JP2003316487A - Electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To notify a user of a state when falling into a suspend state, during operation using a power supplied through a communication interface from a host apparatus, which is provided with a suspend function. <P>SOLUTION: A USB control unit 71 brings a control signal 'SUSPEND' into an H level when a signal from the host apparatus stops for 3 msec. Based on this, a power supply control microcomputer 20 stops the operation of a DC/DC converter 14 and clock oscillator 18 to bring a system control part 7 into an OFF state. Consequently, a digital still camera is shifted to a suspend mode. Also, the microcomputer 20 controls a motor part 11c of a suspend display part 11 to open up a movable cap, and exposes an indicator panel where characters and symbols showing the suspend state are drawn in advance. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device that operates by receiving power supply from a host device having a suspend function via a communication interface.

[0002]

2. Description of the Related Art A digital still camera is capable of picking up an image and recording an image as digital data, which is now widely used. Digital still cameras
In general, since image data is recorded in a removable small semiconductor memory, it is possible to read the captured image data into another device such as a PC (personal computer) through the semiconductor memory. Further, in recent years, an increasing number of digital still cameras have a communication I / F (interface) for directly connecting to a PC or the like by a cable. As such communication I / F, especially USB (Un
iversal Serial Bus) standard is used.

With the USB, it is possible to use a PC or the like as a host controller and supply power from the host controller to the device to which it is connected. Such a function is called USB Bus Powered.

On the other hand, many PCs on the host controller side are recently equipped with a power saving mode. P
When C shifts to power saving mode (suspend), USB
The power supplied to the cable is significantly reduced. For this reason, when connecting to a PC having a power saving mode and operating with the USB bus powered function, the connected device side must also have an operation mode that suppresses power consumption in response to suspend. According to the USB standard, the current consumption during suspension is specified to be within 500 μA.

[0005]

By the way, it has been considered that even a digital still camera operates only by supplying power from a USB cable. In the case of a digital still camera, the LCD (Liquid Crystal D
It is necessary to turn off all display parts such as isplay) panel and LEDs (Light Emitting Diode). For this reason, when the suspend occurs, the user of the digital still camera cannot determine whether the user is in the suspend state or the power off state, which is inconvenient.

The present invention has been made in view of the above problems, and when the operation is performed by the power supplied from the host device having the suspend function through the communication interface, the situation is brought into the suspend state. It is intended to provide an electronic device capable of notifying a user.

[0007]

According to the present invention, in order to solve the above problems, in an electronic device which operates by receiving power supply from a host device having a suspend function through a communication interface, power supply from the host device is performed. And a power saving operation mode in which the host device operates at lower power consumption than the normal operation mode when a suspend occurs in the host device, and detects the occurrence of the suspend and resume in the host device. There is provided an electronic device comprising: an operating state detecting means; and a suspend display means for displaying a suspended state in the power saving operation mode based on the detected state by the operating state detecting means.

Here, the operating state detecting means detects the occurrence of suspend and resume in the host device. As a result, when the host device suspends, the electronic device shifts to the power saving operation mode in which the power consumption is lower than that in the normal operation mode. The suspend display means displays that it is in the suspend state in the power saving operation mode based on the detection state by the operation state detection means. The suspend display means has, for example, a display panel on which characters or symbols indicating a suspended state are drawn, and a movable lid which is opened so that the characters or symbols on the display panel are exposed only in the power saving operation mode. You may.
Alternatively, the suspend display means may be composed of a reflective monochromatic character liquid crystal display device without a backlight.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a digital still camera applicable as an electronic device of the present invention.

A digital still camera 1 shown in FIG. 1 includes an image pickup block 2 for picking up an image and outputting a digital image signal associated therewith, and an image for performing compression / encoding processing and decompression / decoding processing of the image signal. A signal processing unit 3, a memory R / W (reader / writer) 4 for writing / reading data to / from a memory card 4a, an image display unit 5 for displaying a captured image or a reproduced image, and a user The input unit 6 for inputting the operation input and the system control unit 7 for controlling the entire apparatus are connected by an internal bus 8. Further, the system control unit 7 is connected to a USB interface (I / F) 9 for transmitting / receiving data to / from an external device and a power supply control unit 10 for controlling power supply from the battery 10a and the like. . Furthermore, the power supply control unit 10 is connected to a suspend display unit 11 that displays a suspended state.

The image pickup block 2 includes an optical system including a lens on which light from a subject is incident, an iris, a shutter, an image pickup element such as a CCD (Charge Coupled Device) for photoelectrically converting incident light, and an output signal from the image pickup element. It is composed of a signal processing circuit and the like that performs digital conversion processing and the like. Under the control of the system control unit 7, the imaging block 2 sequentially outputs image signals according to incident light from a subject. Further, this image signal is subjected to conversion processing into a digital signal, noise removal processing, image quality correction processing, conversion processing into a luminance / color difference signal, etc. in a signal processing circuit, and the image signal processing unit 3 and the image display unit. Send to 5.

The image signal processing unit 3 receives a JPEG (Joint Photog
raphic Coding Experts Group) Converts into a predetermined data format such as the standard and supplies it to the memory R / W 4. In addition, the memory R / W4 allows the memory card 4a
The image data read from is expanded and decoded, and output to the image display unit 5.

A memory card 4a, which is a removable semiconductor memory, is attached to the memory R / W 4. Memory R / W
4 writes the image data converted into the predetermined data format in the image signal processing unit 3 into the memory card 4a. Also, the image data recorded in the memory card 4 a is read out and sent to the image signal processing unit 3.

The image display unit 5 includes an LCD (Liquid Cryst
al Display) 5a is connected. The image display unit 5
The so-called camera through image captured in the image capturing block 2 or the image read out from the memory card 4a and decoded in the image signal processing unit 3 is displayed on the LCD 5a.
To display. Also, predetermined characters and the like are displayed on-screen according to a control signal from the system control unit 7.

The input unit 6 is composed of, for example, a shutter release button for operating the opening / closing operation of the shutter of the image pickup block 2, a selection switch for selecting an operation mode, etc., and an instruction input according to the operation by the user. The signal is output to the system controller 7.

The system control section 7 is a control processing section for controlling each circuit block in the digital still camera 1.
The operation of each circuit block is controlled based on the instruction input signal from the input unit 6.

The USB interface 9 is composed of a connector (not shown) for attaching a communication cable (USB cable). USB interface 9 is U
It sends and receives data to and from external devices through the SB cable. In addition, the power supplied from the host device such as a PC through the USB cable is output to the power control unit 10.

The power control unit 10 includes a battery 10a and a U
Upon receiving power supply from the host device through the SB interface 9, these are switched, converted into a predetermined voltage, and supplied to each unit in the digital still camera 1. In addition, the power ON / OFF operation in the digital still camera 1 is controlled, and the control is performed when the suspend / resume is generated when the power is supplied from the USB interface 9. Here, the battery 10a is a small removable battery such as a dry cell or a stick type battery, or a rechargeable battery thereof. The power control unit 1
The internal configuration of 0 will be described in detail with reference to FIG.

The suspend display section 11 is a power control section 10.
It operates under control by and displays this when it enters the suspend state. This suspend display unit 11
It operates by the power supplied from the USB interface 9 via the power control unit 10. For this reason, as will be described later, the suspend display section 11 can operate at a current consumption (500 μA) or less during suspend defined by the USB standard while displaying that it is in a suspended state. There is.

Next, a basic image recording / reproducing operation of the digital still camera 1 will be described. When the image recording operation is performed, an image is captured by the imaging block 2 under the control of the system control unit 7, and digital image signals sequentially output in accordance with the imaging are displayed on the image display unit 5. Is entered. As a result, a camera through image is displayed on the LCD 5a.

In this state, when an instruction input for shutter operation is made at the input section 6, the shutter is opened / closed at the image pickup block 2 and one frame of the image signal at this time is extracted to obtain an image. It is output to the signal processing unit 3. The image signal processing unit 3 includes the imaging block 2
The image signal input from the above is subjected to compression / encoding processing and converted into a predetermined data format such as the JPEG standard. The converted image data is sent to the memory R / W 4 and written in the memory card 4a.

Further, when the image reproducing operation is performed,
In response to an instruction input from the input unit 6, the memory R / W 4 reads predetermined image data from the memory card 4a. This image signal is expanded / decompressed in the image signal processing unit 3.
It is decrypted and output to the image display unit 5. As a result, the reproduced image is displayed on the LCD 5a.

By the way, this digital still camera 1
Together with the electric power supplied from the battery 10a,
It is also possible to operate by the power supplied from the host device through the B interface 9. Here, the former will be referred to as a battery operation mode, and the latter will be referred to as a USB bus powered mode. Further, when operating in the USB bus powered mode, it is necessary to support the occurrence of suspend in the host device that is the power supply source. Specifically, it is defined in the USB standard so that the current consumption in the suspended state is suppressed to within 500 μA.

In this digital still camera 1,
In addition to the power supply from the battery 10a and the host device, it is possible to operate by AC input from, for example, a household outlet, but the operation by electric power by AC input conforms to the battery operation mode, and is omitted here. I will decide.

FIG. 2 is a state transition diagram showing the transition of the power control state in the digital still camera 1. The power control state of the digital still camera 1 is divided into three states, a power OFF state, a power ON state, and a suspend mode, as shown in FIG. The power-on state includes the above-mentioned battery operation mode and USB bus powered mode.

From the power-off state, turn the power switch to O
When the operation of setting to N is performed, the state transits to the power ON state. Here, in the USB interface 9, U
When the SB cable is not attached, the operation of turning on the power switch causes a transition to the battery operation mode (step S1). In the battery operation mode, the battery 10a operates by receiving a voltage of, for example, 1.8V to 3.0V from the battery 10a. In addition, from this battery operation mode, the power supply is turned off or the battery 10a is taken out, so that the power is turned off (step S2).

On the other hand, when the USB cable is attached, when the power switch is turned on from the power off state, the mode is changed to the USB bus powered mode (step S3). In the USB bus powered mode, it operates with a voltage of 5V supplied through the USB cable. At this time, the current consumption is specified to be 500 mA or less (however, 100 mA or less before configuration).

In addition, when the operation of turning off the power switch is performed from the USB bus powered mode, or when the USB cable is removed, the power OF is turned off.
Transition to the F state (step S4).

On the other hand, in the USB bus powered mode, when it is detected that the host device has shifted to the power saving operation mode, that is, the suspend has occurred, the mode is shifted to the suspend mode (step S5). The suspend mode is a power saving operation mode in which the current consumption is 500 μA or less as described above.

From the suspend mode, when it is detected that the host device has returned to the normal operation mode, that is, the resume has occurred, it returns to the USB bus powered mode (step S6). Also, from suspend mode to USB
When the cable is removed, the power supply is cut off,
The power is turned off (step S7).

By the way, in the digital still camera 1,
The USB bus powered mode is mainly used when transmitting the data recorded in the memory card 4a to the host device. In this case, the digital still camera 1 uses the USB
Upon receiving a transmission request from the host device through the interface 9, the system controller 7 controls the memory R /
At W4, predetermined data is read from the memory card 4a and transmitted to the host device through the USB interface 9. In addition to this, operations such as writing data transmitted from the host device to the memory card 4a or transmitting a camera through image being captured to the host device may be performed in the USB bus powered mode.

As described above, in the suspend mode, the current consumption must be suppressed within 500 μA, so it is necessary to reduce the functions to be operated as compared with the USB bus powered mode. Specifically, for example, the LCD 5a
The display of must be stopped completely. Also, LCD 5a
In addition to this, for example, when an LED (Light Emitting Diode) or the like is provided, this lighting also needs to be stopped.

Therefore, the user of the digital still camera 1 cannot visually distinguish between the suspend mode and the power off state. For this reason, the digital still camera 1 notifies the user of the transition to the suspend mode by using the suspend display unit 11 capable of displaying at a current consumption value below the specified value.

FIG. 3 is a diagram showing a first embodiment of the suspend display section 11. In FIG. 3, the suspend display unit 1 provided on the external housing of the digital still camera 1 is shown.
The situation of No. 1 is shown. As shown in FIG. 3, the suspend display unit 11 has a display panel 11a in which characters and symbols indicating the suspend mode are drawn in advance by printing or the like.
And a movable lid 11b for covering the display board 11a. Further, a motor unit (not shown) for sliding the movable lid 11b is provided in the housing.

The display board 11a is provided, for example, at a position adjacent to the LCD 5a provided on the back side of the digital still camera 1 or at an upper portion provided with a shutter release button or the like. The size of the display board 11a is, for example, 1 cm.
It is desirable to make the drawn characters and symbols as small as possible within a range where the user can read the drawn characters and symbols as much as possible.

In a state other than the suspend mode, that is, in the battery operation mode, the USB bus powered mode, and the power OFF state, as shown in FIG.
Since the movable lid 11b covers 1a, the display panel 11a is not exposed and the suspend mode is not displayed. On the other hand, in the suspend mode, as shown in FIG.
As shown in (B), the movable lid 11b is slid to the left in the figure by driving the motor, and is stopped so that the characters and symbols on the display board 11a are exposed.

In the suspend display section 11, the characters and symbols drawn in advance are only exposed in the suspend mode, so that power is not consumed while the suspend mode is displayed. Therefore, it is possible to notify the user of the suspend mode while sufficiently satisfying the regulation of the current consumption value in the suspend mode according to the USB standard.

Incidentally, another embodiment of the suspend display section 11 will be described last. Next, the control of the operation mode in the digital still camera 1 will be described in detail.

FIG. 4 is a diagram showing an example of the internal configuration of the power supply controller 10. The power supply control unit 10 includes a switch (SW) 12
a and 12b, diodes 13a and 13b, DC
/ DC converter 14, up converter (UPCO
N) 15, reset (RESET) IC 16, regulators (REG) 17a and 17b, clock oscillator 18, power supply control microcomputer 20, resistors 19a and 19b.
Composed by.

Further, in FIG. 4, the system control unit 7 and the suspend display unit 11 are shown together with the power supply control unit 10. The system control unit 7 includes a USB control unit 71, and the suspend display unit 11 includes a motor unit 11c.

The power supply controller 10 is supplied with a voltage of 1.8V to 3.0V from the battery 10a and a voltage of 5V from the USB interface 9. The switch 12 uses the control signal "FAST CHA" from the power supply control microcomputer 20.
ON / OFF switching of the voltage supplied from the battery 10a is performed based on RGE ".
Control signal “USB UNR” from the power supply control microcomputer 20
The supply voltage from the USB interface 9 is switched ON / OFF based on EG SW ″.

The voltages output from the switches 12a and 12b are supplied to the DC / DC converter 14 and the motor section 11c of the suspend display section 11. DC / DC
The converter 14 has an input voltage of 2.8V and 1.5V.
Is converted to a voltage of and supplied to the system controller 7. Also,
The output voltage from the DC / DC converter 14 is the LCD 5
It is supplied to each unit in the digital still camera 1 including a.

On the other hand, the voltages supplied from the battery 10a and the USB interface 9 are the diode 13 respectively.
It is also supplied to the up converter 15 via a and 13b. The up converter 15 boosts the supplied voltage to a predetermined voltage value and supplies it to the reset IC 16 and the regulator 17a.

The reset IC 16 supplies the supplied voltage to the power supply control microcomputer 20, and resets the power supply control microcomputer 20 according to the supply of the voltage. Based on the control signal "USB PWR" from the power supply control microcomputer 20, the regulator 17a changes the supplied voltage to 3.
Adjust to 1V, USB control unit 71, regulator 17
b and the clock oscillator 18.

The regulator 17b adjusts the supplied voltage to 1.5V and outputs it to the USB controller 71. The clock oscillator 18 is 48 MHz based on the control signal "USB CLK EN" from the power supply control microcomputer 20.
And outputs the clock signal “UCLK” to the USB control unit 71.

The power supply control microcomputer 20 has a reset IC 1
By operating with the voltage supplied via 6, and controlling the operation of the DC / DC converter 14 using the control signal "DD ON", the power of the entire device is turned ON / OFF.
To control. In addition, a control signal “USB JACK IN” having a voltage value adjusted by the resistors 19a and 19b.
In response, the USB interface 9 detects whether the USB cable is connected or disconnected.

Further, the control signal "SUSPEND" from the USB control unit 71 is received, and these control signals "SUS" are received.
Based on "PEND" and "USB JACK IN", it controls the operation mode when a suspend occurs and also controls the operation of the motor section 11c of the suspend display section 11. The power supply control microcomputer 20 operates in the suspend mode. It has the function of switching to a low frequency clock and operating in a power-saving state.

The system control section 7 operates by the voltage supplied from the DC / DC converter 14. However, the USB control unit 71 in the system control unit 7 operates by the supply voltage from the regulators 17a and 17b. Further, the USB control unit 71 operates by receiving the clock signal “UCLK” from the clock oscillator 18. The USB control unit 71 controls communication via the USB interface 9 and the like, and controls the signal “SUSPEN” according to the signal received by the USB interface 9.
D "is output to the power supply control microcomputer 20.

Further, the motor unit 1 of the suspend display unit 11
1c operates based on a control signal from the power supply control microcomputer 20, and slides the movable lid 11b. Here, the operation of the power supply control unit 10 in the battery operation mode is as follows.

When the battery 10a is attached and the USB cable is not attached, the power switch is turned on.
When the operation of turning on is performed, the power supply control microcomputer 20 sets the control signal “FAST CHARGE” to the H level based on the control signal “USB JACK IN” being at the L level. As a result, the switch 12a is turned on, and the voltage from the battery 10a is supplied to the DC / DC converter 14. Further, the power supply control microcomputer 20 sets the control signal "DD ON" to the H level. As a result, the DC / DC converter 14 is turned on, power is supplied to the system control unit 7 and the system control unit 7 is activated, and image capturing and recording operations can be performed.

The operation of the power supply controller 10 in the USB bus powered mode is as follows. When the power switch is turned on when the USB cable is attached, the power control microcomputer 20 determines that the control signal "USB UNREG" is based on the control signal "USB JACK IN" being at the H level. SW "is set to H level. As a result, the switch 12b is turned on, and the voltage from the USB cable is supplied to the DC / DC converter 14. In addition, the control signal "DD ON"
To H level, the DC / DC converter 1
4 is turned on, and the system controller 7 is activated.

Further, the power supply control microcomputer 20 sets the control signal "USB CLK EN" to H level to supply the 48 MHz clock signal "UCLK" from the clock oscillator 18 to the USB control section 71, and at the same time, the control signal " The USB PWR ″ is set to the H level to activate the regulator 17a, and supply of power to the USB control unit 71 is started. As a result, the USB control unit 71
Starts, and communication through the USB interface 9 becomes possible.

By the way, the USB control unit 71 monitors a signal received from the host device through the USB interface 9, and recognizes that the suspend occurs in the host device when this signal is stopped for 3 msec. At this time,
The control signal "SUSPEND" is set to the H level. When the control signal “SUSPEND” becomes H level, the power supply control microcomputer 20 performs control to shift to the suspend mode and starts display on the suspend display unit 11.

FIG. 5 is a flowchart showing the flow of processing in the power supply control microcomputer 20 when shifting to the suspend mode. In step S501, the occurrence of suspend is detected by monitoring the control signal "SUSPEND" from the USB control unit 71. Control signal "S
If USPEND "remains at the L level, the process waits, and if it changes to the H level, the process proceeds to step S502. First, the control process (steps S502 to S505) for opening the movable lid 11b of the suspend display unit 11 is performed. To do.

In step S502, the rotation direction and speed of the motor section 11c of the suspend display section 11 are set to open the movable lid 11b. In step S503, the power of the motor unit 11c is turned on and rotated. As a result, the sliding of the movable lid 11b covering the display panel 11a is started.

In step S504, the motor unit 11
The signal from c is monitored to determine whether or not the opening of the movable lid 11b is completed. If completed, step S505
Go to and wait if not complete. Step S505
At, the motor unit 11c is turned off to stop the rotation. As a result, the characters and symbols on the display board 11a are completely exposed in the suspend display section 11,
The user is notified that the suspend state has been entered.

In step S506, the control signal "D
Both D ON ”and“ USB CLKEN ”are changed to the L level, whereby the DC / DC converter 14 is turned off and the power supply to the system control unit 7 is stopped, and the system control unit 7 (however, USB (Excluding the control unit 71) is turned off, and the clock signal "U" from the clock oscillator 18 to the USB control unit 71
The supply of CLK "is stopped.

When the operation of the DC / DC converter 14 is stopped, the function of each unit in the digital still camera 1 is stopped. For example, the data recorded in the memory card 4a cannot be transmitted, and the operation of the liquid crystal of the LCD 5a and the lighting of the backlight are stopped.

In step S507, the frequency of the operation clock of the power supply control microcomputer 20 itself is switched from 10 MHz to 32 KHz. As a result, the power supply control microcomputer 20 enters a power saving state, and thereafter, the control signal "SUSPE"
Only ND "is monitored.

Here, in the suspend mode, the operation of the DC / DC converter 14 is stopped as described above and the power supply control microcomputer 20 enters the power saving state.
The power supply to is not stopped. The USB control unit 71 is U
Signal reception from the host device is monitored via the SB interface 9 to detect the occurrence of resume in the host device. As described above, by stopping the functions other than the necessary functions, the current consumption in the suspend mode is suppressed to within 500 μA.

Incidentally, based on the USB standard, step S5
The time from the detection of the suspend in 01 to the setting to the power saving state in step S507 needs to be within 10 msec. Therefore, in reality, steps S501 to S5
The processing up to 05 and the processing of steps S506 and S507 may be performed in parallel.

Next, the processing when the resume occurs in the host device will be described. The USB control unit 71 is U
The signal received from the host device through the SB interface 9 is monitored, and when the signal is detected, it is recognized that the resume has occurred, and the control signal "SUSPEND" is set to the L level. The power supply control microcomputer 20 uses the control signal "SUSPEN
When D ″ goes to L level, control to shift to the USB bus powered mode is performed and the display on the suspend display unit 11 is ended.

FIG. 6 is a flow chart showing the flow of processing in the power supply control microcomputer 20 when shifting from the suspend mode to the USB bus powered mode. In step S601, the occurrence of resume is detected by monitoring the control signal "SUSPEND" from the USB control unit 71. If the control signal "SUSPEND" remains at H level, the process waits, and if it changes to L level, the process proceeds to step S602.

In step S602, the control signal "D
Both D ON ”and“ USB CLKEN ”are changed to the H level, whereby the DC / DC converter 14 is turned on, the power supply to the system controller 7 is restarted, and the system controller 7 is turned on. Then, the power supply to each unit in the digital still camera 1 is restarted, the display of the LCD 5a is restarted, and the functions of each unit can be used again as usual. Supply of the clock signal “UCLK” to the USB control unit 71 is resumed, and the USB control unit 71 returns to the normal operation state.

In step S603, the frequency of the operation clock of the power supply control microcomputer 20 itself is switched from 32 KHz to 10 MHz to cancel the power saving state. And
A control process (steps S604 to S607) for closing the movable lid 11b of the suspend display unit 11 is performed.

In step S604, the rotation direction and speed of the motor section 11c of the suspend display section 11 are set so that the movable lid 11b is closed. In step S605, the motor unit 11c is turned on and rotated. As a result, the movable lid 11b is slid in a direction to cover the display board 11a.

In step S606, the motor unit 11
The signal from c is monitored to determine whether the closing of the movable lid 11b is completed. If completed, step S607
Go to and wait if not complete. Step S607
At, the motor unit 11c is turned off to stop the rotation. As a result, the characters and symbols on the display panel 11a of the suspend display unit 11 are completely cut off.

By the way, based on the USB standard, the USB control section 71 needs to set the time from the detection of the resume to the response to the host device to 30 msec or less. FIG. 7 is a time chart showing the processing from the detection of resume to the response to the host device.

FIG. 7A shows a control signal “SUSPEND” output from the USB control unit 71, and FIG. 7B shows a control signal “USB CLK EN” output from the power supply control microcomputer 20 to the clock oscillator 18. C) shows the signal waveforms of the clock signal “UCLK” output from the clock oscillator 18 to the USB control unit 71. In addition, the USB control unit 71 uses the supplied clock signal “U
An oscillation stabilization counter for counting the time until the oscillation state of CLK "stabilizes is provided, and (D) shows the counter value of this transmission stabilization counter.
(E) shows a response signal output to the host device in response to the resume detection in the USB control unit 71.

The power supply control microcomputer 20 uses the control signal "SU
As soon as SPEND ”changes to L level, the control signal“ USB CLK EN ”changes to H level, and the operation of the clock oscillator 18 is started.
The time until the oscillation waveform of 8 stabilizes is usually several msec.
It takes a degree. Therefore, the USB control unit 71 starts counting the oscillation stabilization counter from the time when the input of the clock signal “UCLK” is detected, and the oscillation waveform stabilizes until the count value reaches a predetermined value (“8” in the figure). To wait. Then, when the count value reaches a predetermined value, USB communication is started, and the USB interface 9 is connected to the host device.
Reply "NAK" through.

As described above, the power supply to the USB controller 71 is not stopped even in the suspend mode. For example, when the power supply is started after the resume is detected, the input waveform of the clock signal “UCLK” is stabilized by restarting, and the time until “NAK” is returned becomes significantly long. Therefore, by continuing to receive the power supply even in the suspend mode, the USB control unit 71 can keep the time from the resume detection to the “NAK” reply within 30 msec as defined by the USB standard.

As described above, in the digital still camera 1, when suspend occurs in the host device, the suspend mode is entered and the display 11a is displayed on the suspend display section 11. As a result, the user is notified of the suspended state, and the user can distinguish between the power OFF state and the suspended state. Further, in this suspend display unit 11, after the movable cover 11b is opened by the motor unit 11c, no power is consumed during the display on the display panel 11a. Therefore, the current consumption in the suspend state is 50 based on the USB standard.
It can be suppressed within 0 μA.

The shape and the like of the suspend display portion 11 shown in the above-mentioned embodiments are merely examples, and the present invention is not limited to this. For example, the movable lid 11b shown in FIG. 3 having a different sliding direction, or an opening / closing method other than sliding may be used. In addition, the display board 11a and the movable lid 11
b may be provided inside the external housing, and a display hole may be provided in the external housing so that the display board 11a can be visually recognized from the display hole through a transparent plastic or the like. In this case, for example, the display panel 11a itself may be slid or rotated to switch display / non-display of characters and symbols. In addition, a display function in the suspend mode may be added to a movable mechanism that is conventionally provided on the external housing.

In all of these methods, display means for switching display / non-display of previously drawn characters and symbols does not consume power during display, but other than that, display means whose consumption current is below a specified value is used. May be realized. Hereinafter, a case where a character liquid crystal display device is used will be described as such an example.

FIG. 8 is a diagram showing a second embodiment of the suspend display section. The suspend display section shown in FIG.
The character liquid crystal display device 11d is used. The character liquid crystal display device 11d is a reflective type without a backlight, and can display only a single color. FIG. 8A shows the state in the suspend mode, and the characters indicating the suspend state (here, “SUSPEND M
ODE ”) is displayed. When the USB controller 71 detects the occurrence of suspend in the host device,
Characters as shown in FIG. 8A are displayed under the control of the power supply control microcomputer 20. When the resume occurrence is detected, the power supply control microcomputer 20 controls
The display of characters is stopped as in (B).

Such a character liquid crystal display device 11d is, for example, the LCD 5a on the external casing of the digital still camera 1.
It may be provided at a position adjacent to, a top surface provided with a shutter release button, or the like. Further, it is desirable that the displayed size is as small as possible, for example, 1 cm × 5 cm, within a range in which the displayed characters and symbols can be sufficiently read by the user.

Further, as the character liquid crystal display device 11d, it is possible to apply a device as shown in FIG. 8A, which displays only predetermined characters or symbols and can control only ON / OFF of the display. In the case of such a character liquid crystal display device, the current consumption during display is about several μA.

Alternatively, it is possible to use a segment capable of displaying numbers and some alphabets, etc., by a segment of about 8 to more than 10 letters per character. Further, a dot matrix type having about 5 × 8 pixels per character and capable of displaying alphanumeric characters and some symbols may be used. Even with such a segment display type or dot matrix type, the current consumption during character display can be suppressed to several tens of μA or less.

When the above segment display type or dot matrix type is used, for example, a display device for displaying the remaining number of sheets that can be recorded on the memory card 4a, or the set value of the exposure or operation mode, etc. In the equipped digital still camera, the display device and the display of the suspended state may be combined.

When the character liquid crystal display device as described above is used as the suspending display section 11, the current consumption at the time of displaying that it is in the suspended state is extremely low, so that it can be applied to the present invention.

In the above description, an example in which the present invention is applied to a digital still camera has been shown, but the present invention is not limited to this, and can be applied to general electronic equipment that supports the USB bus powered mode. is there.

[0082]

As described above, the electronic equipment of the present invention operates by receiving power supply through the communication interface, and when detecting the occurrence of suspend in the host equipment, shifts to the power saving operation mode and Since the suspend display means displays the suspended state, the user can be notified that the electronic device has been suspended. The suspend display means has, for example, a display panel on which characters or symbols indicating a suspended state are drawn, and a movable lid which is opened so that the characters or symbols on the display panel are exposed only in the power saving operation mode. You may. Alternatively, the suspend display means may be composed of a reflective monochromatic character liquid crystal display device without a backlight. As a result, it is possible to notify the user by displaying the suspended state within the current consumption range in the suspended state defined by the communication interface.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a digital still camera applicable as an electronic device of the present invention.

FIG. 2 is a state transition diagram showing transition of power control states in the digital still camera.

FIG. 3 is a diagram showing a first exemplary embodiment of a suspend display unit.

FIG. 4 is a diagram illustrating an internal configuration example of a power supply control unit.

FIG. 5 is a flowchart showing the flow of processing in the power supply control microcomputer when shifting to the suspend mode.

FIG. 6 is a flowchart showing the flow of processing in the power control microcomputer when shifting from the suspend mode to the USB bus powered mode.

FIG. 7 is a time chart showing processing from detection of resume to response to host device.

FIG. 8 is a diagram illustrating a second exemplary embodiment of a suspend display unit.

[Explanation of symbols]

1 ... Digital still camera, 2 ... Imaging block, 3
...... Image signal processing unit, 4 ... Memory R / W, 4a ... Memory card, 5 ... Image display unit, 5a ... LCD, 6 ...
Input unit, 7 System control unit, 8 Internal bus, 9
...... USB interface, 10 ...... Power supply control unit, 10
a: Battery, 11: Suspend display section

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5B011 DB22 EA02 EB06 HH01 HH07                       LL12 LL14 MB07                 5C052 AA17 CC11 DD02 GA02 GA03                       GA08 GB01 GC05 GE08                 5C053 FA08 FA27 GB21 LA01 LA11                       LA15

Claims (7)

[Claims] 1. An electronic device that operates by receiving power supply from a host device having a suspend function via a communication interface, and a normal operation mode that operates by power supply from the host device, and generation of a suspend in the host device. A power-saving operation mode that operates at lower power consumption than the normal operation mode, and an operation state detection unit that detects the occurrence of the suspend and resume in the host device; and a detection state by the operation state detection unit. Based on the power saving operation mode, a suspend display means for displaying a suspend state. 2. The suspend display means includes a display panel on which characters or symbols indicating the suspended state are drawn, and a movable display that is opened so that the characters or symbols are exposed only in the power saving operation mode. The electronic device according to claim 1, further comprising: a lid. 3. The electronic apparatus according to claim 1, wherein the suspend display means is constituted by a reflection type monochromatic character liquid crystal display device having no backlight. 4. The character liquid crystal display device displays only in the power saving operation mode.
Electronic device described. 5. The electronic device according to claim 1, wherein the communication interface complies with the USB standard. 6. The electronic device according to claim 1, further comprising: an image pickup unit that picks up an image, and an image recording unit that records the picked-up image as digital data. 7. The electronic device according to claim 6, wherein the data recorded in the image recording means can be transmitted to the host device through the communication interface.