JP2007025523A - Electronic device, electro-optical device, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently secure a period when an electro-optical element is driven. <P>SOLUTION: Unit circuits U are disposed at intersections between pairs of scan lines 13 and reference signal lines 17 and data lines 15. Each unit circuit U includes an electro-optical element 35 driven in accordance with a driving current Sdr, an inverter 34 which outputs the driving current Sdr for a time length according to a potential Va at an input end T, and a capacitive element which has a first electrode E1 connected to the input end T and has a second electrode E2 connected to the reference signal line 17. A plurality of scan lines 13 are successively selected every first period, and a data potential Vdata is supplied to the input end T of the unit circuit U corresponding to a selected scan line 13. A reference signal W[i] which maintains a low potential in the first period when a scan line 13 corresponding to a reference signal line 17 is selected, and has a potential changed with time in a second period different by reference signal lines 17 is supplied to the reference signal line 17. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to the behavior of various driven elements such as organic light emitting diode (hereinafter referred to as “OLED (Organic Light Emitting Diode)”) elements, liquid crystal elements, electrophoretic elements, electrochromic elements, electron emitting elements, and resistive elements. It is related with the technology to control.

Various methods for driving this type of driven element have been proposed. For example, Patent Document 1 discloses a configuration that displays multiple gradations by controlling the pulse width of a drive signal (for example, a current signal) supplied to an OLED element of each pixel. In this configuration, the pulse width of the drive signal is different for each pixel in accordance with the result of comparison between a data signal designating the gradation of each pixel and a signal whose level changes with time such as a triangular wave (hereinafter referred to as “reference signal”). Controlled.
JP 2003-223137 (paragraph 0014 and FIG. 2)

  By the way, in the configuration disclosed in Patent Document 1, one frame is divided into a scanning period and a light emitting period, and a data signal is supplied to all pixels in the scanning period, and then a reference signal is supplied in the light emitting period. As a result, the OLED elements of all the pixels are driven all at once (see particularly FIG. 2 of Patent Document 1). Thus, in the configuration in which the scanning period and the light emission period are separately set within one frame, for example, there is a problem that it is difficult to ensure a sufficient length of the light emission period. If the time length of the light emission period is insufficient, the brightness of each OLED element may be insufficient and the display may become dark. Furthermore, if the time length of the light emission period is short, the pulse width of the drive signal (especially the pulse width corresponding to low luminance) must be shortened. However, characteristics of an electro-optical element such as an OLED element may be deteriorated due to current concentration (for example, supply of spike-like current) in a short period.

  In the configuration of Patent Document 1, a data signal is supplied to one electrode of the capacitor. In this configuration, it may take time to accurately set the potential of the other electrode of the capacitive element when the data signal is supplied. The present invention has been made in view of the circumstances described above.

  The electronic device according to the present invention includes a plurality of first wirings (for example, the scanning lines 13 in FIG. 1), a plurality of second wirings (for example, the data lines 15 in FIG. 1) intersecting the plurality of first wirings, A plurality of unit circuits arranged corresponding to intersections of the plurality of first wires and the plurality of second wires, and reference signals (for example, reference signals W [1] to W in each embodiment) to the plurality of unit circuits. [m]) and a plurality of reference signal lines for supplying each of the plurality of unit circuits, and each of the plurality of unit circuits is driven by supplying a driving voltage or a driving current (for example, the electro-optical element of FIG. 3). 35), driving means for supplying the driving voltage or driving current to the driven element (for example, the inverter 34 in FIG. 3 or a set of the inverter 34 and the transistor 39 in FIG. 7), and the driving means Input end (for example, input in FIG. 3 T) and a switching element (for example, the transistor 31 in FIG. 3) that controls electrical connection between the second wiring and one of the plurality of second wirings, the first electrode connected to the input terminal, And a second electrode connected to one reference signal line of the plurality of reference signal lines, and a capacitor element that accumulates charges between the first electrode and the second electrode.

  In this configuration, when a data signal is supplied from the second wiring to the input terminal of the driving unit via the switching element in the first period, and the reference signal changes after the first period has elapsed, capacitive coupling in the capacitive element causes The potential at the input terminal changes from the potential of the data signal in the immediately preceding first period by the variation of the reference signal. Accordingly, the driven element to which the driving voltage or the driving current is supplied in the driving period having a length corresponding to the potential of the input terminal is driven to a state corresponding to the data signal. Since the potential of the second electrode of the capacitive element is directly set by the reference signal line, there is an advantage that the potential of the two electrodes of the capacitive element can be set in a short time.

  Further, the electronic device according to the present invention includes a plurality of first wirings (for example, the scanning line 13 in FIG. 1), a plurality of second wirings (for example, the data line 15 in FIG. 1) intersecting the plurality of first wirings, A plurality of unit circuits arranged at positions corresponding to intersections of the plurality of first wirings and the plurality of second wirings, and a selection circuit that selects each of the plurality of first wirings for each first period (for example, FIG. 1) A scanning line driving circuit 23), a data supply circuit (for example, the data line driving circuit 25 in FIG. 1) for supplying a data potential to each of the plurality of second wirings in each first period, and a plurality of reference signal lines. On the other hand, a reference signal that maintains a constant potential in the first period in which the first wiring corresponding to the reference signal line is selected and changes in potential over time in a period that differs for each reference signal line (for example, each implementation) Signal that outputs the reference signal W [1] to W [m]) ; And a formed circuit. Further, each of the plurality of unit circuits has a potential of a driven element (for example, the electro-optical element 35 in FIG. 3) driven by supply of a driving voltage or a driving current and an input terminal (for example, the input terminal T in FIG. 3). Corresponding to the driving circuit (for example, the inverter 34 in FIG. 3 or the combination of the inverter 34 and the transistor 39 in FIG. 7) for supplying a driving voltage or driving current to the driven element in a period of a corresponding length, and the unit circuit In the first period in which the first wiring is selected, the switching element (for example, the transistor 31 in FIG. 3) that electrically connects the input terminal and the second wiring, the first electrode connected to the input terminal, and the plurality of And a second electrode connected to one of the reference signal lines, and a capacitive element that accumulates electric charge between the first electrode and the second electrode.

In this configuration, when a data signal is supplied to the input terminal of the driving unit via the switching element in the first period and the reference signal changes with time in the second period after the first period, Due to the capacitive coupling, the potential of the input terminal changes from the data potential in the first period immediately before it by the variation of the reference signal. Therefore, the driven element to which the driving voltage or the driving current is supplied in a period corresponding to the potential of the input terminal is driven to a state corresponding to the data potential. Since the potential of the second electrode of the capacitive element is directly set by the reference signal line, there is an advantage that the potential of the two electrodes of the capacitive element can be set in a short time.
Here, the second period in which the potential of the reference signal changes with time is set individually for each reference signal line, and the timings are different from each other. Therefore, when the data potential of one unit circuit is captured in the first period, the driven elements of the one unit circuit are sequentially driven without waiting for the data potential to be captured by other unit circuits. For example, the driven elements are driven in order from the unit circuit that has completed capturing the data potential. Therefore, according to the present invention, as compared with the conventional configuration in which the period for taking in the data potential in all the unit circuits and the period for causing all the OLED elements to emit light at the same time are set separately, A sufficient period for driving the driven element can be secured.

  Note that the reference signal in the present invention is preferably a signal that maintains a constant potential in at least a part of the first period in which the data signal is written and changes in potential at least in the driving period. However, the potential of the reference signal and the mode of change thereof during other periods can be set as appropriate in accordance with the driving mode and function of the driven element. Further, the interval between the first period and the time point at which the potential of the reference signal starts to change with time can also be set as appropriate according to the driving mode and function of the driven element.

  In a preferred aspect of the present invention, the potentials of the plurality of reference signal lines change at a predetermined period. More specifically, a selection circuit that selects each of the plurality of first wirings, and a signal generation that sequentially supplies the reference signals to the plurality of reference signal lines in the order in which the first wirings are selected. Circuit. According to this aspect, the second period of each reference signal can be secured with a sufficient time length. However, the order of selection of the first wirings and the order of arrival of the second period for the reference signal lines corresponding to the first wirings do not necessarily have to match.

  In a preferred aspect of the present invention, the potential of the input terminal is set by supplying a data signal to the input terminal in the first period via the one second wiring and the switching element. The length of the driving period for supplying the driving voltage or the driving current to the driven element corresponds to the potential of the input terminal set in the first period. According to this aspect, the time length of the drive period in which the drive voltage or drive current is supplied to the driven element can be set according to the data signal. In these aspects, the input terminal is in a floating state in at least a part of a driving period in which a driving voltage or a driving current is supplied to the driven element. According to this aspect, since the leakage of the charge of the first electrode is prevented, the potential at the input terminal can be reliably changed according to the change of the reference signal with time.

In a more specific aspect, the driving unit applies the driving voltage or the driving current to the driven element in a period in which the potential of the input terminal is higher than a predetermined potential and a period in which the potential of the input terminal is lower than a predetermined potential. Supply. For example, the drive means outputs a drive voltage or drive current when the potential at the input end exceeds a predetermined potential (threshold voltage Vth in each embodiment), and the drive voltage when the potential at the input end falls below a predetermined potential. Or stop driving current output. According to this aspect, since the electro-optic element is driven in a binary manner, the driving state of the driven element (for example, the luminance level of the light emitting element) due to the variation in the characteristics of each unit of the unit circuit and the driven element Variations can be suppressed. A typical example of the driving means in this aspect is an inverter.
More specifically, the potential of the one reference signal line is set to at least the first potential when the potential of the input terminal is set by the data signal in the first period, The potential of the one reference signal line at the start of the period is the first potential, and the one reference signal line has a second voltage level different from the first potential in the second period. The potential of the one reference signal line at the end of the second period is the first potential. More specifically, the change in the potential of the one reference signal line in the second period is axisymmetric with respect to the time point when the potential becomes the second potential. That is, the reference signal has a waveform (typically a triangular wave) that is line-symmetric with respect to the midpoint (for example, the midpoint tc in FIGS. 2 and 4) between the start point and the end point of the second period.
According to this aspect, the center of gravity on the time axis of the period during which the driven element is actually driven (for example, the period during which the electro-optic element emits light) can be set as the midpoint of the second period regardless of the data signal. However, the mode of change in the potential of the reference signal line (reference signal waveform) need not be strictly line symmetric. That is, the shortest drive period except for the drive period in which the time length is zero among a plurality of drive periods each corresponding to a separate data signal is on the time axis of the longer drive period and the second period. The potentials of the respective reference signal lines (that is, reference signals) may be set so as to overlap with each other. For example, referring to the example of FIG. 4, among the gradations G0 to G3, for the gradation G1 having the shortest time length in which the driving current Sdr flows is not zero, the driving period is the gradation G2 or The reference signal is generated so as to overlap on the time axis of the second period Pb [i] with respect to the driving period of the gradation G3 (the driving period longer than the driving period corresponding to the gradation G1).

  In a preferred aspect of the present invention, the plurality of reference signal lines extend in a direction intersecting with the plurality of second wirings. According to this configuration, a common reference signal can be reliably transmitted to each unit circuit commonly connected to one first wiring via a simple-shaped reference signal line extending along the first wiring. Can be supplied.

  In still another aspect, each of the plurality of unit circuits has a predetermined input terminal connected to the input terminal prior to a first period in which a data signal is supplied to the input terminal via the one second wiring and the switching element. Reset means (for example, transistor 37 in FIG. 5) for setting the potential is included. According to this aspect, since the input terminal is initialized to a predetermined potential prior to the first period, the potential of the input terminal can be set to the data potential quickly and reliably in the first period.

  The electronic device of each aspect described above is used for various electronic devices. A typical example of this electronic device is a device that uses the electronic device as a display device. Examples of this type of electronic device include a personal computer and a mobile phone. However, the use of the electronic device according to the present invention is not limited to displaying images. For example, the electronic apparatus of the present invention can also be applied as an exposure apparatus (exposure head) for forming a latent image on an image carrier such as a photosensitive drum by irradiation of light.

  The driven element in the present invention includes all elements that are electrically driven. A typical example of the driven element is an electro-optical element (for example, a light-emitting element such as an OLED element) whose optical properties such as luminance and transmittance change by application of electric energy (for example, application of an electric field). The present invention is also specified as an electro-optical device dedicated to driving an electro-optical element. The electro-optical device includes a plurality of scanning lines, a plurality of data lines intersecting the plurality of scanning lines, and a plurality of units arranged corresponding to the intersections of the plurality of scanning lines and the plurality of data lines. A plurality of reference signal lines for supplying a reference signal to the plurality of unit circuits, and each of the plurality of unit circuits is driven by supplying a drive voltage or a drive current; Controlling the electrical connection between the drive means for supplying the drive voltage or the drive current to the electro-optical element, and the input terminal included in the drive means and one of the plurality of data lines. A switching element; a first electrode connected to the input terminal; and a second electrode connected to one reference signal line of the plurality of reference signal lines, the first electrode, the second electrode, To accumulate charge during A driving period for supplying the driving voltage or the driving current to the electro-optical element is within a first period, the data signal is input via the one data line and the switching element. This corresponds to the potential of the input terminal set by being supplied to the terminal. Also with this configuration, the same operations and effects as the electronic device of the present invention are exhibited.

  The present invention is also implemented as a method for driving an electronic device. That is, the driving method according to the present invention is arranged corresponding to a plurality of first wirings and a plurality of second wirings crossing each other, and an intersection of the plurality of first wirings and the plurality of second wirings. A plurality of unit circuits, and a plurality of reference signal lines, each of the plurality of unit circuits being driven by a drive voltage or drive current supply, and the drive voltage or the drive current Drive means for supplying to the driven element; a first electrode connected to an input end included in the drive element; and a second electrode connected to one reference signal line of the plurality of reference signal lines. A driving method of an electronic device including a capacitive element that accumulates electric charge between the first electrode and the second electrode, wherein a second one of the plurality of second wirings in the first period. A data signal is supplied from the wiring to the input terminal. The set potential of the input terminal, to change the respective potentials of said plurality of reference signal lines in a predetermined cycle by. This method also provides the same operation and effect as the electronic device of the present invention.

<A: First Embodiment>
FIG. 1 is a block diagram showing a configuration of an electronic device according to the first embodiment of the present invention. The electronic device D illustrated in the figure is an electro-optical device employed in various electronic devices as means for displaying an image, and includes an element array unit 10 in which a plurality of unit circuits U are arranged in a planar shape. And a circuit for driving each unit circuit U (a scanning line driving circuit 23, a data line driving circuit 25, and a signal generation circuit 27). Note that the scanning line driving circuit 23, the data line driving circuit 25, and the signal generation circuit 27 may be mounted on the electronic device D as independent circuits, or a part or all of these circuits may be a single unit. The electronic device D may be mounted as a circuit.

  As shown in FIG. 1, the element array section 10 includes m scanning lines 13 extending in the X direction and m reference signal lines 17 extending in the X direction in pairs with the scanning lines 13. And n data lines 15 extending in the Y direction orthogonal to the X direction are formed (m and n are both natural numbers). Each unit circuit U is arranged at a position corresponding to the intersection of the pair of scanning line 13 and reference signal line 17 and data line 15. Accordingly, these unit circuits U are arranged in a matrix of m rows × n columns.

  The scanning line driving circuit 23 is a circuit for selecting each of the m scanning lines 13 in order. More specifically, as shown in FIG. 2, the scanning line driving circuit 23 has a predetermined period (hereinafter referred to as “first period”) Pa [1] to Pa [m] set for each frame (1F). The scanning signals Y [1] to Y [m] that sequentially become high level are generated and output to the scanning lines 13, respectively. The scanning signal Y [i] supplied to the scanning line 13 in the i-th row (i is an integer satisfying 1 ≦ i ≦ m) is the i-th first period Pa [i] in one frame (1F). It is a signal that becomes a high level at, and maintains a low level during other periods. The transition of the scanning signal Y [i] to the high level means selection of the i-th row.

  The data line driving circuit 25 shown in FIG. 1 sends a data signal X [1 to each row (n) of unit circuits U corresponding to the scanning line 13 selected by the scanning line driving circuit 23 via each data line 15. ] To X [n]. The data signal X [j] supplied to the data line 15 in the j-th column (j is an integer satisfying 1 ≦ j ≦ n) in the first period Pa [i] in which the i-th scanning line 13 is selected. Is the potential Vdata corresponding to the gradation (luminance) specified for the unit circuit U in the j-th column belonging to the i-th row. The gradation of each unit circuit U is specified by gradation data supplied from the outside.

  The signal generation circuit 27 is a circuit that generates reference signals W [1] to W [m] and outputs them to each of the m reference signal lines 17. As shown in FIG. 2, the reference signal W [i] maintains the potential VH from the start point to the end point of the first period Pa [i] in which the scanning signal Y [i] is at the high level, and this first period Pa [ i] is a signal whose potential varies over time from the start point to the end point of a predetermined period (hereinafter referred to as “second period”) Pb [i].

  The reference signal W [i] in the present embodiment has a waveform from the midpoint tc of the second period Pb [i] (that is, a time point having the same time length from both the start point and the end point of the second period Pb [i]) to the start point. The waveform from the midpoint tc to the end point is a triangular wave that is line symmetric with respect to the midpoint tc. That is, the reference signal W [i] decreases from the potential VH to a potential VL lower than the potential VH from the start point of the second period Pb [i] to the midpoint tc of the second period Pb [i]. From the middle point tc to the end point, the potential increases from the potential VL with the passage of time and reaches the potential VH.

  As shown in FIG. 2, the reference signals W [1] to W [m] have different phases. That is, the timing of each of the second periods Pb [1] to Pb [m] in which the reference signals W [1] to W [m] vary is set individually for each reference signal line 17 (each row) and is different from each other. To do. More specifically, each of the second periods Pb [1] to Pb [m] defined by the reference signals W [1] to W [m] supplied to each reference signal line 17 is related to the reference signal line. Each of the scanning signals Y [1] to Y [m] corresponding to 17 sequentially arrives in the order of the high level. Therefore, as shown in FIG. 2, the reference signal W [i] varies within the range from the potential VH to the potential VL in parallel with the transition of the scanning signal Y [i + 1] of the next row to the high level. .

  Next, a specific configuration of each unit circuit U will be described with reference to FIG. In the figure, only one unit circuit U located in the i-th row and j-th column is shown, but the other unit circuits U have the same configuration.

  As shown in FIG. 3, the unit circuit U includes a transistor 31, a capacitive element 33, an inverter 34, and an electro-optic element 35. The electro-optical element 35 is an OLED element in which a light emitting layer made of an organic EL material is interposed between an anode and a cathode, and emits light at a luminance level corresponding to the current level of the drive current Sdr output from the inverter 34. Note that the integrated value of the luminance level over time corresponds to the luminance.

  The inverter 34 includes a p-channel transistor 341 and an n-channel transistor 342. The source of the transistor 341 is connected to a power supply line to which a higher power supply potential Vdd is supplied. The source of the n-channel transistor 342 is connected to a ground line to which a lower power supply potential (hereinafter referred to as “ground potential”) Vss is supplied. The drains of the transistors 341 and 342 are connected in common to the anode of the electro-optic element 35. Further, the gates of the transistors 341 and 342 are connected to each other at the input terminal T.

  When the potential Va at the input terminal T of the inverter 34 is lower than a predetermined potential (hereinafter simply referred to as “threshold voltage”) Vth, the transistor 341 is turned on and the drive current Sdr is supplied to the electro-optical element 35. . This drive current Sdr is a current that causes the electro-optic element 35 to emit light. On the other hand, when the potential Va exceeds the threshold voltage Vth, the transistor 341 is turned off and the transistor 342 is turned on, so that the supply of the drive current Sdr to the electro-optic element 35 is stopped.

  3 includes a first electrode E1 connected to the input terminal T of the inverter 34 and a second electrode E2 connected to the reference signal line 17, and includes a first electrode E1 and a second electrode E2. Accumulate charges in between. The n-channel transistor 31 is a switching element that is interposed between the input terminal T of the inverter 34 and the data line 15 and controls electrical connection (conduction and non-conduction) between the two. The gate of the transistor 31 is connected to the scanning line 13. Accordingly, the transistor 31 is turned on in the first period Pa [i] in which the scanning signal Y [i] is at the high level, and the transistor 31 is turned off in the period in which the scanning signal Y [i] is kept at the low level.

  Next, a specific operation of the electronic device D according to the present embodiment will be described. Hereinafter, the operation of the unit circuit U in the j-th column belonging to the i-th row will be described by dividing it into a first period Pa [i] and a second period Pb [i].

(a) First period Pa [i]
In the first period Pa [i], the scanning signal Y [i] transitions to a high level, so that the transistor 31 is turned on and the input terminal T and the data line 15 are electrically connected. As a result, the potential Vdata of the data signal X [j] is supplied from the data line 15 to the input terminal T of the inverter 34, and the charge corresponding to the potential Vdata is held in the capacitive element 33. As shown in FIG. 2, the reference signal W [i] supplied to the second electrode E2 of the capacitive element 33 maintains a constant potential (potential VH) in the first period Pa [i]. Va is held at the potential Vdata corresponding to the gradation of the unit circuit U.

(b) Second period Pb [i]
When the first period Pa [i] elapses and the scanning signal Y [i] becomes low level, the transistor 31 shifts to the off state. Therefore, the input terminal T is electrically disconnected from the data line 15 and becomes the floating state. . This state is also maintained in the second period Pb [i]. Therefore, when the reference signal W [i] supplied to the second electrode E2 of the capacitive element 33 varies within the range from the potential VH to the potential VL in the second period Pb [i], capacitive coupling in the capacitive element 33 is performed. Thus, the potential Va (the potential of the first electrode E1) at the input terminal T varies from the potential Vdata set in the immediately preceding first period Pa [i] by the change in the reference signal W [i].

  FIG. 4 is a timing chart showing the relationship between the potential Va at the input terminal T and the drive current Sdr output from the inverter 34. In the figure, the waveform of the potential Va when each gradation (G0 to G3) is designated in the unit circuit U is also shown. Further, the potential V0 to potential V3 in the figure is the potential Vdata of the data signal X [j] when each of the gradations G0 to G3 is designated (that is, the potential Va set in the first period Pa [i]). It is.

  As shown in FIG. 4, the potential Va at the input terminal T changes by ΔV (= VH−VL) in accordance with the fluctuation of the reference signal W [i] in the second period Pb [i]. Since the potential Va is set to the potential Vdata corresponding to the gradation at the start point of the second period Pb [i], the potential Va at the input terminal T in the second period Pb [i] sets the threshold voltage Vth of the inverter 34. The period below (hereinafter referred to as “driving period”) has a time length corresponding to the potential Vdata supplied from the data line 15 in the immediately preceding first period Pa [i]. For example, since the potential Vdata (V1) corresponding to the gradation G1 is higher than the potential Vdata (V2) corresponding to the gradation G2, the time when the potential Va falls below the threshold voltage Vth when the gradation G2 is designated. The length is longer than the time length during which the potential Va falls below the threshold voltage Vth when the gradation G1 is designated. When the gradation G0 is designated, the potential Va exceeds the threshold voltage Vth over the entire period of the second period Pb [i].

  Since the potential Va at the input terminal T varies as described above, the drive current Sdr is supplied from the inverter 34 to the electro-optic element 35 in the drive period of the time length (pulse width) corresponding to the data signal X [j]. During the remaining period, the supply of the drive current Sdr to the electro-optic element 35 is stopped. For example, as shown in FIG. 4, during the drive period in which the drive current Sdr is supplied to the electro-optic element 35 when the gradation G2 is designated, the drive current Sdr is supplied when the gradation G1 is designated. Longer than the driving period. When the gradation G0 is designated, the supply of the drive current Sdr to the electro-optic element 35 is stopped over the entire period of the second period Pb [i]. Since the electro-optical element 35 emits light when the drive current Sdr is supplied, in this embodiment, the electro-optical element 35 emits light at a time density corresponding to the potential Vdata of the data signal X [j]. As a result, the gradation of the electro-optic element 35 is controlled for each unit circuit U.

  Although the operation of one unit circuit U has been described above, the same operation is executed in each unit circuit U in units of rows. More specifically, as shown in FIG. 2, the supply of the potential Vdata to the input terminal T (first period Pa [i]) and the fluctuation of the potential Va according to the reference signal W [i] (second period Pb). [i]) are sequentially performed for each unit circuit U in each row at separate timings. Therefore, when the data signal X [j] is taken into one unit circuit U in the first period Pa [i] (that is, when the potential Vdata is supplied to the input terminal T), the data for the other unit circuits U is stored. The electro-optic elements 35 are sequentially driven without waiting for the capture of the signal X [j]. In other words, the electro-optic element 35 emits light in order from the unit circuit U that has completed taking in the data signal X [j].

  As described above, according to the present embodiment, since the electro-optical element 35 is binary driven by supplying and stopping the drive current Sdr, the current supplied to the electro-optical element 35 (or electro-optical). Compared with a configuration in which the voltage applied to the element 35 is controlled stepwise corresponding to each gradation, the influence of variations in the characteristics of the transistors constituting the electro-optic element 35 and the inverter 34 can be reduced. Furthermore, in this embodiment, since the potential of the second electrode E2 of the capacitive element 33 is set directly by the reference signal line 17, it is possible to set the potential of each electrode of the capacitive element 33 in a short time. is there.

  Moreover, according to the present embodiment, compared to the conventional configuration in which the scanning period for supplying data signals to all unit circuits and the light emission period for simultaneously emitting light to all OLED elements are set separately, A period during which each electro-optic element 35 emits light can be secured for a long time. Accordingly, each electro-optical element 35 can emit light with sufficient luminance. In addition, since the pulse width of the drive current Sdr can be set longer than in the conventional configuration, instantaneous current concentration on the electro-optic element 35 (spike-like current supply) can be avoided and the characteristics of the electro-optic element 35 can be avoided. It becomes possible to suppress degradation of the.

<B: Second Embodiment>
Next, a second embodiment of the present invention will be described. In addition, about the element similar to 1st Embodiment among this embodiment, a common code | symbol is attached | subjected and each detailed description is abbreviate | omitted suitably.

  FIG. 5 is a circuit diagram showing a configuration of one unit circuit U of the electronic device D according to the present embodiment. As shown in the figure, the unit circuit U of the present embodiment has a configuration in which an n-channel transistor 37 is added to the configuration of the first embodiment illustrated in FIG. The transistor 37 is a switching element that is interposed between the input terminal T and the output terminal of the inverter 34 and controls the electrical connection (conduction and non-conduction) between the two.

  The gate of the transistor 37 is connected to a wiring to which a reset signal R [i] is supplied. The reset signal R [i] is a signal that becomes high level in the period before the start of the first period Pa [i] in which the scanning signal Y [i] becomes high level and maintains the low level in other periods. . That is, the reset signal R [1] to the reset signal R [m] are sequentially set to the high level in the order in which each row is selected.

  In the above configuration, when the reset signal R [i] becomes high level, the transistor 37 is turned on, and the input terminal T and the output terminal of the inverter 34 are electrically connected. Accordingly, the potentials at both the input terminal T and the output terminal of the inverter 34 converge to the difference value (Vdd−Vth_P) between the power supply potential Vdd and the threshold voltage Vth_P of the p-channel transistor 341. In this way, by setting the potential Va of the input terminal T to a predetermined value prior to the first period Pa [i], the potential Va of the input terminal T is quickly and reliably set to the potential Vdata in the first period Pa [i]. There is an advantage that it can be set. In addition, since the potential between the electro-optic element 35 and the output terminal of the inverter 34 is initialized to a predetermined value, the time required for the response of the electro-optic element 35 can be made uniform over a plurality of unit circuits U.

<C: Modification>
Various modifications can be made to each of the above embodiments. An example of a specific modification is as follows. In addition, you may combine each following aspect suitably.

(1) Modification 1
In each embodiment, the reference signal W [i] in the second period Pb [i] is exemplified as a triangular wave. However, the waveform of the reference signal W [i] in the second period Pb [i] is appropriately changed. Is done. For example, in each embodiment, the reference signal W [i] whose waveform is line symmetric with respect to the midpoint tc of the second period Pb [i] is illustrated, but in the present invention, the symmetry of the reference signal W [i] Is not required. For example, various waveforms such as a ramp wave, a sawtooth wave (sawtooth wave), and a multi-ramp wave (step wave) are applied to the reference signal W [i] in the second period Pb [i]. Further, not only a waveform in which the potential changes linearly but also a waveform that changes in a curve such as a sine wave may be applied to the reference signal W [i] in the second period Pb [i].

  Further, in each embodiment, the reference signal W [i] is exemplified to have a waveform of one period of the triangular wave in the second period Pb [i]. However, the reference signal W [i] has various waveforms such as the triangular wave and the ramp wave and sawtooth wave exemplified above. A reference signal is a waveform in which a plurality of unit waveforms are continued in the second period Pb [i] (that is, a waveform in which a plurality of unit waveforms are arranged on the time axis so as to repeat the increase and decrease of the potential multiple times). You may apply to W [i]. As described above, in the present invention, the reference signal W [i] whose potential varies with the passage of time in the second period Pb [i] is appropriately set according to the driving mode, function, etc. of the electro-optic element 35. It is possible to select.

  Furthermore, in each embodiment, the configuration in which the potential Va of the input terminal T starts to fluctuate from the potential Vdata in the first period Pa [i] when the second period Pb [i] starts is illustrated, but the second period Pb [i] The waveform of the reference signal W [i] may be selected so that the potential Va of the input terminal T varies at the start point and the end point of i]. For example, the reference signal W [i] illustrated in FIG. 6 may be used. The reference signal W [i] in the figure rises in potential by the change amount Vd at the start point of the second period Pb [i] and decreases in potential by the change amount Vd at the end point of the second period Pb [i]. In addition, as in the first embodiment, the potential drops and rises within the range of the voltage ΔV from the start point to the end point of the second period Pb [i]. The potential Va at the input terminal T varies according to the waveform of the reference signal W [i]. That is, as shown in FIG. 6, the potential Va first rises from the potential Vdata by the amount of change Vd at the start point of the second period Pb [i], and secondly, the interval from the start point to the midpoint tc. At the end of the second period Pb [i], and drops to Vdata at the end of the second period Pb [i]. Also in this configuration, the drive current Sdr is output from the inverter 34 over a time length corresponding to the data signal X [j], as in each embodiment.

(2) Modification 2
The specific configuration of the unit circuit U is not limited to the example shown in FIG. For example, the conductivity type of each transistor is arbitrarily changed from the example of FIG. In each of the embodiments, the configuration in which the output terminal of the inverter 34 and the anode of the electro-optic element 35 are directly connected is illustrated. However, as shown in FIG. For example, 39 gates may be connected. The transistor 39 is a means for generating a drive current Sdr, and is interposed between a power supply line to which the power supply potential Vdd is supplied and the anode of the electro-optic element 35. When the transistor 341 is turned on and the power supply potential Vdd is output from the inverter 34, the transistor 39 is turned on. At this time, the drive current Sdr flows through the electro-optic element 35 to emit light. On the other hand, when the ground potential Vss is output from the inverter 34, the transistor 39 is turned off, so that the supply of current is stopped and the electro-optic element 35 is turned off. Also with this configuration, the same operations and effects as those of the embodiments are achieved.

  Further, the means for outputting the drive current Sdr (drive means in the present invention) is not limited to the inverter 34. For example, instead of the inverter 34 of FIGS. 3, 5, and 7, a comparator that compares the potential Va of the input terminal T with a predetermined potential and outputs a drive current Sdr according to the result may be installed. . For example, the comparator outputs the power supply potential Vdd when the potential Va is lower than a predetermined potential, and outputs the ground potential Vss when the potential Va is higher than the predetermined potential. Also with this configuration, the same operations and effects as those of the embodiments are achieved. Further, the signal supplied to the electro-optical element 35 may be a current signal (the drive current Sdr illustrated in each embodiment) or a voltage signal. As described above, the driving means in the present invention is a drive signal (the drive current Sdr or the drive) according to the potential Va of the input terminal T (more specifically, according to the magnitude of the potential Va and the predetermined potential). Any element that outputs (voltage) is sufficient, and its specific configuration is not questioned.

(3) Modification 3
In each embodiment, the configuration in which the reference signal line 17 is formed so as to correspond to each of the plurality of scanning lines 13 (that is, for each row) is illustrated, but the correspondence between the scanning line 13 and the reference signal line 17 is illustrated. The relationship is not limited to this. For example, the reference signal line 17 is formed so as to correspond to each of the groups obtained by dividing the m scanning lines 13 into predetermined lines, and each reference signal line 17 is connected to each unit circuit U belonging to one group. It is good also as a structure. In this configuration, the capturing of the data signal X [j] is executed for each row, while the driving of the electro-optic element 35 due to the variation of the reference signal W [i] is executed for each group.

(4) Modification 4
In the second embodiment, the configuration in which the input terminal T of the inverter 34 is electrically connected to the output terminal prior to the first period Pa [i] is illustrated, but the connection destination of the input terminal T of the inverter 34 is appropriately set. Changed to For example, the transistor 37 is interposed between the wiring maintained at a predetermined potential and the input terminal T of the inverter 34, and the inverter 37 is turned on prior to the first period Pa [i]. The configuration may be such that the input terminal T of 34 is initialized to a predetermined potential.

(5) Modification 5
In the above embodiment, an OLED element is exemplified as the electro-optical element 35, but the electro-optical element employed in the electronic apparatus of the present invention is not limited to this. For example, instead of an OLED element, an inorganic EL element, a field emission (FE) element, a surface-conduction electron (SE) element, a ballistic electron surface emitting (BS) element, Various self-luminous elements such as LED (Light Emitting Diode) elements, and various electro-optical elements such as electrophoretic elements and electrochromic elements can be used. The present invention is also applied to a sensing device such as a biochip. The driven element of the present invention is a concept including all elements driven by application of electric energy, and an electro-optical element such as a light emitting element is merely an example of the driven element.

<D: Application example>
Next, an electronic apparatus using the electronic apparatus (electro-optical apparatus) according to the present invention will be described. FIG. 8 is a perspective view showing the configuration of a mobile personal computer that employs the electronic device D according to any one of the embodiments described above as a display device. The personal computer 2000 includes an electronic device D as a display device and a main body 2010. The main body 2010 is provided with a power switch 2001 and a keyboard 2002. Since this electronic device D uses an OLED element as the electro-optic element 35, it is possible to display an easy-to-see screen with a wide viewing angle.

  FIG. 9 shows a configuration of a mobile phone to which the electronic device D according to the embodiment is applied. A cellular phone 3000 includes a plurality of operation buttons 3001, scroll buttons 3002, and an electronic device D as a display device. By operating the scroll button 3002, the screen displayed on the electronic device D is scrolled.

  FIG. 10 shows a configuration of a personal digital assistant (PDA) to which the electronic device D according to the embodiment is applied. The information portable terminal 4000 includes a plurality of operation buttons 4001, a power switch 4002, and an electronic device D as a display device. When the power switch 4002 is operated, various kinds of information such as an address book and a schedule book are displayed on the electronic device D.

  The electronic apparatus to which the electronic apparatus (electro-optical apparatus) according to the present invention is applied includes the digital still camera, television, video camera, car navigation apparatus, pager, and electronic notebook in addition to those shown in FIGS. Electronic paper, calculator, word processor, workstation, video phone, POS terminal, printer, scanner, copier, video player, equipment equipped with a touch panel, and the like. Further, the use of the electronic device according to the present invention is not limited to the display of images. For example, in an image forming apparatus such as an optical writing type printer or an electronic copying machine, a writing head that exposes a photosensitive member according to an image to be formed on a recording material such as paper is used. However, the electronic device of the present invention is used. The unit circuit referred to in the present invention is a concept including not only a circuit constituting a pixel of a display device (a so-called pixel circuit) but also a circuit as a unit of exposure in the image forming apparatus.

1 is a block diagram illustrating a configuration of an electronic device according to a first embodiment of the present invention. 6 is a timing chart showing waveforms of a scanning signal Y [i] and a reference signal W [i]. It is a circuit diagram which shows the structure of one unit circuit. 6 is a timing chart showing a relationship between a potential Va and a drive current Sdr. It is a circuit diagram which shows the structure of one unit circuit in the electronic device of 2nd Embodiment of this invention. It is a timing chart which shows the waveform of reference signal W [i] concerning a modification. It is a circuit diagram which shows the structure of the unit circuit which concerns on a modification. It is a perspective view which shows the specific form of the electronic device which concerns on this invention. It is a perspective view which shows the specific form of the electronic device which concerns on this invention. It is a perspective view which shows the specific form of the electronic device which concerns on this invention.

Explanation of symbols

D: Electronic device, 10: Element array section, 13: Scan line, 15: Data line, 17: Reference signal line, 23: Scan line drive circuit, 25: Data line drive circuit, 27 ... ... Signal generation circuit, 37 ... transistor, 33 ... capacitance element, 34 ... inverter, T ... input terminal of inverter, 35 ... electro-optic element, Y [i] ... scanning signal, X [j] ... ... data signal, Vdata ... potential of data signal, W [i] ... reference signal, Sdr ... drive current, Va ... potential of input terminal of inverter.

Claims (14)

A plurality of first wires;
A plurality of second wirings intersecting the plurality of first wirings;
A plurality of unit circuits arranged corresponding to intersections of the plurality of first wirings and the plurality of second wirings;
A plurality of reference signal lines for supplying a reference signal to the plurality of unit circuits,
Each of the plurality of unit circuits is
A driven element that is driven by the supply of a driving voltage or a driving current;
Driving means for supplying the driving voltage or the driving current to the driven element;
A switching element that controls electrical connection between an input terminal included in the driving unit and one second wiring of the plurality of second wirings;
A first electrode connected to the input terminal and a second electrode connected to one reference signal line of the plurality of reference signal lines, and a charge between the first electrode and the second electrode An electronic device comprising: The electronic device according to claim 1, wherein the plurality of reference signal lines intersect the plurality of second wirings. The electronic device according to claim 1, wherein the potential of each of the plurality of reference signal lines changes at a predetermined period. A selection circuit for selecting each of the plurality of first wirings;
The electronic device according to claim 3, further comprising: a signal generation circuit that sequentially supplies the reference signals to the plurality of reference signal lines in an order in which the first wiring is selected. 2. The electronic device according to claim 1, wherein a potential of the input terminal is set by supplying a data signal to the input terminal via the one second wiring and the switching element in the first period. The electronic device according to claim 5, wherein a length of a driving period in which the driving voltage or the driving current is supplied to the driven element corresponds to the potential of the input terminal set in the first period. 7. The electronic device according to claim 5, wherein the potential of the input terminal varies according to a change in potential of the one reference signal line from a potential set by the data signal in the first period. . The electronic apparatus according to claim 7, wherein the input terminal is in a floating state in at least a part of a driving period in which the driving voltage or the driving current is supplied to the driven element. In the first period, the driving unit is configured to drive the driving voltage in any one of a period in which the potential of the input terminal set by the data signal is higher than a predetermined potential and a period in which the potential of the input terminal is lower than a predetermined potential. The electronic device according to claim 5, wherein the driving current is supplied to the driven element. The potential of the one reference signal line is set to at least a first potential when the potential of the input terminal is set by the data signal in the first period,
The potential of the one reference signal line at the start of the second period is the first potential,
The one reference signal line becomes a second potential having a voltage level different from the first potential in the second period,
The electronic apparatus according to claim 9, wherein the potential of the one reference signal line at the end of the second period is the first potential. 11. The electronic device according to claim 10, wherein a change in the potential of the one reference signal line in the second period is axisymmetric with respect to a point in time when the one reference signal line becomes the second potential. Each of the plurality of unit circuits includes a reset unit configured to set the input terminal to a predetermined potential prior to a first period in which a data signal is supplied to the input terminal via the one second wiring and the switching element. The electronic device according to claim 1. A plurality of scan lines;
A plurality of data lines intersecting the plurality of scanning lines;
A plurality of unit circuits arranged corresponding to intersections of the plurality of scanning lines and the plurality of data lines;
A plurality of reference signal lines for supplying a reference signal to the plurality of unit circuits,
Each of the plurality of unit circuits is
An electro-optic element that is driven by supplying a driving voltage or a driving current;
Drive means for supplying the drive voltage or the drive current to the electro-optic element;
A switching element that controls electrical connection between an input terminal included in the driving unit and one of the plurality of data lines;
A first electrode connected to the input terminal and a second electrode connected to one reference signal line of the plurality of reference signal lines, the gap between the first electrode and the second electrode; A capacitive element that accumulates electric charge,
The driving period for supplying the driving voltage or the driving current to the electro-optic element is such that a data signal is supplied to the input terminal via the one data line and the switching element within the first period. An electro-optical device characterized by corresponding to the potential of the input terminal set by An electronic apparatus comprising the electronic device according to claim 1 or the electro-optical device according to claim 13.

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