Information processing device and control method

There is disclosed an information processing device with an operator unit capable of providing adequate operationality for both of display devices or drive modes which respectively require different rewrite times. The information processing device includes: at least one display device; an operator unit that is displaced from a reference point; a displacement detection unit that detects a displacement amount of the operator unit; a signal supply unit that supplies the at least one display device with a control signal for changing display on the at least one display device, depending on the displacement amount detected by the displacement detection unit; and a load controller that controls a load applied to the operator unit, depending on a display rewrite time per unit information amount in the at least one display device.

The entire disclosures of Japanese Patent Applications No. 2006-222568 filed on Aug. 17, 2006 and No. 2007-151833 filed on Jun. 7, 2007 are expressly incorporated by reference herein.

BACKGROUND

1. Technical Field

The present invention relates to an information processing device having an operator unit.

2. Related Art

Many of the devices having on-board displays tend to be equipped with a rotary operator unit such as a jog dial (registered trademark). A rotary operator unit is constituted of a rotor which rotates about an axis, and a sensor which detects and converts a rotation angle and a rotation amount of the rotor into signals. A device to be operated by the rotary operator unit changes data displayed as a reference so as to be slidable depending on a rotation amount. An operator who operates such a device turns the rotary operator unit quickly at first, to gain a wide span, and then turns the unit slowly when desired data becomes proximate. In this manner of operation, the operator can efficiently find out the data to be presented on a display from a large amount of data including a combination of different types of data.

JP-B-2571793 and JP-A-6-102997 are publications each of which, discloses a mechanism for improving operationality of an operator unit. An input device disclosed in the former publication employs a touch sensor. The touch sensor is triggered to vibrate when a selector icon on a display overlaps a selectable unit. The latter publication discloses a mouse which employs a cover drive mechanism for driving up and down a mouse cover. The height of this mouse cover is controlled depending on the type of a unit which is overlapped by a selector icon on a display.

Recent developments have been made on a display device using a memorable display medium, which is called an electronic paper. A memorable display medium can maintain a state of display without application of a voltage, and accordingly attains an effective feature of performing display with low power consumption. Examples of such a memorable display medium are cholesteric liquid crystal or electrophoretic display.

Memorable media commonly have a defective feature in that a longer time is required to complete a refresh operation as compared with non-memory type display media. One approach to resolving this defect is considered to reside in the employment of a non-memory type display medium such as TN (Twisted Nematic) liquid crystal provided in an electronic paper. An alternative approach is to allow a memorable display medium to run even in a drive mode for fast rewrite with low display quality, in addition to a normal drive mode for slow rewrite with high display quality. In any case, it is difficult for techniques described in both of the above publications to provide adequate operationality for display devices or drive modes between which a rewrite time differs.

SUMMARY

The invention provides an operator unit capable of ensuring adequate operationality in display devices or drive modes between which time required for rewriting differs.

According to an aspect of the invention, there is provided an information processing device including: at least one display device; an operator unit that is displaced from a reference point; a displacement detection unit that detects a displacement amount of the operator unit; a signal supply unit that supplies the at least one display device with a control signal for changing display on the at least one display device, depending on the displacement amount detected by the displacement detection unit; and a load controller that controls a load applied to the operator unit, depending on a display rewrite time per unit information amount in the at least one display device.

In the information configured as described above, the load applied to the operator unit is controlled depending on display rewrite times per unit information amount of the display device.

Alternatively, the information processing device may include a plurality of display devices having respectively different display speeds, wherein the signal supply unit supplies the control signal to one of the plurality of display devices, and the load controller controls the load applied to the operator unit, depending on the one of the plurality of display devices as a destination to which the control signal is supplied.

In the information processing device configured as described above, the load applied to the operator unit is controlled depending on the destination to which the control signal is supplied.

Further alternatively, in the information processing device, the load controller controls the load applied to the operator unit so that the load decreases as a rewrite speed of one of the plurality of display devices, as the destination, increases.

In the information processing device configured as described above, the load applied to the operator unit is controlled so that the load decreases as the rewrite speed of the display device increases.

Also alternatively, in the information processing device, one of the at least one display device can be driven in a plurality of drive modes respectively having different display rewrite times per unit information amount, and the load controller controls the load applied to the operator unit, depending on one of the plurality of drive modes in which the one of the at least one display device is driven.

In the information processing device configured as described above, the load applied to the operator unit is controlled depending on the drive mode of the display device.

Further alternatively, in the information processing device, the load controller controls the load applied to the operator unit so that the load applied to the operator unit decreases as a rewrite speed of the one of the at least one display device which is driven in the one of the plurality of drive modes increases.

In the information processing device configured as described above, the load applied to the operator unit is controlled so that the load decreases as the rewrite speed of the display device increases.

Further alternatively, in the information processing device, the one of the at least one display device includes a display medium using cholesteric liquid crystal, and the plurality of drive modes includes drive modes based on a DDS (Dynamic Drive Scheme) and a conventional scheme.

In the information processing device configured as described above, the load applied to the operator unit is controlled depending on whether the drive mode of the display device is of a DDS or a conventional scheme.

Also alternatively, in the information processing device, the load is a force which hinders displacement of the operator unit.

In the information processing device configured as described above, a force which hinders displacement of the operator unit is controlled depending on the display rewrite time per unit information amount of the display device.

Further alternatively, in the information processing device, the load is a displacement amount which is required to trigger rewrite of a unit information amount of the display on the display device.

In the information processing device configured as described above, the displacement amount which is required to trigger rewrite of a unit information amount of display on the display device is controlled depending on the display rewrite time per unit information amount of the display device.

Also alternatively, in the information processing device, the signal supply unit outputs an instruction about a rewrite of the display on the at least one display device each time the displacement amount detected by the displacement detection unit exceeds a threshold.

In the information processing device configured as described above, a control signal indicative of an instruction about rewrite of display on the display device is supplied each time the displacement amount exceeds a threshold.

Also alternatively, in the information processing device, the at least one display device includes a display medium using cholesteric liquid crystal.

In the information processing device configured as described above, the load applied to the operator unit is controlled depending on the display rewrite time per unit information amount of the at least one display device including the display medium using cholesteric liquid crystal.

Also alternatively, the information processing device further includes a light emitting unit that emits light, synchronized with timing at which the control signal is supplied to the at least one display device.

Also alternatively, the information processing device further includes an audio output unit that outputs a sound, synchronized with timing at which the control signal is supplied to the at least one display device.

In the information processing devices configured as described above, light or a sound is outputted synchronized with supply timing of the control signal.

Also alternatively, in the information processing device, the operator unit is of a type which turns about an axis, and the displacement amount is a rotation amount of the operator unit.

In the information processing device configured as described above, the load applied to the operator unit is controlled depending on the display rewrite time per unit information amount of the display device.

According to another aspect of the invention, there is provided a control method for use in an information processing device including at least one display device, an operator unit that is displaced from a reference point, a displacement detection unit that detects a displacement amount of the operator unit, and a signal supply unit that supplies the at least one display device with a control signal for changing display on the at least one display device, depending on the displacement amount detected by the displacement detection unit, the control method including controlling a load applied to the rotator unit, depending on a display rewrite time per unit information amount in the at least one display device, wherein the signal supply unit supplies the control signal for changing the display on the at least one display device, depending on a rotation amount detected by a rotation detection unit.

In the control method configured as described above, the load applied to the operator unit is controlled depending on the display rewrite time per unit information amount of the display device.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

1. First Embodiment

The first embodiment of the invention will now be described. In this embodiment, an image which should be displayed on a display device of an information processing device is selected by a rotary operator unit. The display device is driven in one of two drive modes, i.e., a mode of prioritizing image quality and a mode of prioritizing drive speed. Load applied to the rotary operator unit is controlled according to the drive modes.

FIG. 1shows a schematic hardware structure of the information processing device according to the first embodiment.FIG. 2shows an appearance of the information processing device. As shown inFIG. 1, this information processing device has a main display10(display device), a press-down operator unit20, a rotary operator unit30, and a controller40for controlling these components.

The main display10includes a cholesteric liquid crystal panel11, a segment electrode drive circuit12, and a common electrode drive circuit13. The cholesteric liquid crystal panel11has a structure in which a cholesteric liquid crystal layer is sandwiched between two glass substrates from up and down sides. The two glass substrates are provided with transparent electrodes. A temperature sensor91is bonded to a substantially central position of the lower face of the lower one of the two glass substrates. In the information processing device according to the first embodiment, an image is displayed under control of the controller40. Specifically, the controller40causes the cholesteric liquid crystal layer to vary orientation states of itself by controlling the segment electrode drive circuit12and common electrode drive circuit13so as to apply predetermined voltages between transparent electrodes of both glass substrates of the cholesteric liquid crystal panel11.

Each ofFIG. 3show a cross section of the cholesteric liquid crystal panel11along with an orientation state of cholesteric liquid crystal. The cholesteric liquid crystal panel11includes an upper glass substrate14, upper transparent electrodes15, a cholesteric liquid crystal layer16, lower transparent electrodes17, a lower glass substrate18, and a light absorption plate19. The transparent electrodes15and17function as data electrodes and scanning electrodes for applying voltages to the cholesteric liquid crystal layer16. As shown inFIG. 2, the upper glass substrate14of the cholesteric liquid crystal panel11is exposed outside through an opening part in a casing90of the display device.

FIG. 4shows a structure of the cholesteric liquid crystal panel11. The cholesteric liquid crystal panel11has an n×m matrix wiring which includes n rows of scanning electrodes (Y1, Y2, . . . , Yn) and m columns of data electrodes (X1, X2, . . . , Xm). In this case, n and m are positive integers. In the first embodiment, the cholesteric liquid crystal panel11is a so-called passive matrix display device, and therefore, scanning and data electrodes can respectively function as scanning lines and data lines. At regions where the scanning and data electrodes intersect each other (intersections between the scanning and data electrodes), electro-optical units16aare formed. Each of the electro-optical units16ahas two electrodes and an electro-optical layer sealed between the two electrodes (wherein the two electrodes are a data electrode (also called a pixel electrode or segment electrode) and a scanning electrode (also called a common electrode)). This embodiment utilizes, as the electro-optical layer, a liquid crystal layer including cholesteric liquid crystal which is a memorable liquid crystal. The memorable liquid crystal refers to a liquid crystal capable of maintaining a display state without supply of electric power. Each of electro-optical units16aare applied with a voltage depending on a voltage (hereinafter a “scanning voltage”) applied to a related scanning electrode and on a voltage (hereinafter a “data voltage”) applied to a related data electrode. A voltage applied to each electro-optical layer is referred to as a “drive voltage”. Optical characteristics of the electro-optical layers (e.g., optical rotation, light scattering, and the like) vary depending on applied voltages. The electro-optical units16aform an image owing to variation of optical characteristics of the electro-optical layers. Basically, one electro-optical unit16acorresponds to one pixel. In case of a color display which achieves color expression on RGB color coordinate system, one electro-optical unit16acorresponds to one of R, G, and B color components included in one pixel.

InFIG. 3, the orientation state (of cholesteric liquid crystal) in an electro-optical unit16atransits between a planar orientation (hereinafter “P-orientation”) shown inFIG. 3A, a focal conic orientation (hereinafter “F-orientation”) shown inFIG. 3B, and a homeotropic orientation (hereinafter “H-orientation”) shown inFIG. 3C. In the P-orientation state, light entering from the upper glass substrate14is reflected thereby expressing white. Inversely, in the F-orientation state, the entering light is absorbed and reaches the light absorption plate19thereby expressing black. By transiting the orientation state to an intermediate orientation state between the P-orientation and the H-orientation, an intermediate tone can be expressed. Once the orientation state transits to the P- or H-orientation, the P- or H-orientation is maintained without application of a voltage. As will be described in detail later, switching from the P-orientation to the F-orientation always needs to go through the H-orientation as a temporary transitional stage, which cannot be maintained without application of a voltage.

InFIG. 1, the press-down operator unit20and rotary operator unit30are to allow users to make various input operations. Both of the operator units will now be described in detail below. The press-down operator unit20is to convert a user's press-down operation into a signal. The press-down operator unit20includes two buttons21and22, and a sensor (not shown) which detects press-down of the buttons21and22. As shown inFIG. 2, the buttons21and22of the press-down operator unit20are exposed to the outside of the casing90of the display device.

FIG. 5is a side view of the rotary operator unit30.FIG. 6is a top view of a face denoted by an arrow A inFIG. 5. The rotary operator unit30is designed to convert user's rotational operation into a signal. As shown in the figures, the rotary operator unit30includes a rotary knob31, a rotary encoder32, a load controller33, and a rotary shaft34which links these components to one another. The rotary knob31has a flat cylindrical shape. A hole is cut in upward from the substantial center of a lower end face of the rotary knob31. An upper end of the rotary shaft34is inserted in the hole. In this manner, the rotary shaft34is fixed to the rotary knob31. As shown inFIG. 2, the rotary knob31is exposed to the outside of the casing90of the display device. A mark31aindicative of a rotation reference position is marked on an upper end face of the rotary knob31.

The rotary encoder32has a rotary slit disc32a, a fixed plate32b, a light emitting unit32c, and a light receiving unit32d. The light emitting unit32cand light receiving unit32dsandwich both of the disc32aand plate32b. The rotary slit disc32ahas a through hole in the center of the disc itself. The rotary shaft34is inserted into the through hole so that the rotary slit disc32ais fixed to the rotary shaft34. Slits having a so-called absolute pattern is formed in the rotary slit disc32a. The fixed plate32bis fixed to the upper face of the rotary slit disc32a. The fixed plate32bhas plural holes extending parallel to a line extending radially from the rotary shaft34. The light emitting unit32chas the same number of LEDs (Light Emitting Diodes) as the holes in the fixed plate32b. The LEDs are fixed, arranged exactly above the holes of the fixed plate32b. The light receiving unit32dhas the same number of optical sensors as the number of LEDs. The optical sensors are arranged at positions where the sensors can receive light passing though the fixed plate32band the rotary slit disc32a. There is prepared a table in which angles of the rotary slit disc32aare related to binary data indicative of combinations of presence or absence of light received by the optical sensors. By referring to this table at respective necessary occasions, rotation angles of the rotary slit disc32acan be specified based on a light receiving condition.

The load controller33includes a rotation hindering member33a, an electromagnet33b, and a magnetic force control circuit33c. The rotation hindrance member33aincludes a substantially cylindrical base material, and eight permanent magnets r which are fixed to the side wall of the base material, arranged at substantially equal intervals. The electromagnet33bhas an iron core and a coil wound around the iron core. The electromagnet33bgenerates a magnetic force corresponding to electric power supplied by the magnetic force control circuit33c, so as to act on the rotation hindrance member33a. Therefore, as the magnetic force is reduced, rotational load applied to the rotary knob31is reduced. Inversely, as the magnetic force is increased, rotational load applied to the rotary knob31is increased.

FIG. 7is a graph showing load-angle curves of the electromagnet33b.FIG. 7shows an example in which the rotary knob31is rotated to 45 degrees in a state of strong magnetic force (curve B) and a state of weak magnetic force (curve C). That is, in these two states, the rotary knob31is rotated so that one permanent magnet r attracted by the electromagnet33bis forced away from the electromagnet33buntil a next permanent magnet r comes attracted. According toFIG. 7, the load gradually increases from the beginning of rotation operation and steeply decreases from a time point when a particular angle is reached, regardless of strength or weakness of the magnetic force. Further, the load denoted by a solid curve B in the state of strong magnetic force is higher than the load denoted by a chain curve C in the state of weak magnetic force. Thus, with the load in the state of strong magnetic force, users find it more difficult to turn the rotary knob31than with the other load.

Returning toFIG. 1, the controller40includes an ADC (Analog/Digital Converter)41, a segment power generation circuit42, a common electrode power generation circuit43, a CPU44, a RAM45, a ROM46, a main display drive control circuit47, and an I/O controller48.

The ADC41converts an analog signal output from the temperature sensor91, as a detected temperature, into a digital signal. The ADC41supplies the CPU44with the digital signal which indicates the temperature at the substantially central position of the cholesteric liquid crystal panel11. The segment power generation circuit42and common electrode power generation circuit43respectively supply electric power to the segment electrode drive circuit12and common electrode drive circuit13.

The CPU44performs various processing calculations, using the RAM45as a work area. The ROM46stores various programs and tables described later. The I/O controller48controls exchanges of various signals between the CPU44and the press-down operator unit20and rotary operator unit30.

Next, load setup processing and image switching processing according to the first embodiment will be described.

FIG. 8is a flowchart showing the load setup processing. In case of the processing shown inFIG. 8, a user operates the press-down operator unit20to let the cholesteric liquid crystal panel11show a drive mode selection screen, and a drive mode is selected on the screen thereby to trigger the processing.

FIG. 9shows the drive mode selection screen. This screen invites selection of either a high-speed drive mode or a low-speed drive mode. In the display device of the information processing device according to the first embodiment, the low-speed drive mode is a default mode. Therefore, when the screen is displayed first, the low-speed drive mode has been selected. In the low-speed drive mode, liquid crystal is driven according to a conventional drive scheme. This mode is desirable if image quality is given higher priority than drive speed. In the high-speed drive mode, liquid crystal is driven according to a DDS (Dynamic Drive Scheme). This mode is desirably selected if drive speed is given a higher priority than image quality.

The DDS and the conventional drive scheme will now be described below.

FIG. 10shows examples of voltage application cycles. As shown inFIG. 10, according to the DDS, a drive cycle of cholesteric liquid crystal is divided into four stages, i.e., a preparation phase (or reset phase), a selection phase, an evolution phase (or hold phase), and a non-selection phase. Phases of these cyclic periods are shifted for each scanning line Y of an image and voltages specific to these periods are applied in a manner of pipelined-processing.

Drive voltages applied during the above periods respectively, will now be specifically described. At first, a drive voltage for transiting to the H-orientation state, all the electro-optical units16aconstituting a line as a target line to drive is applied during the preparation phase. During the selection phase, there is applied a drive voltage for selecting whether the electro-optical units16ain the target line should be maintained in the H-orientation state or allowed to be relaxed to a transitional planar orientation state (hereinafter “TP-orientation”) in which the spiral structure of liquid crystal is slightly relaxed. Further during the evolution phase, there is applied such a drive voltage as to maintain the orientation state of H-oriented electro-optical units16aand as to transit P-oriented electro-optical units16ato the F-orientation. During the non-selection phase, drive voltages are erased (though voltages are not strictly reduced to zero in some cases). Depending on the level of the drive voltage applied during the selection phase among these voltages, the orientation state of the cholesteric liquid crystal transits to either the P-orientation or F-orientation subsequently during the evolution phase (or hold phase) through the non-selection phase.

FIG. 11shows reflectance—voltage curves of the cholesteric liquid crystal. Specifically,FIG. 11shows relationships between drive voltages applied to P-oriented and N-oriented cholesteric liquid crystal and orientation states to which the P- and N-oriented cholesteric liquid crystal transits after the drive voltages are removed rapidly. The vertical axis represents reflectances while the horizontal axis represents drive voltages. The voltages V1to V4are thresholds for drive voltages, at which orientation states transit. If the cholesteric liquid crystal is P-oriented, the orientation state gradually transits to the F-orientation while a drive voltage is applied increasing from V1to V2. Accordingly, transparency increases and black appears finally as the color of the light absorption plate19itself. Further, the F-orientation is maintained while a drive voltage is applied varying from V2to V3. While a drive voltage is applied varying from V3to V4, the F-orientation transits to the H-orientation so that the reflectance accordingly increases again. On the other side, if the cholesteric liquid crystal is F-oriented, the orientation state does not transit while a drive voltage is applied varyingly from V1to V3. While a drive voltage is applied further varyingly from V3to V4, the F-orientation transits to the H-orientation, thereby increasing the reflectance. Thus, according to the DDS, the orientation states to which the cholesteric liquid crystal transits during periods successive to the preparation phase are decided depending on the level of the drive voltage applied to each of the electro-optical units16aduring the preparation phase.

FIG. 12shows transition of orientation states of cholesteric liquid crystal. At first, during the preparation phase, a drive voltage of V4or higher is applied so that each electro-optical unit16awhich has been P- or F-oriented transits to the H-orientation. Further during the selection phase, each unit16ais applied with a drive voltage corresponding to an orientation state specific to a color to be expressed. That is, when white is to be expressed a drive voltage of V2or higher is applied and when black is to be expressed a drive voltage of V1or lower is applied. If the drive voltage of V4or lower is applied, the orientation state first transits to the TP-orientation. Further during the evolution phase when a drive voltage of V4or lower is applied, the orientation state transits to the F-orientation, which is maintained up to the next drive cycle. Otherwise, if a drive voltage of V2or higher is applied during the selection phase, the H-orientation is maintained unchanged. Successively, during the evolution phase, a drive voltage capable of maintaining the H-orientation is applied. Further successively during the non-selection phase, the drive voltage is erased rapidly, and the orientation state accordingly transits to the P-orientation. The P-orientation is maintained until the next drive cycle.

On the other hand, according to the conventional drive scheme, each of the voltages specific to the periods described above is applied to the scanning lines one after another. Since this scheme is well-known, a detailed description of a drive cycle, applied voltages, and the like according to this scheme will be omitted herefrom.

Referring again toFIG. 8, the CPU44monitors in a step S110whether a drive mode is selected on the drive mode selection screen or not. If a drive mode is selected, an identifier for identifying the selected drive mode is stored in the RAM45. The CPU44takes the processing further forward to a step S120.

In the step S120, the CPU44determines whether the drive mode has been changed from a low-speed drive mode as a default mode to a high-speed drive mode or not. If the mode has been changed to the high-speed drive mode, the CPU44takes the processing forward to the step S130. If the drive mode has not been changed to the high-speed drive mode, the CPU44takes the processing forward to a step S140.

In the step S130, the CPU44supplies a signal for setting the load controller33into a high-load state, to the magnetic force control circuit33cvia the I/O controller48. Upon receiving the supplied signal, the magnetic force control circuit33csupplies the electromagnet33bwith electric power which is necessary to apply a load denoted by the solid curve B inFIG. 7to the rotary knob31.

In the step S140, the CPU44supplies a signal for setting the load controller33into a low-load state, to the magnetic force control circuit33cvia the I/O controller48. Upon receiving the supplied signal, the magnetic force control circuit33csupplies the electromagnet33bwith electric power which is necessary to apply the load denoted by the chain curve C inFIG. 7to the rotary knob31.

FIG. 13is a flowchart showing image switching processing. While a series of processing shown inFIG. 13is executed, the I/O controller48continues supplying the CPU44with signals indicative of the rotation amount and rotation direction which are detected by the rotary encoder32.

In the step S210, the CPU44monitors whether or not the rotation amount indicated by the signal supplied from the I/O controller48reaches an angle as a threshold for switching images, which is stored in the RAM45. After the rotation amount reaches the threshold, the CPU44takes the processing forward to a step S220.

In the step S220, the CPU44obtains a digital signal indicative of a temperature detected by the temperature sensor91from the ADC41.

In a step S230, the CPU44refers to identifiers stored in the RAM45to determine whether the low-speed drive mode or the high-speed drive mode has been selected.

If it is determined in the step S230that the high-speed drive mode has been selected, the CPU44reads parameters for the high-speed drive mode from a table in the ROM46. The “parameters for the high-speed drive mode” are prepared in advance for the high-speed drive mode, and waveforms for black and white (e.g., thresholds of V1to V4shown inFIG. 10) are decided. Otherwise, if it is determined that the low-speed drive mode has been selected, the CPU44reads parameters for the low-speed drive mode from the table in the ROM46.

The “parameters for the low-speed drive mode” are prepared in advance for the low-speed drive mode, and waveforms for black and white (e.g., thresholds of V1to V4shown inFIG. 10) are decided.

The thresholds indicated as parameters stored in the table have been obtained on the basis of actual measurement, as values which cause cholesteric liquid crystal at a reference temperature (e.g., 25° C.) to transit between orientation states.

After reading the parameters, the CPU44changes the parameters depending on a temperature detected (S260). Specifically, the thresholds V1and V2applied during the selection phase shown inFIG. 10are changed depending on the detected temperature.

The reason why the thresholds are changed depending on the detected temperature will now be described with reference toFIG. 14.

FIG. 14schematically shows relationships between selected voltages and reflectances of cholesteric liquid crystal. The horizontal axis represents voltages while the vertical axis represents reflectances. Each of the reflectances is of a relative brightness, assuming that a reflective brightness of a standard white plate as a reference is 100%. A higher reflectance means that the cholesteric liquid crystal is oriented closer to the F-orientation and looks more blackish. As shown inFIG. 14, a voltage with which the reflectance of cholesteric liquid crystal transits to 100% (white) and a voltage with which the reflectance transits to 0% (black) shift to the higher voltage side as the temperature increases. Inversely, both the voltages shift to the lower voltage side as the temperature decreases. Thus, the reflectance-voltage characteristic of the cholesteric liquid crystal depends on the temperature. Accordingly, this embodiment utilizes a structure in which drive parameters are changed depending on a detected temperature.

Referring again toFIG. 13, in a step S270, the CPU44changes parameters read out in the step S250, depending on the detected temperature as well.

After the parameters are changed in the step S260or S270, the CPU44specifies an image data set to be displayed on the cholesteric liquid crystal panel11from among a series of image data sets stored in the ROM46, and obtains the specified image data. The image data set is specified in a manner described below. At first, the ROM46stores in advance plural image data sets, respectively related to unique file names. In the step S280, an image file related to a file name ranked immediately before or after the file name of the image being now displayed in the order of referencing file names is specified, provided that the file names are arranged in ascending order. Whether the image file to be specified should be related to a file name immediately before or after the file name of the image being now displayed is determined depending on which of a forward or backward rotation directions the rotary knob31is turned in.

In the step S290, the CPU44supplies the main display drive control circuit47with the image data set obtained in the step S280and the parameters changed in the step S260or S270. Upon reception of the supplied image data set and the parameters, the main display drive control circuit47specifies waveforms of drive voltages which cause transition of the cholesteric liquid crystal, in accordance with the parameters. Based on the image data, the main display drive control circuit47also specifies colors of pixels on each main scanning line of an image to be displayed. Further, the main display drive control circuit47supplies the segment power generation circuit42and the common electrode power generation circuit43sequentially with control signals for respectively causing transitions of the orientation states of the electro-optical units16acorresponding to the pixels. In this manner, the orientation states of the electro-optical units16atransit, line by line, according to either the DDS or the conventional drive scheme. When the transitions are completed for all lines, rewrite of the image is completed.

In the first embodiment as described above, the rotational load applied to the rotary operator unit as an operator unit for instructing switching of an image displayed on the main display is switched depending on whether a high-speed drive mode or low-speed drive mode is selected. Thus, loads corresponding to drive modes can be applied through the rotary operator unit.

2. Second Embodiment

The second embodiment of the invention will now be described. In the second embodiment, the information processing device has a sub-display (second display device) separate from a main display (first display device). The sub-display uses a different display medium from cholesteric liquid crystal, for e.g., a display medium having a different writing speed. An operation target to be operated by the rotary operator unit can be selected from the main display and the sub-display. Of the rotary operator unit, an angular size as a threshold at which images are switched is controlled depending on whether the operation target is the main display or the sub-display. Further, the light blinks each time a rotation of the rotary operator unit is detected as the rotary operator unit is operated. As a result, improved visibility can be attained when users operate the rotary operator unit.

The main display10is a primary display of an electronic paper and has effective features such as high definition capability and low power consumption. To make full use of the effective features, the main display10is usually utilized to present a main document so that the user can thoroughly read the main document. However, the main display10achieves only a low rewrite speed. Therefore, the rewrite of a display is executed for the entire page (or the entire part of a page), and scrolling is not carried out. On the other hand, the sub-display50is a subsidiary display and is capable of high-speed rewrite. Therefore, the sub-display50is usually utilized to present supplemental information such as an operation menu, a file search window, or bibliographic information concerning a document displayed on the main display. Since the sub-display is capable of high-speed rewrite, scrolling may be allowed depending on the operations of the rotary operator unit. However, the sub-display50has less effective features such as low resolution, high power consumption, and a small screen size, and is therefore not desirable for display of a main document.

FIG. 15shows a schematic hardware structure of the information processing device according to the second embodiment.FIG. 16shows an appearance of the information processing device. As shown inFIG. 15, this information processing device has a main display10, a press-down operator unit20, a rotary operator unit30, a controller40, a sub-display50, and a LED60. The controller40includes a sub-display drive control circuit49in addition to an ADC41, a segment power generation circuit42, a common electrode power generation circuit43, a CPU44, a RAM45, a ROM46, a main display drive control circuit47, and an I/O controller48. Details of the structure of the main display10are the same as those described in the first embodiment and will be omitted from the figures.

The LED60is an optical unit which emits light upon reception of a signal supplied from the I/O controller48. As shown inFIG. 16, the LED60is exposed to the outside of the casing90of the display device.

The sub-display50differs from the main display10in that the sub-display utilizes a display medium (e.g., nematic liquid crystal) which has superior resistance against temperature changes and a superior drive speed to those of cholesteric liquid crystal. As shown inFIG. 2, an upper glass substrate of a liquid crystal panel of the sub-display50is exposed to the outside through an opening part in the casing90of the display device.

The sub-display drive control circuit49in the controller40supplies the sub-display50with a control signal thereby to display an image on the liquid crystal panel.

In the information processing device according to the second embodiment, the structure of the rotary operator unit30differs from that of the first embodiment. The structure of the rotary operator unit30in the second embodiment will be described in detail with reference toFIGS. 17 and 18.

FIG. 17is a side view of the rotary operator unit30.FIG. 18are top views showing a face denoted by an arrow D inFIG. 17. The rotary knob31and rotary encoder32which constitute the rotary operator unit30have the same structures as those in the first embodiment, which will be omitted from the detailed description below.

A load controller33shown in the figures includes a gear33e, a hard sphere33f, a spring33g, and an actuator33h. The gear33ehas a through hole in its center. A rotary shaft34is inserted in the through hole, and the gear33eis fixed to the rotary shaft34. The gear33eand the hard sphere33fare connected through the spring33g. The actuator33hmoves in a direction toward the gear33eand in an opposite direction, thereby adjusting the energizing force with which the hard sphere33fis pressed against the side face of the gear33e.

As the actuator33hmoves away from the gear33ein the opposite direction, the hard sphere33fperfectly takes off from the side wall of the gear33e. Then, the load acting on the rotating rotary knob31becomes substantially zero. As the actuator33hmoves further from this state in the direction toward the gear33e, the hard sphere33fmakes contact with the side wall of the gear33e. Then, a load which hinders rotation is applied from the time point when the hard sphere33fengages in one of the splines (or grooves). As the actuator33hfurther moves in the direction toward the gear33e, as shown inFIG. 18B, the rotational load applied to the rotary knob31becomes heavier since the rotary knob31is connected to the gear33ethrough the rotary shaft34.

An image switching processing which characterizes the second embodiment will now be described.

FIG. 19is a flowchart showing the image switching processing. While a series of processings shown in the figure is carried out, the I/O controller48continues supplying the CPU44with signals indicative of a rotation amount and a rotation direction of the rotary knob31, which are detected by the rotary encoder32. The information processing device uses different software programs respectively for controlling the main display10and the sub-display50is given lower priority than the main display10.

In a step S310, the CPU44determines whether the software program for controlling the main display10has been started up or not. If the software program is determined as having been started up (S310: YES), the CPU44sets an angle of 45 degrees as a threshold for switching images, which is stored in the RAM45. Thereafter, each time when the angle of 45 degrees is reached by the rotation amount of the rotary knob31which is specified based on the signal supplied from the I/O controller48, an image data set to be displayed on the cholesteric liquid crystal panel11is obtained from a series of image data sets stored in the ROM46and is then supplied to the main display drive control circuit47. A procedure for obtaining the image data set is the same as that in the step S280shown inFIG. 13. Upon reception of the supplied image data set, the main display drive control circuit47supplies the segment power generation circuit42and the common electrode power generation circuit43with control signals for causing the electro-optical units16ato transit their own orientation states in accordance with the image data set, thereby rewriting the image now displayed on the cholesteric liquid crystal panel11.

After setting the threshold for switching images to 45 degrees, the CPU44supplies the actuator33hwith a signal for setting the load controller into a load application state, via the I/O controller48, in a step S330. Upon reception of the supplied signal, the actuator33hmoves in the direction toward the gear33e. As the actuator33hmoves in this way, a load for hindering rotation of the rotary knob31is applied. After supplying the signal to the actuator33h, the CPU44returns the processing to the step S310.

If it is determined in the step S310that the software program for controlling the main display10has not been started up (S310: NO), the CPU44determines whether the software program for controlling the sub-display50has been started up or not, in the step S340.

If the software program for controlling the sub-display50is determined as having been started up (S340: YES), the CPU44sets 15 degrees as the angle of the threshold for switching images, which is stored in the RAM45. Thereafter, each time the angle of 15 degrees as the threshold is reached by the rotation amount of the rotary knob31which is specified based on the signal supplied from the I/O controller48, an image data set to be displayed on the cholesteric liquid crystal panel11is obtained from the series of image data sets stored in the ROM46and is then supplied to the sub-display50.

After setting the threshold for switching images to 15 degrees, the CPU44supplies the actuator33hwith a signal for setting the load controller into a load removal state, via the I/O controller48, in a step S360. Upon receiving the supplied signal, the actuator33hmoves in the opposite direction away from the gear33e. As the actuator33hmoves in this way, the load for hindering rotation of the rotary knob31is removed. After supplying the signal to the actuator33h, the CPU44returns the processing to the step S310.

If the software program for controlling the sub-display50is determined as not having been started up (S340: NO), the CPU44waits for supply of a signal from the I/O controller48. If a signal indicative of a rotation angle is supplied (S370YES), the CPU44supplies a signal indicating lighting-up of the LED60to the LED60via the I/O controller48, in a step S380. Upon supply of this signal, the LED60lights up for a predetermined time period. In this manner, the LED blinks each time the rotary encoder32of the rotary operator unit30detects rotation of the rotary knob31.

In the second embodiment as described above, the threshold for switching images is controlled depending on whether the operation target is the main display10or the sub-display50. Although the sub-display has a faster drive speed than the main display, the threshold for switching images is controlled depending on the operation target. Accordingly, the rotary operator unit may have loads respectively corresponding to operation targets.

The invention may be practiced in various forms of modifications as follows. Two or more of the following modifications can be utilized in combination with the first or second embodiment.

In the first embodiment, the electromagnetic force for hindering rotation of the rotary knob is increased in the high-speed drive mode in which the drive speed of liquid crystal is fast. In the low-speed drive mode in which the drive speed of liquid crystal is slow, the electromagnetic force is reduced. As a result, an operation feel of the rotary knob varies following the drive speed of liquid crystal. In this respect, the configuration of the first embodiment can be modified so that the angle as a threshold for switching images is switched depending on whether the high-speed drive mode or the low-speed drive mode is selected.

In the second embodiment, the rotation angle as a threshold for switching images is reduced when the sub-display is operated by rotation of the rotary knob. On the other hand, the rotation angle is increased when the main display is operated by rotation of the rotary knob. In this manner, the operation feel of the rotary knob varies following the drive speed of liquid crystal. In this respect, the configuration of the second embodiment can be modified so as to utilize an electromagnet as in the first embodiment. Specifically, magnifications of the electromagnetic force for hindering rotation of the rotary knob can be switched between the time when the sub-display is an operation target and when the main display is an operation target.

In the second embodiment, operation targets to be operated by the rotary knob are two of the main display and sub-display. However, three or more displays can be operation targets. Specifically, the configuration of the second embodiment can be modified so that three or more displays are operated by one rotary operator unit. In this case, the threshold value for switching images can be switched depending on which of the three or more displays the operation target is which is now being operated.

The above embodiments have been described referring to examples in which the rotary encoder of the load controller is an absolute rotary encoder. However, an incremental rotary encoder can substitute for the absolute rotary encoder. In case of an incremental rotary encoder, a relative rotation amount can be detected although an absolute angle of rotation of the rotated rotary knob cannot be detected. In this case, the configuration may be modified so that an image file related to a file name ranked immediately before or after the file name of the image being now displayed in the order of referencing file names is specified each time the relative rotation amount exceeds a threshold.

In the above embodiments, a series of image data sets which can be displayed on the liquid crystal panel are stored in a ROM. However, plural image data sets may be stored in advance in a different type of storage device such as a flash ROM or hard disk, and any of the plural image data sets can be specified and displayed on the liquid crystal panel, in accordance with an operation on the rotary operator unit.

In the second embodiment, a LED is exposed from the casing of the liquid crystal display device. By blinking of the LED, users are notified that the rotation amount of the rotary knob exceeds a threshold angle. In this respect, there can be an in-built loudspeaker instead of the LED, and users can then be notified of an excess of the rotation amount of the rotary knob over a threshold angle by a beep or click sound from the loudspeaker.

In the second embodiment, the threshold for switching images is set to 45 degrees when the main display is an operation target of the rotary operator unit. When the sub-display is an operation target of the rotary operator unit, the threshold for switching images is set to 15 degrees. However, the angular thresholds are not limited to these degrees. Thresholds other than these degrees can be set as long as the threshold to be set when the main display is an operation target is greater than another threshold to be set when the sub-display is an operation target.

In the first embodiment, the load applied to the rotary operator unit is switched between two values respectively corresponding to the high-speed drive mode and the low-speed drive mode. However, the drive speed of a liquid crystal may vary depending on the data amount of an image data set as a target to be displayed. Accordingly, the configuration may be modified so that the load is finely adjusted afterward in accordance with the data amount of an image data set as a target to be displayed. A structure and operation of such a modification will now be described conceptually below. That is, “a rotary operator unit includes: a display medium that displays information; a storage unit that stores a plurality of image data sets; a selection unit that selects a drive mode of the display medium; a rotary unit that rotates about an axis; a rotation amount detection unit that detects a rotation amount of the rotary unit; a display controller that reads out an image data set specified depending on the rotation amount detected, from the storage unit, and causes the display medium to display the image data set specified; and a load application unit that applies a load to the rotary unit, to hinder rotation of the rotary unit, specifies a reference amount for the load to apply, in accordance with the drive mode selected by the selection unit, and adjusts the reference amount specified, depending on a data amount of the image data set read out.”

In the second embodiment, the image to be displayed on the main display10is not limited to an image expressing a main document. For example, supplemental information such as a menu screen for operating the information processing device can be displayed on the main display10. In this case, the load may be switched in accordance with the type of an image to be displayed, for e.g., the load is increased when displaying a document while the load is reduced when displaying a menu.

The loads applied to the rotary operator unit are not limited to those described in the first and second embodiments. Specifically, the “load” of the operator unit is an amount of work which is required to rewrite a unit information amount of a displayed image in a display device as an operation target. Since W=F×Δx (here, W, F and Δx denotes work, force and displacement, respectively), the “load” of the operator unit refers to at least one of the force and displacement, which is required for rewriting a unit information amount of a displayed image. In other words, in any embodiment or modification, any type of information processing device may be used as far as the information processing device controls at least one of the force and the displacement amount, depending on display rewrite time per unit information amount in a display device, wherein the force is required for moving the rotary unit by a unit displacement amount, and the displacement amount is required for triggering an instruction to rewrite display.

The above embodiments have been described with reference to examples in which the operator unit is of a rotary type. However, the operator unit is not limited to a rotary type. An operator unit having a structure using a slidable lever or a so-called trackball or an operator unit having any other type of structure can be used as far as the operator unit outputs a signal corresponding to displacement of the operator unit from a reference point (e.g., a rotation axis, an end of a slidable lever, the center of a trackball, etc.)

Also, the above embodiments have been described with reference to examples in which a cholesteric liquid crystal layer is used as the display medium in a display device. However, the display medium is not limited to cholesteric liquid crystal. For example, an electrophoretic medium or any other type of memorable display medium can be used. The number of displays included in one information processing device is not limited to those exemplified in the above embodiments. For example, in the first embodiment, the information processing device can include two or more displays. In this case, at least one of the plural display devices needs to be driven in plural drive modes having respectively different rewrite speeds. In the second embodiment, for example, the information processing device can include three or more displays. In this case, at least one of the plural display devices needs to utilize a display medium having a different rewrite speed than those of the other displays.