JP2006155581A - Clock signal control unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clock signal control unit capable of suppressing an electromagnetic wave emitted from electronic equipment and preventing an arithmetic processing speed in the electronic equipment or an operating speed of the electronic equipment from lowering unnecessarily. <P>SOLUTION: The clock signal control unit controls a clock signal to be supplied to one or more pieces of electronic equipment and includes: a clock signal generating means for generating a clock signal of a specified frequency; a frequency spread means for spreading the frequency of the clock signal generated by the clock signal generation means on the basis of a specified spreading factor; and a spreading factor set means for setting the spreading factor in accordance with a use state of the electronic equipment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for suppressing electromagnetic interference (EMI) caused by electromagnetic waves radiated from an electronic device, and in particular, by supplying a frequency-spread clock signal to a control unit (CPU or the like) of the electronic device. The present invention relates to a technology for suppressing electromagnetic interference by reducing electromagnetic waves radiated from equipment.

  Conventionally, for electromagnetic waves radiated from information processing devices, telecommunications equipment, electronic office equipment, etc. (hereinafter referred to as “electronic equipment”), CISPR (International Radio Interference Special) The allowable upper limit value is regulated by a committee) or VCCI (Voluntary Control Council for Radio Wave Interference). Therefore, in general, the electronic device is provided with an electromagnetic shield, a ferrite bead, a choke coil, and the like to reduce electromagnetic waves radiated from the electronic device.

On the other hand, as one of the measures for reducing the electromagnetic wave radiated from the electronic device and suppressing the EMI, the clock signal frequency-spread by the spread spectrum clock generator (hereinafter referred to as “SSCG”) is supplied to the control unit of the electronic device. There has been known a technique for suppressing electromagnetic waves radiated from the electronic device to the allowable upper limit value or less by supplying (for example, see Patent Document 1). This SSCG spreads the frequency of a clock signal generated by a clock signal generator such as a crystal oscillator having a crystal resonator based on a predetermined spreading factor, and the frequency-spread clock signal is electronically transmitted. This is supplied to the control unit of the device.
JP 2002-33858 A

  By the way, since the clock signal determines the arithmetic processing speed of the CPU or the like in the control unit of the electronic device, the arithmetic processing speed is lowered by spreading the frequency downward by the SSCG. Become. In order to suppress the EMI, a certain decrease in the calculation processing speed cannot be denied, but it is desirable that the decrease in the calculation processing speed in the electronic device is small.

  However, since the spreading factor in the conventional SSCG is set to a constant value as described above, the clock signal is always frequency-spread based on the constant spreading factor regardless of the electromagnetic wave radiated from the electronic device. Will be supplied to the electronic device. Therefore, for example, even when the electromagnetic wave radiated from the electronic device is temporarily reduced due to the operating state or installation environment of the electronic device, the frequency of the clock signal is spread more than necessary. In this case, since the frequency of the clock signal is unnecessarily spread, the processing speed of the CPU, the operation speed of the electronic device, etc. in the control unit of the electronic device that operates in synchronization with the frequency spread clock signal is unnecessary. The problem of deteriorating arises.

  Accordingly, the present invention has been made in view of the above circumstances, and its object is to suppress electromagnetic waves radiated from an electronic device, and to calculate the processing speed and operation of the electronic device in the electronic device. An object of the present invention is to provide a clock signal control device capable of preventing an unnecessary decrease in speed.

In order to achieve the above object, a clock signal control device according to the present invention is a clock signal control device that controls a clock signal supplied to one or a plurality of electronic devices, and generates a clock signal having a predetermined frequency. Generating means, frequency spreading means for spreading the frequency of the clock signal generated by the clock signal generating means based on a predetermined spreading factor, and spreading factor setting for setting the spreading factor according to the usage state of the electronic device Means.
According to this configuration, since the diffusivity is set according to the usage state of the electronic device, it is possible to suppress electromagnetic waves radiated from the electronic device, and to perform arithmetic processing speed and operating speed of the electronic device. Can be prevented.

  In the above clock signal control device, it is preferable that the spreading factor setting means sets the spreading factor according to the usage state of the electronic device before starting the supply of the clock signal to the electronic device. (Claim 19) In this case, before the start of supply of the clock signal to the electronic device, the diffusivity can be set in advance according to the use state of the electronic device, and the electromagnetic wave radiated from the electronic device is allowed. It is possible to prevent the upper limit from being exceeded.

  The clock signal control device may further include a spreading factor storage unit that stores in advance a spreading factor corresponding to a plurality of usage states of the electronic device, and the spreading factor setting unit is configured to correspond to the usage state of the electronic device. It is preferable to select and set the diffusion rate stored in the diffusion rate storage means. (Claim 2) In this case, a diffusion rate corresponding to a plurality of usage states of the electronic device is stored in advance, and a diffusion rate stored in the diffusion rate storage means is selected according to the usage state of the electronic device. Therefore, the calculation process for obtaining the spreading factor is not required, and the spreading factor can be easily set.

  In the clock signal control device described above, it is preferable that the usage state of the electronic device is a connection state of the electronic device that is directly or indirectly connected to the clock signal control device. (Claim 3) In this case, it is possible to set a spreading factor according to the connection state of the electronic device directly or indirectly connected to the clock signal control device.

  The clock signal control device may further include communication means for transmitting / receiving data to / from the electronic device, and the connection state of the electronic device is preferably the number of connections of the electronic device or the type of the communication means. (Claim 4) In this case, it is possible to set a spreading factor according to the number of electronic devices connected directly or indirectly to the clock signal control device or the type of the communication means.

  Further, in the clock signal control device, the usage state of the electronic device is a connection state of the electronic device directly or indirectly connected to the clock signal control device and an operation state of the electronic device. Is preferred. (Claim 5) In this case, it is possible to set a spreading factor according to a connection state of the electronic device directly or indirectly connected to the clock signal control device and an operation state of the electronic device.

  In the clock signal control device, it is preferable that the spreading factor setting means sets a spreading factor larger when the electronic device is operating than when the electronic device is not operating. (Claim 6) In this case, when the electronic device is operating, a larger diffusion rate is set than when the electronic device is not operating. When the electronic device is operating, more electromagnetic waves are radiated than when the electronic device is not operating. Therefore, the electromagnetic wave radiated | emitted from an electronic device can be suppressed by setting the diffusivity when the electronic device is operating larger than the diffusivity when the electronic device is not operating.

In the above clock signal control device, it is preferable that the spreading factor setting means sets a previous spreading factor corresponding to an electromagnetic wave radiated from the electronic device detected in advance according to a use state of the electronic device. . (Claim 7)
That is, the diffusivity is a known value corresponding to the electromagnetic wave in each usage state of the electronic device. Here, the electromagnetic wave is specifically an electromagnetic wave detected on the basis of parameters capable of measuring the degree of influence on the electronic device such as the intensity of the electromagnetic wave, the intensity of the electromagnetic wave noise, the frequency of the electromagnetic wave, and the amplitude of the electromagnetic wave. It is. In this case, since the spreading factor corresponding to the electromagnetic wave radiated from the electronic device detected in advance according to the usage state of the electronic device is set, the clock with an appropriate frequency is not reduced unnecessarily. A signal can be supplied.

In the above clock signal control device, the spreading factor setting means may have an allowable upper limit value in which the intensity of electromagnetic waves radiated from the electronic device detected in advance according to the usage state of the electronic device is defined in advance. It is preferable to set the diffusion rate to be as follows. (Claim 8)
In this case, the intensity of the electromagnetic wave radiated from the electronic device detected in advance according to the usage state of the electronic device is set to a diffusion rate that is equal to or lower than a predetermined allowable upper limit value. Therefore, the electromagnetic wave radiated from the electronic device can be suppressed to the allowable upper limit value, and a clock signal having an appropriate frequency can be provided without unnecessarily reducing the frequency of the clock signal.

In the clock signal control device, the communication unit includes a serial communication interface and a parallel communication interface, and the electronic device includes a serial communication device that performs communication via the serial communication interface, and a parallel communication interface. And the spreading factor setting means includes a first connection state in which the serial communication device and the parallel communication device are not connected, and a second connection in which only the serial communication device is connected. Determining a connection state among a state, a third connection state in which only the parallel communication device is connected, and a fourth connection state in which the serial communication device and the parallel communication device are connected; The spreading factor according to the determined connection state It is preferable that the constant. (Claim 9)
In this case, the communication means includes a serial communication interface and a parallel communication interface, and the electronic device communicates with the serial communication device that performs communication via the serial communication interface and the parallel communication that performs communication via the parallel communication interface. Including devices. A first connection state in which the serial communication device and the parallel communication device are not connected; a second connection state in which only the serial communication device is connected; a third connection state in which only the parallel communication device is connected; and the serial communication device And the fourth connection state to which the parallel communication device is connected is determined, and the spreading factor corresponding to the determined connection state is set.

  Therefore, since the amount of electromagnetic waves radiated differs between serial communication and parallel communication, an appropriate spreading factor can be set according to the connection state of the serial communication device and the parallel communication device.

In the above clock signal control device, the spreading factor setting means sets the spreading factor in the second connection state to be larger than the spreading factor in the first connection state, and spreads the third connection state in the previous period. Preferably, the rate is set larger than the spreading factor of the second connection state, and the spreading factor of the fourth connection state is set larger than the spreading factor of the third connection state. (Claim 10)
In this case, the spreading factor of the second connection state is set larger than the spreading factor of the first connection state, the spreading factor of the third connection state is set larger than the spreading factor of the second connection state, 4 is set larger than the spreading factor of the third connection state. That is, since the radiation amount of electromagnetic waves increases in the order of the first connection state, the second connection state, the third connection state, and the fourth connection state, the diffusivity is changed according to these connection states. Thus, an appropriate spreading factor can be set for each connection state. Note that the frequency of the clock signal can be further diffused by increasing the spreading factor.

Further, in the clock signal control device, when the spreading factor setting unit determines that the first connection state is established, the frequency of the clock signal generated by the clock signal generation unit is not diffused and the electronic signal is not spread. It is preferable to supply the device. (Claim 11)
In this case, when it is determined that the state is the first connection state, the frequency of the clock signal is supplied to the electronic device without being spread. That is, when the serial communication device and the parallel communication device are not connected, the radiation amount of the electromagnetic wave can be suppressed to the allowable upper limit value or less, so that it is not necessary to spread the frequency of the clock signal, and the generated clock signal is directly converted into an electronic signal. Can be supplied to equipment.
In the clock signal control device, the spreading factor setting means includes a first operation state in which the serial communication device and the parallel communication device do not operate, a second operation state in which only the serial communication device operates, It is determined which of the third operation state in which only the parallel communication device operates and the fourth connection state in which the serial communication device and the parallel communication device operate, and the determined connection state It is preferable to set the diffusion rate according to the operation state. (Claim 18)
According to this configuration, the first operation state in which the serial communication device and the parallel communication device do not operate, the second operation state in which only the serial communication device operates, the third operation state in which only the parallel communication device operates, and It is determined which of the fourth connection states in which the serial communication device and the parallel communication device are operating, and a spreading factor is set according to the determined connection state and operation state.

  Therefore, an appropriate spreading factor can be set according to the connection state of the serial communication device and the parallel communication device and the operation state of the connected serial communication device and the parallel communication device, and the clock frequency can be set more finely. It is possible to reliably prevent an unnecessary decrease in the arithmetic processing speed and operation speed of the electronic device.

In the clock signal control device, the electronic device includes at least one of a scanner unit, a paper feeding unit, an image forming unit, and a post-processing unit included in the image forming device, and the image forming device includes the clock signal. Preferably, the diffusion rate setting means sets the diffusion rate according to the connection state of at least one of the scanner unit, the paper feeding unit, the image forming unit, and the post-processing unit. (Claim 12)
In this case, the electronic device includes at least one of a scanner unit, a paper feeding unit, an image forming unit, and a post-processing unit included in the image forming apparatus, and the image forming apparatus includes a clock signal control device. And since the diffusivity is set according to at least one connection state among the scanner unit, the paper feed unit, the image forming unit, and the post-processing unit, it is possible to suppress electromagnetic waves radiated from the image forming apparatus, An unnecessary decrease in the operation speed of the image forming apparatus can be prevented.

In the clock signal control device described above, it is preferable that the use state of the electronic device is a connection state of the electronic device that is directly or indirectly connected to the clock signal control device. (Claim 13)
In this case, a spreading factor corresponding to a plurality of connection states of the electronic device connected directly or indirectly to the clock signal control device is stored in advance, and the spreading factor storage unit stores the spreading factor according to the connection state of the electronic device. Since the stored spreading factor is selected, calculation processing for obtaining the spreading factor is not required, the spreading factor can be easily set, and the spreading factor according to the connection state of the electronic device can be set. Can do.

The clock signal control device may further include communication means for transmitting / receiving data to / from the electronic device, and the connection state of the electronic device is preferably the number of connections of the electronic device or the type of the communication means. (Claim 14)
In this case, the spreading factor corresponding to the number of the electronic devices connected directly or indirectly to the clock signal control device or the type of the communication means is stored in advance, and the spreading factor is determined according to the connection state of the electronic device. Since the spreading factor stored in the storage means is selected and set, there is no need for a calculation process for obtaining the spreading factor, the spreading factor can be easily set, and according to the connection state of the electronic device. The spreading factor can be set.

In the clock signal control device, the communication unit includes a serial communication interface and a parallel communication interface, and the electronic device includes a serial communication device that performs communication via the serial communication interface, and a parallel communication interface. And the spreading factor storage means includes a first connection state in which the serial communication device and the parallel communication device are not connected, and a second connection in which only the serial communication device is connected. A spreading factor corresponding to each connection state of a state, a third connection state in which only the parallel communication device is connected, and a fourth connection state in which the serial communication device and the parallel communication device are connected; The spreading factor setting means includes the first connection. State, the second connection state, the third connection state, and the fourth connection state are determined, and the diffusion rate stored in the diffusion rate storage means is determined. It is preferable to select and set a spreading factor corresponding to the determined connection state. (Claim 15)
In this case, the communication means includes a serial communication interface and a parallel communication interface, and the electronic device includes a serial communication device that performs communication via the serial communication interface, and a parallel communication device that performs communication via the parallel communication interface. Is included. In addition, a first connection state in which the serial communication device and the parallel communication device are not connected, a second connection state in which only the serial communication device is connected, a third connection state in which only the parallel communication device is connected, and the serial communication device And the spreading factor corresponding to each connection state of the fourth connection state to which the parallel communication device is connected is stored in advance in the spreading factor storage means. Then, it is determined which of the first connection state, the second connection state, the third connection state, and the fourth connection state, and the diffusion stored in advance in the diffusion rate storage means A spreading factor corresponding to the determined connection state is selected from the rates and set.

  Therefore, since the amount of electromagnetic waves radiated differs between serial communication and parallel communication, an appropriate spreading factor can be set according to the connection state of the serial communication device and the parallel communication device.

In the above clock signal control device, the spreading factor corresponding to the second connection state is larger than the spreading factor corresponding to the first connection state, and the spreading factor of the third connection state is It is preferable that the diffusion rate of the fourth connection state is larger than that of the second connection state, and that the diffusion rate of the fourth connection state is larger than that of the third connection state. (Claim 16)
In this case, the spreading factor of the second connection state is set larger than the spreading factor of the first connection state, and the spreading factor of the third connection state is set larger than the spreading factor of the second connection state. The spreading factor in the fourth connection state is set larger than the spreading factor in the third connection state. That is, since the radiation amount of electromagnetic waves increases in the order of the first connection state, the second connection state, the third connection state, and the fourth connection state, the diffusivity is stored according to these connection states. Thus, an appropriate spreading factor can be set for each connection state. Note that the frequency of the clock signal can be further diffused by increasing the spreading factor.

In the clock signal control device, the spreading factor storage unit stores the first connection state and a zero percent spreading factor in association with each other, and the spreading factor setting unit stores the first connection state. Is determined by selecting and setting a zero percent spreading factor corresponding to the first connection state from spreading factors stored in advance in the spreading factor storage unit, and the frequency spreading unit When the spreading factor of zero percent is set by the spreading factor setting unit, it is preferable that the frequency of the clock signal generated by the clock signal generating unit is supplied to the electronic device without spreading. (Claim 17)
In this case, the first connection state and the zero-percent spreading factor are stored in association with each other, and when it is determined that the first connection state is established, the spreading factor stored in advance in the spreading factor storage unit is stored. From among them, a zero percent spreading factor corresponding to the first connection state is selected and set. When a zero percent spreading factor is set, the frequency of the clock signal is supplied to the electronic device without being spread. Therefore, when the serial communication device and the parallel communication device are not connected, the radiation amount of the electromagnetic wave can be suppressed below the allowable upper limit value, so that it is not necessary to spread the frequency of the clock signal, and the generated clock signal is directly electronically Can be supplied to equipment.

A clock signal control device according to the present invention is a clock signal control device that controls a clock signal supplied to one or a plurality of electronic devices, and a clock signal generated by a clock signal generation unit that generates a clock signal of a predetermined frequency. Frequency spreading means for spreading the frequency of the signal based on a predetermined spreading factor, and spreading factor setting means for setting the spreading factor according to the usage state of the electronic device. (Claim 20)
According to this configuration, the frequency of the clock signal generated by the clock signal generation device that generates the clock signal of the predetermined frequency is spread based on the predetermined spreading factor, and the spreading factor corresponding to the usage state of the electronic device is set. Therefore, it is possible to suppress electromagnetic waves radiated from the electronic device and to prevent an unnecessary decrease in the arithmetic processing speed and the operation speed of the electronic device.

  According to the present invention, since the diffusivity according to the usage state of the electronic device is set, the electromagnetic wave radiated from the electronic device can be suppressed, and the arithmetic processing speed and the operating speed of the electronic device can be reduced. Can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.

  Here, FIG. 1 is a schematic configuration diagram of an information processing device 2 provided with a clock signal control device 1 according to an embodiment of the present invention, and FIG. 2 shows the intensity of electromagnetic waves emitted from the information processing device 2 and the information processing. 3 is a graph showing an example of a relationship with the connection state of the communication interface 20 of the device 2, FIG. 3 is a diagram showing an example of spreading factor information stored in the ROM 13 of the clock signal control device 1, and FIG. 4 is the clock signal control device. FIG. 5 illustrates another example of the procedure of the clock signal supply process performed by the control unit of the clock signal control apparatus. FIG. 6 is a flowchart illustrating an example of an image forming apparatus to which the clock signal control apparatus according to the present invention is applied.

  First, a schematic configuration of an information processing apparatus 2 including a clock signal control apparatus 1 according to an embodiment of the present invention will be described with reference to FIG.

  The information processing apparatus 2 (an example of an electronic device) uses a serial communication interface 21 that inputs and outputs data using a single signal line and a plurality of signal lines (for example, 8 or 16) to input data. The communication interface 20 (an example of communication means) having a parallel communication interface 22 that performs output, an arithmetic means such as a CPU and an ASIC, and peripheral devices (ROM, RAM, etc.) thereof are monitored and the connection state of the communication interface 20 is monitored. , A control unit 23 that comprehensively controls the information processing apparatus 2, and a clock signal control apparatus 1 that supplies an operation clock signal (a clock signal of a reference clock signal or a spread clock signal described later) to the control unit 23. And comprising.

  As shown in the figure, the clock signal control device 1 is installed in the information processing device 2 in a state of being connected to the control unit 23 via a bus or a control line. That is, the clock signal control device 1 and the information processing device 2 (control unit 23) are directly connected to each other.

  Further, in the information processing apparatus 2, a serial communication device 3 (an example of an electronic device) is connected to the serial communication interface 21 of the communication interface 20 as necessary. That is, when the serial communication device 3 is connected to the information processing device 2, the clock signal control device 1 and the serial communication device 3 are indirectly connected via the information processing device 2. Become. When a parallel communication device 4 (an example of an electronic device) is connected to the parallel communication interface 22 of the communication interface 20 as necessary, the clock signal control device 1 and the parallel communication device 2 are connected via the information processing device 2. The communication device 4 is indirectly connected.

  In this embodiment, one serial communication interface 21 and one parallel communication interface 22 are provided. However, the present invention is not particularly limited to this, and a plurality of serial communication interfaces 21 and a plurality of parallel communication interfaces 22 are provided. It may be done. In the present embodiment, only the serial communication interface 21 may be provided, or only the parallel communication interface 22 may be provided.

  Next, details of the clock signal control device 1 will be described. The clock signal control device 1 is typified by a spread spectrum clock generator (SSCG) that supplies an operation clock signal to one or a plurality of electronic devices. The clock signal control device 1 is composed of a crystal oscillator having a crystal resonator or the like, and generates a reference clock signal having a frequency of 400 MHz (an example of a clock signal generation device), and is generated by the clock signal generation unit 11 A clock frequency spreading unit 12 for spreading the frequency of the reference clock signal based on a predetermined spreading factor, and a ROM 13 for storing information relating to the spreading factor (hereinafter referred to as “spreading rate information”) and various control programs. A clock signal supply process described later by executing a process in accordance with a control program stored in the ROM 13 (an example of a spreading factor storage means) and an arithmetic means such as a CPU or ASIC and its peripheral devices (RAM and the like). (See the description of the flowchart of FIG. 4) There. Each component is connected by an internal bus 15.

  The clock signal control device 1 according to the present embodiment is configured to include the clock signal generation unit 11 therein, but is not limited thereto, and the clock signal is externally connected to the clock signal control device 1. The frequency of the reference clock signal supplied from a signal generator (not shown) may be diffused and output.

  In this case, the frequency of the clock signal generated by the clock signal generation device that generates the clock signal of the predetermined frequency is spread based on the predetermined spreading factor, and the spreading factor corresponding to the usage state of the electronic device is set. In addition to being able to suppress electromagnetic waves radiated from the electronic device, it is possible to prevent an unnecessary decrease in the arithmetic processing speed and the operation speed of the electronic device.

  In the present embodiment, a clock signal (hereinafter referred to as “spread clock signal”) frequency-spread as necessary by the clock signal control device 1 configured as described above is sent to the control unit 23 of the information processing device 2. By being supplied, electromagnetic waves radiated from the information processing apparatus 2 are reduced.

  Here, the electromagnetic waves radiated from the information processing apparatus 2 will be described. In the information processing apparatus 2, the control unit 23 operates based on the operation clock signal supplied from the clock signal control apparatus 1, so that electromagnetic waves are radiated from the information processing apparatus 2. The intensity of the electromagnetic wave radiated from the information processing apparatus 2 varies depending on the connection state between the communication interface 20 and the serial communication device 3 or the parallel communication device 4. This is because the electromagnetic waves are amplified by a connection wiring for connecting the serial communication device 3 and the parallel communication device 4 to the communication interface 20. That is, in the information processing apparatus 2, the intensity of the electromagnetic wave radiated from the information processing apparatus 2 depends on the connection state of the serial communication device 3 and the parallel communication device 4. Note that the connection state in the present embodiment is an example of the number of electronic devices connected to the communication interface 20 of the information processing apparatus 2 or the type of connection unit, and the serial communication device 3 or the serial communication device 4. However, the present invention is not limited to this, and may be the operating state of the serial communication device 3 or the serial communication device 4. On the other hand, as described above, the allowable upper limit of the intensity of the electromagnetic wave radiated from the information processing apparatus 2 is regulated by CISPR, VCCI, or the like. In the present embodiment, description will be made assuming that the allowable upper limit value is set to 37 dB.

  Next, an example of the relationship between the connection state of the communication interface 20 and the intensity of electromagnetic waves radiated from the information processing apparatus 2 will be described using the graph of FIG. FIG. 2 is a graph showing an example of the relationship between the intensity of the electromagnetic wave radiated from the information processing apparatus 2 and the connection state of the communication interface 20 of the information processing apparatus 2. Note that FIG. 2 shows that the control unit 23 of the information processing device 2 is radiated from the information processing device 2 when the frequency supplied from the clock signal control device 1 operates based on a reference clock signal having a frequency of 400 MHz. The measured value of the intensity of the electromagnetic wave is shown.

  As shown in FIG. 2, when a reference clock signal having a frequency of 400 MHz is supplied to the control unit 23 of the information processing apparatus 2, the measured value of the intensity of the electromagnetic wave radiated from the information processing apparatus 2 is the serial communication device. 3 and the parallel communication device 4 are not connected together (hereinafter referred to as “connection state A”), 37 dB, and when only the serial communication device 3 is connected (hereinafter referred to as “connection state B”), 40 dB, 43 dB in a state where only the parallel communication device 4 is connected (hereinafter referred to as “connection state C”), a state where both the serial communication device 3 and the parallel communication device 4 are connected (hereinafter referred to as “connection state D”). ) Is 46 dB. As described above, when the connection state of the communication interface 20 of the information processing device 2 is the connection states B, C, and D, the intensity of the electromagnetic wave radiated from the information processing device 2 is set to the allowable upper limit (37 dB). ) Will be exceeded.

  As described above, in the conventional SSCG, the spread clock signal in which the frequency of the reference clock signal is spread based on a constant spread rate is supplied to the control unit 23, whereby the intensity of the electromagnetic wave is set to the allowable upper limit value. It is suppressed to the following. However, since the diffusivity is constant, the electromagnetic wave intensity (46 dB) in the connection state D at which the intensity of the electromagnetic wave radiated from the information processing device 2 is maximized is suppressed to the allowable upper limit value or less. It is necessary to determine the diffusion rate that can be achieved. Therefore, even in the connection states A, B, and C in which the intensity of the electromagnetic wave radiated from the information processing device 2 is 37, 40, and 43 dB, the spread clock signal that is frequency-spread with the spreading factor corresponding to the connection state D Is supplied to the control unit 23. Therefore, in the conventional SSCG, there is a problem that the calculation processing speed of the control unit 23 in the connection states A, B, and C and the operation speed of the information processing device 2 controlled by the control unit 23 are unnecessarily lowered. Has occurred.

  In this clock signal control apparatus 1 that can improve this problem, the spreading factor corresponding to each of the connection states A, B, C, and D is stored in advance in the ROM 13 as spreading factor information. In addition, an appropriate diffusion rate can be extracted from the ROM 13.

  Hereinafter, details of the spreading factor information stored in the ROM 13 will be described. FIG. 3 is a diagram showing an example of spreading factor information stored in the ROM 13 of the clock signal control device 1. .

  As shown in FIG. 3, the spreading factor information in the present embodiment includes the connection state (connection state A, B, C, D) of the communication interface 20 and the actually measured value of the electromagnetic wave intensity according to the connection state. (Actually measured values shown in FIG. 2) and the spreading factor according to the connection state are associated with each other. That is, each of the spreading factors corresponds to an electromagnetic wave radiated from the information processing apparatus 2 detected in advance according to a possible connection state of the communication interface 20, and is known according to each connection state. Is the value of Specifically, the electromagnetic wave is an electromagnetic wave detected on the basis of parameters capable of measuring the degree of influence on the electronic device such as the intensity of the electromagnetic wave, the intensity of the electromagnetic wave noise, the frequency of the electromagnetic wave, and the amplitude of the electromagnetic wave. It is. In the present embodiment, the intensity of electromagnetic waves will be described as an example.

  Further, each spreading factor shown in FIG. 3 can suppress the intensity of the electromagnetic wave radiated from the information processing device 2 to the allowable upper limit (37 dB) in the connection state of the communication interface 20 corresponding to each spreading factor. It is determined in advance.

  As shown in FIG. 3, the connection state A in which the serial communication device 3 and the parallel communication device 4 are not connected together is associated with an electromagnetic wave intensity of 37 dB and a spreading factor of 0%. The connection state B in which only the serial communication device 3 is connected is associated with an electromagnetic wave intensity of 40 dB and a diffusivity of −1%. Further, the connection state C in which only the parallel communication device 4 is connected is associated with an electromagnetic wave intensity of 43 dB and a diffusivity of -2%. Furthermore, the connection state D in which the serial communication device 3 and the parallel communication device 4 are connected together is associated with an electromagnetic wave intensity of 46 dB and a diffusivity of −3%.

  Note that the ROM 13 in the present embodiment stores the connection state of the serial communication device 3 and the parallel communication device 4, the electromagnetic wave intensity, and the spreading factor in association with each other, but the present invention is particularly limited to this. Instead, the connection state of the serial communication device 3 and the parallel communication device 4 and the spreading factor may be stored in association with each other.

  As described above, the clock signal control device 1 is configured, and a clock signal supply process (to be described later) is executed by the control unit 14 so that the spreading factor corresponding to the connection states A, B, C, and D is the ROM 13. The spread clock signal that is appropriately selected from the spread rate information (see FIG. 3) and frequency-spread based on the spread rate is supplied to the control unit 23 of the information processing apparatus 2.

  In addition, the intensity of the electromagnetic wave radiated from the electronic device detected in advance according to the usage state of the electronic device is set to a diffusivity that is equal to or lower than a predetermined allowable upper limit value. Thereby, the intensity of the electromagnetic wave radiated from the information processing device 2 can be suppressed to the allowable upper limit value or less, and the calculation processing speed of the control unit 23 and the information processing device controlled by the control unit 23 are controlled. Thus, an unnecessary decrease in the operation speed of 2 can be prevented.

  Next, an example of the procedure of the clock signal supply process executed by the control unit 14 of the clock signal control device 1 according to the control program stored in the ROM 13 will be described using the flowchart of FIG. FIG. 4 is a flowchart for explaining an example of the procedure of the clock signal supply process executed by the control unit 14 of the clock signal control apparatus 1. Hereinafter, S1, S2,... Represent processing procedure (step) numbers in the control unit 14.

  When the information processing device 2 is powered on, as shown in FIG. 4, the clock signal control device 1 sets a clock frequency spreading factor setting process for setting a spreading factor according to the connection state of the communication interface 20 ( Through steps S1 to S8), a series of clock signal supply processes for spreading the frequency of the reference clock signal based on the set spreading factor and supplying the spread clock signal with the spread frequency to the control unit 23 Is executed by the control unit 14. The control unit 14 that executes the clock frequency spreading factor setting process corresponds to a clock frequency spreading factor setting unit.

  First, in step S1 in the clock frequency spreading factor setting process, the connection state of the communication interface 20, that is, the serial communication device 3 or the parallel communication device 4 is connected to the serial communication interface 21 or the parallel communication interface 22. Information indicating whether or not there is a connection state (hereinafter referred to as “connection information”) is transmitted from the control unit 23 monitoring the connection state to the control unit 14. The control unit 14 acquires the connection information.

  In the subsequent step S2, it is determined whether or not the serial communication device 3 is connected based on the connection information, and the process branches. That is, the control unit 14 determines whether or not the serial communication device 3 is connected to the serial communication interface 21. If it is determined that the serial communication device 3 is not connected, the process proceeds to step S3. If it is determined that the serial communication device 3 is connected, the process proceeds to step S4.

  In the next step S3 and step S4, it is determined whether or not the parallel communication device 4 is connected based on the connection information, and the process branches.

When it is determined that the serial communication device 3 is not connected (NO in step S2),
In step S <b> 3, the control unit 14 determines whether or not the parallel communication device 4 is connected to the parallel communication interface 22. If it is determined that the parallel communication device 4 is not connected (NO in step S3), the control unit 14 determines that the connection state of the communication interface 20 is the serial communication device 3 and the parallel communication device 4. Are in the connection state A that are not connected together.

  In subsequent step S5, the control unit 14 selects and sets the spreading factor 0% corresponding to the connection state A from the spreading factor information (see FIG. 3) stored in the ROM 13. Thereafter, the process proceeds to step S9.

  On the other hand, when it is determined that the parallel communication device 4 is connected (YES in step S3), the control unit 14 determines that the connection state of the communication interface 20 is the connection in which only the parallel communication device 4 is connected. It is determined that the state is C.

  In subsequent step S6, the control unit 14 selects and sets the spreading factor -2% corresponding to the connection state C from the spreading factor information (see FIG. 3) stored in the ROM 13. Thereafter, the process proceeds to step S9.

  On the other hand, when it is determined that the serial communication device 3 is connected (YES in step S2), in step S4, the control unit 14 determines whether or not the parallel communication device 4 is connected to the parallel communication interface 22. To do. If it is determined that the parallel communication device 4 is not connected (NO in step S4), the connection state of the communication interface 20 is the connection state B in which only the serial communication device 3 is connected. Judge.

  In subsequent step S7, the control unit 14 selects and sets a spreading factor of 1% corresponding to the connection state B from the spreading factor information (see FIG. 3) stored in the ROM 13. Thereafter, the process proceeds to step S9.

  When it is determined that the parallel communication device 4 is connected (YES in step S4), the control unit 14 determines that the connection state of the communication interface 20 indicates that both the serial communication device 3 and the parallel communication device 4 are connected. It is determined that the connection state D is connected.

  In subsequent step S8, the control unit 14 selects and sets a spreading factor-3% corresponding to the connection state D from the spreading factor information (see FIG. 3) stored in the ROM 13. Thereafter, the process proceeds to step S9.

  Next, in step S9, the control unit 14 transmits the spreading factor set in the clock frequency spreading factor setting process (S1 to S8) to the clock frequency spreading unit 12. The clock frequency spreading unit 12 spreads the frequency of the reference clock signal generated by the clock signal generating unit 11 based on the transmitted spreading factor.

  Since the frequency spreading method of the reference clock signal by the clock frequency spreading unit 12 is a well-known technique, detailed description thereof is omitted here. The 400 MHz frequency of the reference clock signal is 396 to 400 MHz (average 398 MHz) if spread at a spread rate of -1%, 392 to 400 MHz (average 396 MHz) if spread at a spread rate of -2%, and -3% spread If it spreads at a rate, it becomes 388 to 400 MHz (average 394 MHz). That is, the clock frequency spreading unit 12 can further spread the frequency of the clock signal by increasing the spreading factor. Note that a spreading factor of 0% indicates that the frequency is not spread.

  As described above, when it is determined that the state is the connection state A, the frequency of the clock signal is supplied to the control unit 23 without being spread. That is, when the serial communication device 3 and the parallel communication device 4 are not connected, the radiation amount of the electromagnetic wave is also suppressed within the allowable upper limit value, so that it is not necessary to spread the frequency of the clock signal, and the generated clock signal is It can be directly supplied to the control unit 23.

  In step S <b> 10, the clock frequency spreading unit 12 supplies the frequency-spread spread clock signal to the control unit 23 of the information processing apparatus 2. Thereby, a series of the clock signal supply processing executed by the control unit 14 of the clock signal control device 1 is completed. Thereafter, a spread clock signal that has been frequency spread based on the set spreading factor is continuously supplied from the clock frequency spreading unit 12 of the clock signal control device 1 to the control unit 23 of the information processing device 2. .

  In this way, in the information processing apparatus 2, the spread clock signal that has been frequency spread based on the spreading factor set according to the actual connection state of the communication interface 20 when the information processing apparatus 2 is used is controlled by the control unit 2. Supplied to the unit 23. That is, a spread clock signal that is frequency-spread with a minimum spreading factor necessary for suppressing the intensity of the electromagnetic wave radiated from the information processing apparatus 2 to the allowable upper limit value is supplied to the control unit 23. Therefore, it is possible to prevent an unnecessary decrease in the calculation processing speed of the control unit 23 and the operation speed of the information processing apparatus 2 controlled by the control unit 23.

  In addition, since the spreading factor is set according to the usage state of the electronic device such as the serial communication device 3 and the parallel communication device 4, it is possible to suppress electromagnetic waves radiated from the electronic device and to perform arithmetic processing in the electronic device. It is possible to prevent an unnecessary decrease in the speed and the operating speed of the electronic device.

  Further, the spreading factor corresponding to a plurality of usage states of the electronic devices such as the serial communication device 3 and the parallel communication device 4 is stored in advance, and the diffusion rate stored in the spreading factor storage unit according to the usage state of the electronic device. Since the rate is selected and set, a calculation process for obtaining the spreading factor is not required, and the spreading factor can be easily set.

  Furthermore, the connection state A (corresponding to the first connection state) in which the serial communication device 3 and the parallel communication device 4 are not connected, and the connection state B (corresponding to the second connection state) in which only the serial communication device 3 is connected. ), Connection state C in which only the parallel communication device 4 is connected (corresponding to the third connection state), and connection state D in which the serial communication device 3 and the parallel communication device 4 are connected (corresponding to the fourth connection state) The connection rate is set according to the determined connection state. Therefore, since the amount of electromagnetic waves radiated differs between serial communication and parallel communication, an appropriate spreading factor can be set according to the connection state of the serial communication device 3 and the parallel communication device 4.

  In addition, the spreading factor of the connection state B is set larger than the spreading factor of the connection state A, the spreading factor of the connection state C is set larger than the spreading factor of the connection state B, and the spreading factor of the connection state D is set to the connection state C. Is set to be larger than the diffusion rate. That is, since the radiation amount of electromagnetic waves increases in the order of connection state A, connection state B, connection state C, and connection state D, by changing the diffusion rate according to these connection states, appropriate diffusion for each connection state The rate can be set. Note that the frequency of the clock signal can be further diffused by increasing the spreading factor.

  Specifically, the intensity of the electromagnetic wave is suppressed to the allowable upper limit value of 37 dB when the connection state of the communication interface 20 is any of the connection states A, B, C, and D. It is diffused with a lean diffusion rate. Note that the connection state of the communication interface 20 is merely an example of the usage state of the information processing device 2, and the usage state of the information processing device 2 is directly or indirectly connected to the clock signal control device 1. This may be the connection state of other electronic devices, the number of connections of the electronic devices, or the type of communication interface.

  Furthermore, in the present embodiment, the spreading factor corresponding to the connection state of the communication interface 20 of the information processing apparatus 2 is set in advance before the supply of the operation clock signal to the control unit 23 of the information processing apparatus 2 is started. . Therefore, it is possible to prevent the intensity of electromagnetic waves radiated from the information processing apparatus 2 from exceeding the allowable upper limit value. Note that the present invention is not limited to this, and if the setting of the spreading factor is appropriately changed according to the connection state of the communication interface 20 by repeatedly executing the clock frequency spreading factor setting process (S1 to S8) at all times, the situation Accordingly, a spread clock signal that is frequency-spread based on an appropriate spreading factor is supplied to the control unit 23 of the information processing apparatus 2 as needed.

  In the present embodiment, 37 dB in the connection state A is described as the minimum value of the intensity of the electromagnetic wave radiated from the information processing device 2. Of course, the connection state of the communication interface 20 and the information processing When the intensity of the electromagnetic wave is 37 dB or less of the allowable upper limit value depending on the usage state of the device 2 and the like, there is no need to suppress the allowable upper limit value. Needless to say, the reference clock signal may be configured to be supplied.

  In the present embodiment, the spreading factor is set according to the connection state of the communication interface 20, but the present invention is not particularly limited to this, and the connection state of the communication interface 20 and the electronic device connected to the communication interface 20 The spreading factor may be set according to the operation state.

  FIG. 5 is a flowchart for explaining another example of the procedure of the clock signal supply process executed by the control unit 14 of the clock signal control apparatus 1. In FIG. 5, the same processes as those in FIG.

First, in step S1, information indicating the connection state of the communication interface 20, that is, whether the serial communication device 3 or the parallel communication device 4 is connected to the serial communication interface 21 or the parallel communication interface 22 (hereinafter referred to as “connection”). Information ”), the serial communication device 3 connected to the serial communication interface 21 and the parallel communication device 4 connected to the parallel communication interface 22.
Operating state. In other words, information indicating the operation state of whether the serial communication device 3 and the parallel communication device 4 are operating (hereinafter referred to as “operation information”) is transmitted from the control unit 23 monitoring the subsequent state to the control unit. 14 is transmitted. The control unit 14 acquires connection information and operation information.

If it is determined in step S3 that the parallel communication device 4 is connected (YES in step S3), in step S11, the control unit 14 operates the parallel communication device 4 based on the acquired operation information. Judge whether or not. If it is determined that the parallel communication device 4 is not operating (NO in step S11), the process proceeds to step S5, and the spreading factor is set to 0%. On the other hand, if it is determined that the parallel communication device 4 is operating (YES in step S11), the process proceeds to step S6, and the spreading factor is set to -2%.
That is, when only the parallel communication device 4 is connected and the parallel communication device 4 is operating (corresponding to the third operation state), the spreading factor is set to -2%, and only the parallel communication device 4 Is connected and the parallel communication device 4 is not operating (corresponding to the first operating state), the spreading factor is set to 0%. As described above, for example, even if the parallel communication device 4 is operated, the spreading factor is not changed unless the parallel communication device 4 is operated, and the spreading factor is changed only for a defect in which the parallel communication device 4 is operating. Be changed.
If it is determined in step S2 that the serial communication device 3 is connected (YES in step S2), and it is determined in step S4 that the parallel communication device 4 is not connected (NO in step S4). In step S12, the control unit 14 determines whether or not the serial communication device 3 is operating based on the acquired operation information. If it is determined that the serial communication device 3 is not operating (NO in step S12), the process proceeds to step S5, and the spreading factor is set to 0%. On the other hand, when it is determined that the serial communication device 3 is operating (YES in step S12), the process proceeds to step S7, and the spreading factor is set to -1%.

That is, when only the serial communication device 3 is connected and the serial communication device 3 is operating (corresponding to the second operation state), the spreading factor is set to −1%, and only the serial communication device 3 is When connected and the serial communication device 3 is not operating (corresponding to the first operating state), the spreading factor is set to 0%. Thus, even if the serial communication device 3 is connected, the spreading factor is not changed unless the serial communication device 3 is operating, and the spreading factor is only changed when the serial communication device 3 is operating. Be changed.

In step S2, it is determined that the serial communication device 3 is connected (
If YES in step S2), if it is determined in step S4 that the ballerel communication device 4 is connected (YES in step S4), in step S13, the control unit 14
Determines whether the serial communication device 3 is operating based on the acquired operation information. If it is determined that the serial communication device 3 is operating (YES in step S13), the process proceeds to step S14.

 It is determined that serial communication device 3 is connected (YES in step S2), and it is determined that parallel communication device 4 is connected (YES in step S4). When it is determined that the serial communication device 3 is operating (YES in step S13), in step S14, the control unit 14 determines whether the parallel communication device 4 is operating based on the acquired operation information. To do. If it is determined that the parallel communication device 4 is not operating (NO in step S14). The process proceeds to step S7, and the diffusion rate is set to -1%. When it is determined that the parallel communication device 4 is operating (YES in step S14). The process proceeds to step S8, and the spreading factor is set to −3%.

 That is, when the serial communication device 3 and the parallel communication device 4 are connected and only the serial communication device 3 is operating (corresponding to the second operation state), the spreading factor is set to −1%, When serial communication device 3 and parallel communication device 4 are connected and both serial communication device 3 and parallel communication device 4 are operating (corresponding to the fourth operation state), the spreading factor is set to −3%. Is done.

  On the other hand, it is determined that the serial communication device 3 is connected (YES in step S2), it is determined that the parallel communication device 4 is connected (YES in step S4), and the serial communication device 3 is not operating. If determined (NO in step S13), in step S15. The control unit 14 determines whether or not the parallel communication device 4 is operating based on the acquired operation information. If it is determined that the parallel communication device 4 is not operating (NO in step S15), the process proceeds to step S5, and the spreading factor is set to 0%. If it is determined that the parallel communication device 4 is operating (YES in step S15), the process proceeds to step S6, where the spreading factor is set to -2%.

That is, when the serial communication device 3 and the parallel communication device 4 are connected and only the parallel communication device 4 is operating (corresponding to the third operation state), the spreading factor is set to -2%, When serial communication device 3 and parallel communication device 4 are connected and both serial communication device 3 and parallel communication device 4 are not operating (corresponding to the first operation state), the spreading factor is set to 0% Is done.

 As described above, even if the serial communication device 3 and the parallel communication device 4 are connected, if at least one of the serial communication device 3 and the parallel communication device 4 is not operating, the spreading factor is not changed and the serial communication device 3 is not connected. The spreading factor is changed only when at least one of the device 3 and the parallel communication device 4 is operating.

  In the above-described embodiment, the information processing apparatus 2 has been described as an example of an electronic apparatus. However, the present invention is not limited thereto, and other examples of the electronic apparatus include an image processing apparatus, an image forming apparatus, an information processing apparatus, Examples include telecommunications equipment and electronic office equipment.

  For example, when the clock signal control device 1 is used in an image forming apparatus (not shown), the spreading factor is set according to the usage state of the image forming apparatus. Specifically, it is conceivable that the diffusion rate is set according to the connection state of various option units such as a scanner unit, a paper feed unit, and a post-processing unit mounted on the image forming apparatus.

  FIG. 6 is a diagram showing an example of an image forming apparatus to which the clock signal control device according to the present invention is applied. An image forming apparatus 2 ′ shown in FIG. 6 includes a clock signal control device 1, a control unit 23, a scanner unit, a paper feeding unit, an image forming unit 7, and a post-processing unit 8. The image forming apparatus 2 ′ is a copier, a facsimile machine, a printer apparatus, or a multifunction machine having these functions.

The control unit 23 controls the scanner unit 5, the paper feeding unit 6, the image forming unit 7, and the post-processing unit 8 using the clock signal controlled by the clock signal control device 1. The scanner unit 5 reads the original book and acquires image data of the read original.
The paper feed unit 6 feeds the recording paper according to the image formation timing. The image forming unit 7 forms an image on the recording paper fed by the paper feeding unit 6. Post-processing unit 8
Performs various post-processing such as sorting and stapling on the recording paper on which the image is formed by the image forming unit 7.

 Note that the image forming apparatus 2 ′ does not need to include all of the scanner unit 5, the paper feeding unit 6, the image forming unit 7, and the post-processing unit 8, but includes only necessary units according to the type of the image forming apparatus 2 ′. May be. Further, the image forming apparatus 2 ′ may include other units in addition to the above units if necessary. Examples of the other units include an image processing unit that performs various image processing on the image data, an operation unit that receives various operations of the causer, and the like.

 In this case, the clock signal restoration device 1 suppresses the electromagnetic wave radiated from the image forming device 2 ′ measured in advance in each of the plurality of connection states of the various option units to the allowable upper eye value. The diffusion rate that can be recorded in advance is recorded in the ROM 13 (corresponding to the storage means). And. When the image forming apparatus 2 ′ is used, the diffusion rate stored in the ROM 13 is selected and set according to the actual connection state of the various option units.

  As a result, the image forming apparatus 2 ′ is supplied with a spread clock signal having a frequency spread based on the spreading factor according to the connection state of the various option units. The radiated electromagnetic wave can be suppressed to the allowable upper limit value or less, and an unnecessary decrease in the operation speed of the image forming apparatus can be prevented.

 Further, since the diffusivity is set according to the connection state of at least one of the scanner unit 5, the paper feeding unit 6, the image forming unit 7, and the post-processing unit 8, electromagnetic waves radiated from the image forming apparatus 2 ′ are In addition to being able to suppress, it is possible to prevent an unnecessary decrease in the operation speed of the image forming apparatus 2 ′.

1 is a schematic configuration diagram of an information processing apparatus including a clock signal control device according to an embodiment of the present invention. The graph which shows an example of the relationship between the intensity | strength of the electromagnetic waves radiated | emitted from information processing apparatus, and the connection state of the communication interface of information processing apparatus. The figure which shows an example of the spreading | diffusion rate information memorize | stored in ROM of the clock signal control apparatus which concerns on embodiment of this invention. The flowchart explaining an example of the procedure of the clock signal supply process performed by the control part of the clock signal control apparatus which concerns on embodiment of this invention. The flowchart explaining the other example of the procedure of the clock signal supply process performed by the control part of the clock signal control apparatus which concerns on embodiment of this invention. 1 is a diagram illustrating an example of an image forming apparatus to which a clock signal control device according to an embodiment of the present invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Clock signal control apparatus 2 ... Information processing apparatus (an example of electronic equipment)
3. Serial communication device (an example of electronic equipment)
4. Parallel communication device (an example of electronic equipment)
11: Clock signal generator (an example of a clock signal generator)
12 ... Clock frequency spreading unit 13 ... ROM (an example of spreading factor storage means)
14: Control unit (an example of clock frequency spreading factor setting means)
15 ... Internal bus 20 ... Communication interface (an example of a connection unit)
21 ... Serial communication interface 22 ... Parallel communication interface 23 ... Control unit

Claims (20)

A clock signal control device for controlling a clock signal supplied to one or a plurality of electronic devices,
Clock signal generating means for generating a clock signal of a predetermined frequency;
Frequency spreading means for spreading the frequency of the clock signal generated by the clock signal generating means based on a predetermined spreading factor;
A clock signal control device comprising: a spreading factor setting unit that sets the spreading factor according to a use state of the electronic device. A diffusion rate storage means for preliminarily storing a diffusion rate according to a plurality of usage states of the electronic device;
2. The clock signal control device according to claim 1, wherein the spreading factor setting unit selects and sets a spreading factor stored in the spreading factor storage unit according to a use state of the electronic device.   2. The clock signal control device according to claim 1, wherein the usage state of the electronic device is a connection state of the electronic device directly or indirectly connected to the clock signal control device. A communication means for transmitting and receiving data to and from the electronic device;
4. The clock signal control apparatus according to claim 3, wherein the connection state of the electronic device is the number of connections of the electronic device or the type of the communication means.   2. The use state of the electronic device includes a connection state of the electronic device directly or indirectly connected to the clock signal control device and an operation state of the electronic device. Clock signal control device.   6. The clock signal control apparatus according to claim 5, wherein the spreading factor setting means sets a spreading factor larger when the electronic device is operating than when the electronic device is not operating.   2. The clock signal according to claim 1, wherein the spreading factor setting unit sets a previous spreading factor corresponding to an electromagnetic wave radiated from the electronic device detected in advance according to a use state of the electronic device. Control device.   The diffusivity setting means sets the diffusivity so that the intensity of the electromagnetic wave radiated from the electronic device detected in advance according to the usage state of the electronic device is equal to or less than a predetermined allowable upper limit value. 8. The clock signal control apparatus according to claim 7, wherein The communication means includes a serial communication interface and a parallel communication interface,
The electronic device includes a serial communication device that performs communication via a serial communication interface, and a parallel communication device that performs communication via a parallel communication interface.
The spreading factor setting means includes a first connection state in which the serial communication device and the parallel communication device are not connected, a second connection state in which only the serial communication device is connected, and a connection state in which only the parallel communication device is connected. 3 and the fourth connection state to which the serial communication device and the parallel communication device are connected are determined, and the spreading factor corresponding to the determined connection state is set. The clock signal control device according to claim 4, wherein     The spreading factor setting means sets the spreading factor of the second connection state to be larger than the spreading factor of the first connection state, and sets the spreading factor of the third connection state in the previous period to the diffusion of the second connection state. 10. The clock signal control device according to claim 9, wherein the clock signal control device is set to be larger than a rate, and the spreading factor of the fourth connection state is set to be larger than the spreading factor of the third connection state.   The spread ratio setting means supplies the frequency of the clock signal generated by the clock signal generation means to the electronic device without spreading when it is determined that the first connection state is established. Item 12. The clock signal control device according to Item 9. The electronic device includes at least one of a scanner unit, a paper feeding unit, an image forming unit, and a post-processing unit included in the image forming apparatus,
The image forming apparatus includes the clock signal control device,
4. The clock signal according to claim 3, wherein the spreading factor setting unit sets the spreading factor according to a connection state of at least one of a scanner unit, a paper feeding unit, an image forming unit, and a post-processing unit. Control device.   3. The clock signal control device according to claim 2, wherein the use state of the electronic device is a connection state of the electronic device that is directly or indirectly connected to the clock signal control device. A communication means for transmitting and receiving data to and from the electronic device;
14. The clock signal control apparatus according to claim 13, wherein the connection state of the electronic device is the number of connections of the electronic device or the type of the communication means. The communication means includes a serial communication interface and a parallel communication interface,
The electronic device includes a serial communication device that performs communication via a serial communication interface, and a parallel communication device that performs communication via a parallel communication interface.
The spreading factor storage means includes a first connection state in which the serial communication device and the parallel communication device are not connected, a second connection state in which only the serial communication device is connected, and a connection state in which only the parallel communication device is connected. 3 in advance, and a spreading factor corresponding to each connection state of the fourth connection state to which the serial communication device and the parallel communication device are connected is stored in advance.
The spreading factor setting means determines the connection state among the first connection state, the second connection state, the third connection state, and the fourth connection state, and 15. The clock signal control device according to claim 14, wherein a spreading factor corresponding to the determined connection state is selected and set from spreading factors stored in advance in the spreading factor storage means.   The spreading factor of the second connection state is greater than the spreading factor corresponding to the first connection state, the spreading factor of the third connection state is greater than the spreading factor of the second connection state, 16. The clock signal control device according to claim 15, wherein a spreading factor in the fourth connection state is larger than a spreading factor in the third connection state. The spreading factor storage means stores the first connection state and a zero percent spreading factor in association with each other,
If the spreading factor setting means determines that the first connection state is present, a zero percent spread corresponding to the first connection state is selected from the spreading factors stored in advance in the spreading factor storage means. Select and set the rate,
The frequency spreading means supplies the frequency of the clock signal generated by the clock signal generating means to the electronic device without spreading when the spreading ratio of zero percent is set by the spreading ratio setting means. The clock signal control device according to claim 15.   The spreading factor setting means includes a first operation state in which the serial communication device and the parallel communication device do not operate, a second operation state in which only the serial communication device operates, and a third operation state in which only the parallel communication device operates. It is determined which one of the operation states and the fourth connection state in which the serial communication device and the parallel communication device operate, and the spreading factor corresponding to the determined connection state and operation state is determined. The clock signal control device according to claim 9, wherein the clock signal control device is set.     2. The clock signal control device according to claim 1, wherein the spreading factor setting unit sets the spreading factor according to a use state of the electronic device before starting to supply a clock signal to the electronic device. . A clock signal control device for controlling a clock signal supplied to one or a plurality of electronic devices,
A frequency spreading means for spreading the frequency of the clock signal generated by the clock signal generating means for generating a clock signal of a predetermined frequency based on a predetermined spreading factor;
A clock signal control device comprising: a spreading factor setting unit that sets the spreading factor according to a use state of the electronic device.