JP2013200483A - Display device and driving method thereof - Google Patents

Display device and driving method thereof Download PDF

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JP2013200483A
JP2013200483A JP2012069569A JP2012069569A JP2013200483A JP 2013200483 A JP2013200483 A JP 2013200483A JP 2012069569 A JP2012069569 A JP 2012069569A JP 2012069569 A JP2012069569 A JP 2012069569A JP 2013200483 A JP2013200483 A JP 2013200483A
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potential
light
electrode
light extraction
state
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JP2012069569A
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JP5813549B2 (en
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Takeshi Hioki
毅 日置
Yutaka Nakai
豊 中井
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Toshiba Corp
株式会社東芝
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Abstract

PROBLEM TO BE SOLVED: To provide a display device reducing drive voltage and a driving method thereof.SOLUTION: A display device contains a light emission unit emitting light, plural light guide units, plural light extraction units and a control unit. The light guide unit leads light. The light extraction unit has a first electrode and a second electrode and faces the light guide unit. The light extraction part forms a first state and a second state in which a light extraction amount is different by the light extraction part and the light guide unit being contact or non-contact depending on electric potential difference between the first and second electrodes. The control unit is connected to the first and second electrodes, and sets the second electrode to a first potential in a first period and sets the second electrode to a second potential which is lower than the first potential in a second period. In the first period, the first electrode is set to the second potential in the first state and set to the first potential in the second state. In the second period, the first electrode is set to the first potential in the first state and set to the second potential in the second state.

Description

  Embodiments described herein relate generally to a display device and a driving method thereof.

  For example, a display device using a plurality of light guide structures that guide light has been proposed. In this display device, display is performed by extracting light from a predetermined position of the light guide structure to the outside of the light guide structure. In a display device, it is desired to lower the drive voltage.

JP 2009-237456 A

  Embodiments of the present invention provide a display device with a reduced driving voltage and a driving method thereof.

  According to the embodiment of the present invention, a display device including a light emitting unit, a plurality of light guide units, a plurality of light extraction units, and a control unit is provided. The light emitting unit emits light. The plurality of light guides extend in a first direction and guide the light. The plurality of light guides are arranged in a second direction that intersects the first direction. The plurality of light extraction portions have a first electrode and a second electrode, and face the light guide portion. The plurality of light extraction portions may be configured such that the light extraction portion and the light guide portion are brought into a contact state or a first non-contact state due to a potential difference between the first electrode and the second electrode. It is possible to form a first state and a second state in which light extraction amounts from the light guide portion are different from each other by changing a waveguide state of light guided through the light portion. The control unit is connected to the first electrode and the second electrode. The control unit sets the potential of the second electrode to the first potential in the first period and the second potential in the second period. The electrode potential is set to a second potential lower than the first potential. In the first period, the control unit sets the potential of the first electrode to the second potential when the light extraction unit is set to the first state, and sets the light extraction unit to the second state. The potential of the first electrode is set to the first potential. In the second period, the control unit sets the potential of the first electrode to the first potential when the light extraction unit is set to the first state, and sets the light extraction unit to the second state. The potential of the first electrode is set to the second potential.

1 is a schematic plan view showing a display device according to a first embodiment. It is a typical sectional view showing the display concerning a 1st embodiment. It is a schematic diagram which shows operation | movement of the display apparatus which concerns on 1st Embodiment. It is a schematic diagram which shows operation | movement of the display apparatus which concerns on 1st Embodiment. FIG. 5 is a schematic cross-sectional view showing the operation of the display device according to the first embodiment. FIG. 6A and FIG. 6B are graphs showing the characteristics of the display device according to the first embodiment. It is a schematic diagram which shows operation | movement of the display apparatus which concerns on 2nd Embodiment. It is a schematic diagram which shows operation | movement of the display apparatus which concerns on 2nd Embodiment. FIG. 9A and FIG. 9B are schematic cross-sectional views illustrating the operation of the display device according to the second embodiment. FIG. 10A and FIG. 10B are graphs showing the characteristics of the display device according to the second embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between the parts, and the like are not necessarily the same as actual ones. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
Note that, in the present specification and each drawing, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

(First embodiment)
FIG. 1 is a schematic plan view illustrating the configuration of the display device according to the first embodiment.
As illustrated in FIG. 1, the display device 110 according to the present embodiment includes a light emitting unit 10, a plurality of light guide units 20, a plurality of light extraction units 30, and a control unit 60.

  The light emitting unit 10 emits light. In this example, the light emitting unit 10 includes a plurality of light sources 10s. For example, a light emitting diode is used as the light source 10s. The main wavelengths of light emitted from the light source 10s are, for example, about 460 nanometers (nm), about 530 nm, and about 660 nm. The main wavelength of the light emitted from the light source 10s is set so that full color display with the three primary colors of light is possible.

  The light guide unit 20 extends in the first direction. The plurality of light guides 20 are arranged in a second direction that intersects the first direction.

  The second direction is, for example, perpendicular to the first direction. However, a plane may be formed by the first direction and the second direction. Hereinafter, the case where the second direction is perpendicular to the first direction will be described.

  The first direction is the X-axis direction. The second direction is the Y-axis direction. A direction perpendicular to the first direction and the second direction is defined as a third direction (Z-axis direction). The third direction may intersect with the plane formed by the first direction and the second direction. Hereinafter, the case where the third direction is perpendicular to the first direction and the second direction will be described.

  The light guide 20 has one end 21 and the other end 22. The light guide unit 20 guides the light emitted from the light emitting unit 10. In this example, the light source 10 s faces the one end 21 of the light guide unit 20. The light source 10 s is optically connected to the light guide unit 20. In the light guide unit 20, for example, light is guided from one end 21 toward the other end 22.

  Each of the plurality of light extraction units 30 faces the light guide unit 20.

  In this specification, “opposite” includes not only a state of directly facing each other but also a state of facing each other with another element interposed therebetween.

  The light extraction unit 30 extends, for example, in the Y-axis direction. A portion where the light guide unit 20 and the light extraction unit 30 face each other corresponds to a pixel. The pixels are arranged in a matrix in the XY plane. An example of the configuration of the light extraction unit 30 will be described later.

  In this example, the control unit 60 includes a scanning drive circuit 61, a light source drive circuit 62, and a video processing circuit 63. The scanning drive circuit 61 is connected to the light extraction unit 30 by, for example, a scanning line 61l (for example, the scanning line 61a and the scanning line 61b). The scanning line 61l extends in the Y-axis direction. The scanning drive circuit 61 scans the light extraction unit 30 along the X-axis direction. The light source driving circuit 62 is connected to the light source 10s and drives the light source 10s. The video processing circuit 63 is connected to the scanning drive circuit 61 and the light source drive circuit 62. A video signal SV and an external power supply PW are supplied to the video processing circuit 63 from the outside of the display device 110. For example, the video processing circuit 63 supplies a signal based on the video signal SV to the light source driving circuit 62. The video processing circuit 63 supplies a current (voltage) and a control signal based on the external power source PW to the scanning drive circuit 61 and the light source drive circuit 62.

  For example, the control unit 60 sequentially selects the light extraction units 30 arranged in the Y-axis direction, operates the pixels by line sequential driving, and performs a display operation.

FIG. 2 is a schematic cross-sectional view illustrating the configuration of the display device according to the first embodiment.
2 is a cross-sectional view taken along line A1-A2 of FIG.
As shown in FIG. 2, the light guide 20 has a side surface 20 s between one end 21 and the other end 22. The side surface 20s is, for example, parallel to the XY plane.

  The light extraction unit 30 faces the side surface 20s. Each of the light extraction units 30 includes a first electrode 31a and a second electrode 31b. In this example, the light extraction unit 30 further includes a displacement layer 31 c and an optical path conversion layer 33. The displacement layer 31c is provided between the first electrode 31a and the second electrode 31b. The first electrode 31a is disposed between the optical path conversion layer 33 and the second electrode 31b. Between the second electrode 31b and the light guide unit 20, the displacement layer 31c, the first electrode 31a, and the optical path conversion layer 33 are disposed. The position of the first electrode 31a and the position of the second electrode 31b may be interchanged with each other.

  The thickness of the displacement layer 31c in the Z-axis direction (for example, volume may be changed) due to a potential difference (voltage) applied between the first electrode 31a and the second electrode 31b. For the displacement layer 31c, for example, a ferroelectric material such as lead zirconate titanate is used.

  Due to the change in the thickness of the displacement layer 31c, for example, in one state, the optical path conversion layer 33 (light extraction unit 30) is separated from the light guide unit 20 (corresponding to the first non-contact state), and another In the state, the optical path conversion layer 33 (light extraction unit 30) is in contact with the light guide unit 20.

  As described above, the displacement layer 31c is displaced by the potential difference applied between the first electrode 31a and the second electrode 31b of the light extraction unit 30, and the optical path conversion layer 33 is in contact with the light guide unit 20 or not. The contact state (first contact state) is controlled.

  The optical path conversion layer 33 includes, for example, a resin and fine particles dispersed in the resin. The refractive index of the fine particles is different from the refractive index of the resin. An acrylic resin (with a refractive index of about 1.49) is used as the resin, and titanium oxide (for example, a refractive index of about 2) is used as the fine particles. In the optical path conversion layer 33, the traveling direction of light can be changed at the interface between the resin and the fine particles. The change in the traveling direction of light is based on at least one of refraction and scattering at the interface between the resin and the fine particles. Thereby, the optical path conversion layer 33 has a function of changing the optical path.

  The light guide 20 is transmissive in the visible light range. For the light guide unit 20, for example, an acrylic resin is used. When the atmosphere is covered with an acrylic resin, the interface between the light guide 20 and the atmosphere has an acrylic resin refractive index (about 1.49) and an air refractive index (about 1). It becomes the interface. Therefore, it is possible to guide light that satisfies the total reflection condition at this interface.

  The light L11 emitted from the light source 10s is introduced into the light guide unit 20 from one end 21 of the light guide unit 20, for example. By controlling the emission angle of the light emitted from the light source 10s, the guided light L12 in the light guide 20 can be guided while repeating total reflection on the side surface 20s of the light guide 20.

  As shown in FIG. 2, in the n-th (n is an integer of 2 or more) light extraction unit 30, the optical path conversion layer 33 is in contact with the light guide unit 20. The nth light extraction unit 30 is referred to as a selection state light extraction unit SS. In the light extraction unit 30 excluding the nth light extraction unit 30, the optical path conversion layer 33 is not in contact with the light guide unit 20. The light extraction unit 30 excluding the nth light extraction unit 30 is referred to as a non-selection light extraction unit NS.

  The potential difference applied between the first electrode 31a and the second electrode 31b of the selected state light extraction unit SS is applied between the first electrode 31a and the second electrode 31b of the non-selection state light extraction unit NS. It is different from the potential difference. In a portion where the light guide unit 20 and the light extraction unit 30 are not in contact with each other (a portion of the non-selection light extraction unit NS), the guided light L12 is entirely transmitted through the light guide unit 20 due to a difference in refractive index from the air interposed therebetween. Guided while meeting reflection conditions. In the portion of the light guide unit 20 where the light extraction unit 30 and the light guide unit 20 are in contact (selection state light extraction unit SS), the guided light L12 is an optical path conversion layer 33 in contact with the light guide unit 20. The refractive index of the light enters the optical path conversion layer 33 due to refraction. The traveling direction of the light incident on the optical path conversion layer 33 is changed, and is extracted out of the light guide unit 20 as extracted light L13. According to the operation of the light extraction unit 30, the light source driving circuit 62 causes the light source 10s to emit light adjusted to a desired color and light intensity, thereby enabling local and selective light extraction operations.

  As described above, the light extraction unit 30 is configured such that the light extraction unit 30 and the light guide unit 20 are brought into a contact state or a non-contact state due to a potential difference between the first electrode 31a and the second electrode 31b. A plurality of states (for example, a first state and a second state) having different light extraction amounts from the light guide unit 20 can be formed by changing the waveguide state of the light guided 20.

  The controller 60 is electrically connected to the first electrode 31a and the second electrode 31b. For this connection, for example, the scanning line 61l is used. The control unit 60 controls the potential of the first electrode 31a and the potential of the second electrode 31b, thereby changing the distance between the light extraction unit 30 and the light guide unit 20 and guiding the light guide unit 20 to light. The waveguide state of (guided light L12) is changed to form two or more states (first state and second state) in which light extraction amounts from the light guide unit 20 are different from each other.

  For example, the first state is a state in which the light extraction unit 30 is in contact with the light guide unit 20. The second state is a state where the light extraction unit 30 is not in contact with the light guide unit 20. These states are interchanged, the first state is a state in which the light extraction unit 30 is not in contact with the light guide unit 20, and the second state is a state in which the light extraction unit 30 is in contact with the light guide unit 20. good. In the following description, it is assumed that the light extraction unit 30 is in contact with the light guide unit 20 in the first state, and the light extraction unit 30 is not in contact with the light guide unit 20 in the second state.

  In the display device having such a configuration, the driving voltage of the scanning line 61l for operating the light extraction unit 30 needs to be relatively high, for example, 20 volts (V) or more and 120 volts. It is desirable to reduce the driving voltage of the scanning line 61l from the viewpoint of power consumption reduction and component reliability. In the display device 110 according to the present embodiment, the drive voltage is reduced.

  In the display device 110 according to the present embodiment, for example, a display operation is performed by line sequential driving. Hereinafter, an example of the operation (driving method) of the control unit 60 will be described as a case of performing the line sequential operation. In the line-sequential operation, the light extraction unit 30 connected to one scanning line 61l is set in a light extraction state for a certain period, and light corresponding thereto is introduced from the light source 10s to the light guide unit 20, whereby the line Perform unit light extraction operation.

  That is, when the plurality of light extraction units 30 are arranged in the X-axis direction, the control unit 60 sequentially sets the plurality of light extraction units 30 in the first state along the X-axis direction. And the control part 60 makes the some light extraction part 30 except the light extraction part 30 made into the 1st state into a 2nd state.

FIG. 3 is a schematic view illustrating the operation of the display device according to the first embodiment.
FIG. 3 is an example of a timing chart relating to an output signal from the control unit 60 (scan driving circuit 61). In this example, the second electrodes 31b of the plurality of light extraction units 30 are connected to each other. That is, a common wiring is connected to the second electrodes 31 b of the plurality of light extraction units 30. The potential of the second electrode 31b is set to the common potential Vcom. By applying a common potential to the plurality of second electrodes 31b, the configuration of the scan driving circuit 61 can be simplified. Moreover, the load of the process at the time of patterning the 2nd electrode 31b can be reduced.

  The horizontal axis in FIG. 3 is time t. In FIG. 3, as an example, the potential V (n−1) of the first electrode 31a of the (n−1) th light extraction unit 30, and the potential Vn of the first electrode 31a of the nth light extraction unit 30 The potential V (n + 1) of the first electrode 31a of the (n + 1) th light extraction section 30 is shown.

As shown in FIG. 3, the first period F1 and the second period F2 are set. For example, the first period F1 and the second period F2 are alternately repeated. Each of the first period F1 and the second period F2 corresponds to, for example, a display frame period. Between t 0 to t 5 is the first period F1. between t 5 to t 10 is the second period F2.

The period from t 1 to t 2 , the period from t 2 to t 3 , and the period from t 3 to t 4 are the (n−1) -th, n-th, and n, respectively, in the first period F 1. This corresponds to the selection period ts of the line sequential operation of the (n + 1) th scanning line 61l. period from t 6 to t 7, the period from t 7 to t 8, and the period from t 8 to t 9 is in the second period F2, respectively, the (n-1), the n-th and, This corresponds to the selection period ts of the line sequential operation on the (n + 1) th scanning line 61l. For example, the time when each of the light extraction units 30 enters the first state is set as the selection period ts of each of the light extraction units 30. The time when each of the light extraction units 30 enters the second state is defined as a non-selection period tn of each of the light extraction units 30.

  That is, the selection period ts is a period in which any one of the plurality of light extraction units 30 is in the first state, and the non-selection period tn is a period in which the light extraction unit 30 is in the second state. is there.

  As illustrated in FIG. 3, the control unit 60 sets the potential of the second electrode 31b (in this example, the common potential Vcom) to the first potential E1 in the first period F1, and the second electrode 31b in the second period F2. (The common potential Vcom in this example) is set to a second potential E2 lower than the first potential E1.

  In this example, the first potential E1 is a voltage Va, and the second potential E2 is a voltage −Va. In this example, Va is a positive voltage and -Va is a negative voltage. The absolute value of Va is substantially equal to the absolute value of -Va. The absolute value of Va is, for example, 90% to 110% of the absolute value of -Va.

  In the first period F1, the potential V (n−1), the potential Vn, and the potential V (n + 1) related to the first electrode 31a are the second potential in the selection period ts of each light extraction unit 30. E2 is set to the first potential E1 during the non-selection period tn. In the second period F2, the potential V (n−1), the potential Vn, and the potential V (n + 1) are set to the first potential E1 in the selection period ts of each light extraction unit 30, In the non-selection period tn, the second potential E2 is set.

  In other words, the control unit 60 sets the potential of the first electrode 31a to the second potential E2 when the light extraction unit 30 is set to the first state in the first period F1, and sets the light extraction unit 30 to the second state. When setting, the potential of the first electrode 31a is set to the first potential E1. On the other hand, in the second period F1, the control unit 60 sets the potential of the first electrode 31a to the first potential E1 when the light extraction unit 30 is set to the first state, and sets the light extraction unit 30 to the second state. In doing so, the potential of the first electrode 31a is set to the second potential E2.

  In this example, the polarity of the waveform applied to the common potential Vcom is inverted between two frames. The potentials of the first electrode 31a (the potential V (n−1), the potential Vn, and the potential V (n + 1)) are the same as the common potential Vcom in the non-selection period tn excluding the selection period ts of the line sequential operation. It is. The potential of the first electrode 31a is different from the polarity of the common potential Vcom in each selection period ts.

FIG. 4 is a schematic view illustrating the operation of the display device according to the first embodiment.
4 shows the (n−1) th light extraction unit 30, the nth light extraction unit 30, and the (n + 1) th light extraction unit 30 when the operation illustrated in FIG. 3 is performed. The potential differences Vd (n−1), Vdn, and Vd (n + 1) between the first electrode 31a and the second electrode 31b are exemplified. These potential differences correspond to effective voltages applied to the light extraction unit 30.

  As illustrated in FIG. 4, in the selection period ts in each light extraction unit 30, 2Va that is twice the value of Va and 2 of −Va is provided between the first electrode 31 a and the second electrode 31 b. A double value of −2 Va is applied.

FIG. 5 is a schematic cross-sectional view illustrating the operation of the display device according to the first embodiment.
FIG. 5 illustrates the state of the potential when the nth light extraction unit 30 is in the selection period ts in the first period F1.
As illustrated in FIG. 5, in the (n−1) th and (n + 1) th light extraction units 30, Va is applied to the first electrode 31 a and the second electrode 31 b. No potential difference is generated between the two electrodes 31b. On the other hand, in the nth light extraction unit 30, -Va is applied to the first electrode 31a and Va is applied to the second electrode 31b, and therefore, between the first electrode 31a and the second electrode 31b. Is applied with a potential difference (effective voltage) of 2Va. In the nth light extraction part 30, the displacement layer 31c is displaced by the electric field generated between the first electrode 31a and the second electrode 31b, and in the nth light extraction part, the optical path conversion layer 33 is the light guide part 20. The light extraction operation is performed.

  On the other hand, for example, a driving method in which the common potential Vcom (the potential of the second electrode 31b) is constant (for example, the ground potential) and the potential of the first electrode 31a is changed can be considered. At this time, the potential of the first electrode 31a is changed between Va and -Va. At this time, the potential difference between the first electrode 31a and the second electrode 31b is Va.

  On the other hand, in the present embodiment, the common potential Vcom (the potential of the second electrode 31b) is changed, and the first electrode 31a is set to the opposite high and low (polarity) potential in accordance with the change. Thus, the potential difference between the first electrode 31a and the second electrode 31b can be 2Va.

  In other words, in the embodiment, a desired voltage in the light extraction unit 30 is supplied by supplying a voltage that is ½ of the potential difference between the first electrode 31 a and the second electrode 31 b necessary for the operation of the light extraction unit 30. Can be realized. That is, the driving voltage of the scanning line 61l can be halved.

  Thus, according to the display device 110 according to the embodiment, a display device with a reduced driving voltage can be provided. For example, even if a relatively inexpensive scan driving circuit with a low withstand voltage is used, an effective voltage twice as high as the voltage available in the driving circuit can be applied to the light extraction unit 30.

  In the embodiment, for example, the polarity of the common potential Vcom (potential level relationship) is switched between the first period F1 and the second period F2. Accordingly, the polarity of the potential difference between the first electrode 31a and the second electrode 31b is reversed. In this way, by reversing the polarity of the applied waveform, it is possible to suppress the application of a biased voltage between the first electrode 31a and the second electrode 31b. Thereby, for example, the operation of the displacement layer 31c is stabilized and, for example, the life is improved.

  Hereinafter, an example of the result of examining the optical response characteristics of the display device 110 according to the embodiment will be described.

FIG. 6A and FIG. 6B are graphs illustrating characteristics of the display device according to the first embodiment.
These drawings schematically show an example of measurement results of response characteristics of light extracted from the light guide unit 20 by one light extraction unit 30.
In these figures, the horizontal axis is time t. The vertical axis in FIG. 6B indicates the waveform of the voltage Vop applied between the first electrode 31a and the second electrode 31b. The vertical axis in FIG. 6A is the light energy amount Ie (arbitrary scale) of the extracted light.

As shown in FIG. 6B, the voltage Vop is 0 in the period before the time t x (corresponding to the non-selection period tn), and the period between the time t x and the time t x + 1 (selected) The voltage Vop is 2Va in the period ts), and the voltage Vop is 0 in the period after the time tx + 1 (non-selection period tn).

As shown in FIG. 6A , the light energy amount Ie reaches a predetermined value Is at time t xd1 after time t x . On the other hand, after time t x + 1 , the amount of light energy Ie changes relatively quickly. Thus, it was found that the delay in the rise of the optical response is larger than the delay in the fall.

  The transition from the non-selection period tn to the selection period ts corresponds to the transition of the light extraction unit 30 from the light guide unit 20 to the contact state from the non-contact state. The transition from the selection period ts to the non-selection period tn corresponds to a transition from the state in which the light extraction unit 30 is in contact with the light guide unit 20 to the non-contact state. If the light extraction unit 30 is separated from the light guide unit 20 even a little, the light extraction state is immediately eliminated, so that the amount of light energy Ie is drastically decreased, and it is considered that the fall delay is small as described above. On the other hand, in order to shift from the state where the light extraction unit 30 is separated from the light guide unit 20 by a certain distance to the contact state, it is necessary to move the certain distance. For this reason, it is considered that the delay time at the rise is relatively long as described above.

When the delay of the optical response is long, for example, the display brightness is lowered and the display quality is lowered. This characteristic of optical response is a newly discovered problem.
In the following embodiments, this delay in optical response is suppressed.

(Second Embodiment)
FIG. 7 is a schematic view illustrating the operation of the display device according to the second embodiment.
FIG. 7 is an example of a timing chart relating to an output signal from the control unit 60 (scan driving circuit 61) in the display device 110 according to the present embodiment. Hereinafter, differences from the first embodiment will be described, and description of parts similar to those of the first embodiment will be omitted.

  The control unit 60 sets the first electrode 31a to the third potential E3 in the pre-period tp before the selection period ts. As described above, the selection period ts is a period in which any one of the plurality of light extraction units 30 is in the first state. The pre-period tp is a period preceding the selection period ts and continuing from the selection period ts. In this pre-period tp, the light extraction unit 30 (at least one of them) excluding the light extraction unit 30 of interest is in the second state. The third potential E3 is a potential between the first potential E1 and the second potential E2.

  In this example, the first potential E1 is Va, the second potential E2 is −Va, and the third potential E3 is, for example, a ground potential (0 volt potential). For example, the absolute value of the difference between the first potential E1 and the third potential E3 is substantially equal to the absolute value of the difference between the second potential E2 and the third potential E3. For example, the absolute value of the difference between the first potential E1 and the third potential E3 is not less than 90% and not more than 110% of the absolute value of the difference between the second potential E2 and the third potential E3.

FIG. 8 is a schematic view illustrating the operation of the display device according to the second embodiment.
FIG. 8 illustrates the operations of the (n−1) th light extraction unit 30, the nth light extraction unit 30, and the (n + 1) th light extraction unit 30 when the operation illustrated in FIG. 4 is performed. The potential differences Vd (n−1), Vdn, and Vd (n + 1) between the first electrode 31a and the second electrode 31b are exemplified.

  As illustrated in FIG. 8, 2Va or −2Va is applied between the first electrode 31a and the second electrode 31b in the selection period ts in each light extraction unit 30. In the pre-period tp, V or −V is applied between the first electrode 31a and the second electrode 31b.

  For example, when the (n−1) th light extraction unit 30 is in the selection period ts, a pre-period tp related to the selection period ts of the nth light extraction unit 30 is provided. In the pre-period tp, a predetermined voltage is applied in advance to the nth light extraction unit 30. Thereby, in the pre-period tp, the n-th light extraction unit 30 performs the preliminary operation before the selection period ts.

FIG. 9A and FIG. 9B are schematic cross-sectional views illustrating the operation of the display device according to the second embodiment.
FIG. 9A shows that the (n−1) th light extraction unit 30 is in the selection period ts, the nth light extraction unit 30 is in the pre-period tp, and the (n + 1) th light extraction unit 30 is not selected. The state when it is period tn is illustrated. In FIG. 9B, the (n−1) th light extraction unit 30 is in the non-selection period tn, the nth light extraction unit 30 is in the selection period ts, and the (n + 1) th light extraction unit 30 is not selected. The state when it is period tn is illustrated.

  As illustrated in FIG. 9A, the (n−1) th light extraction unit 30 that is in the state of the selection period ts is in contact with the light guide unit 20. The (n + 1) th light extraction unit 30 in the non-selection period tn is in a first non-contact state with the light guide unit 20. The nth light extraction unit 30 in the state of the pre-period tp is in a second non-contact state with the light guide unit 20. The distance between the light extraction unit 30 and the light guide unit 20 in the second non-contact state is shorter than the distance between the light extraction unit 30 and the light guide unit 20 in the first non-contact state. In the pre-period tp, the nth light extraction unit 30 is in the preliminary operation state.

  As illustrated in FIG. 9B, when the nth light extraction unit 30 is in the selection period ts, the nth light extraction unit 30 is in contact with the light guide unit 20. Since the distance between the light extraction unit 30 and the light guide unit 20 is shortened in advance in the pre-period tp, the movement distance is short and the response time is shortened.

FIG. 10A and FIG. 10B are graphs illustrating characteristics of the display device according to the second embodiment.
The time t x , the time t xd1 , and the time t x + 1 shown in these figures are the same as those described with reference to FIGS. 6 (a) and 6 (b).

As shown in FIG. 10B, in the pre-period tp before the period from time t x to time t x + 1 (corresponding to the selection period ts), the first electrode 31a and the second electrode 31b The voltage Vop between is Va, for example. In the selection period ts, the voltage Vop is 2Va.

As shown in FIG. 10 (a), change in the amount of light energy Ie is completed in a short time from the time t x is the start of the selection period ts to time t dx2. Thus, in this embodiment, the delay in the rise of the optical response can be shortened.

For example, by setting t xp so that t xd1 −t x = t x −t xp , the optical response can be shortened to t xd2 −t x . In FIG. 10A and FIG. 10B, the potential difference of va is previously applied to the (n + 1) th light extraction unit 30 during the period in which a potential difference of 2Va is applied to the nth light extraction unit 30. This is because the preliminary drive for the displacement operation can be performed.

According to the present embodiment, it was confirmed that (t xd1 −t x ) / (t x + 1 −t x ) is about 1/3. For example, the optical response in FIG. 10A can be obtained by setting t xp to be t x −t xp = t xd1 −t x = (t x + 1 −t x ) / 3. For example, (t d2 -t x ) / (t xd1 -t x ) is 1/4 or less, that is, the response speed at the time of rising can be increased by 4 times or more.

(Third embodiment)
The present embodiment relates to a method for driving a display device. The display device to which the present driving method is applied is, for example, the display device 110 described above.
In this driving method, the potential of the second electrode 31b is set to the first potential E1 in the first period F1, and the potential of the second electrode 31b is set to the second potential E2 lower than the first potential E1 in the second period F2. To do. In the first period F1, the potential of the first electrode 31a is set to the second potential E2 when the light extraction unit 30 is set to the first state, and the first electrode is set when the light extraction unit 30 is set to the second state. The potential of 31a is set to the first potential E1. In the second period F2, the potential of the first electrode 31a is set to the first potential E1 when the light extraction unit 30 is set to the first state, and the first electrode 31a is set to the second state F2 when the light extraction unit 30 is set to the second state. The potential is set to the second potential E2.
As a result, the drive voltage can be reduced.

In addition, this driving method may further perform the preliminary operation. That is, the light extraction unit 30 excluding the light extraction unit 30 in the pre-period tp following the selection period ts before the selection period ts in which any one of the plurality of light extraction units 30 is in the first state. The potential of the first electrode 31a is set to the third potential E2 between the first potential E1 and the second potential E2 while at least one of the above is set to the second state.
Thereby, the delay in optical response can be shortened, and a higher quality display can be provided.

  According to the embodiment, a display device with a reduced driving voltage and a driving method thereof can be provided.

  In the present specification, “vertical” and “parallel” include not only strictly vertical and strictly parallel, but also include, for example, variations in the manufacturing process, and may be substantially vertical and substantially parallel. is good.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, a light emitting unit, a light source, a light guide unit, a light extraction unit, a first electrode, a second electrode, a displacement layer, an optical path conversion layer, a control unit, a scanning drive circuit, a light source drive circuit, and a video processing circuit included in the display device With regard to the specific configuration of each element such as those described above, the present invention is similarly implemented by appropriately selecting from the well-known ranges by those skilled in the art, and is included in the scope of the present invention as long as similar effects can be obtained. .

  Moreover, what combined any two or more elements of each specific example in the technically possible range is also included in the scope of the present invention as long as the gist of the present invention is included.

  In addition, all display devices and driving methods that can be implemented by a person skilled in the art based on the display device and driving method described above as embodiments of the present invention as appropriate include the gist of the present invention. It belongs to the scope of the present invention.

  In addition, in the category of the idea of the present invention, those skilled in the art can conceive of various changes and modifications, and it is understood that these changes and modifications also belong to the scope of the present invention. .

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Light-emitting part, 10s ... Light source, 20 ... Light guide part, 20s ... Side surface, 21 ... One end, 22 ... Other end, 30 ... Light extraction part, 31a ... First electrode, 31b ... Second electrode, 31c ... Displacement Layer: 60: Control unit 61: Scanning drive circuit 61a, 61b, 61l: Scanning line 62: Light source drive circuit 63: Video processing circuit 110: Display device E1-E3: First to third potentials F1, F2: first and second periods, Ie: light energy amount, Is: value, L11: light, L12: guided light, L13: light, NS: non-selection state light extraction unit, PW: external power supply, SS: Selection state light extraction unit, SV ... Video signal, Vcom ... Common potential, Vop ... Voltage, tn ... Non-selection period, tp ... Preliminary period, ts ... Selection period

Claims (6)

  1. A light emitting portion for emitting light;
    A plurality of light guides extending in a first direction and guiding the light, wherein the plurality of light guides are arranged in a second direction intersecting the first direction;
    A plurality of light extraction portions each having a first electrode and a second electrode and facing the light guide portion, wherein the light extraction portion and the light guide portion are caused by a potential difference between the first electrode and the second electrode. The first state and the first state in which the light extraction amount from the light guide unit is different by changing the waveguide state of the light guided through the light guide unit by being in contact with the light unit or in the first non-contact state. A plurality of light extraction portions capable of forming two states;
    A control unit connected to the first electrode and the second electrode;
    The control unit sets the potential of the second electrode to a first potential in a first period, sets the potential of the second electrode to a second potential lower than the first potential in a second period,
    In the first period, the control unit sets the potential of the first electrode to the second potential when the light extraction unit is set to the first state, and sets the light extraction unit to the second state. The potential of the first electrode is set to the first potential,
    In the second period, the control unit sets the potential of the first electrode to the first potential when the light extraction unit is set to the first state, and sets the light extraction unit to the second state. A control unit for setting the potential of the first electrode to the second potential;
    A display device comprising:
  2.   The control unit includes the light extraction unit according to any one of the plurality of light extraction units before the selection period in which the light extraction unit of the plurality of light extraction units is in the first state and continuous with the selection period. 3. The display according to claim 2, wherein the potential of the first electrode is set to a third potential between the first potential and the second potential while at least one of the light extraction portions except for is placed in the second state. apparatus.
  3.   In the preliminary period, any one of the light extraction units is in a second non-contact state with the light guide unit, and any of the light extraction units and the light guide in the second non-contact state. The display device according to claim 2, wherein a distance between the light guide unit and the light guide unit is shorter than a distance between the light extraction unit and the light guide unit in the first non-contact state.
  4.   The display device according to claim 2 or 3, wherein an absolute value of a difference between the first potential and the third potential is equal to an absolute value of a difference between the second potential and the third potential.
  5. A light emitting part for emitting light, and a plurality of light guiding parts extending in a first direction and guiding the light, wherein the plurality of light guiding parts are arranged in a second direction intersecting with the first direction. A plurality of light extraction portions each having a light guide portion, a first electrode, and a second electrode and facing the light guide portion, wherein the light is caused by a potential difference between the first electrode and the second electrode; A first state in which light extraction amounts from the light guide unit are different from each other by changing a waveguide state of light guided through the light guide unit by bringing the extraction unit and the light guide unit into a contact state or a non-contact state. And a plurality of light extraction units capable of forming the second state, and a display device driving method comprising:
    In the first period, the potential of the second electrode is set to the first potential; in the second period, the potential of the second electrode is set to a second potential lower than the first potential;
    In the first period, when the light extraction portion is set to the first state, the potential of the first electrode is set to the second potential, and when the light extraction portion is set to the second state, the first electrode Is set to the first potential,
    In the second period, when the light extraction portion is set to the first state, the potential of the first electrode is set to the first potential, and when the light extraction portion is set to the second state, the first electrode A display device driving method for setting the potential of the display device to the second potential.
  6.   In the pre-period following the selection period before the selection period in which any one of the plurality of light extraction units is in the first state, the light extraction unit excluding any of the light extraction units The display device driving method according to claim 5, wherein the potential of the first electrode is set to a third potential between the first potential and the second potential while at least one of the second states is set.
JP2012069569A 2012-03-26 2012-03-26 Display device and driving method thereof Expired - Fee Related JP5813549B2 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003197994A (en) * 2001-08-31 2003-07-11 Ngk Insulators Ltd Method for compensating displacement deterioration of piezoelectric/electrostrictive actuator
JP2006099062A (en) * 2004-09-27 2006-04-13 Idc Llc Method and system for writing data to mems display element
JP2009237456A (en) * 2008-03-28 2009-10-15 Toshiba Corp Display device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003197994A (en) * 2001-08-31 2003-07-11 Ngk Insulators Ltd Method for compensating displacement deterioration of piezoelectric/electrostrictive actuator
JP2006099062A (en) * 2004-09-27 2006-04-13 Idc Llc Method and system for writing data to mems display element
JP2009237456A (en) * 2008-03-28 2009-10-15 Toshiba Corp Display device

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