JP2002207528A - Portable electronic equipment and changeover method for clock frequency thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a clock frequency to reduce electric power consumption in portable electronic equipment with a display device. SOLUTION: The portable electronic equipment has the detachable display device 11 and a microprocessor controlling the display of the display device 11. The electronic equipment detects by a display device attachment/detachment detection means 19 whether the display device 11 is connected to an electronic equipment body 20. When the display device 11 is not connected to the electronic equipment body 20, the clock frequency of the microprocessor is reduced, and the MPU skips the processing for the display.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable electronic device powered by a battery and a clock frequency switching method thereof.
In particular, the present invention relates to a portable electronic device having a display device and a power saving control method thereof.

[0002]

2. Description of the Related Art A portable electronic device having a conventional display device will be described below using a portable audio device as an example. In the portable electronic device, a battery is used as a power source, and various items predetermined for each device are displayed on the display device. For example, in the case of a mini-disc (hereinafter also referred to as MD) device, the number of the track currently recorded or reproduced, the elapsed time in the track, the remaining battery level, and the like are displayed. Such a portable electronic device is provided with system control means having a microprocessor (hereinafter also referred to as MPU).
Performed by the PU.

In a portable audio device, a display device is a built-in type that is fixed to the audio device main body, a display device that is connected to a signal line or a power line but cannot be detached, or a display device that is connected by a signal line or a power line. There is a removable type. The power of the display device may be supplied from the audio device main body, or the display unit may have an independent battery power supply. Furthermore, some audio devices include a display device fixed to the audio device main body and a display device for remote control.

[0004] Incidentally, portable audio equipment is provided with various power saving devices for extending the life of a battery. One of them is to reduce the clock frequency of the MPU from a steady state under certain conditions to save the power of the device. The certain condition described above is, for example, in the case of an MD device, when data read from a recording medium at the time of reproduction is in a state where the data is almost fully stored in a buffer memory. Is stopped, the reproduction mode is set to the power saving mode, and the clock frequency is reduced.

[0005]

However, in the conventional portable electronic device, the display device operates even in the above-described power saving mode, and the display of the display device must be controlled. The frequency could not be reduced significantly. When the clock frequency is significantly reduced, there are problems that scrolling in the display cannot be performed smoothly, the time displayed for updating every second cannot be displayed smoothly, and user operations are not displayed promptly. For this reason, the clock frequency has been reduced to only about 1/2 of the reference frequency in the steady state. Therefore, there has been a problem that significant power saving cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a portable electronic device having a display device, in which a clock frequency is significantly reduced to reduce power consumption. is there.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first invention is a portable electronic device having a display device and a microprocessor for controlling the display of the display device. In the device, when display is not performed on the display screen of the display device, the clock frequency of the microprocessor is set lower than when display is performed on the display screen, and the display control is performed by the microprocessor. It is a portable electronic device that is not required.

According to the optical disk reproducing apparatus of the present invention, in a portable electronic device using the display device, the state of the display device is checked, and when it is determined that the display is not actually performed, the MPU is used. Therefore, the clock frequency of the MPU is set to be lower than the clock frequency at the time of display on the display screen, and the MPU does not perform the display processing. As a result, even if the clock frequency is lowered, the MPU can perform processing necessary for the portable electronic device to operate normally and reduce power consumption. Thus, the life of the battery that drives the portable electronic device can be extended.

According to a second aspect, in the portable electronic device according to the first aspect, the display device is a detachable display device, and further includes a display device attachment / detachment detecting means for detecting the attachment / detachment state of the display device. When the display device is not connected to the portable electronic device body including the microprocessor,
A portable electronic device in which a clock frequency of the microprocessor is reduced so that the display control by the microprocessor is not performed.

According to the portable electronic device of the present invention, when the display device is not connected to the main body of the electronic device, the display on the display device is not performed. This makes it easy to recognize that the load on the MPU is light and the clock frequency can be reduced. Note that when the display device is not connected to the portable electronic device main body, the clock frequency of the microprocessor is set to be lower than the clock frequency when the display device is connected to the portable electronic device main body. Down to.

According to a third aspect, in the portable electronic device according to the first aspect, the display device has a power switch dedicated to the display device, and a power on / off detection means for detecting whether the power switch is on or off. A portable electronic device having a clock frequency of the microprocessor when the power switch is turned off so that the display control by the microprocessor is not performed.

According to the portable electronic device of the present invention, even if the power of the display device is supplied from the main body of the portable electronic device or the display device itself has the power supply, By checking whether the power switch of the device is turned on or off, it can be easily recognized whether or not the display device is used. The power switch of the display device is turned off.
If it is F, the clock frequency of the microprocessor is reduced so as to be lower than the clock frequency when the power switch is ON.

According to a fourth aspect, in the portable electronic device according to the first aspect, the display device is a display device to which power is supplied from a portable electronic device main body including a microprocessor. A portable electronic device in which, when power is not supplied from the main body to the display device, the clock frequency of the microprocessor is reduced so that the display control by the microprocessor is not performed.

According to the portable electronic device of the present invention, when the voltage of the battery for driving the electronic device body falls below a predetermined value for some reason, power is supplied to the display device to save power. May be stopped. In such a case, the power consumed by the MPU can also be reduced. In the case where power is not supplied from the portable electronic device body to the display device, the clock frequency of the microprocessor is changed to the case where power is supplied from the portable electronic device body to the display device. Lower so that it is lower than the clock frequency.

According to a fifth aspect, in the portable electronic device according to the first aspect, the portable electronic device further includes communication detection means for detecting the presence or absence of communication between the display device and the main body of the portable electronic device including the microprocessor. When data is not supplied from the display device to the portable electronic device body for a predetermined time or more, the clock frequency of the microprocessor is reduced,
A portable electronic device in which the display control by the microprocessor is not performed.

According to the portable electronic device of the present invention, a situation in which no new information is displayed even when the display device is connected to the portable electronic device body and the power switch of the display device is turned on. Can be recognized. When communication is not performed between the MPU and the display device, the clock frequency of the microprocessor is reduced to be lower than the clock frequency of the MPU when communication is performed between the MPU and the display device. In the determination of the presence or absence of the communication, it is determined that there is no communication when the communication has not been performed for a predetermined time or more.

A sixth aspect of the present invention is the portable electronic device according to the first aspect, further comprising a non-removable display device and a removable display device as the display device, and further comprising a power supply for the non-removable display device. Power supply monitoring means for monitoring the on / off state of the display device, and display device attachment / detachment detection means for detecting the attachment / detachment state of the detachable display device, wherein the power supply of the non-detachable display device is shut off and the detachable When the display device is not connected to the main body of the portable electronic device, the clock frequency of the microprocessor is reduced so that the display control by the microprocessor is not performed.

According to the portable electronic device of the present invention, in a portable electronic device in which a detachable built-in display device and a detachable display device are mounted, both display devices are not used. At some point, a power saving operation is performed.

According to a seventh aspect of the present invention, there is provided a clock frequency switching method for a portable electronic device comprising at least a display device and a microprocessor for controlling display of the display device, wherein a display is performed on a display screen of the display device. When there is no clock frequency switching method of the portable electronic device, the clock frequency of the microprocessor is set lower than when the display is performed on the display screen, and the display control by the microprocessor is not performed. is there.

According to an eighth invention, in the clock frequency switching method for a portable electronic device according to the seventh invention, the display device is a detachable display device, and the display device includes the microprocessor. A clock frequency switching method for a portable electronic device in which a clock frequency of the microprocessor is reduced when the device is not connected to the device main body so that the display control by the microprocessor is not performed.

According to a ninth aspect, in the clock frequency switching method for a portable electronic device according to the seventh aspect, when the power switch of the display device is turned off, the clock frequency of the microprocessor is reduced, and A clock frequency switching method for a portable electronic device in which the display control is not performed by a processor.

According to a tenth invention, in the clock frequency switching method for a portable electronic device according to the seventh invention, the display device is a display device to which power is supplied from a portable electronic device body including a microprocessor. When not supplying power to the display device from the portable electronic device body, lower the clock frequency of the microprocessor,
A clock frequency switching method for a portable electronic device in which the display control is not performed by the microprocessor.

According to an eleventh invention, in the clock frequency switching method for a portable electronic device according to the seventh invention, data transmitted from the display device is received by the portable electronic device body including the microprocessor for a predetermined time or more. If not, reduce the clock frequency of the microprocessor,
A clock frequency switching method for a portable electronic device in which the display control is not performed by the microprocessor.

[0024]

Embodiments of the present invention will be described below. In the portable electronic device of the present invention, attention is paid to the large load of the MPU for display processing or display control, and the display state such as whether the display is being performed on the display device or whether the display is updated is detected. However, as a result of the detection, when the display is not performed or when the display is not updated for a predetermined time or more, the clock frequency of the MPU of the system control unit is set to the clock frequency when the display is performed on the display screen. The power consumption in the MPU is significantly reduced by preventing the MPU from performing processing for displaying on the display device.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the portable electronic device of the present invention, and FIG. 2 is a diagram showing the detachable display device shown in FIG. 1 provided with a key circuit for remote operation. It is a figure showing a detection method. FIG. 3 is a flowchart showing a clock frequency switching process according to the portable electronic device of the first embodiment of the present invention. In FIG. 1, a portable electronic device 10 is composed of an electronic device main body 20 and a detachable display device 11, and the electronic device main body 20 and the detachable display device 11 are connected by a connector via a cable.

The electronic device main body 20 includes a system control means 15 for controlling the entire electronic device main body 20 and a display device attaching / detaching detecting means 19 for detecting whether or not the detachable display device 11 is mounted on the electronic device main body 20. And other controlled units 13 controlled by the system control unit 15. The system control means 15 includes the MPU 17 and the MP
Clock generating means 23 for generating a clock of U17;
And a clock frequency switching means 21 for transmitting a control signal for switching the frequency of the clock generated by the clock generating means 23. The information on the current clock frequency and the mode information indicating the mode at the time of recording / reproduction are given from the system control unit 15 to the clock frequency switching unit 21, and the display device attachment / detachment detection unit 19 sends the clock frequency switching unit 21 Information on the attachment / detachment state of the display device is provided. When the mode information changes from the steady mode to the power saving mode, the clock frequency switching means 21 switches the clock frequency to half of the clock frequency (reference frequency) in the steady mode, and furthermore, the detachable display device 1
When 1 is not mounted, the clock frequency is switched to 1/8 of the reference frequency.

The portable electronic device 10 has a mini disk (M
D) Taking the case of a device as an example, the following is the case where the normal mode is automatically changed to the power saving mode during reproduction. That is, the data read from the recording medium is almost completely stored in the buffer memory, or the thread motor is in a non-operating state. In each case, the load on the MPU is reduced. Is the case. In these cases, the reproduction mode is changed from the steady mode to the power saving mode by the judgment of the MPU 17,
The clock frequency is switched to half of the steady state frequency (reference value). At this time, the MPU 17 performs a display process. Further, when the detachable display device 11 is not mounted as described above, the clock frequency is switched to 1/8 of the reference frequency. At this time, the MPU 17 skips the display processing without performing the display processing.

In FIG. 2, reference numeral 17 denotes the system control means 1.
Reference numeral 33 denotes a key switch circuit integrated with the detachable display device 11. The MPU 17 is provided with at least an input port Vin, a power output terminal Vdd, and a ground terminal G, and a key switch circuit 33 including a key circuit 35 and a hold switch 37 can be detachably connected to these three lines. It is configured as follows. That is, the key switch circuit 33 is an operating means integrally formed with the detachable display device 11, and for giving four operation commands, for example, "stop, play, fast forward, fast reverse" according to the switches S1 to S4. It is configured as a remote control device.

In the key circuit 35, a resistor R0 is connected between the power supply output Vdd and the input port Vin, and four resistors R1 to R4 are connected in series to the input port Vin. One end of each of the four key switches S1 to S4 is connected to each of the connection point of the resistances R1 and R2, the connection point of the resistances R2 and R3, the connection point of the resistances R3 and R4, and the end of the resistance R4. The other ends are commonly connected and grounded through a hold switch 37. The hold switch 37 is provided to prevent an erroneous operation of the key.
It is always in the ON state, and is in the OFF state during the hold.

The detachable display device 11 is connected to the electronic device main body 2.
0, that is, when the key switch circuit 33 is not connected to the MPU 17, the input port Vin is at the ground level, and when the detachable display device 11 is mounted on the electronic device body 20, That is, when the key switch circuit 33 is connected to the MPU 17, the voltage of the input port Vin approaches Vdd, and changes to four types depending on which of the key switches S1 to S4 is operated. Therefore, the display device attachment / detachment detecting means 19 can easily detect the attachment / detachment state of the detachable display device 11 in accordance with the voltage of the input port Vin.

Hereinafter, the switching process of the clock frequency according to the portable electronic device of the first embodiment of the present invention will be described. FIG. 3 is a flowchart showing a clock frequency switching process according to the portable electronic device of the first embodiment of the present invention. As described above, when certain conditions are satisfied during playback, the playback mode is automatically switched to the power saving mode. "S" in FIG.
"start" indicates a point in time when the mode is switched to the power saving mode. In FIG. 3, when the reproduction mode is automatically switched to the power saving mode, is the display device mounted? (Step S11), and if Yes, Step S
The process proceeds to step S13, and if No, the process proceeds to step S15. In steps S15 and S17, if the clock frequency of the MPU is not 1/8 of the reference value, the clock frequency is switched by the clock frequency switching means 21 to 1/8 of the reference value, and the process proceeds to step S23. Step S13 and step S1
In step 9, if the clock frequency is not 1/2 of the reference value, the clock frequency is switched to 1/2 of the reference value by the clock frequency switching means 21, and the process proceeds to step S21.

In step S21, the MPU 17 performs processing related to display. In step S23, the MPU 17 performs processing other than display processing (non-display processing), and proceeds to step S25. The display processing is, for example, data transfer, display data creation, scroll processing, and the like. The non-display processing is, for example, in the case of an MD device, key input processing, communication with a dedicated IC for decoding processing, and volume control. And sound quality control, ATRA
Memory control for C and the like. In step S25, is the power saving mode released? If the MPU 17 has issued an instruction to cancel the power saving mode, the determination in step S2 is Yes.
Then, if No, the process returns to step S11. In step S27, the clock frequency of the MPU is returned to the reference value, and this flow ends. In the flow shown in FIG. 3, when the display device is not mounted, the MPU skips processing and control related to display.

FIG. 4 is a block diagram showing a second embodiment of the portable electronic device of the present invention. Elements having the same function and the same effect in FIG. 4 and FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The main differences between FIG. 4 and FIG. 1 are that a display device 11b is provided instead of the detachable display device 11, a power switch 25 dedicated to the display device is provided, This is the point that the power on / off detection means 27 is provided without the detachment detection means 19. Display device 11b
May be a removable type or a non-removable type.

In the portable electronic device 30 shown in FIG.
The power on / off detection means 27 detects whether the power switch 25 of the display device 11b is ON or OFF, and uses the result as power switch information as the clock frequency switching means 21.
Give to. The system control unit 15 gives the clock frequency switching unit 21 information on the current clock frequency and mode information indicating the mode at the time of recording / reproduction. The clock frequency switching unit 21 responds to the mode information and the power switch information. A control signal for switching the clock frequency is supplied to the clock generation means 23, and the clock generation means 2
3 outputs a clock having a frequency corresponding to the control signal to the MPU 1
Give 7

Clock frequency switching means 2 from MPU 17
1 is the steady mode, the clock frequency of the MPU is controlled to a reference value,
U17 also performs display processing. When the mode information is the power saving mode and the power switch 25 is ON, M
The frequency of the PU clock is controlled to の of the reference value,
The MPU 17 also performs a display process. Further, when the mode information is the power saving mode and the power switch 25 is OFF, the frequency of the clock of the MPU is controlled to 1/8 of the reference value, and the MPU 17 performs display processing for displaying on the display device 11b. Skip display control.

FIG. 5 is a block diagram showing a third embodiment of the portable electronic device of the present invention. Elements having the same function and the same function in FIGS. 5 and 4 are denoted by the same reference numerals, and the description thereof will be omitted. The main difference between FIG. 5 and FIG. 4 is that in the portable electronic device 40 shown in FIG.
7 is provided with a display device 11c and a power supply detecting means 39 in place of the power supply switch 25, and there is no power switch 25.
0c to the display device 11c. That is, the display device 11c does not have its own power supply.
According to this embodiment, for some reason, for example, when the voltage of the battery that drives the electronic device main body 20c falls below a predetermined value, the power supply to the display device 11c may be stopped to save power. Yes, in such a case, MPU1
7 can also reduce the power consumed.

In the portable electronic device 40 shown in FIG.
The power supply detecting means 39 detects whether power is supplied from the electronic device main body 20c including the MPU 17 to the display device 11c, and supplies the result to the clock frequency switching means 21 as power supply information. Clock frequency switching means 2
1 supplies a control signal for switching a clock frequency according to the mode information and the power supply information to the clock generation means 23, and the clock generation means 23 generates a clock having a frequency corresponding to the control signal and supplies the clock to the MPU 17. give.

Clock frequency switching means 2 from MPU 17
1 is the steady mode, the clock frequency of the MPU is controlled to a reference value,
U17 performs a normal display process. Further, when the mode information is the power saving mode and the power is supplied from the electronic device main body 20c to the display device 11c, the frequency of the MPU clock is controlled to の of the reference value, and the MPU 17
Performs normal display processing. Further, the mode information is the power saving mode, and the display device 1
When power is not supplied to 1c, the clock frequency of the MPU is controlled to 1/8 of the reference value, and the MPU 17 skips without performing display processing or display control for displaying on the display device 11c.

FIG. 6 is a block diagram showing a portable electronic device according to a fourth embodiment of the present invention. Elements having the same function and the same effect in FIGS. 6 and 5 are denoted by the same reference numerals, and the description thereof is omitted. The main difference between FIG. 6 and FIG. 5 is that the portable electronic device 50 shown in FIG. 6 does not have the power supply detecting means 39 but has the communication detecting means 29, and the display device 11d has its own power supply. That is, it is not necessary to have it.

In the portable electronic device 50 shown in FIG.
The communication detecting means 29 detects the presence or absence of communication between the MPU 17 and the display device 11d, and gives the result to the clock frequency switching means 21 as communication detection information. The clock frequency switching means 21 supplies a control signal for switching the clock frequency to the clock generation means 23 according to the mode information and the communication detection information, and the clock generation means 23 generates a clock having a frequency corresponding to the control signal. MPU
Give 17

Clock frequency switching means 2 from MPU 17
1 is the steady mode, the clock frequency of the MPU is controlled to a reference value,
U17 also performs display processing. Further, when the mode information is the power saving mode and communication is being performed between the MPU 17 and the display device 11d, the frequency of the MPU clock is controlled to の of the reference value, and the MPU 17 also performs display processing. . Further, the mode information is a power saving mode,
When communication is not performed between the PU 17 and the display device 11d, the frequency of the MPU clock is controlled to 1/8 of the reference value, and the MPU 17 skips display processing and display control for displaying on the display device 11c. . Note that the communication detecting unit 29 determines that communication is not being performed only when communication has not been performed for a predetermined time or more.

FIG. 7 is a block diagram showing a fifth embodiment of the portable electronic device of the present invention. Elements having the same function and the same effect in FIG. 7 and FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. The main difference between FIG. 7 and FIG. 1 is that the portable electronic device 60 shown in FIG. 7 has a built-in display device 31 in which the electronic device main body 20e is not detachable, and whether the power supply of the built-in display device 31 is turned on. It is provided with a power supply monitoring means 41 for monitoring whether or not the power supply is monitored.

In the portable electronic device 60 shown in FIG.
The power supply monitoring unit 41 checks whether the power of the built-in display device 31 is ON or OFF, and supplies the result to the clock frequency switching unit 21 as built-in display power supply information. The clock frequency switching means 21 supplies a control signal for switching a clock frequency to the clock generation means 23 according to the mode information, the built-in display power information, and the detachable state of the detachable display device 11, to the clock generation means 23. The MPU 17 generates a clock having a frequency corresponding to the control signal.
Give to.

Clock frequency switching means 2 from MPU 17
1 is the steady mode, the clock frequency of the MPU is controlled to a reference value,
U17 also performs processing for display. When the mode information is the power saving mode and the power of the built-in display device 31 is turned on or the detachable display device 11 is connected, the frequency of the clock of the MPU is １ ／ of the reference value.
The MPU 17 also performs display processing. Further, the mode information is the power saving mode, and the built-in display device 31
Is turned off and the detachable display device 11 is not connected, the MPU clock frequency is controlled to 1/8 of the reference value, and the MPU 17 is connected to the built-in display device 31 and the detachable display device. The display processing and display control for displaying the information 11 and 11 are skipped.

As described in detail above, according to the present invention,
In a portable electronic device using a display device, the connection state and power supply state of the display device are checked, and when it is determined that the load of the MPU is light, such as when the display device is not used, the clock frequency of the MPU is displayed. Lower than the clock frequency when displaying on the screen, and MPU
Reduce the power consumption of the MPU by not performing the display processing. Thus, the life of the battery that drives the portable electronic device can be extended.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a portable electronic device according to the present invention.

FIG. 2 is a diagram showing a display device attachment / detachment detection method when the detachable display device has a key circuit for remote operation.

FIG. 3 is a flowchart illustrating a clock frequency switching process according to the portable electronic device of the first embodiment of the present invention.

FIG. 4 is a block diagram showing a second embodiment of the portable electronic device of the present invention.

FIG. 5 is a block diagram showing a third embodiment of the portable electronic device of the present invention.

FIG. 6 is a block diagram showing a fourth embodiment of the portable electronic device of the present invention.

FIG. 7 is a block diagram showing a fifth embodiment of the portable electronic device of the present invention.

[Explanation of symbols]

Reference Signs List 11 detachable display device (display device) 11b, 11c, 11d display device 13 controlled part of portable electronic device 15 system control means 17 MPU (microprocessor) 19 display device detachment detection means 20, 20b, 20c, 20d Reference Signs List 20e Portable electronic device main body 21 Clock frequency switching means 23 Clock generation means 25 Power switch 27 Power on / off detection means 29 Communication detection means 31 Built-in display device (non-detachable display device) 33 Key switch circuit 39 Power supply detection means 41 Power monitoring means

Claims (11)

[Claims] 1. A portable electronic device comprising a display device and a microprocessor for controlling display of the display device,
When the display is not performed on the display screen of the display device, the clock frequency of the microprocessor is set lower than when the display is performed on the display screen, and the display control by the microprocessor is not performed. Characteristic portable electronic devices. 2. The portable electronic device according to claim 1, wherein said display device is a detachable display device, said display device comprising a display device detachment detecting means for detecting a detached state of said display device, wherein said display device includes said microprocessor. If not,
2. The portable electronic device according to claim 1, wherein the clock frequency of the microprocessor is reduced, and the display control by the microprocessor is not performed. 3. The display device has a power switch dedicated to the display device, and power on / off detection means for detecting whether the power switch is on or off. 2. The portable electronic device according to claim 1, wherein the clock frequency of the microprocessor is reduced, and the display control by the microprocessor is not performed. 4. The display device, wherein power is supplied from a portable electronic device main body including a microprocessor, and when the power is not supplied from the portable electronic device main body to the display device. 2. The portable electronic device according to claim 1, wherein the clock frequency of the microprocessor is reduced, and the display control by the microprocessor is not performed. 5. A portable electronic device main body including the microprocessor and a communication detecting means for detecting the presence or absence of communication between the display device and the portable electronic device main body, wherein data is transmitted from the display device to the portable electronic device main body for a predetermined time. If not supplied, the clock frequency of the microprocessor is reduced,
The portable electronic device according to claim 1, wherein the display control is not performed by the microprocessor. 6. A display device comprising: a non-detachable display device and a detachable display device as said display device; and power supply monitoring means for monitoring whether the power of said non-detachable display device is turned on and off, and said detachable display. A display device attachment / detachment detecting means for detecting an attachment / detachment state of the device, wherein a power supply of the non-attachable display device is cut off and the detachable display device is not connected to the portable electronic device main body. 2. The portable electronic device according to claim 1, wherein the clock frequency of the microprocessor is reduced, and the display control by the microprocessor is not performed. 7. A clock frequency switching method for a portable electronic device comprising at least a display device and a microprocessor for controlling the display of the display device, wherein a display is not performed on a display screen of the display device. A clock frequency switching method for a portable electronic device, wherein a clock frequency of the microprocessor is set lower than when a display is performed on the display screen, and the display control by the microprocessor is not performed. 8. The display device is a detachable display device, and when the display device is not connected to a portable electronic device body including the microprocessor, the clock frequency of the microprocessor is reduced. The method according to claim 7, wherein the display control is not performed by a microprocessor. 9. The portable device according to claim 7, wherein when the power switch of the display device is turned off, the clock frequency of the microprocessor is reduced, and the display control by the microprocessor is not performed. Clock frequency switching method for electronic equipment. 10. The display device to which power is supplied from a portable electronic device main body including a microprocessor, wherein the power supply is not supplied from the portable electronic device main body to the display device. 8. The clock frequency switching method for a portable electronic device according to claim 7, wherein the clock frequency of the microprocessor is reduced, and the display control by the microprocessor is not performed. 11. When the data transmitted from the display device has not been received by the portable electronic device body including the microprocessor for a predetermined time or more, the clock frequency of the microprocessor is reduced, and the display by the microprocessor is performed. 8. The method according to claim 7, wherein no control is performed.
A clock frequency switching method for the portable electronic device according to the above.