFP is provided with an image carrier such as a photosensitive drum and an LSU (Laser Scanning Unit), and irradiates the surface of the image carrier with laser light controlled by the LSU based on the read electronic data or the received electronic data. Then, an electrostatic latent image is formed, and the electrostatic latent image is developed with toner. Then, the visible image is transferred onto a recording sheet or the like by a transfer device, and is fixed by a fixing device. By sequentially performing this process, the MFP can execute the printer function.

  As described above, in the MPF, electronic data is transmitted / received by communication using a telephone line. However, there is a possibility that noise, for example, external noise from a commercial power source described below may be mixed in the telephone line transmitted / received depending on the situation.

  That is, in many homes and offices, a commercial power source is used as a power source for devices such as MFPs. In addition, when a telephone line is captured (off-hook), a loop circuit is formed, and a loop current due to application of a DC voltage flows to perform communication. When there is some trouble or accident, inconvenience in the arrangement of the telephone line and the power line, etc., the commercial power source may be mixed into the telephone line in a contact or non-contact manner. As a result, external noise is mixed.

  If such commercial power supply is left unattended, the facsimile controller, line control (I / F) unit, and other circuits of devices connected to the telephone line may be damaged.

  In view of this, there has been proposed a power supply mixing detection method and apparatus that can accurately detect that alternating current from an AC power supply such as a commercial power supply is mixed in the apparatus even when the mixed current is small (see Patent Document 1).

The power supply mixing detection method and apparatus of (Patent Document 1) detects, for example, an AC current of 0 to 600 mA flowing out from the ground including the mixed current from the AC power supply, and this is detected by a current probe (ground outflow current acquisition means). Only the current in a predetermined frequency range of about 47 Hz to 63 Hz corresponding to the frequency of the AC power supply is detected by the low-pass filter and the high-pass filter, and this detection current detects the mixed current from the AC power supply. A determination value for determining whether or not it is included is set by the CPU based on the detection current, and the value of the detection current is compared with this determination value to determine whether or not a mixed current is included. When it is determined that the mixed current from the AC power source is included based on the result, an alarm is output.
JP 2004-187441 A

  The power supply mixing detection method and apparatus described above (Patent Document 1) uses a current probe that detects an alternating current flowing out of the ground of about 0 to 600 μA. An AC signal having a frequency range of about 47 Hz to 63 Hz is calculated as an effective value by an effective value calculator, converted to a digital signal by an A / D converter, and supplied to the CPU.

  When the CPU receives this digital signal, it sets this digital signal as the current measurement value for every predetermined unit measurement time such as, for example, 5 seconds, which is the minimum measurable time of the apparatus. This measurement value is calculated as an averaged value during this unit measurement time.

  The current measurement value set for each predetermined unit measurement time is compared with the determination value set as the next determination value in the previous unit measurement time, which is one previous to the current unit measurement time in the CPU. Then, it is determined whether or not there is a mixture based on a comparison result between two adjacent determination values.

  In this determination value setting, a value obtained by adding a predetermined electric mixture determination coefficient α to the previous measurement value in the unit measurement time is set as the determination value for the current measurement value. In other words, a value obtained by adding a predetermined electric mixture determination coefficient α to the current measured value is set as the next determination value, and this electric mixture determination coefficient α is an experience of an electric mixture risk constant D. Determined from the value.

  As can be seen from the above, the technique of (Patent Document 1) uses an electric current probe, calculates an effective value, and calculates an average value over a long time of 5 seconds. The coefficient α is added to obtain a determination value. In addition to using the current probe, it is necessary to repeat the calculation, and the determination accuracy uses the constants of the electric mixture determination coefficient α and the electric mixture risk constant D, and therefore cannot be expected so much.

  If it is possible to easily and inexpensively determine the mixing of AC power in MFPs and other communication devices that are now prevalent and are expected to accelerate further in the future, the cost of these devices can be reduced and mixing of AC power can be reduced. Circuit protection and failure avoidance.

  Therefore, the present invention prevents damage to an AC power source mixing detection device that can easily and inexpensively determine that an AC power source is mixed, and a circuit using the same, particularly a circuit around a communication device. An object of the present invention is to provide a circuit protection device capable of performing the above.

In order to solve such a problem, the AC power supply detection device according to the present invention includes a polarity inversion detection means for detecting the polarity inversion of the line, and the polarity inversion detection means after the polarity inversion detection means detects the polarity inversion. A counting means for sequentially counting the time until the polarity is detected next, a calculating means for calculating an average value of a plurality of count values counted by the counting means, and an average value calculated by the calculating means If it is included in the specified value range, it is determined that AC power is mixed in the line. If it is not included in the specified value range, it is determined that AC power is not mixed. And a judging means.

  The circuit protection device according to the present invention includes the AC power supply mixing detection device, and shuts off the line when the mixing determination unit of the AC power supply detection device determines that AC power is mixed in the line. Means are provided.

  According to the AC power supply mixing detection apparatus of the present invention, it can be determined easily and inexpensively with high accuracy that an AC power supply is mixed.

  In addition, according to the circuit protection device of the present invention, it is possible to easily and inexpensively determine that an AC power source is mixed. In the case of an overcurrent or overvoltage, the circuit is cut off, a circuit around the communication device, etc. Can prevent damage.

The invention of claim 1 of the present invention in order to solve the above problems, the polarity inversion detection means for detecting a polarity inversion of the line, after the polarity inversion detection means detects the polarity inversion, the polar inversion detection means Next, a counting unit that sequentially counts the time until polarity reversal is detected, a calculating unit that calculates an average value of a plurality of count values counted by the counting unit, and an average value calculated by the calculating unit is a predetermined value If it is included in the value range, it is determined that the AC power is mixed in the line, and if it is not included in the predetermined value range, it is determined that the AC power is not mixed. And an AC power supply mixing detection device.

  By this configuration, the time until the polarity reversal detection means detects the next polarity reversal is sequentially counted, and by calculating and determining the average value, it is simple and inexpensive that the AC power is mixed, Can be determined with high accuracy.

According to the second aspect of the present invention, the polarity reversal detecting means for detecting the polarity reversal of the line, and the polarity reversal detecting means detects the polarity reversal after the polarity reversal detecting means detects the polarity reversal. At least the counting means for sequentially counting the time until the counting, the first average value of the nth and (n + 1) th times counted by the counting means, and the second average value of the (n + 1) th time and (n + 2) th time are calculated. When the calculation means and the first and second average values calculated by the calculation means are included in a predetermined value range within a predetermined period, it is determined that AC power is mixed in the line. An AC power source mixing detection device comprising: a mixing determination unit that determines that no AC power source is mixed when a predetermined number is not included in a predetermined value range within a predetermined period.

  With this configuration, it can be determined very simply and inexpensively with extremely high accuracy that an AC power source is mixed.

The invention of claim 3 of the present invention is an invention dependent on the invention of claim 2, comprising a detection means for detecting a voltage value of the line or a current value flowing into the equipment through the line, and the mixing judgment means is a voltage value or An AC power source characterized in that an AC power source is included in the line when the current value is equal to or greater than a predetermined value and the average value calculated by the calculating means is included in the range of the predetermined value It is a mixing detection device.

  With this configuration, it is possible to determine that the AC power supply should be avoided at a level that damages the device only when the voltage value of the line or the current value flowing into the device through the line is a predetermined value.

The invention of claim 4 of the present invention is an invention dependent on the invention of claim 3, comprising a detection means for detecting a voltage value of the line or a current value flowing into the device through the line, and the mixing judgment means is a voltage value or If the current value is equal to or greater than the predetermined value and the first and second average values calculated by the calculation means are included in the predetermined value range within a predetermined period, the AC power is mixed into the line. It is an AC power source mixing detection device characterized in that

  With this configuration, only when the voltage value of the line or the current value flowing into the device through the line is a predetermined value, it can be determined with high accuracy as an AC power source that should be avoided at a level that damages the device.

According to a fifth aspect of the present invention, the AC power supply mixing detection device according to any one of the first to fourth aspects of the invention is provided, and the mixing judgment means of the AC power supply mixing detection device is connected to the AC power supply. The circuit protection device is characterized in that it is provided with a blocking means for blocking the line when it is determined that the signal is mixed.

  With this configuration, it is possible to easily and inexpensively determine that AC power is mixed, and in the case of overcurrent or overvoltage, the line can be cut off to prevent mainly damage to circuits around the communication. .

(Embodiment 1)
The AC power supply mixing detection device and circuit protection device according to Embodiment 1 of the present invention will be described. FIG. 1 is a hardware configuration diagram of the circuit protection device according to the first embodiment of the present invention, FIG. 2 is an explanatory diagram for explaining the operation and determination principle of the AC power supply detection device according to the first embodiment of the present invention, and FIG. 4 is a functional block diagram of the AC power supply mixing detection device and circuit protection device according to Embodiment 1 of the present invention, and FIG. 4 is a flowchart of the operation procedure of the AC power supply detection device and circuit protection device according to Embodiment 1 of the present invention.

  The AC power supply detection device and the circuit protection device according to the first embodiment are mounted on the telephone line connection unit of a multifunction peripheral (MFP). However, any apparatus such as a facsimile can be used as long as it is an apparatus that performs communication using a telephone line. The configuration of the MFP is as described above.

  In FIG. 1, reference numeral 1 denotes a diode bridge connected to a telephone line (TIP, RING) provided with a call signal detector (not shown) for matching the polarities of input signals on the telephone line. Reference numeral 2 shown in FIG. 1 is a line capturing unit used to capture a line when an incoming call is received and to block the line when commercial power is mixed (mixed AC power supply of the present invention). A line interface unit (hereinafter referred to as a line I / F unit) having a configuration to be described later.

  The line capture unit 2 includes a switch (not shown) that is opened and closed by a CPU 5 described later when the call signal detection unit detects an incoming call, and between the positive and negative output terminals of the diode bridge 1 and the line I / F unit 3 and the diode bridge 1. Between. A telephone line is formed by opening and closing the switch to form a line loop, and the telephone line is connected to the line I / F unit 3.

  Further, by opening this switch by the CPU 5, the line can be cut off when commercial power is mixed. That is, in the first embodiment, the line capturing unit 2 is provided with a blocking means (switch) for circuit protection processing of the line between the line I / F unit 3 and the diode bridge 1.

  The line I / F unit 3 is a terminal part of the telephone line. The line I / F unit 3 takes out an alternating current component and detects the reversal of the polarity. In addition, the line I / F unit 3 is a two-wire for connecting an analog signal to a digital signal. A 4-wire switching circuit 3b and the like are provided. The line I / F unit 3 is configured as a hybrid IC.

  In FIG. 1, 3a is a polarity reversal detection unit (polarity reversal detection means of the present invention) that detects the polarity reversal of this alternating current component. The polarity reversal detection unit 3a is connected to, for example, a pair of diodes whose anodes and cathodes are connected in parallel to the line capturing unit 2 in parallel, and a discharge capacitor and a transistor (switching element) on the output side of each diode. Each time the polarity changes, the charge stored in the capacitor turns on / off the transistor, and this switching action detects the polarity for each positive and negative polarity.

  Further, 3c is an overcurrent detection unit (detection means of the present invention) that detects when an overcurrent flows through the telephone line. The overcurrent detection unit 3c includes a current limiting circuit and a comparator, and when there is an overcurrent, the transistor is turned on / off to detect the overcurrent. In this case, an overcurrent is detected by a current value flowing into the device through the telephone line, but instead of the overcurrent detection unit 3c, an overvoltage detection unit that detects an overvoltage by detecting a voltage value of the telephone line. May be.

  Next, the line control unit 4 will be described. The line control unit 4 is also integrated into an IC. The line control unit 4 is provided with means for determining whether or not commercial power is mixed in the polarity inversion detected by the polarity inversion detection unit 3a. In FIG. 1, 4a determines that there is a possibility that AC power is mixed in the line when the polarity reversal detection unit 3a detects polarity reversal. It is a mixing determination means for determining that there is no mixing.

  Here, the operation performed by the mixing determination unit 4a will be described. The AC component detected by the polarity inversion detection unit 3a includes an input signal component and a noise component. In the case where the main component of the noise component is external noise and it is considered that commercial power is mixed, in the first embodiment, the mixing determination unit 4a determines that this mixing has occurred. FIG. 2 shows the operation and determination principle of the AC power supply mixing detection apparatus.

As shown in FIG. 2, the polarity reversal detection unit 3a sets the polarity reversal point where the polarity of the component is reversed and zero crosses with GND (ground potential) in the frequency band of the commercial power source among the AC components, that is, in the frequency band near 50 Hz and 60 Hz. , And the time interval t _n between the polarity inversion points corresponding to a half cycle of this component (n = 1, 2,..., That is, the time until the next polarity inversion in the present invention is detected). If t _n + t _{n + 1} corresponds to the frequency of commercial power, it can be determined that commercial power may be mixed, and if not, commercial power is mixed It can be judged that there is no.

However, when considering zero crossing, it is not always true that the DC voltage applied to the telephone line is constant. There is a possibility that the waveform shifts up and down as a whole, and a short length occurs in the time interval t _n between the polarity reversal points where the zero crossing occurs. If the monitoring time is short, even if the time interval t _n between the polarity inversion points for a short time corresponds to the frequency of the commercial power supply, this may have occurred accidentally. Is not necessarily mixed.

Therefore, the mixing determination unit 4a according to the first embodiment is for accurately monitoring the polarity reversal period and monitoring the continuity of the polarity reversal even in such a case. In order to solve this problem, the mixing determination unit 4a is provided with a polarity inversion cycle monitoring unit 4a1 (calculation unit of the present invention) that calculates the polarity inversion cycle t _n to determine mixing.

The polarity reversal cycle monitoring means 4a1 does not monitor the time interval t _n (n = 1, 2,...) Between the polarity reversal points shown in FIG. 2, but becomes one cycle defined as the polarity reversal cycle. Monitor T _n = (t _n + t _{n + 1} ). t _n, monitored by calculating the T _n from t _{n + 1.} Since the period to be monitored is T _n , instead of T _n = (t _n + t _{n + 1} ), one period or more of T _n = (t _n + t _{n + 1} + t _{n + 2} ), Further, (Σt _n ) of M time intervals t _n (n = 1, 2,..., M) can be adopted. Accordingly, at least a binary time interval t _n is required for the polarity reversal period, but it is not limited to this as long as it is binary or more.

Furthermore, ingress judgment means 4a counts the number of times this polarity inversion period T _n matches the polarity inversion period T of the commercial power supply within a certain period of time, which is a commercial power supply is mixed when it is determined that the sufficient rational number Judge that Therefore, the contamination determination unit 4a, polarity inversion continuity monitoring unit 4a2 to perform the determination continuity by counting the number of times the polarity inversion period T _n met the T is provided.

  Returning to FIG. 1, reference numeral 5 denotes a CPU (central processing unit) that performs system control. In the case of the first embodiment, system control of the entire MFP is performed. In addition to the line control unit 4, the CPU 5 is connected to an image processing unit, a printing device unit, a scanner unit, an AC control unit, and the like through a bus (not shown), and performs overall control thereof.

  Reference numeral 5a denotes an encoding / decoding unit that compresses or expands facsimile data, and 5b denotes a modem unit that converts an analog signal into a digital signal. Facsimile data to be transmitted is selected from MH (Modified Huffman), MR (Modified Read), MMR (Modified Modified Read), and other encoding methods (compression methods), encoded and compressed, and received. The facsimile data is decrypted and decompressed.

5c is a time interval corresponding to a half cycle with a time interval between zero-crossing points based on time θ _n of time axis θ shown in FIG. 2 (corresponding time indicated by t _n of polarity reversal point; not shown). _{t n (n = 1,2, ····} ) together with counts (clock), a period of time necessary for the continuity determination, for example, 300ms in counting means for counting the (counting means of the present invention) is there. Time is measured by counting the number of clocks using a reference clock for the CPU 5. The time measuring means 5c can be provided not in the CPU 5 but in the line control unit 4 that performs line control.

Subsequently, reference numeral 6 denotes a storage unit including a non-volatile memory such as a ROM (Read Only Memory), a RAM (Random Access Memory), and a flash memory (Flash Memory). The CPU 5 constitutes a function realizing means for reading each program in the storage unit 6 into the RAM and executing each function. 6a is a first polarity inversion cycle storage unit for storing T _n = (t _n + t _{n + 1} ) calculated by the polarity inversion cycle monitoring unit 4a1 of the mixing determination unit 4a, and 6b is also calculated by the polarity inversion cycle monitoring unit 4a1. The second polarity inversion cycle storage unit stores T _{n + 1} = (t _{n + 1} + t _{n + 2} ). The values T _n and T _{n + 1} stored in the bipolar polarity inversion cycle storage unit are compared with a predetermined specified value T described later. T _n is a first average value in the present invention, and T _{n + 1} is a second average value in the present invention.

  Accordingly, the first polarity reversal cycle storage unit 6a has one and the other polarity, for example, one positive and negative cycle each being a half cycle, and the second polarity reversal cycle storage unit 6b has the other polarity. One of the following polarities, for example, the negative half cycle, which is each half cycle, and the subsequent positive half cycle are updated and stored.

  Reference numeral 6c denotes a number storage unit for storing the count value counted by the polarity inversion continuity monitoring unit 4a2 of the mixing determination unit 4a. Reference numeral 6d denotes a set value unit that stores a specified value used when the mixing determination unit 4a makes a determination. A condition indicating a sufficiently reasonable range even if it is determined as the cycle of the commercial power supply, a condition indicating a sufficiently reasonable range even when determined as the frequency of the commercial power supply, and the like are stored in the set value unit 6d as specified values. . This specified value will be described later.

  Therefore, the functional blocks A to F of the AC power supply detection device and the circuit protection device described above will be described. Each of the blocks A to F is realized by each function realizing unit that implements the CPU 5 by reading a program for executing each function into the RAM and calculating it by the CPU 5, and hardware for processing the processing result.

First, in the polarity reversal detection block A of FIG. 3, the polarity reversal detection unit 3a detects the polarity reversal of the AC component, and the time measuring means 5c indicates a time interval indicating the positive / negative polarity for one cycle at time θ _n , that is, polarity reversal. The time interval t _n of the previous half cycle and the time interval t _{n + 1} of the half cycle after polarity inversion are counted.

Next, in the polarity inversion cycle monitor block B, the time interval t _n and time interval t _{n + 1} counted by the time measuring means 5c are detected by the polarity inversion cycle monitoring means 4a1 by the polarity inversion cycle T _n and the polarity inversion cycle T _{n. +1} is calculated and stored in the first polarity inversion cycle storage unit 6a and the second polarity inversion cycle storage unit 6b. The polarity inversion period T _n can be converted into the frequency f _n of the AC component to be detected, and this can be stored and used.

For example, T ₁ = (t ₁ + t ₂ ), T ₂ = (t ₂ + t ₃ ), T ₃ = (t ₃ + t ₄ ), and so on, where n is an odd number (n = 1, 3,..., The first polarity inversion cycle storage unit 6a of the storage unit 6, and when n is an even number (n = 2, 4,...), The second polarity inversion cycle storage unit 6b. Stored in As time elapses, the polarity inversion cycle T _n is rewritten to T _{n + 2} and T _{n + 1} is rewritten to T _{n + 3} , so that the first polarity inversion cycle storage unit 6a and the second polarity inversion cycle storage unit 6b are rewritten. Are updated in turn. Incidentally, calculated using T _n which are counted when converted into frequency f _n.

In the comparison block C with the commercial power source, the polarity inversion period T _n or the frequency f _n calculated by the polarity inversion period monitor block B at each time θ _n (n = 1, 2,...) A specified value corresponding to the cycle T of the commercial power supply (for example, the upper and lower limits of T are 19 ms ± 4 ms) or the frequency (45 Hz to 65 Hz including 50 Hz and 60 Hz) is compared.

Further, in the polarity reversal continuity monitor block D, the polarity reversal continuity monitoring means 4a2 (Δθ = θ) every time period Δθ from time θ _n to time θ _{n + j} (j = 1, 2,...). _n− θ _{n + j} (for example, Δθ = 300 ms), the presence / absence of continuity is determined based on the number N of T _n determined to match the cycle T of the commercial power source within a predetermined range within this fixed period. . At this time, it is determined that there is continuity when N falls within the range of (31 ± 6) / 300 ms.

  If the polarity reversal continuity monitor block D results in damage to the circuit of a device such as an MFP, it exceeds the allowable limit and is urgent, the commercial power supply is mixed. Because there is, you have to cut off the telephone line where commercial power is mixed. If the contamination level does not damage the circuit, hum noise may be taken depending on the cause.

  Next, in the overcurrent detection block E, when it is determined in the polarity reversal continuity monitor block D that the commercial power supply is mixed, in order to more accurately check whether the commercial power supply is mixed or not, an overcurrent is detected. An overcurrent is detected by the detector 3c. Since a current of about 40 mA normally flows when a normal telephone line is connected, in the first embodiment, a current of 160 mA or more is determined as an overcurrent that may cause damage.

  In the circuit protection processing block F, when the current detected by the overcurrent detection block E is determined to be an overcurrent, the CPU 5 outputs a telephone line disconnection command, and the switch of the line capturing unit 2 is opened (OFF). ) And disconnect the line.

  Next, the operation procedure of the AC power supply detection device and the circuit protection device according to Embodiment 1 of the present invention will be described based on the flowchart of FIG. Note that the program installed in the AC power supply detection device and the circuit protection device of the present invention causes the computer (CPU 5) to execute the following steps.

  In FIG. 4, when the call signal detection unit detects an incoming call and the CPU 5 captures the line by the line capture unit 2 (step 1), the polarity reversal detection unit 3a detects the polarity reversal and waits until the polarity reversal can be detected. (Step 2) This detection is repeated.

When the polarity inversion detection unit 3a detects the polarity inversion monitors the continuity from matches between the polarity inversion cycle T _n and period of the commercial power supply (step3). Thereafter, until a certain period, for example, 300 ms elapses, it is determined whether the polarity reversal cycle T _n is within a specified value (a reasonable range in which it can be determined that the commercial power cycle T matches) or whether the polarity reversal cycle is consistent. (Step 4). In the case of the first embodiment, this condition is 15 ms ≦ T _n ≦ 23 ms, and corresponds to the above-described upper and lower limit values of T being 19 ms ± 4 ms.

Subsequently, for each fixed period, it is determined whether the number N of times that the polarity reversal cycle T _n matches the cycle T of the commercial power supply during the fixed period matches (contains) within the specified value (step 5). In the case of the first embodiment, this condition is whether or not (31 times ± 6 times) / 300 ms. In other words, if 25 times ≦ N ≦ 37 times in 300 ms, it is determined that they match. Thereafter, when 300 ms elapses and the number of times N does not match the specified value, the process returns to step 2 and step 2 to step 5 are repeated. This routine may be repeated at regular intervals, or may be repeated periodically.

  The procedure from step 1 to step 5 described above is the minimum operation that the AC power supply detection device of the first embodiment should have. However, step 6 to be described below is a step of not detecting that the commercial power source is mixed when the noise level is low, and detecting the case where the allowable limit is exceeded, and the AC power source mixing detection apparatus of the first embodiment is step 6. Can be included.

  In step 1 to step 5, if it is determined that commercial power is mixed in the telephone line (when the determination result in step 5 is YES), whether or not an overcurrent exceeding an allowable limit is detected by the overcurrent detection unit 3c. Is confirmed (step 6). As described above, the overvoltage may be detected not by the overcurrent detection unit 3c but by the overvoltage detection unit.

  If the overcurrent is at a level that does not damage the circuits such as the line I / F unit 3, the line control unit 4, and the CPU 5 of a device such as an MFP, the process returns to step 2. If this exceeds an allowable limit, for example, 160 mA, and there is an urgency to damage the circuit, the CPU 5 outputs a command to shut off the telephone line, opens the switch of the line capturing unit 2, and cuts off the telephone line. (Step 7).

  It should be noted that the disconnection of the telephone line in step 7 may be performed immediately when it is determined in step 5 that commercial power is mixed in the telephone line.

  As described above, according to the AC power supply detection device of the first embodiment, it is possible to easily and inexpensively determine that the AC power is mixed.

  In addition, according to the circuit protection device of the first embodiment, it is possible to easily and inexpensively determine that an AC power source is mixed, and to disconnect a line in the case of overcurrent or overvoltage. In particular, damage to the circuit around the communication device can be prevented.

  The present invention relates to an AC power supply detection device and a circuit protection device that can be applied to communication devices such as MFPs and facsimiles.

1 is a hardware configuration diagram of a circuit protection device according to Embodiment 1 of the present invention. Explanatory drawing explaining the operation | movement and determination principle of the alternating current power supply mixing detection apparatus in Embodiment 1 of this invention Functional block diagram of the AC power supply mixing detection device and circuit protection device according to Embodiment 1 of the present invention Flowchart of operation procedure of AC power supply mixing detection device and circuit protection device in Embodiment 1 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diode bridge 2 Line | wire capture part 3 Line | wire interface part 3a Polarity inversion detection part 3b 2 wire | wire-4 wire switching circuit 3c Overcurrent detection part 4 Line control part 4a Mixing judgment means 4a1 Polarity inversion period monitoring means 4a2 Polarity inversion continuity monitoring means 5 CPU
5a Coding / decoding unit 5b Modem unit 5c Timekeeping means 6 Storage unit 6a First polarity inversion cycle storage unit 6b Second polarity inversion cycle storage unit 6c Number of times storage unit 6d Setting value unit

Claims (5)

Polarity reversal detection means for detecting the reversal of the polarity of the line;
After the polarity reversal detection means detects the polarity reversal, the counting means for sequentially counting the time until the polarity reversal detection means next detects the polarity reversal,
Calculating means for calculating an average value of a plurality of count values counted by the counting means;
When the average value calculated by the calculation means is included in the range of the predetermined value, it is determined that the AC power is mixed in the line, and when the average value is not included in the range of the predetermined value An AC power supply mixing detection apparatus comprising: a mixing determination unit that determines that power is not mixed. Polarity reversal detection means for detecting the reversal of the polarity of the line;
After the polarity reversal detection means detects the polarity reversal, the counting means for sequentially counting the time until the polarity reversal detection means next detects the polarity reversal,
Calculating means for calculating at least the n-th and (n + 1) -th first average values counted by the counting means, and the (n + 1) -th and (n + 2) -th second average values;
If the first and second average values calculated by the calculation means are included in a predetermined value range within a predetermined period and a predetermined number, it is determined that AC power is mixed in the line, An AC power source mixing detection apparatus comprising: a mixing determination unit that determines that no AC power source is mixed when a predetermined number of values are not included in the range of values. A detection means for detecting a voltage value of the line or a current value flowing into the device through the line, wherein the mixing determination means has the voltage value or the current value equal to or greater than a predetermined value and the average value calculated by the calculation means is a predetermined value; 3. The AC power supply mixing detection apparatus according to claim 2, wherein it is determined that an AC power supply is mixed in the line when it is included in the value range. A detection unit configured to detect a voltage value of the line or a current value flowing into the device through the line, and the mixing determination unit includes the first and second values calculated by the calculation unit when the voltage value or current value is equal to or greater than a predetermined value. 4. The AC power supply mixing detection according to claim 3, wherein it is determined that AC power is mixed in the line when a predetermined number of average values are included in a predetermined value range in a predetermined period. apparatus. When the AC power supply mixing detection device according to any one of claims 1 to 4 is provided and the mixing determination unit of the AC power supply mixing detection device determines that the AC power is mixed in the line, A circuit protection device comprising a blocking means for blocking.

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