JP4545726B2 - Image display device and image display module - Google Patents

Description

  The present invention relates to a display device, and in particular, simplifies the configuration of the storage means in an image display device using an image display panel incorporating a storage means for each pixel, suppresses a decrease in aperture ratio, and reduces power consumption. And an image display module using the image display device.

  As a thin and lightweight image display device, an image display device using various image display panels such as a liquid crystal display panel, a plasma display panel, or an organic EL (electroluminescence) panel is known. An image display panel that constitutes this type of image display apparatus has a so-called active display, in which a large number of pixels are arranged in a matrix, and an active element for controlling lighting (ON) and extinguishing (OFF) of each pixel is provided. Matrix type image display devices have become mainstream. As the active element used in the image display device, a thin film transistor, a thin film diode, or the like is widely used.

  In the following description, an image display apparatus using a liquid crystal display panel mainly including a thin film transistor as an active element will be described as an example of the image display panel. However, the other types of image display panels described above and this image display panel are used. It goes without saying that the present invention can also be applied to image display devices. Further, one pixel corresponds to each pixel in monochrome display, and in the case of one color pixel, it means a unit pixel (sub-pixel) responsible for each color. However, hereinafter, a unit pixel in the case of a single color pixel is also simply referred to as a pixel, unless particularly required.

In order to control active elements such as thin film transistors and thin film diodes engaged in on / off of pixels as the above active matrix type image display device, so-called static type semiconductor memory means (hereinafter referred to as image memory elements or simply memory elements) Is also provided for each pixel to reduce power consumption (for example, see Patent Document 1 below). Patent Document 2 below includes a data holding unit that holds image data supplied to a plurality of pixels, in order to provide a liquid crystal display device that can reduce power consumption. A liquid crystal display device that applies a voltage to a liquid crystal based on the stored image data is disclosed. A dynamic semiconductor memory element is used for the data holding means of the liquid crystal display device disclosed in the latter publication.
JP-A-8-194205 Japanese Patent Laid-Open No. 2001-306038

However, since the image memory element provided for each pixel of the image display panel constituting the conventional image display apparatus as described above is configured using a semiconductor element or a semiconductor element and a capacitor, a large number of pixels are included in the pixel region. A semiconductor element needs to be built in, or a large area is required to construct a capacitor. In other words, a device including a conventional static image memory element requires a large number of transistors, making it difficult to produce an image display panel and reducing the effective display area in the pixel area, that is, the aperture ratio.

In addition, in the case of a device equipped with a dynamic image memory element, since information is stored using a capacitor, a region for forming the capacitor is necessary in the pixel region. It becomes smaller and the aperture ratio decreases. Further, in the dynamic type image memory element, the charge accumulated in the capacitor decreases with time in accordance with the stored image data. Therefore, it is necessary to periodically refresh the stored image data so that the stored image data does not change. For this reason, the circuit configuration inside and outside the pixel becomes complicated, and a circuit for refreshing is required, which increases the circuit scale.

  Furthermore, since the image memory device disclosed in the prior art is a volatile memory in which image data in the memory disappears when the power is turned off, a voltage is always applied to such an image memory device. In other words, it is necessary to rewrite data when the power is turned on again, which is one of the obstacles to the reduction of power consumption.

  As described above, the image display apparatus using the conventional image display panel has many problems to be solved. A first object of the present invention is to simplify the configuration of an image memory element provided for each pixel of an image display panel to suppress a reduction in the aperture ratio of the pixel, and image data is retained in the pixel even when the power is turned off. Another object of the present invention is to provide an image display apparatus configured with an image display panel that achieves low power consumption.

  A second object of the present invention is to provide an image display module with low power consumption using the above image display device.

  In order to achieve the first object, the present invention provides a plurality of pixels in a matrix at intersections of a plurality of scanning electrode line lines and a plurality of signal (display data) electrode lines intersecting the scanning electrode line lines. An image display panel having a display element, a scanning electrode line selection circuit for selecting the scanning electrode line of the image display panel, a signal electrode line driving circuit for driving the signal electrode line, and display data for each pixel The image display apparatus is configured with the storage means for storing. The storage means is composed of a resistor connected to each pixel, and stores display data in the pixel based on a resistance value of the resistor.

  The storage means (hereinafter also referred to as an image memory element) is preferably controlled by a current signal, and can be a nonvolatile storage means. The image memory element uses a phase change of a storage medium constituting the image memory element or a resistance change accompanying the phase transition. As the phase change medium, a material that resists by a phase change between a crystalline state and an amorphous state can be used, and a GeSbTe-based phase change medium is preferably used. The pixels connected to the image memory element can be electrically separated from the scanning electrode lines and the signal electrode lines. In that case, as in the simple matrix type, the rewriting means which is always electrically connected to the scanning line and the signal line can be directly driven by the scanning electrode line and the signal electrode line.

  Further, it is possible to provide a reading means for reading the data stored in the storage means. By providing calculation means for calculating the image data (also referred to as display data or display signal) read by the reading means and the next image data to be displayed next, the read image data and the next image data are compared and different. Only in this case, the data stored in the storage means can be rewritten. A plurality of storage means can be provided in one pixel.

  In order to achieve the second object, the present invention provides a display element comprising a plurality of pixels in a matrix at intersections of a plurality of scanning electrode lines and a plurality of signal electrode lines intersecting the scanning electrode lines. An image display panel comprising: a recording device that records display data on the image display device; and a display drive device that displays display data recorded on the image display panel by the recording device. The panel can be selectively connected to one of the recording device and the display driving device or both of them simultaneously.

  The image display panel has a nonvolatile storage means for storing display data for each pixel, a scanning line connection unit for inputting a scanning signal to the scanning line, and a display data signal to the signal line. A signal line connection unit for driving, a drive line connection unit for inputting a drive signal for driving the pixel, and a power line connection unit.

  The recording device is connected to a scanning line selection circuit, a signal line driving circuit and a signal control circuit for driving the scanning lines and the signal lines of the liquid crystal display device, and to the signal line connecting portion and the driving line connecting portion. A recording device connecting section.

  The storage device is connected to the image display panel via the recording device connection unit, and the storage unit stores the data stored in the storage unit by inputting a rewrite signal of the storage unit to the scanning line connection unit and the signal line connection unit. rewrite.

  The display drive device includes a counter electrode drive circuit and a power supply circuit, and a display drive device connection unit connected to the drive line connection unit and the power supply line connection unit of the image display panel, and the image display panel includes the display drive device connection unit. The display drive device is connected via a display drive device connection unit to display the display data stored in the image display panel.

  Further, a plurality of image memory elements can be provided in one pixel of the image display panel, and a plurality of images can be switched by switching them.

  The present invention is not limited to the above-described configuration and the configuration of the embodiments described later, and it goes without saying that various modifications can be made without departing from the technical idea of the present invention.

  As described above, according to the present invention, the non-volatile memory based on the resistance change is provided in the pixel, thereby simplifying the configuration of the display panel having a display data storage function, improving the aperture ratio, and reducing the consumption. It is possible to provide an image display device that retains image data in pixels even when power is turned off.

  Embodiments of the present invention will be described below in detail with reference to the drawings of the embodiments.

  FIG. 1 to FIG. 7 are explanatory views of a first embodiment of a liquid crystal display device according to the present invention, in which the present invention is applied to a liquid crystal display panel as an image display panel constituting the liquid crystal display device. FIG. 1 is a circuit diagram for explaining the structure of one pixel constituting the image display panel, that is, the liquid crystal display panel of the image display apparatus according to the first embodiment of the present invention, and FIG. 2 is a liquid crystal having the pixel shown in FIG. It is a block diagram of the image display apparatus comprised using the display panel.

The pixel of this embodiment shown in FIG. 1 is composed of a thin film transistor (hereinafter simply referred to as TFT) 17 as a switching element, a liquid crystal element 5, and an image memory element 1, and is surrounded by a dotted line 127 in FIG. It is shown by. This pixel is arranged as a pixel 127 at the intersection of the scanning electrode line 7 driven by the scanning line selection circuit 103 and the signal electrode line 9 driven by the signal line driving circuit 101 in FIG. Reference numeral R _LC indicates the resistance value of the liquid crystal element 5, and R _PC indicates the resistance value of the image memory element 1. Reference numeral 15 denotes a reference electrode line for applying a voltage to the liquid crystal element 5 and flowing a current to the image memory element 1, 25 a pixel electrode, Gm an mth scanning electrode line, and Dn an nth. A signal electrode line is shown.

  The image display device shown in FIG. 2 is an active matrix liquid crystal display device that displays an image by controlling the TFT 17 provided in the pixel 127. This image display device has a matrix of a large number of scanning electrode lines 7 and a large number of signal electrode lines 9 intersecting the scanning electrode lines 7 on the inner surface of a first substrate 77 made of an insulating plate such as glass. As described above, the pixels 127 are arranged in a matrix at the intersections of the scanning electrode lines 7 and the signal electrode lines 9. The pixel electrode 25 driven by the thin film transistor 17 of a large number of pixels arranged in a matrix is liquid crystal by an electric field formed between the counter electrode 3 formed on the inner surface of the second substrate preferably made of glass or the like (not shown). The orientation of the element 5 is controlled.

  The image memory element 1 shown in FIG. 1 is provided in one pixel 127, and holds image data (display data) to be displayed on the pixel 127. The image memory element 1 can record image data by reversibly changing resistance, and can rewrite the recorded image data. In normal use, the recorded image data is a non-volatile memory that does not disappear.

The image memory element 1 is switched by a pulse current from the signal electrode line 9 and controls a resistance state to be switched by changing a current value and a pulse width of the pulse current. 2, numbered sequentially scan electrode line 7 at the top as G _1, also in the case of the leftmost signal electrode line 9 numbered sequentially as D _1, the scanning electrode lines of the number G _m 7 a circuit diagram of a pixel at the intersection of D _n-th signal electrode line 9 corresponds to FIG. When the _Gm- th scanning electrode line 7 is selected and the voltage becomes high level, the n-type TFT 17 whose gate is connected to the scanning electrode line 7 is turned on, and the current signal flowing through the signal electrode line 9 at this timing (That is, image data) is taken into the TFT 17 and flows to the reference electrode line 15 through the image memory element 1. The resistance value of the image memory element 1 changes according to the current value or pulse width flowing through the pixel memory element 1, and the resistance value is stored as image data.

In this embodiment, the pixel electrode 25 of the liquid crystal element 5 (shown by the connection point between the liquid crystal element 5 and the TFT in the figure) is connected to the reference electrode line 15 via the image memory element 1, and the counter electrode of the liquid crystal element 5 The drive voltage applied between the reference electrode line 15 and the reference electrode line 15 is applied to the image memory element 1 and the liquid crystal element 5 connected in series. Therefore, a voltage determined by resistance division between the resistor _RPC of the image memory element 1 and the resistor _RLC of the liquid crystal element 5 among the drive voltages is applied to the liquid crystal element 5 as an effective liquid crystal drive voltage. Resistance R _PC of the image memory device 1 is a liquid crystal driving voltage is changed accordingly when changes in switching the display state of the liquid crystal element 5 is switched.

FIG. 3 is an explanatory diagram of voltage-reflectance characteristics of a normally closed mode liquid crystal element used in the liquid crystal display panel of the first embodiment of the present invention. The reflectance is shown as a relative value. The drive voltage between the counter electrode 3 and the reference electrode line 15 is V, the threshold voltage at which the liquid crystal element 5 is in the closed state is V _min , the threshold voltage at which the liquid crystal element 5 is in the open state is V _max , and the resistance in the high resistance state of the image memory element 1 is When RH and the resistance in the low resistance state are RL,
V _min ≧ R _LC V / (R _LC + RH)
V _max ≦ R _LC V / (R _LC + RL)
By satisfying the condition, the display state of the liquid crystal element 5 can be switched using the resistance change of the image memory element 1. Further, it is desirable that R _LC ≧ RH. That is, when R _LC ≧ RH, the current injected from the TFT 17 mainly flows through the image memory element 1, and the current can be effectively used for switching of the image memory element 1. Similarly, in the normally open mode, the threshold voltage may be satisfied.

  FIG. 4 is a waveform diagram of current pulses for switching the image memory element 1 used in the first embodiment of the present invention. In this embodiment, a thin film (phase change film) of a phase change medium that reversibly changes between two phases of crystal and amorphous is used as the storage medium of the image memory element 1. Resistance is different between the crystalline state and the amorphous state of the phase change medium. Generally, the crystalline state (also referred to as a crystalline phase) has a low resistance, and the amorphous state (also referred to as an amorphous phase) has a high resistance. A phase change can be caused by heating the memory medium.

In this embodiment, the memory medium constituting the image memory element is heated by using Joule heat generated by flowing an electric current to cause a phase change. When an image memory medium made of a phase change film is changed to an amorphous phase (hereinafter referred to as a reset operation), a current equal to or higher than I _reset in FIG. 4 is supplied to melt the phase change film. The molten phase change film is amorphized by setting the current flow time T _reset to be equal to or longer than the time when the phase change film is heated to the melting point or more and less than the time when the molten phase change film is rapidly cooled to become amorphous. To do. On the other hand, in the case of crystallization (hereinafter referred to as a set operation), annealing is performed by flowing a current not less than I _th and less than I _reset for a time T _set sufficient for the phase change film to crystallize. Crystallize.

As described above, when the phase is changed from crystal to amorphous (reset operation), a current equal to or higher than I _reset is supplied for a short time to melt and rapidly cool the phase change medium. When the phase is changed from amorphous to crystal (set operation), a current between I _th and I _reset is applied for a long time, and the crystal is maintained at a temperature equal to or higher than the crystallization temperature. Regardless of the state before the phase change, it is possible to erase the previous phase state and rewrite it to a new phase state by flowing the current with the same pulse waveform. As a material for the phase change medium, it is desirable to use a chalcogenide-based material such as GeSbTe-based, InSbTe-based, or AgInSbTe-based. In this example, compositions of GeSb ₂ Te ₄ , In ₂ SbTe ₃ , and Ag ₅ In ₅ Sb ₇₀ Te ₂₀ were used.

Since these phase change media cause a phase change with a current pulse of 50 ns or less, they can be switched at high speed (crystalline phase or amorphous phase). In this embodiment, 30 ns to 50 ns is used as T _reset , and 50 ns to 100 ns is used as T _set . If the composition of these phase change media is changed, the phase change rate can be slowed down, so that the phase change rate can be adjusted in accordance with the drive performance of the drive circuit. In GeSb ₂ Te ₄ , the resistance changes from 100 times to 1000 times between the crystalline state and the amorphous state.

Further, the GeSbTe system is excellent in the number of repeated rewrites, and the InSbTe system has a large resistance ratio between crystal and amorphous, and it is desirable to select an appropriate material in accordance with the characteristics of the image display device. Since these materials have a glass transition temperature sufficiently higher than room temperature, the state of each phase is maintained for a long time and functions as a nonvolatile memory. In addition to the chalcogenide system, a material that causes a metal-insulator transition depending on temperature, such as VO ₂ , can also be used. A material that causes a metal-insulator transition accompanying a structural phase transition can also be used.

  FIG. 5 is an explanatory diagram of signal waveforms for driving the image display panel. The voltage VGm of the scanning electrode line 7 shown in FIG. 2 is selected once every frame period by the scanning line selection circuit 103 and becomes high level. An image data signal is supplied to the signal electrode line 9 from the signal line driving circuit 101. In this embodiment, a current signal for rewriting the image memory element 1 is supplied as an image data signal. In the pixel formed at the intersection of the mth scan electrode line 7 and the nth signal electrode line 9, when the voltage VGm of the mth scan electrode line 7 becomes high level, the TFT 17 is turned on and becomes conductive. At this time, the current IDn flowing through the signal electrode line 9 passes through the TFT 17 and is supplied to the image memory element 1.

As described with reference to FIG. 4, when the phase is changed from the crystalline phase to the amorphous phase (reset operation), a current higher than I _reset is passed for a short time to change the phase from the amorphous phase to the crystalline phase (set operation). _Causes a longer current to flow between I _th and I _reset . The selection time of one scanning line is about 16 μs even when the normal frame period is about 60 Hz and the number of scanning lines is 1000, which is sufficiently longer than the rewriting time of the image memory element 1. In the present embodiment, the liquid crystal element 5 is turned off when the image memory element 1 is reset, and the liquid crystal element 5 is turned on when the image memory element 1 is set. Also changes. A driving voltage VCOM for driving the liquid crystal element 5 is applied to the counter electrode 3.

  In this embodiment, the drive voltage VCOM is an AC voltage that reverses its polarity every frame period. Therefore, by reversing the polarity of the base voltage VLCmn of the signal electrode line 9 in the same manner as the drive voltage VCOM, the potential difference between the signal electrode line 9 and the counter electrode 3 can be reduced, and the current flowing through the liquid crystal element 5 can be reduced. The current is reduced so that most of the current flows through the image memory element 1. The polarity of the signal current IDn is also inverted in accordance with the inversion of the drive voltage VCOM.

  In this embodiment, since a non-volatile memory is provided as an image memory element in a pixel, it is not necessary to write image data until the display image changes after the image data is once written to the image memory element 1. . Therefore, the image display panel (image display device) that holds image data using a conventional capacitor had to refresh the data at regular intervals even when still images were displayed. In the example, no refresh is required. Accordingly, when displaying information such as characters and still images, only the liquid crystal driving voltage needs to be supplied until the display image changes. Further, since a non-volatile memory is used, flicker due to the alternating liquid crystal drive voltage does not occur, and the drive frequency of the liquid crystal drive voltage can be slowed to such an extent that the liquid crystal does not deteriorate. Therefore, the power consumption due to the charge / discharge of the liquid crystal capacitance accompanying the liquid crystal drive and the charge / discharge of the floating capacitance of the wiring can be greatly reduced, and the power consumption can be reduced.

  In addition, when it is possible to switch between still image display using an image memory and moving image display without using an image memory element, it is desirable that one frame time is an integral multiple of the image data writing time. This is because moving image display and still image display can be switched using a clock that matches the frequency of moving image display. Further, when displaying a moving image, it is not necessary to rewrite data at a high speed and hold the data, so that one frame time may be the same as the data writing time. In addition, when displaying a moving image, it is not necessary to store image data. Therefore, a switch for separating the image memory element from the pixel may be provided so that the image memory element 1 is not used. Since the number of rewrites of the image memory element can be reduced, the reliability of the image memory element is improved.

  During the image data writing time, the counter electrode 3 may have a high impedance so that no current flows through the liquid crystal element 5. In this case, it is not necessary to apply an AC voltage to the signal electrode line 9 or to invert the current. Further, alternating current for driving the liquid crystal may be supplied to the reference electrode line 15, and alternating current may be supplied to both the counter electrode 3 and the reference electrode line 15.

  FIG. 6 is a cross-sectional view of the main part of the first substrate constituting the liquid crystal display panel in the first embodiment of the present invention. In the figure, reference numeral 77 is a glass substrate, 51 is a gate electrode, 69 is an insulating film (gate insulating film), 71 is a silicon film, 79 is an N + silicon film, 53 is a source electrode, 55 is a drain electrode, and 61 is a memory. An element electrode, 67 is a phase change film, and 25 is a pixel electrode. As in FIG. 1, reference numeral 1 denotes an image memory element, and 17 denotes a thin film transistor.

  In this embodiment, the TFT is formed using amorphous silicon (a-Si) as the silicon film 71. A gate electrode 51 and an image memory element electrode 61 are formed on a glass substrate 77. The image memory element electrode 61 in contact with the phase change film 67 preferably has high heat resistance. By using a refractory metal such as tantalum Ta, molybdenum tantalum MoTa, molybdenum tungsten MoW, tungsten W, or molybdenum Mo, which is often used as a material for the gate electrode 51 of the TFT, the gate electrode 51 and the image memory element electrode 61 are formed. They can be formed simultaneously using the same material. An insulating film 69 is formed on the gate electrode 51 and the image memory element electrode 61 of the TFT 17 using silicon oxide (SiOx) or silicon nitride (SiNx).

  A contact hole is formed in the insulating film 69, and a phase change film 67 is formed so as to be in contact with the image memory element electrode 61. An amorphous silicon film 71 is formed on the insulating film 69 immediately above the gate electrode 51 of the TFT 17. An N + silicon layer 79 is formed thereon, and a source electrode 53 and a drain electrode 55 of the TFT 17 are formed from a metal such as aluminum.

  The source electrode 53 also covers the phase change film 67 as a partial electrode of the image memory element 1. Further, the source electrode 53 is also connected to the pixel electrode 25. A channel portion of the TFT 17 is formed so that the source electrode 53 and the drain electrode 55 are separated, and the TFT 17 is formed. Further, a protective film (not shown) is formed on the top. When a transparent electrode is used as the pixel electrode 25, a transmissive image table panel can be formed. When a metal film such as aluminum is used as the pixel electrode 25, a reflective image display panel is obtained. In the case of the reflection type, the pixel electrode 25, the TFT 17, and the image memory electrode 61 may be separated vertically, and the pixel electrode 25 may be formed so as to cover the TFT 17 and the image memory element electrode 61. In that case, the aperture ratio is large. it can.

The phase change film 67 is heated by a current signal flowing from the source electrode 53 of the TFT and the image memory element electrode 61. The width of the phase change film 67 is narrowed on the image memory element electrode 61 side, current concentration occurs here, and the amount of heat generation increases. Therefore, the phase change film 67 has a higher temperature on the image memory element electrode 61 side and is easily melted. Therefore, the image memory element electrode 61 desirably has a melting point higher than that of the phase change film 67. Further, the heat generated in the phase change film 67 escapes well to the source electrode 53 side having a large thermal conductivity, and is rapidly cooled when the current is cut off. As the image memory element electrode 61, silicide such as tantalum silicide TaSi ₂ can also be used.

  The TFT 17 is not limited to the one using the amorphous silicon of this embodiment, but may be made using polysilicon (p-Si) or single crystal silicon. In addition to the inverted stagger type of the present embodiment, a normal stagger type, a coplanar type, or the like can also be used for the TFT structure.

The resistance value RH of the phase change film 67 in the high resistance state is desirably as large as the resistance R _LC of the liquid crystal element 5. On the other hand, it is desirable that the voltage for passing a current through the image memory element 1 is low. For this purpose, it is desirable to increase the resistance value RH by reducing the cross-sectional area while maintaining the thickness of the phase change film 67.

  FIG. 7 is a block diagram illustrating the configuration of the image display apparatus in the first embodiment of the present invention. In the figure, the signal line control circuit 101 includes a serial-parallel (S / P) conversion circuit 105, a line memory 107, and a voltage-current conversion circuit 109. Reference numeral 111 denotes a signal control circuit, which controls signal lines based on an image signal processing circuit 113 that converts an image signal input from an external signal source (not shown) into an image data signal that is displayed on a liquid crystal display panel, and a synchronization signal. The driver control circuit 115 generates control signals for the circuit 101 and the scanning line selection circuit 103.

  The signal control circuit 111 that receives the image signal and the synchronization signal from the external signal source sends image data from the image signal processing circuit 113 to the signal line control circuit 101, and outputs a control signal from the driver control circuit 115. In the signal control circuit 101, the image data signal transmitted as a serial signal in the serial-parallel signal conversion circuit 105 is converted into parallel signals for the number of signal electrode lines 9, and the image data for one scanning line is stored in the line memory 107. Remember. The image data stored in the line memory 107 is converted into a current value by the voltage-current conversion circuit 109 and output in accordance with the timing of the control signal.

  The scanning line selection circuit 103 selects the scanning electrode line 7 in synchronization with the control signal to make it high level, and scans the scanning electrode lines 7 that are sequentially selected. The power supply circuit 117 generates a reference voltage for the data signal, a required voltage to be applied to the scanning electrode line 7 and the counter electrode 3, converts the voltage applied to the counter electrode 3 by the counter electrode driving circuit 119 to an AC, Apply.

  Compared to conventional nonvolatile memories such as flash memories, the nonvolatile memory using the phase change medium described above is characterized in that it can be rewritten at high speed and with low voltage and low power consumption. In addition, the number of rewrites is large, and rewriting at 60 Hz has a lifetime of 10 years or more, and has a sufficient lifetime when displaying moving images. Further, this type of memory has a feature that the cell area is small and the reduction of the aperture ratio of the image display panel is small even if a memory element is mounted. By using this memory as an in-pixel memory element of an image display panel (image display device), effects of low power consumption, high aperture ratio, and long life can be obtained. Further, since the memory element can be made small, it is suitable for a high-definition image display device. In that case, high-quality color image data can be displayed by using area gradation even in binary display.

  In the above, the embodiments of the present invention using liquid crystal have been described for the liquid crystal display panel using the counter electrode and the liquid crystal display device using the liquid crystal display panel, but the liquid crystal display panel and the liquid crystal display device used in the present invention, and The display mode or element structure is not particularly limited. For example, the present invention can be similarly applied to an image display apparatus using an in-plane switching type liquid crystal display panel. As the display mode, TN (Twisted Nematic) liquid crystal, guest host liquid crystal, PDLC liquid crystal, or the like can be used. Further, when a cholesteric liquid crystal exhibiting bistability is used, the display is stored in the liquid crystal, so that the display can be held even when the liquid crystal driving voltage is turned off. When this bistable cholesteric liquid crystal is used, the image memory element does not need to be non-volatile, and an element whose resistance changes reversibly may be used. In addition, when the characteristics change when the memory medium is exposed to light, it is desirable to shield the memory medium from light.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 8 is a circuit diagram illustrating the configuration of one pixel of a liquid crystal display panel which is an image display panel according to the second embodiment of the present invention. In the figure, reference numeral 17a denotes a first TFT, 17b denotes a second TFT, 21 denotes a bypass resistor, and _RBP denotes a resistance value thereof. The same reference numerals as those in FIG. 1 correspond to the same functional parts. When the scanning electrode line 7 is selected and becomes high level, the first TFT 17a and the second TFT 17b are brought into conduction. Therefore, the current data signal flowing through the signal electrode line 9 flows through the image memory element 1 through the first TFT 17a, and the image memory element 1 is switched to a memory state corresponding to the current data.

When the high resistance state of the image memory element 1 is RH, the resistance of the bypass resistor 21 is R _BP , and the resistance of the liquid crystal element 5 is R _LC , if the relationship of RH <R _BP <R _LC is satisfied, The current data signal introduced from the first TFT 17 a mainly flows through the image memory element 1 and is effectively used for switching of the image memory element 1. At this time, since the second TFT 17 b is also conductive, the current that slightly flows to the liquid crystal element 5 passes through the bypass resistor 21, and hardly any current flows through the liquid crystal element 5.

When the scanning electrode line 7 becomes low level, both the first TFT 17a and the second TFT 17b are turned off, and the resistance R of the liquid crystal element 5 against the voltage applied between the reference electrode line 15 and the counter electrode (not shown). since the voltage determined by the resistance division of the resistor R _PC of the _LC and the image memory device 1 is applied to the liquid crystal element 5, it is possible to switch the display of the liquid crystal display device 5 according to the resistance of the image memory device 1. According to the present embodiment, the same effect as the above embodiment can be obtained, and high-quality color image data can be displayed.

  FIG. 9 is a circuit diagram illustrating the configuration of one pixel of a liquid crystal display panel which is an image display panel according to the third embodiment of the present invention. In the figure, reference numeral 1a is a first image memory element, 1b is a second image memory element, and the same reference numerals as those in FIG. 8 correspond to the same functional parts. In FIG. 9, when the scanning electrode line 7 is selected and becomes high level, the TFT 17 becomes conductive. The current data signal that has flowed through the signal electrode line 9 passes through the TFT 17 and flows through the first image memory element 1a or the second memory element 1b to switch to a memory state corresponding to the current data. By controlling the voltage of the signal electrode line 9, it is possible to select the image memory elements 1a and 1b through which a current flows. By continuously rewriting the first image memory element 1a and the second image memory element 1b, the resistances of the first memory element 1a and the second memory element 1b can be controlled independently.

When the scanning electrode line 7 becomes a low level, the TFT 17 is turned off, and the liquid crystal element 5 has the first image memory element 1a and the first image element in response to the voltage applied between the reference electrode line 15 and the counter electrode (not shown). Since the voltage determined by the resistance division of the second image memory element 1 b is applied to the liquid crystal element 5, the display of the liquid crystal element 5 can be switched by the resistance change of the image memory element 1. That is, when the resistance of the first image memory element 1a and the second image memory element 1b is the same,
VH = V · RH / (RH + RL)
≒ V
VL = V · RL / (RH + RL)
≒ 0
VM = V · RH / (RH + RH)
≒ V / 2
Therefore, the liquid crystal element 5 can display halftones in addition to the on and off states.

  In this embodiment, since the voltage applied to the liquid crystal element 5 does not depend on the resistance of the liquid crystal element 5, the image quality is stabilized regardless of changes in the resistance of the liquid crystal element 5 and variations in resistance of the liquid crystal material. In addition, the liquid crystal driving voltage can be efficiently applied to the liquid crystal element 5. The voltage VL is close to zero volts, and the on / off ratio of the voltage applied to the liquid crystal is good. According to the present embodiment, in addition to the above-described effects, the same effects as the above-described embodiments can be obtained, and high-quality color image data can be displayed.

  FIG. 10 is a circuit diagram illustrating the configuration of one pixel of a liquid crystal display panel which is an image display panel according to the fourth embodiment of the present invention. In the figure, reference numeral 19 is a p-type TFT, 21 is a resistor, 13 is a power supply electrode line, 11 is a drive voltage supply electrode, and the same reference numerals as those in the previous embodiment correspond to the same functional parts. In FIG. 10, when the scanning electrode line 7 is selected and becomes high level, the first TFT 17a becomes conductive and the p-type TFT 19 is cut off. The current data signal that has flowed through the signal electrode line 9 passes through the first TFT 17 a and flows through the image memory element 1 and the resistor 21. The image memory element 1 switches the memory state according to the flowing current data.

  When the scanning electrode line 7 becomes low level, the first TFT 17a is cut off and the p-type TFT 19 is turned on, so that the DC voltage between the power electrode line 13 and the reference electrode line 15 is between the image memory element 1 and the resistor 21. Is applied. A voltage corresponding to the resistance division between the image memory element 1 and the resistor 21 is applied to the gate of the second TFT 17b, and the gate voltage of the second TFT 17b changes according to the resistance value of the image memory element 1. By determining the resistance value of the resistor 21 so that the second TFT 17b is turned on / off by this voltage change, the on / off state of the second TFT 17b can be controlled according to the resistance value of the memory element 1.

  That is, when the resistance of the image memory element 1 is high, the gate voltage decreases, so the second TFT 17b is turned off. Conversely, when the resistance of the image memory element 1 is low, the gate voltage increases and the second TFT 17b becomes Turn on. When the second TFT 17b is turned on, the voltage of the driving voltage supply power source 11 is applied to the liquid crystal element 5, and when the second TFT 17b is turned off, the driving voltage is not applied. The on / off state of the liquid crystal element 5 can be controlled.

  In this embodiment, since the voltage applied to the liquid crystal element 5 is switched using the second TFT 17b, the liquid crystal element 5 can be sufficiently switched on and off. In addition, since the resistance of the image memory element 1 only needs to change within a range in which the gate of the second TFT 17b can be controlled, the influence on the image quality due to variations in the resistance value of the image memory element 1, characteristic changes due to repeated operations, and the like. There is almost no and the image quality is stable. In this embodiment, the p-type TFT 19 is controlled by using the scanning electrode line 7, but an n-type TFT is used in place of the p-type TFT 19, and a signal line for controlling the n-type TFT is separately provided. A circuit can also be configured using only n-type TFTs.

  FIG. 11 is a circuit diagram illustrating the configuration of one pixel of a liquid crystal display panel which is an image display panel according to the fifth embodiment of the present invention. In the figure, the same reference numerals as those in the previous embodiment correspond to the same functional parts. In FIG. 11, when the scanning electrode line 7 is selected and becomes high level, the first TFT 17a and the second TFT 17b are turned on, and the p-type TFT 19 is turned off. The current data signal that has flowed through the signal electrode line 9 passes through the first TFT 17a and flows from the image memory element 1 through the second TFT 17b to the image memory element 1, and the image memory element 1 stores the memory corresponding to the current data. Switch to state. Since this current flows from the image memory element 1 through the second TFT 17 b to the reference electrode line 15, no current flows through the liquid crystal element 5.

  When the scanning electrode line 7 becomes low level, the first TFT 17a and the second TFT 17b are turned off and the p-type TFT 19 is turned on, so that the drive voltage is supplied to the image memory element 1 and the liquid crystal element 5 through the p-type TFT 19. A drive voltage from the electrode 11 is applied, and a voltage corresponding to the memory state of the image memory element 1 is applied to perform pixel display.

Normally, the liquid crystal element 5 has a high resistance and the flowing current is small. Therefore, according to the present embodiment, the power consumed by the liquid crystal element 5 and the image memory element 1 during image display is small, and lower power consumption is realized. it can. Further, since the resistance value of the image memory element 1 can be continuously changed by controlling the value of the current flowing through the image memory element 1 between I _reset and I _th , gradation display is performed on the liquid crystal element 5. It is also possible.

In addition, since the current for switching the image memory element 1 is a short-time pulse, the second TFT 17b may not be provided when the current can flow to the reference electrode line 15 through the capacitance of the liquid crystal element 5. . That is, when the resistance value of the liquid crystal pixel is larger than the resistance value of the phase change memory (image memory element 1) and can be ignored, the impedance of the image memory element 1 and the liquid crystal element 5 is the resistance value R _PC of the image memory element 1. And √ {R _PC + (1 / 2πfc) ² } with respect to the frequency f.
It is expressed. Therefore, when R _PC and (1 / 2πfC) are approximately the same or R _PC is larger, current can flow through the capacitance of liquid crystal element 5.

A single pulse having a pulse width T that flows through the image memory element 1 may be converted to f = 1 / 2T. Therefore, a pulse having a pulse width of 100 ns corresponds to 5 MHz. That is, when the pulse width is short as in the phase change medium of the present embodiment, it is desirable that current easily flows through the liquid crystal capacitance. When current flows through the capacitance of the liquid crystal element 5, the liquid crystal element is not heated by the resistance of the liquid crystal element, and deterioration of the liquid crystal is suppressed.

  FIG. 12 is a circuit diagram of one pixel of a liquid crystal display panel which is an image display panel according to the sixth embodiment of the present invention. In this embodiment, in addition to the rewriting circuit of the image memory element 1, a memory reading circuit 123 for reading the state of the image memory element is provided. The memory read circuit 123 includes a switch 125. First, the display operation of the image display apparatus will be described. In the case of display, the switch 125 is switched to the power supply circuit 117 side so that the reference electrode line 15 is connected to the power supply circuit 117. When the scanning electrode line 7 is selected and becomes high level, the TFT 17 is turned on. The current data signal that has flowed through the signal electrode line 9 passes through the TFT 17 and flows through the image memory element 1 to switch to the memory state corresponding to the current data.

When the scanning electrode line 7 becomes low level, the TFT 17 is turned off, and the driving voltage between the reference electrode line 15 and the counter electrode 3 is applied to the liquid crystal element 5 and the image memory element 1, and the resistance value of the image memory element 1 is determined. Thus, a display is made on the liquid crystal element 5. Next, in the read operation of the image memory element, the switch 125 is switched so that the reference electrode line 15 is connected to the memory read circuit 123 side. A read current of I _th or less is passed through the signal electrode line 9. When the scanning electrode line 7 becomes high level, it flows through the image memory element 1 through the TFT 17. By monitoring the voltage of the drive voltage supply electrode 11 shown in FIG. 11 in the memory read circuit 123, the state of the image memory element 1 can be read. By making this read current sufficiently smaller than I _th, the resistance value of the image memory element 1 does not change even when a read operation is performed, and the read can be performed any number of times.

  FIG. 13 is a block diagram of an image display apparatus according to the sixth embodiment of the present invention. In the image display apparatus of this embodiment, the signal line driving circuit 101 described in FIG. 7 is provided with the memory reading circuit 123 and the image data arithmetic circuit 121 shown in FIG. The image data arithmetic circuit 121 has a line memory equivalent to the line memory 107 in FIG. 7 that holds data from the serial-parallel signal conversion circuit (S / P conversion circuit) 105. The memory readout circuit 123 provided in the signal line driver circuit 101 is an image stored in the pixels 127 for one line selected by the scanning line selection circuit 103 (only one pixel in one line is shown in FIG. 13). Data is read out and sent to the image data calculation circuit 121.

  In the signal line driving circuit 101, the image data signal transmitted as a serial signal is converted into a parallel signal corresponding to the number of the signal electrode lines 9 in the serial-parallel signal conversion circuit 105, and the line included in the image data calculation circuit 121. Image data for one scanning line is sent to the memory. The image data calculation circuit 121 compares the image data held in the line memory with the data read from the image memory element in the pixel 127. Only when the two data are different as a result of the comparison, the rewrite data is sent to the voltage-current conversion circuit 109.

  The voltage-current conversion circuit 109 converts the rewrite data from the image data calculation circuit 121 into a current, and outputs it according to the timing of the control signal. The scanning line selection circuit 103 selects the scanning electrode line 7 to be high level, and sequentially performs scanning. The power supply circuit 117 generates a reference voltage for the data signal and a voltage to be applied to the scanning electrode line 7 and the counter electrode 27. The counter electrode drive circuit 119 converts the drive voltage applied to the counter electrode into an alternating current and applies it to the counter electrode 27.

  FIG. 14 is an explanatory diagram of signal waveforms for driving the image display panel according to the sixth embodiment of the present invention. In the figure, VGm is a voltage applied to the mth scanning electrode line 7, IDn is a current (signal current) flowing through the signal electrode line 9, r is a read current, and w is a write current. VCOM represents a driving voltage for driving the liquid crystal element 5, and VLC represents a voltage applied to the liquid crystal element 5. The voltage VGm of the scanning electrode line 7 is selected once every writing cycle by the scanning line selection circuit 103 and becomes high level. A current data signal is supplied to the signal electrode line 9 from the signal line driving circuit 101.

In the pixel at the intersection of the mth scan electrode line 7 and the nth signal electrode line 9, when the voltage VGm of the mth scan electrode line 7 becomes high level, the TFT 17 in FIG. The current IDn flowing through the signal electrode line 9 is supplied to the image memory element 1 through the TFT 17. During this selection signal is in a high level, flow reading out current r and the write current w. First, the read current r is supplied to read the memory information of the image memory element 1. The difference between the memory information and the next image signal held in the line memory provided in the image data calculation circuit 121 is taken, and the signal line drive circuit 101 applies the write current to the signal electrode line 9 only when the two data are different. And the image memory element 1 is switched.

  A driving voltage VCOM for driving the liquid crystal element 5 is applied to the counter electrode 27. In this embodiment, the drive voltage VCOM is an AC voltage that reverses its polarity every frame period. FIG. 14 shows the case where this one frame period is equal to one writing period. When displaying an image such as a still image, one frame period may be longer than one writing period. By reversing the polarity of the base voltage VGm of the signal electrode line 9 at the same timing as the drive voltage VCOM, the potential difference between the signal electrode line 9 and the counter electrode 27 is reduced, and the current flowing through the liquid crystal element 5 is reduced. The current was allowed to flow through the image memory element 1. The polarity of the signal current IDn was also inverted in accordance with the inversion of the drive voltage VCOM.

  The selection time of the scanning electrode line 7 is about 16 μs even when the normal frame period is about 60 Hz and the number of scanning lines is 1000, which is sufficiently longer than the reading and rewriting time of the image memory element. . Therefore, reading and writing can be performed during the selection time of one scanning line.

  In the present embodiment, since the data stored in the pixel can be rewritten only in a different pixel in the next image data, the number of rewrites of the image memory element 1 can be reduced. Therefore, even if the image memory element 1 having a short repetition life is used, the performance can be maintained and displayed over a long period of time. Further, since the data of the image memory element in the pixel can be read, it can function as an image memory without providing an image memory separately. Other effects of the present embodiment are the same as those of the previous embodiment.

  FIG. 15 is a circuit diagram of a pixel portion of a liquid crystal display panel constituting an image display apparatus according to a seventh embodiment of the present invention. In the present embodiment, a heater 59 is provided to rewrite the image memory element 1, and a circuit for switching the image memory element 1 and a circuit for driving the liquid crystal element 5 are separated. The image memory element 1 is connected in series with the liquid crystal element 5, and a heater 59 is installed in the vicinity of the image memory element 1. The heater 59 is driven by the TFT 17.

  In FIG. 15, when the scanning electrode line 7 is selected and becomes a high level, the TFT 17 becomes conductive and a current flows through the heater 59. The image memory element 1 receives heat from the heater 59 and switches the memory state. The memory state of the image memory element 1 is controlled by controlling the temperature and energization time of the heater 59. Since a voltage determined by resistance division between the liquid crystal element 5 and the image memory element 1 is applied to the liquid crystal element 5 with respect to a voltage applied between the reference electrode line 15 and the counter electrode, depending on the resistance state of the image memory element 1 A display is made on the liquid crystal element 5. According to the present embodiment, since the circuit for driving the image memory element 1 and the circuit for driving the liquid crystal element 5 are separated, it is sufficient to always apply a driving voltage to the liquid crystal element 5, and the configuration of the driving circuit is simple. Become.

  FIG. 16 is a cross-sectional view for explaining a structural example of a heater and an image memory element provided in a pixel portion of a liquid crystal display panel constituting an image display apparatus according to a seventh embodiment of the present invention. In FIG. 16, a heater electrode 59 is formed on a substrate 77 (the heater electrode is the heater itself of FIG. 15, and thus the same reference numerals are given to both). As a material of the heater electrode 59, a refractory metal such as tantalum Ta, molybdenum / tantalum MoTa, molybdenum / tungsten MoW, tungsten W, molybdenum Mo, or the like may be used. These materials are often used for the gate wiring of a liquid crystal display device, have good consistency with a normal manufacturing process of a liquid crystal display panel, and can be formed simultaneously with the gate wiring of a TFT.

  Since the heat generation can be concentrated by narrowing the width of the heater electrode 59, a part of the heater electrode 59 is used as the heat generating portion 60. A high thermal conductivity dielectric film 75 having a high heat transfer rate such as aluminum nitride (AlN) or silicon nitride (SiN) is formed on the heat generating portion 60, and silicon oxide (SiO2) or zirconium oxide is formed in the other portions. A low thermal conductivity dielectric film 73 having a low thermal conductivity such as (ZrO2) is formed as an insulating film. A phase change film 67 is formed on the high thermal conductive dielectric film 75, and one electrode 61a and the other electrode 61b of the image memory element are formed thereon. The other electrode 61 b of the image memory element is formed so as to cover the phase change film 67.

  The heat generated in the heat generating part 60 of the heater electrode 59 is mainly conducted through the high thermal conductive dielectric film 75 and superheats the phase change film 67. This heat flows from the phase change film 67 to the other electrode 61 b of the image memory element with high thermal conductivity covering the phase change film 67. By forming the metal film of the other electrode 61b of the image memory element on the phase change film 67, the other electrode 61b of the image memory element functions as a so-called heat-drawing film, and the molten phase change film is rapidly cooled. It becomes amorphous.

The film that also functions as the heat-drawing film does not necessarily need to use the other electrode 61b, and may be another film that is electrically insulated from the phase change film 67, and it is desirable to use a metal having high thermal conductivity. . Further, since the heat generating portion 60 is insulated by using the low heat conductive film 73, the heat from the heat generating portion 60 is efficiently concentrated on the phase change film 67 in a very small area from the high heat conductive dielectric film 75 having a small area. Heat to. Since the heat capacity of the heated region is small, the phase change film can be rapidly cooled. Further, since the other electrode 61b of the image memory element is away from the heat generating portion 60, the other electrode 61b of the image memory element is conducted and heat is released, so that the other electrode 61b needs to be a refractory metal. There can be used metal such as aluminum. Silicides such as tantalum silicide TaSi ₂ can also be used for the heater electrode 59.

  FIG. 17 is a circuit diagram of a pixel portion of a liquid crystal display panel constituting an image display apparatus according to an eighth embodiment of the present invention. In the liquid crystal display panel of this embodiment, a heater 59 is provided to rewrite the image memory element 1 described with reference to FIG. 15 to the one using the simple matrix type liquid crystal element 50. The image memory element 1 is connected in series with the liquid crystal element 50, and a heater 59 is provided in the vicinity of the image memory element 1.

  In FIG. 17, when the scanning electrode line 7 is selected and becomes high level, a current flows from the signal electrode line 9 to the heater 59 to generate heat. The memory state of the image memory element 1 is switched by receiving heat from the heater 59. The memory state of the image memory element 1 is controlled by controlling the temperature and energization time of the heater 59. Since a voltage determined by resistance division between the liquid crystal element 50 and the image memory element 1 is applied to the liquid crystal element 50 with respect to a voltage applied between the reference electrode line 15 and the counter electrode 3, the voltage depends on the resistance value of the image memory element 1. Displayed on the liquid crystal element 50.

  In this embodiment, a liquid crystal display device using a simple matrix type liquid crystal display panel has an image memory element. By switching the storage state of the image memory element, an image to be displayed can be controlled according to the storage state of the image memory element. The image memory element rewriting means constituted by the heater 59 directly coupled to the scanning electrode line 7 and the signal electrode line 9, and the image memory element 1 and the liquid crystal element 50 are separated from each other in circuit, and can be driven independently. it can.

  According to this embodiment, since no active element such as a TFT is used, an image memory element can be provided in a pixel even in a very simple configuration of a simple matrix type.

  FIG. 18 is a circuit diagram of a pixel portion of a liquid crystal display panel constituting an image display apparatus according to the ninth embodiment of the present invention. The liquid crystal display panel of this embodiment uses a simple matrix type liquid crystal element 50 as in the embodiment described with reference to FIG. One terminal of the first image memory element 1a is connected to the scanning electrode line 7, one terminal of the second image memory element 1b is connected to the signal electrode line 9, and the other terminal of the first image memory element 1a is connected. Both the terminal and the other terminal of the second image memory element 1 b are connected to the pixel electrode 25 of the liquid crystal element 50.

  In this embodiment, first, all pixels of the image display panel are scanned to write image data. When writing image data, the scanning electrode line 7 is selected to have a low impedance. When the scanning electrode line 7 becomes low impedance, a current flows from the signal electrode line 9 to the first image memory element 1a and the second image memory element 1b, and the memory states thereof are switched. Since the same current flows in the first image memory element 1a and the second image memory element 1b, both memory states have the same resistance value. After the image data is written in all the pixels 50, the scanning electrode line 7 and the signal electrode line 9 are set to the same potential so as to become the reference voltage. A voltage determined by resistance division between the liquid crystal element 50, the first image memory element 1a, and the second image memory element 1b is applied to the liquid crystal element 50 with respect to a voltage difference applied between the reference voltage and the counter electrode. The liquid crystal element 5 is driven and displayed according to the resistance state of the image memory element 1a and the second image memory element 1b.

  In this embodiment, the data writing to the pixel and the display are separated in time, which is suitable for an image display apparatus that displays the same image data for a long time. Further, the first image memory element 1a and the second image memory element 1b are non-volatile memories. By using this non-volatile memory, image data is retained even if the power is turned off once. Data can be retained.

  In this embodiment, since the first image memory element 1a and the second image memory element 1b are connected in parallel to the liquid crystal element 59, even if the resistance of both memory elements varies, This is averaged, and the display variation is reduced. Furthermore, image data can be stored without using transistor elements such as TFTs, and the pixel configuration is simple. In particular, the phase change film used for the first and second memory elements 1a and 1b and the electrode connected to the liquid crystal element 50 can be formed using the same layer film, and the phase change film is not necessarily electrically. Therefore, two memory elements can be easily manufactured without the need for processing by etching or the like.

  FIG. 19 is a circuit diagram of a pixel portion of a liquid crystal display panel according to the tenth embodiment of the present invention. 20 is a configuration diagram when image data is written in an image display module configured by connecting a liquid crystal display panel having the pixel configuration shown in FIG. 19 to a recording apparatus, and FIG. 21 shows the pixel configuration shown in FIG. It is a block diagram at the time of displaying image data with the image display module comprised by connecting the liquid crystal display panel which has it to a display drive device.

  In the liquid crystal panel of this embodiment, three image memory elements are provided in one pixel as shown in FIG. One pixel shares one end of the first TFT 17a and the second TFT 17b, the first image memory element 1a, the second image memory element 1b, and the third image memory element 1c, and is parallel to the liquid crystal element 5. Is connected to. The other ends of the image memory elements 1a, 1b, and 1c are connected to the first reference electrode line 15a, the second reference electrode line 15b, and the third reference electrode line 15c, respectively.

  The liquid crystal display panel 175 includes a scanning line connection pad 29, a signal line connection pad 31, a power supply line connection pad 33, and selection line connection pads 35a, 35b, and 35c. These connection pads scan the signal line drive circuit 101. It is configured to be detachable from the line drive circuit 103 and a recording device 131 having a power source. The recording device 131 includes a signal line driving circuit 101, a scanning line driving circuit 103, a power source (not shown), and a signal control circuit 111.

  That is, the recording device 131 is connected to the liquid crystal panel 175 and the image display module shown in FIG. 20 or the display driving device 133 is connected to constitute the image display module shown in FIG. As described above, by selectively connecting the image display panel 175 to the recording device or the display driving device, the image data recording operation to the liquid crystal display panel 175 and the display operation of the recorded image data can be used separately. It is a thing. Hereinafter, the operation of the image display module configured as described above will be described with reference to FIG.

  First, in FIG. 20, when writing image data to the pixels of the liquid crystal display panel 175, the liquid crystal display panel 175 is connected to the recording device 131 via the scanning line connection pad 29 and the signal line connection pad 31. When the scanning electrode 7 is selected by the scanning line selection circuit 103 and becomes the high level by the image data signal from the signal control circuit 111 for inputting the image signal from the external signal source and the timing control signal such as a clock, the first TFT 17a is turned on. Turn on. In the image data writing operation to the liquid crystal display panel 175, it is not necessary to apply a voltage to the power electrode line 13, and the power electrode line 13 has a high impedance. Therefore, the current flows through the resistor 21 and does not flow toward the power electrode line 13 side. The first TFT 17a is connected to the first image memory element 1a, the second image memory element 1b, and the third image memory element 1c via the resistor 21.

  The selection time of the scanning electrode line 7 is divided into three in the present embodiment, corresponding to the number of memory elements, and the first reference electrode line 15a, the second reference electrode line 15b, and the third reference electrode line are divided by the scanning line selection circuit 103. 15c are selected sequentially. When the first reference electrode line 15a is selected, the second reference electrode line 15b and the third reference electrode 15c are set to high impedance so that the current data signal as the image data signal is the first image memory. The element 1a flows and the first memory element 1a is set to a desired state. Subsequently, different image data is written in the second image memory element 1b and the third image memory element 1c.

  When displaying the written image data, the first reference electrode line 15a, the second reference electrode line 15b, and the third reference electrode line 15c of the liquid crystal display panel 175 are selected lines as shown in FIG. The display drive circuit 133 is connected via the connection pads 35a, 35b, and 35c. The selection line connection pads 35a, 35b, and 35c are connected to the switching circuit 129, and the power supply line connection pad 33 is connected to the drive voltage supply electrode line 11 from the liquid crystal drive circuit 119 and the power supply electrode line 13 from the power supply circuit 117. At this time, the recording device 131 shown in FIG. 20 can be detached from the liquid crystal display panel 175. A DC voltage from the power supply circuit 117 is applied to the power supply electrode line 13 via the power supply line connection pad 33, and an AC voltage from the liquid crystal drive circuit 119 is applied to the drive voltage supply electrode.

  The switching circuit 129 selects the first reference electrode line 15a, the second reference electrode line 15b, and the third reference electrode line 15c. When the first reference electrode line 15a is selected by the switching circuit 129, the DC voltage from the power supply electrode line 13 is applied to the resistor 21 and the image memory element 1a in FIG. The voltage applied to the gate of the second TFT 17b changes according to the resistance value of the first image memory element 1a, and the second TFT 17b is turned on / off according to the gate voltage. When the second TFT 17b is turned on, the voltage of the drive voltage supply electrode line 11 is applied to the liquid crystal element 5. When the second TFT 17b is turned off, no voltage is applied to the liquid crystal element 5, and the display state of the liquid crystal element 5 is switched.

  Next, when the switching circuit 129 is switched to the second reference electrode line 15b, an image based on the image data recorded in the second image memory element 1b is displayed. Similarly, when the switching circuit 129 is switched to the third reference electrode line 15c, an image based on the image data recorded in the third image memory element 1c is displayed. In this embodiment, since three memory elements are provided in a pixel, three types of images can be switched and displayed. However, by further increasing the number of image memory elements, more images can be switched and displayed. Can do.

  As described above, the image display panel 175 of this embodiment is provided with a non-volatile memory in the pixel. Once recording is performed, even if there is no external memory, only the driving voltage is supplied to the in-pixel non-volatile memory. The stored image data can be displayed. Therefore, as described above, the recording device 131 may not be provided at the time of display.

  As described above, by mounting a plurality of memory elements in one pixel and switching and displaying the image memory elements, a plurality of images can be switched and displayed without supplying image data from the outside. For this reason, the image display device of this embodiment can be used for posters, hanging advertisements, signboards, and the like, and can display with movement only by the image display panel 175 and the display driving device 133. Since the image display panel 175 can rewrite the contents of the image memory element, the image data can be rewritten and used repeatedly.

  In this manner, by connecting the recording device 131 to the image display panel 175 and recording an image, it is possible to write image data to a plurality of display modules 175 using the same recording device 131. At the time of display, a display driving device 133 that supplies voltage may be used, and an image display device that can display various images at low cost can be obtained. Further, the number of images that can be displayed can be increased by increasing the number of image memory elements in one pixel. The display driving device 133 may be an image display device integrated with the image display panel 175.

  In this embodiment, the liquid crystal element is used as the image display element. However, the image display element to be used is not limited to the liquid crystal element, and a display panel using electroluminescence such as an organic light emitting element, field emission, or the like. The same display can be performed using various display panels such as a panel, a plasma display, and the like using a matrix electrode.

  FIG. 22 is a circuit diagram illustrating the configuration of one pixel of the pixel portion of the display panel according to the eleventh embodiment of the present invention. In this embodiment, an organic electroluminescence display element (OLED) 6 is used as an image display element. An image memory element 1 for storing image data is provided in one pixel, and holds data to be displayed on the pixel of the OLED element 6. In the present embodiment, the image memory element 1 can record and rewrite data by reversibly changing the resistance value in the same manner as described in the above embodiments. Non-volatile memory that does not lose data.

  The image memory element 1 is switched by applying a pulse current from the signal electrode line 9, and the switching resistance state is controlled by changing the current value and the pulse width of the pulse current. When the scanning electrode line 7 is selected and the voltage becomes high level, the TFT 17 is turned on. At this timing, the data current signal that has flowed through the signal electrode line 9 is taken into the TFT 17 and flows through the image memory element 1 to the reference electrode line 15. The resistance of the image memory element 1 changes according to the value of the current flowing through the image memory element 1 or the pulse width, and storage is performed.

  As shown in the present embodiment, when the current for driving the OLED element 6 flows from the reference electrode line 15 through the OLED element 6 to the counter electrode side, the signal electrode line with respect to the reference electrode line 15 The image memory element 1 is switched without causing the pulse current from the signal electrode line 9 to flow through the OLED element 6 by lowering the potential of 9 so as to have a reverse voltage with respect to the OLED element 6. One pixel electrode 250 of the OLED element 6 is connected to the reference electrode line 15 through the image memory element 1. When the image memory element 1 is in a low resistance state, the counter electrode 30 and the reference electrode of the OLED element 6 are connected. A current flows by the drive voltage applied between the lines 15 to emit light, and display is performed. When the image memory element 1 is in a high resistance state, the current flowing through the OLED element 6 is equal to or less than the threshold value, and the OLED element 6 is turned off. The drive current of the OLED element 6 is equal to or less than the threshold current Ith that changes the state of the image memory element 1, and the state of the image memory element 1 is not changed by the drive current of the OLED element 6.

In this embodiment, since the resistance value of the image memory element 1 can be continuously changed by controlling the current value flowing through the image memory element 1 between I _reset and I _th , gradation display is performed on the OLED element 6. Is possible.

  In this embodiment, the OLED element 6 can be controlled by one TFT 17, and gradation display is also possible. In addition, since the image memory element can be configured without using a storage capacitor used in a normal OLED element, the pixel configuration is simplified. Further, since the image memory element 1 has non-volatility, when the same image is displayed, the image memory element 1 does not need to be refreshed and the rewriting frequency can be reduced, so that low power consumption Is possible.

  FIG. 23 is a plan view showing an example of an electronic device in which the image display device of the present invention is mounted, and FIG. 24 is a system configuration diagram of the electronic device shown in FIG. This electronic device is a portable device (PDA) called an electronic book. This electronic device has a function of downloading book data (content) such as a novel from a line such as the Internet or an external data source such as a personal computer. The image display device of the present invention is mounted on the display unit 153 of the electronic book 151. An input key 155 and an input dial 157 are provided on a part of the apparatus body.

  As shown in FIG. 24, the system of the electronic book 151 includes an image display device 159, a display controller 161, a microprocessor (MPU) 163, a memory 165, a power source (battery) 167, an input device 169, and an interface (I / F) 171. Are connected to the system bus 175. Display data in the memory 165 is processed by the MPU 163 via the system bus 175 and sent to the display controller 161. The display controller 161 controls the display device 159 to visually display the data in the memory 165 on the display unit 153. The pixel of the display panel of the image display device that constitutes the display unit 153 has a nonvolatile memory.

  As described in the above embodiment, this nonvolatile memory can be used as an image memory, and the stored contents of the image memory may be read out. The input device 169 such as the input dial 157 or the input key 155 is operated to perform operations such as turning a page on the display unit 153 or selecting a book to be displayed. Book data and the like are taken into the memory 165 from the external data source via the interface 171.

  Since the image memory element included in the display panel constituting the image display device of the present invention can be formed minutely and the aperture ratio of the pixel can be increased, it is suitable for displaying a high-definition image. In particular, when displaying on the screen once, such as newspapers, books, comics, etc., the same image is displayed until reading is completed. Therefore, the effect of low power consumption is great, and it is suitable for this kind of electronic equipment. That is, until the display image is rewritten, the image display unit may be driven to reduce power consumption. Further, in the case of using a liquid crystal display device, since the nonvolatile memory is used, the frame frequency can be lowered to such an extent that the liquid crystal element is not deteriorated, so that the power consumption can be further reduced. In view of reducing power consumption, it is desirable to use a reflective image display device that does not require an auxiliary illumination light source in principle. Further, when a liquid crystal display device is used as the image display device, it can be colored using a color filter, as is usually done.

  It goes without saying that the image display device of the present invention is not limited to the above-described portable electronic device, but can be similarly applied to other image display devices.

1 is a circuit diagram illustrating a configuration of one pixel constituting an image display panel, that is, a liquid crystal display panel, of an image display device according to a first embodiment of the present invention. It is a block diagram of the image display apparatus comprised using the liquid crystal display panel which has a pixel shown in FIG. It is explanatory drawing of the voltage-reflectance characteristic of the liquid crystal element of the normally closed mode used for the liquid crystal display panel of 1st Example of this invention. It is a wave form diagram of the current pulse which switches the image memory element used for 1st Example of this invention. It is explanatory drawing of the signal waveform which drives an image display panel. It is principal part sectional drawing of the 1st board | substrate which comprises the liquid crystal display panel in 1st Example of this invention. It is a block diagram explaining the structure of the image display apparatus in 1st Example of this invention. It is a circuit diagram explaining the structure of one pixel of the liquid crystal display panel which is an image display panel which concerns on 2nd Example of this invention. It is a circuit diagram explaining the structure of one pixel of the liquid crystal display panel which is an image display panel which concerns on 3rd Example of this invention. It is a circuit diagram explaining the structure of one pixel of the liquid crystal display panel which is an image display panel which concerns on 4th Example of this invention. It is a circuit diagram explaining the structure of one pixel of the liquid crystal display panel which is an image display panel which concerns on 5th Example of this invention. It is a circuit diagram of one pixel of the liquid crystal display panel which is an image display panel which concerns on 6th Example of this invention. It is a block diagram of the image display apparatus which concerns on 6th Example of this invention. It is explanatory drawing of the signal waveform which drives the image display panel which concerns on 6th Example of this invention. It is a circuit diagram of the pixel part of the liquid crystal display panel which comprises the image display apparatus concerning 7th Example of this invention. It is sectional drawing explaining the structural example of the heater provided in the pixel part of the liquid crystal display panel which comprises the image display apparatus based on 7th Example of this invention, and an image memory element. It is a circuit diagram of the pixel part of the liquid crystal display panel which comprises the image display apparatus based on 8th Example of this invention. It is a circuit diagram of the pixel part of the liquid crystal display panel which comprises the image display apparatus concerning 9th Example of this invention. It is a circuit diagram of the pixel part of the liquid crystal display panel which concerns on 10th Example of this invention. FIG. 20 is a configuration diagram when image data is written in an image display module configured by connecting a liquid crystal display panel having the pixel configuration shown in FIG. 19 to a recording apparatus. FIG. 20 is a configuration diagram when image data is displayed by an image display module configured by connecting a liquid crystal display panel having the pixel configuration shown in FIG. 19 to a display driving device. It is a circuit diagram explaining the structure of one pixel of the pixel part of the display panel which concerns on 11th Example of this invention. It is a top view which shows an example of the electronic device which mounted the image display apparatus of this invention. It is a system block diagram of the electronic device shown in FIG.

Explanation of symbols

1, 1a, 1b, 1c... Image memory element, 3... Counter electrode, 5... Liquid crystal element, 6. ..Signal electrode line, 11... Drive voltage supply electrode line, 13... Power supply electrode line, 15, 15a, 15b, 15c... Reference electrode line, 17, 17a, 17b, 17c. .. Thin film transistor (TFT), 19... P-type TFT, 21... Resistance, 23... Heater, 25. Scan electrode line connection pad, 31 ... Signal electrode line connection pad, 33 ... Power supply line connection pad, 35, 35a, 35b, 35c ... Selection line connection pad, 51 ... Gate Electrode 53 ... Source electrode 55 ... Drain electrode 57 ... High melting point Metal electrode, 59... Heater electrode, 60... Heat generating part, 61 a, 61 b... Image memory element electrode, 63... Metal film, 65. ..Phase change film 69... Insulating film 71... Silicon film 73... Low heat conduction dielectric film 75... High heat conduction dielectric film 77. , 79... N + silicon layer, 101... Scanning line selection circuit, 103... Signal line drive circuit, 105... Serial-parallel conversion circuit, 107. ... Voltage-current conversion circuit 111... Signal control circuit 113... Image signal processing circuit 115 115 Driver control circuit 117 117 Power supply circuit 119 .Counter electrode drive circuit, 121... Image data arithmetic circuit, 123. ... Memory readout circuit, 125... Switch, 127... Pixel, 129... Switching circuit, 131... Recording device, 133. Book, 153... Display unit, 155... Input key, 157... Input dial, 159 ... Image display device, 161 ... Display controller, 163 ... Microprocessor (MPU), 165... Image memory, 167... Battery, 169... Input device, 171.

Claims (4)

An image display panel which is constituted by a display device comprising a plurality of pixels in a matrix at intersections of a plurality of signal electrode lines intersecting the scanning electrode lines and the plurality of scanning electrode lines, provided for each pixel of the image display panel storage means that is, an image display module; and a display driving unit for displaying the display data stored in the image display panel and the recording device, by the recording device for recording the display data to the image display panel,
The image display panel is provided for each pixel and stores non-volatile storage means for storing display data, a scanning line connection unit for inputting a scanning signal to the scanning electrode line, and display data on the signal electrode line. A signal line connection unit for inputting a drive signal, a drive line connection unit for inputting a drive signal for driving the pixel, and a power supply line connection unit ,
The recording apparatus includes: a scanning line selection circuit that drives the scanning electrode lines and the signal electrode lines of the image display panel; a signal line driving circuit and a signal control circuit; and the signal line connecting unit and the driving line connecting unit. A recording apparatus connecting unit to be connected, and detachable from the image display module ;
The image display panel is selectively to one of the display driving device and the recording device, or both are at the same time can be connected,
The storage device is connected to the image display panel via the recording device connection unit, and the storage unit stores the data stored in the storage unit by inputting a rewrite signal of the storage unit to the scanning line connection unit and the signal line connection unit. An image display module characterized by rewriting . Each pixel of the image display panel has a plurality of the storage means and a selection signal line for selecting the plurality of storage means, and rewrites the storage data of the storage means selected by the selection signal line. The image display module according to claim 1 . The display drive device includes a counter electrode drive circuit and a power supply circuit, and a display drive device connection portion connected to the drive line connection portion and the power supply line connection portion of the image display panel.
The display drive device is connected to the image display panel via the display drive device connection unit, and display data stored in each pixel of the image display panel is displayed on the image display panel. Item 4. The image display module according to Item 1. A selection signal line for selecting a plurality of the storage means provided in each pixel of the image display panel;
The display driving device has a switching circuit for switching the connection with the selection signal line,
Claims, characterized in that the display and select the plurality of storage devices having more on the image display panel to the switching circuit, a plurality of images based on the display data stored in the selected storage unit to the image display panel Item 4. The image display module according to Item 3 .

Images