JPH1196042A - Device for reducing electromagnetic radiation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent electromagnetic wave interference (EMI) strong in specific frequency from being generated from the periphery of a microprocessor(MC). SOLUTION: In the case of executing the correction or change of a program, EMI generated from the periphery of the MC included in a control part 40 is received by an antenna 11 and detected by a detection circuit 20 and the detection signal is converted into a DC level by a smoothing filter 30. The control part 40 compares the converted DC level with a reference value, judges the compared result and automatically changes the processing steps of the MC based on the judged result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal device such as a personal computer having a built-in microprocessor for executing predetermined processing steps according to a program.
The present invention relates to an electromagnetic radiation reduction device that automatically reduces electromagnetic waves (hereinafter, referred to as “EMI”) generated from the terminal device.

[0002]

2. Description of the Related Art In a terminal device such as a personal computer, a control board on which a microprocessor is mounted and a board on which peripheral devices and the like are mounted are provided in a housing, and the microprocessor controls the entire terminal device by the microprocessor. It has become. In this type of terminal device, electromagnetic radiation may be generated from around the microprocessor during operation. Therefore, in the conventional electromagnetic radiation reduction device, in order to suppress the electromagnetic radiation from the control board, etc., the casing is metal-shielded, or a special shielding measure is taken for the control board, etc., and comprehensive measures are taken. I have.

[0003]

However, the conventional electromagnetic radiation reducing device has the following problems (a) and (b), and it is difficult to solve these problems. (A) Problem of miniaturization and weight reduction of portable terminal device In a portable terminal device, miniaturization and weight reduction are required for easy carrying. As one method for reducing the weight of the device, a case for housing an internal device is formed by molding with plastic or the like. However, if the casing is formed by molding, it is not possible to shield EMI radiation generated from inside,
Not only does the device not meet the electromagnetic emission standards of the device, but also may interfere with other devices in the vicinity. Therefore, it is also practiced to shield the electromagnetic radiation by plating the inside of the molded housing with metal. However, such a method has a problem in that the number of manufacturing steps of the device increases and the cost increases. As another method of blocking electromagnetic radiation, measures such as partially shielding a control board or the like with a metal panel have been taken. However, such measures increase the weight of the device and cannot achieve the miniaturization and weight reduction required for the portable terminal device.

[0004] (b) Problems on Software [0004] In a state where a microprocessor mounted in a terminal device is operating and performing various processes, an electromagnetic radiation component having a frequency synchronized with these processes may become strong. However, conventional electromagnetic radiation reduction devices have not been able to take sufficient measures since their causes have not been investigated. Also, if a software bug occurs after entering the final stage of software development, it is necessary to modify the program to remove the bug. However, when the program is modified, it is necessary to measure the electromagnetic radiation each time to take measures to suppress the electromagnetic radiation, which causes a problem that the software development TAT (Turn Around Turn) cannot be shortened. Even if a process to reduce electromagnetic radiation was applied at the manufacturing stage, it was necessary to change the program to upgrade the software after shipping these terminal devices to the field. It is also done. In such a case, it is also possible to detect an electromagnetic radiation component generated from the terminal device and to re-evaluate whether or not the electromagnetic radiation standard is satisfied. However, when the electromagnetic radiation standard is exceeded, since the terminal device has been shipped to the field, it is difficult to take countermeasures, and as a result, there is a problem that a sufficient software version cannot be upgraded. SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the prior art and to provide an electromagnetic radiation reducing apparatus that prevents EMI strong at a specific frequency from being generated around a microprocessor.

[0005]

According to a first aspect of the present invention, there is provided a terminal device including a microprocessor for executing predetermined processing steps according to a program. Detecting means for detecting EMI generated from the EMI, converting means for converting the EMI detected by the detecting means to a DC level, comparing means for comparing the DC level converted by the converting means with a reference value, and A step varying unit that is executed by program control of a processor, determines a comparison result of the comparison unit, and changes the number of processing steps of the microprocessor based on the determination result. In a second aspect of the present invention, in the electromagnetic radiation reduction device of the first aspect, the step varying means includes a step of setting the micro level so that when the comparison result of the comparison means is DC level> reference value, DC level ≦ reference value. The configuration is such that the number of processing steps of the processor is reduced. According to the present invention, since the electromagnetic radiation reducing device is configured as described above, the built-in software automatically changes the program steps and monitors the EMI detected by the detecting means under program control of the microprocessor. While monitoring (monitoring) and changing the program step, the EMI is monitored and the program step is finely adjusted automatically by the step variable means.

[0006]

FIG. 2 is a perspective view showing the appearance of a portable terminal device according to an embodiment of the present invention. The portable terminal device 1 has a housing 1a molded of plastic or the like in order to reduce the weight, and a control board on which a microprocessor is mounted, peripheral devices, and the like are mounted in the housing 1a. A substrate and the like are provided. When the terminal device 1 is installed on a desk or the like and used, the network line 2 is connected,
Data is input using an input electronic pen 3 or the like, and communication with the outside via the network line 2 is enabled. In this type of portable terminal device 1, it is usually assumed that the network line 2 is disconnected and carried.
The whole is small and lightweight. FIG. 1 (a),
FIG. 2B is a configuration diagram of an electromagnetic radiation reduction device showing an embodiment of the present invention, FIG. 2A is a schematic configuration diagram, and FIG. 2B is a circuit diagram. The electromagnetic radiation reduction device shown in FIG. 1A is mounted on a control board 10 provided in the portable terminal device 1 in FIG. An antenna 11 for receiving an electromagnetic radiation component is provided on the control board 10, and a detection means (for example, a detection circuit) 20 for detecting the received electromagnetic radiation component is connected to the antenna 11. A conversion unit (for example, a smoothing filter) 30 that converts the detected EMI into a DC level is connected to an output side of the detection circuit 20, and a control unit 40 is connected to the output side. The control unit 40 has a function of inputting an output signal of the filter 30 from a built-in input circuit and performing program control of the entire electromagnetic radiation reduction device by a built-in microprocessor or the like. FIG. 1B shows a circuit diagram of the electromagnetic radiation reduction device.

In FIG. 1B, for example, on a surface of a control board 10 on which a circuit of an electromagnetic radiation reducing device is mounted, an antenna 11 stretched on a loop in a printed pattern, for example.
Are formed. The antenna 1 includes the antenna 1
1 and a transformer (hereinafter referred to as a “transformer”) 12 for performing DC isolation.
Further, a detection circuit 20 is connected to the transformer 12. The detection circuit 20 detects E from the output signal of the transformer 12
A high frequency detection diode 21 for detecting MI and a high frequency capacitor 22 for smoothing an output signal of the diode 21 are connected, and a filter 30 is connected to the capacitor 22. The filter 30 includes two resistors 3
1 and 32 and two smoothing capacitors 33 and 34, and a control unit 40 is connected to the output side. The control unit 40 compares a DC level output from the filter 30 with a reference value (for example, a reference voltage Vr) (for example, a two-input operational amplifier, hereinafter referred to as a two-input “op-amp”) 41. A switch 44 for instructing tuning of electromagnetic radiation, an input / output port (hereinafter, referred to as "I / O port") 46, and a microprocessor 4 for program-controlling the entire electromagnetic radiation reducing device.
7. An EPROM (Erasable Programmable) for storing the execution program of the microprocessor 47.
Read Only Memory) and E
An EEPROM (Electrically Erasable & Progra
It comprises a non-volatile memory 49 such as an mmable ROM.

[0008] Of the two input terminals of the two-input operational amplifier 41 constituting the control unit 40, one input terminal is connected to the output side of the filter 30, and the other input terminal is connected via a voltage dividing resistor 42. Connected to the power supply voltage VCC,
The reference voltage Vr is applied by being connected to the ground SG via the voltage dividing resistor 43. Operational amplifier 41
Is connected to the input terminal of the I / O port 46, and the other input terminal of the I / O port 46 is connected to the ground SG via the switch 44.
The switch 44 is connected to a power supply voltage VCC via a pull-up resistor 45 for stabilizing an output signal.
The I / O port 46 is used to turn on / off the digitized signal.
It has a function of inputting OFF to the microprocessor 47 and the like. The microprocessor 47 includes an operational amplifier 41
And a function of changing the number of processing steps of the microprocessor by determining the output signal of the microprocessor. An I / O port 46, a program memory 48, and a non-volatile memory 49 are connected to the bus of the microprocessor 47.
Is connected. The read signal and the write signal from the microprocessor 47 to the peripheral circuit are also I / O signals.
Although connected to the O port 46 and the non-volatile memory 49 and the like, these may have a known circuit configuration, and are general signal groups of the microprocessor 47.
In (b), it is omitted.

Next, (1) the overall operation of the electromagnetic radiation reducing apparatus of FIG. 1, (2) the operation of the program of the microprocessor of FIG. 1, and (3) the operation of the specific processing module of the microprocessor of FIG. explain. (1) Overall Operation of the Electromagnetic Radiation Reduction Device of FIG. 1 When the portable terminal device 1 of FIG.
MI is emitted. The emitted electromagnetic radiation component is received by the antenna 11. The received electromagnetic radiation component is detected by the diode 21 and the capacitor 22 of the detection circuit 20 after the transformer 12 converts the impedance and insulates the ground signal. The detected signal is smoothed by the filter 30, the peak voltage detected in a short time is slightly averaged by the filter 30, and the peak voltage is held. When a predetermined time corresponding to a time constant mainly determined by the resistors 31 and 32 and the capacitor 34 of the filter 30 elapses, the held peak voltage decreases, and the signal level from the antenna 11 via the transformer 12 becomes effective again. Is detected.

The output signal of the filter 30 is supplied to the operational amplifier 4
The reference signal Vr is compared with a reference voltage Vr set in advance by 1 and, when the reference voltage Vr exceeds a predetermined value, an ON signal “1” is sent from the operational amplifier 41 to the I / O port 46.
The switch 44 connected to the I / O port 46 is, for example, hidden and mounted in a part of the terminal device 1 that cannot be easily touched, and is pressed like a thin pencil lead through a small hole. The ON state of the switch 44 is input to the I / O port 46. The microprocessor 47 connected to the I / O port 46 accesses the I / O port 46 by operating software on the program memory 48 in which the execution program is stored, and outputs the output of the switch 44 and the operational amplifier 41. The value of the signal can be arbitrarily read. Further, a fixed value which is a factor for reducing EMI is written and stored in a nonvolatile memory 49 connected to the microprocessor 47. This stored value is retained even when the power of the terminal device 1 is turned off. When the power is turned on again, the stored value is read out by the microprocessor 47 executing the program in the program memory 48.

(2) Operation of Program of Microprocessor of FIG. 1 FIG. 3 is a flowchart showing an operation of a program of the microprocessor 47 of FIG. Step S1 in FIG.
In step S2, when the power supply voltage VCC is applied to the terminal device 1, in step S2, the microprocessor 47 determines whether or not the switch 44 is on according to a program stored in the program memory 48. When the software is to be upgraded at the time of shipment of the product or in the field, since the EMI needs to be adjusted, the switch 44 is turned on. If the switch 44 is in the ON state in step S2, the microprocessor 47 determines that the mode is the tuning mode, and based on the determination result, TUNE bi.
It is stored in the program memory 48 as t → 1. Also,
If the switch 44 is off in step S2, the microprocessor 47 determines that the operation mode is the normal operation mode, and based on the determination result, determines in step S4 whether the TU is
NEbit → 0 is stored in the program memory 48. Thereafter, the microprocessor 47 proceeds to step S5.
, An ordinary application program stored in the program memory 48 is executed. Here, among application programs, routines that include particularly repetitive programs and loop software (for example, generally referred to as driver software) are selected in advance as subroutines. It is divided as modules A and B. Step S5
When the application program is executed, the specific processing module A is executed by the application program.
Or, B is called, and the microprocessor 47 executes predetermined processing steps according to the called program of the module A or B.

(3) Operation of the Specific Processing Module of the Microprocessor of FIG. 1 FIG. 4 is a flowchart showing the operation of the specific processing module of FIG. In step S11 of FIG. 4, the specific processing module A is read from the application program in the program memory 48 by the microprocessor 47.
Is called. This specific processing module A includes a lot of loop processing and repetition processing. A dummy counter processing is embedded in this routine in advance, and the count value of this dummy counter routine is calculated by the dummy X of the dummy counter value. , The program running process steps are made variable. In step S12, the fixed value dummy X stored in the non-volatile memory 49 is read and set in the soft counter CNT. Thereafter, through step S14, step S13 is repeated until the value of the soft counter CNT becomes 0,
Thus, the processing steps including the application processing of the specific processing module A in step S12 and the application processing of the specific processing module B in step S15 are varied depending on the value of the dummy X. After the process of step S15 is completed, step S
At 16, the program determines whether or not the signal detected by the antenna 11, the transformer 12, the detection circuit 20, and the filter 30 has been turned on by the operational amplifier 41 exceeding the reference voltage Vr, that is, whether or not the EMI is over. .

The output signal of the operational amplifier 41 includes the processing of the specific processing module A of step S11, the counter processing of steps S12 to S14, and the processing of the specific processing module B of step S15, which were running immediately before. By looping the program, the generated specific frequency component is approximately detected. Since the time range to be measured is selected so as to be determined by the time constant of the filter 30, the electromagnetic radiation component generated in this range can be determined when EMI over is determined in step S16. If EMI over is detected in step S16, step S17
TUNE bit is 1 (ie, the switch 44
Is turned on and the tuning mode is instructed) is determined, and if so, step S
In step 18, the value of the dummy X is incremented by 1 and this value is
The values are updated by writing to the non-volatile memory 49 through 9, S20, and S21, and the main processing is repeatedly performed from this processing.

By repeating this, the value of the dummy X is automatically changed, and finally at step S16 E
When the MI over is in the off state, that is, when the electromagnetic radiation falls below the set reference, in step S22, TUNE bi
t is turned off, and the value of the dummy X at this time is stored and held in the nonvolatile memory 49 in step S21. If the TUNE bit is off, step S
If EMI over is detected in step 16, the automatic adjustment needs to be performed again, or the terminal device 1 is abnormal, so that re-tuning is required. In step S23, the display unit of the terminal device 1 (for example, , A message is displayed on a liquid crystal (LCD) display. At this time, the operation of the terminal device 1 can be stopped in some cases.

As described above, this embodiment has the following advantages (a) to (f). (A) Since the program steps can be automatically adjusted by the program stored in the program memory 48, there is no need to re-measure the electromagnetic radiation of the terminal device 1 or to take measures against this even when the software is changed. (B) As a countermeasure against electromagnetic radiation of the terminal device 1, a component such as a toroidal core material exhibiting high resistance to a high frequency or a ferrite bead filter is not required unlike the related art, so that the number of components is reduced. And the terminal device 1 can be realized at a low price. (C) Since it is not necessary to form the housing of the terminal device from metal and perform EMI shielding as in the related art, it is possible to form the housing 1a by molding a plastic or the like to take measures against electromagnetic radiation. For this reason, the terminal device 1 is inexpensive,
In addition, since the terminal device 1 can be reduced in size and weight, the terminal device 1 can be effectively realized. (D) Control board 1 on which microprocessor 47 is mounted
Since it is not necessary to perform partial shielding with a metal shield plate or the like as in the related art, the control board 10 can be reduced in size and weight. (E) When the software version of the terminal device 1 is upgraded, the function for automatically adjusting the program steps is provided, so that it is not necessary to re-measure the electromagnetic radiation standard. Therefore, it is possible to easily upgrade the software version even in the field. (F) Since the cost of the control board 10 for electromagnetic radiation measures such as filter and shield enhancement as conventionally performed can be reduced, the terminal device 1 can be realized at lower cost.

The present invention is not limited to the above embodiment, and various modifications are possible. For example, there are the following modifications (i) and (ii). (I) Detection circuit 20, filter 30, and operational amplifier 4
1 can be configured by other circuits than those shown. (Ii) The processes in FIGS. 3 and 4 can be changed to processes in procedures other than those illustrated.

[0017]

As described above in detail, according to the first and second aspects of the present invention, in a terminal device having a built-in microprocessor, EMI generated from the periphery of the microprocessor is detected by the detection circuit and detected. The EMI is converted into a DC level by the conversion means, the converted DC level is compared with a reference value by the comparison means, and the comparison result is determined by the program control of the microprocessor. The processing steps of the processor are automatically varied. As a result, it is possible to prevent EMI that is strong at a specific frequency from being generated from the vicinity of the microprocessor, thereby reducing the size and weight of the terminal device and upgrading the software so that the electromagnetic radiation standard is not exceeded. Can easily solve conventional software problems such as

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an electromagnetic radiation reduction device showing an embodiment of the present invention.

FIG. 2 is a perspective view of the appearance of the portable terminal device according to the embodiment of the present invention.

FIG. 3 is a flowchart showing an operation of a program of the microprocessor of FIG. 1;

FIG. 4 is a flowchart showing an operation of the specific processing module of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Terminal device 1a Housing 10 Control board 11 Antenna 20 Detection circuit 30 Filter 40 Control unit 41 Operational amplifier 47 Microprocessor 48 Program memory 49 Non-volatile memory

Claims (2)

[Claims] 1. A terminal device having a built-in microprocessor for executing predetermined processing steps in accordance with a program, comprising: a detecting means for detecting an electromagnetic wave generated from around the microprocessor; and a DC level for converting the electromagnetic wave detected by the detecting means to a DC level. Converting means for converting; a comparing means for comparing the DC level converted by the converting means with a reference value; executed by program control of the microprocessor, determining a comparison result of the comparing means, and based on the determination result. An electromagnetic radiation reducing device, comprising: a step variable means for changing the number of processing steps of the microprocessor. 2. The method according to claim 1, wherein the step varying means reduces the number of processing steps of the microprocessor so that when the comparison result of the comparing means is DC level> reference value, DC level ≦ reference value. Claim 1.
Electromagnetic radiation reduction device as described.