JP2008015174A - Driving method of light deflection apparatus and image projection display apparatus - Google Patents

Abstract

In an optical deflecting device that tilts and displaces a plate-shaped member having a light reflection region, the kinetic energy of the plate-shaped member is reduced, and residual vibration due to collision with a landing site at an excessive speed is reduced.
SOLUTION: A plurality of restricting members 108 provided at an end portion of a substrate 101 and provided with stoppers 108a on the top thereof, a light reflecting region and a conductor layer on the upper surface, and a fulcrum member 106 provided at the center of the substrate 101. And a plate member 107 movably disposed and supported in a space between the substrate 101, the fulcrum member 106 and the stopper 108a, and a plurality of electrodes 103a and 103b provided on the substrate so as to face the plate member 107, The plate member 107a has means for establishing the potential of the plate member by electrostatic induction from an electrode or a plurality of electrodes that are in electrical contact with the conductor layer of the plate member to establish the potential, and the plate member 107a starts tilting displacement After that, the absolute values of the potentials of the plurality of electrodes in the second tilt direction are increased or decreased.
[Selection] Figure 1

Description

  The present invention relates to a method for driving an optical deflection apparatus and an image projection display apparatus using the same.

  An optical deflecting device in which hundreds of thousands to millions of micromirrors are arranged in a two-dimensional array is used for a projection device or the like. A semiconductor memory device is connected to each micromirror, and the tilt direction of the designated micromirror can be switched by an instruction of the address. As a result, an image with an address designated is projected on the screen.

  As such an optical deflecting device, the present applicant has filed an optical deflecting device in which a plate-like member having a light reflection region is inclined and displaced with the fulcrum member as a fulcrum in a space limited by the regulating member, thereby deflecting the light. Yes. Patent Document 1 proposes an optical deflecting device having a feature that a plate-like member does not have a hinge like a torsion bar and can be freely tilted and displaced within a range limited by a regulating member.

  In addition to this, there has already been filed an optical deflecting device that can control the start of the tilt displacement of the plate-like member by an address electrode connected to the semiconductor memory device. In this application, when the dimension of the plate-like member is about 10 μm square, the drive voltage is several tens of volts to complete the tilt displacement in several μsec from the rotational speed determined by the moment of inertia and the drive force. On the other hand, a general LSI operating voltage is expected from the area range of a semiconductor memory device such as an SRAM that can be configured with an area of about a plate-like member, and the operating voltage is about 5V. A driving method is disclosed that can control the presence or absence of the tilt displacement of the plate-like member with the operating voltage of such a semiconductor memory device.

Further, the present applicant has proposed an optical deflecting device in which the optical deflecting devices are arranged in an array and provided with a plate-like member having a light reflecting region in Japanese Patent Application No. 2004-320821. The present invention is an optical deflecting device in which a plate-like member having a light reflection region rotates about a rotation axis or a fulcrum and changes the reflection direction of incident light, and performs a light deflection operation. The plate-like member is a conductor layer. And an electrode for applying a potential by being in contact with or fixed to the conductor layer, and a plurality of electrode groups disposed opposite to the plate member, and the plurality of electrode groups A plurality of one-dimensional or two-dimensional optical deflecting devices that switch the tilt direction of the plate-like member by electrostatic attraction generated by the potential difference between any electrode and the electrode that applies a potential to the conductor layer, that is, electrostatic torque. In the driving method of the optical deflection array, at least the following three stages are set as the optical deflection operation in a series of processes. The state of the first stage includes a state in which data specifying the inclination direction of the plate-like member as the first inclination direction or the second inclination direction is written and stored in a semiconductor memory device arranged immediately below or adjacent to the optical deflection apparatus, As the two-stage state, the state in which the plate member of the optical deflector is switched to the first inclination direction based on the designated data and the light is deflected, and the third stage state is designated data. The most important feature is that the tilt direction of the plate-like member of an arbitrary light deflecting device is switched to the second tilt direction to deflect light.
A typical drive waveform example at this time is shown in FIG. The waveform in FIG. 12 is substantially the same voltage from the start to the end of the inclination displacement of the plate-like member.

JP 2004-78136 A

  When an image is projected by an array of light deflecting devices, the gradation expression is generally expressed by the length of time during which light is output. For example, in an 8-bit 256 gradation, the minimum unit is about 20 μsec. Within such time, the time of the tilt displacement from the first tilt direction to the second tilt direction, the time of the tilt displacement from the second tilt direction to the first tilt direction, and the data in the semiconductor memory device in the optical deflector Need to include the time to transfer. If residual vibration occurs even after the plate-like member has completed the tilt displacement, the plate-like member is lifted with respect to the opposing electrodes in the inclined direction. Can not be driven by. That is, by reducing the time during which there is residual vibration, a sufficient time for sending data is secured.

  Here, a conventional driving method is shown in FIG. As shown in FIG. 12A, state 1, state 2, state 3, and then state 1 are repeated. The length of state 1 changes corresponding to the length representing the gradation.

  An example of the driving method in the state 3 will be described with reference to FIG. In the same figure, (a) shows the state which the plate-shaped member inclines in the 1st inclination direction. The drive waveform at this time is applied to the electrode c, and tilt displacement starts. (B) shows a state in which the plate-like member is accelerated by electrostatic force and the inclination displacement advances, and the plate-like member is displaced to an inclination angle parallel to the substrate, and (c) shows that the plate-like member is further accelerated and approaches the landing. (D) shows the state in which the plate-like member has completed the tilt displacement. However, since the plate-like member lands on the landing portion at an excessive speed, vibration may occur up and down due to an impact as indicated by a broken line in (d). This vibration is hereinafter referred to as “residual vibration”. When such residual vibration occurs, the plate-like member floats up against the opposing electrodes in the inclined direction, so that it is not possible to drive in the next stage to prevent malfunction due to electrostatic force reduction, and data It is not possible to secure sufficient time for sending.

  An optical deflector array may be composed of more than one million devices, and it is important that the plate members have a margin and can control the starting of the individual plate members. Here, consider a case where the plate-like member is inclined in the first inclination direction. Electrostatic force when a low voltage VH, which is about the operating voltage of the semiconductor memory device, is applied between a plurality of electrodes on the inclined side of the plate-shaped member and the plate-shaped member, a plurality of electrodes and a plate on the far side of the plate-shaped member The potential difference E can be set to several times the low voltage VH in a state where the electrostatic force due to the potential difference E between the shaped members is constrained. For example, in the case of VH = 5V, E = 35V, E / VH = 7, the driving voltage of the plate member is necessary to leave the electrostatic force in the tilt direction, and it is difficult to use up to the maximum of 35V. When the maximum value is used, the moment with respect to the plate-like member becomes zero, the force that pulls the plate-like member in the first inclined direction is canceled, and when the plate-like member is lifted by disturbance such as vibration of the plate-like member, This is because the electric power is weakened and the tilt displacement is caused by the electrostatic force in the second tilt direction.

  Furthermore, when reducing the area of the optical deflecting device, it is necessary to simultaneously reduce the area of the semiconductor memory device formed in the lower layer. When the area of the semiconductor memory device is reduced, it is necessary to reduce the operating voltage of the constituent MOS transistors. That is, the H level of the semiconductor memory device is lowered. For example, from 5V to 3.3V or 2.0V. This keeps the plate-like member in the inclined direction, so that a high potential difference is given between the plurality of electrodes facing the plate-like member. For this reason, if this high electric potential becomes low, there exists a problem that the electrostatic force which fastens a plate-shaped member falls.

The present invention increases or decreases the voltage applied to the plurality of electrodes far from the plate-like member that generates an electrostatic force that tilts and displaces the plate-like member having the light reflection region at an arbitrary time after the start of the tilt displacement, Driving method and image of optical deflecting device capable of reducing kinetic energy of plate member, reducing residual vibration caused by collision with landing site at excessive speed, and reducing damage of surface of landing site due to excessive impact It is an object of the present invention to provide a projection display device.
In the present invention, after the plate-like member starts to be tilted, the potential of the electrode on the inclined side of the plate-like member is increased, so that a margin for holding the plate-like member in the first inclined direction can be increased. An object of the present invention is to provide a driving method for an optical deflection apparatus and an image projection display apparatus.

  In order to achieve the above object, according to the first aspect of the present invention, the substrate has a substrate, a plurality of restricting members, a fulcrum member, a plate-like member, and a plurality of electrodes, and each of the plurality of restricting members has a stopper on the top. The fulcrum member has a top, the fulcrum member is provided on the substrate, the plate member does not have a fixed end, has a light reflection region on the upper surface, and is at least partially A conductive layer made of a conductive member, and is movably disposed in a space between the substrate, the fulcrum member and the stopper, and the plurality of electrodes are substantially opposite to the conductive layer of the plate member. A plurality of electrodes each provided on the substrate and having a means for establishing the potential by electrostatic induction from a plurality of electrodes or electrodes that are in electrical contact with the conductive layer of the plate-like member to establish a potential; And the plate-like member causes the fulcrum member to As described above, a light deflecting device that deflects light by changing the reflection direction of a light beam incident on the light reflection region by tilting displacement from the first tilt direction to the second tilt direction, and the plate-like member starts tilt displacement. Later, the absolute value of the potential of the plurality of electrodes in the second tilt direction is increased or decreased.

  According to a second aspect of the present invention, in the driving method of the optical deflecting device according to the first aspect, the absolute value of the potentials of the plurality of electrodes in the second tilt direction is decreased after the plate member starts tilt displacement. It is said.

  According to a third aspect of the present invention, in the driving method of the optical deflection apparatus according to the first aspect, the potential of the plurality of electrodes in the second tilt direction is set to 0 V after the plate-like member starts the tilt displacement. .

  According to a fourth aspect of the present invention, in the driving method of the optical deflecting device according to the first or second aspect, the plate-like member is moved to the second inclined direction side immediately after completion of the inclination to the electrode side located on the second inclined direction side. The absolute value of the electric potential of a plurality of electrodes is increased.

  According to a fifth aspect of the present invention, in the driving method of the optical deflecting device according to the first aspect, the plurality of electrodes on the second tilt direction side with respect to the potential induced in the plate-like member after the plate-like member starts the tilt displacement. It is characterized in that the deviation from the potential of is reduced.

  According to a sixth aspect of the present invention, in the driving method of the optical deflecting device according to the first aspect, the plurality of electrodes on the second tilt direction side with respect to the potential induced in the plate-like member after the plate-like member starts the tilt displacement. The deviation from the potential is 0V.

  According to a seventh aspect of the present invention, there is provided an optical deflection apparatus in which a plate-like member having a light reflection region rotates about a rotation axis or a fulcrum and changes a reflection direction of an incident light beam to perform a light deflection operation. A plurality of electrode groups disposed opposite to the plate-like member, the electrode having an electrode for applying a potential by contact, fixation or electrostatic induction to the conductor layer, The inclination direction of the plate-like member is switched from the first inclination direction to the second inclination direction by an electrostatic attractive force generated by a potential difference between an arbitrary electrode and an electrode that applies a potential to the conductor layer, and the second inclination of the plate-like member. The absolute value of the potential of the plurality of electrodes on the first tilt direction side is increased at an arbitrary time after the potential of the plurality of electrodes on the direction side has increased.

  According to an eighth aspect of the present invention, in the driving method of the optical deflecting device according to the seventh aspect, after the deviation between the potential of the plate member and the plurality of electrode potentials in the second tilt direction increases, the plate member starts tilting displacement. Thereafter, the deviation from the potential of the plurality of electrodes on the first tilt direction side with respect to the potential of the plate-like member is increased.

  The invention of claim 9 is characterized in that the method for driving an optical deflection apparatus according to any one of claims 1 to 8 is used.

  According to the first aspect of the present invention, the speed at which the plate-like member is displaced is adjusted by increasing or decreasing the drive voltage at an arbitrary time after the plate-like member starts the inclination displacement, and the landing is completed. The impact at the location is reduced, and residual vibration after landing of the plate-like member can be suppressed. In the state with residual vibration, when the waveform of the next state is applied, the tilt displacement may malfunction.By reducing the residual vibration, the drive waveform can be switched in a shorter time. By reducing the impact with the landing location of the plate-like member, the surface damage of the landing location can be reduced.

  According to the second aspect of the present invention, the driving voltage is reduced after the inclination displacement of the plate-like member is started, so that the speed at the time of landing of the plate-like member is reduced, so that the residual vibration can be suppressed, resulting from the residual vibration. It is possible to reduce the impact with the landing location, shorten the drive waveform switching time, and reduce the damage on the surface of the landing location.

  According to the invention described in claim 3, by reducing the drive voltage to 0 V after the start of the tilt displacement of the plate-like member, the speed at the time of landing of the plate-like member can be reduced, the residual vibration can be suppressed, and the residual vibration is caused. It is possible to reduce the impact with the landing location, shorten the drive waveform switching time, and reduce the surface damage of the landing location.

  According to the invention of claim 4, the plate member is moved to the electrode side in the second inclination direction by increasing the absolute value of the potential of the plurality of electrodes on the second inclination direction side just before the inclination of the plate member is completed. Attracting with electrostatic force, it is possible to suppress the impact of the plate-like member at the landing location, reduce the impact with the landing location due to the impact (residual vibration), shorten the drive waveform switching, and reduce the surface damage of the landing location You can plan.

  According to the fifth aspect of the present invention, the deviation of the potential of the opposing electrode from the potential electrostatically induced in the plate member after the start of the tilt displacement of the plate member is reduced. The residual vibration can be suppressed. For this reason, it is possible to reduce the impact with the landing location due to the residual vibration, shorten the drive waveform switching time, and reduce the damage on the surface of the landing location.

  According to the sixth aspect of the present invention, the deviation of the potential of the opposing electrode with respect to the potential electrostatically induced in the plate-like member after the start of the tilt displacement of the plate-like member is reduced to 0V. Speed can be reduced, and residual vibration can be suppressed. For this reason, it is possible to reduce the impact with the landing location due to the residual vibration, shorten the drive waveform switching time, and reduce the damage on the surface of the landing location.

  According to the seventh aspect of the present invention, at an arbitrary time after the potentials of the plurality of electrodes on the second inclined direction side of the plate-shaped member increase in order to start the inclined displacement of the plate-shaped member, the first inclined direction side By increasing the absolute value of the potential of the plurality of electrodes, it is possible to widen the margin for retaining the plate-like member in the first tilt direction.

  According to the eighth aspect of the present invention, the deviation between the potential of the plurality of electrodes on the second tilt direction side and the potential induced electrostatically in the plate-like member to start the tilt displacement of the plate-like member is increased. Since the deviation from the potential of the plurality of electrodes on the first tilt direction side with respect to the plate-like member potential is increased at an arbitrary time, it is possible to widen the margin for retaining the plate-like member in the first tilt direction.

  According to the ninth aspect of the invention, by using the method of driving the optical deflection apparatus according to any one of the first to eighth aspects, the brightness / darkness control of the pixels by the on / off control of the optical deflection apparatus is good. To provide a high-definition image projection display device that can operate at high speed, has long-term reliability, can be driven at a low voltage, and can improve the contrast ratio. Can do.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 shows one configuration of an optical deflection apparatus according to the present invention. In FIG. 1A, a plurality of electrode groups 103a and 103c are provided on a substrate denoted by reference numeral 101 via an insulating film 102, and these are covered with an insulating film (not shown). A fulcrum member 106 serving as a fulcrum and an electrode is disposed on the insulating film 102. As shown in FIG. 1B, the fulcrum member 106 has a conductor layer 107b and a light reflection region, and constitutes a mirror. A plate-like member 107a is supported at the center from below. The conductor is exposed at the top of the fulcrum member 106, and is in electrical contact with the conductor layer 107b of the plate-like member 107a so that the potential can be communicated. The plate-like member 107a is supported by the fulcrum member 106 so as to be swingable in the left-right direction in FIG. In the four corners which are the end portions of the substrate 101, the regulating members 108 are respectively disposed with the insulating film 102 interposed therebetween. A stopper 108 a is formed on the upper portion of each regulating member 108. The plate-like member 107a supported so as to be swingable to the left and right around the fulcrum member 106 is movably disposed in the space between the substrate 101, the fulcrum member 106, and the stopper 108a, and the regulating member 108 and the stopper 108a. The movement is restricted so as not to jump out when moving.

  The place of the substrate 101 where the plate-like member 107 a swings and lands can be provided as the landing place 109. By providing an organic film having a low surface energy on the surface of the landing location 109, it is possible to reduce the force that prevents the plate-like member 107a from being inclined due to the adhesion force due to the capillary force or the van der Waals force.

  The inclination angle (oscillation angle) in one direction of the plate member 107a is a sine arc sin of an inverse trigonometric function of a half of the length of the plate member 107a and the height of the fulcrum member 106 in contact with the plate member 107. Is the angle required by. The plate-like member 107a is oscillated and inclined and displaced by comparing the electrostatic force due to the conductor layer 107b and the electrode a and the electrostatic force due to the conductor layer 107a and the electrode c. Further, even if the conductor layer 107a of the plate-like member 107 is temporarily separated from the electrically connected electrode on the substrate 101, the conductor layer 107b of the plate-like member 107a can hold an electric charge, and an equivalent electrostatic force works. The electrostatic force does not disappear at that time. Further, since the electrostatic force works, the plate-like member 107a can contact the electrode side again. As shown in FIG. 2, the optical deflection apparatus according to this embodiment can be used by being arranged in a two-dimensional array. For example, it can be applied as a light valve of an image projection display device such as a projector. Alternatively, a hinge having weak rigidity can be formed on the plate member 107a.

  In the conventional driving method as shown in FIG. 12, the voltage applied to the electrode a on one side across the fulcrum member is approximately until the plate-like member almost completes the inclination displacement, that is, just before the inclination to the electrode side is completed, Apply until the residual vibration of the member is reduced. A high level, that is, H level potential of the semiconductor memory device is applied to the fulcrum member, and the potential of the electrode group facing the plate member is driven at a potential that tilts in the first tilt direction, and then tilts in the second tilt direction. The electric potential is applied so as to maintain the tilt direction. The drive waveform at this time will be described as an example of the drive waveform in state 3 shown in FIG. 12, but the operation is the same if the positions in the first and second tilt directions are replaced. It can also be applied to state 2 described below.

  In the driving method shown in FIG. 12, when a potential that causes the plate member to be tilted is applied, the potential of the electrode on the side where the plate member is inclined is low level, that is, L level potential or H level of the semiconductor memory device. Set to potential.

  On the other hand, in the driving method according to the present invention, after the plate-like member 107a starts to be inclined, the potential of the inclined electrode is increased. If the potential of the plate-like member 107a and the electrode on the side on which it is inclined are substantially the same, the plate-like member 107a easily starts tilting displacement. However, if there is a potential difference between the potential of the plate-like member 107a and the potential on the side where the plate-shaped member 107a is inclined as much as the H level potential of the semiconductor memory device, the electrostatic force thereby prevents the inclination displacement. The present invention uses the principle that the electrostatic force is stronger when the distance between the electrodes is closer even with the electrostatic force for the same potential difference. In addition, the ratio of the potential difference between the electrode group near the plate member 107a and the plate member to the potential difference between the electrode group far from the plate member 107a and the plate member 107a can be easily increased several times. It becomes a feature.

  Hereinafter, a method for driving the optical deflection apparatus according to the present invention will be described.

  The electrostatic force is inversely proportional to the square of the distance between the electrode and the plate member 107a. For this reason, a high voltage is required at the time of starting the tilt displacement, but the distance between the electrode and the plate-like member 107a approaches as the tilt displacement progresses, so that the electrostatic force that rotates (oscillates / tilts) even if the voltage is lowered. Can be secured to some extent. Or if it carries out the inclination displacement to the middle, the plate-shaped member 107a can continue an inclination by inertia. It is also a feature of the present optical deflecting device that the plate-like member 107a is not suspended by the torsional hinge, so that the restoring force due to rigidity does not act as it lands in the second inclined direction.

  By preventing the kinetic energy of the plate-like member 107a from becoming excessive in this way, it is possible to reduce the impact when the plate-like member 107a lands in the second inclined direction and to suppress the residual vibration. If there is no residual vibration, the plate member 107a can switch the inclination direction immediately after landing, and can immediately start transmission of a data signal to the semiconductor memory device connected to the plate member 107a. As a result, the gradation representation of the image projection display device using the light deflection device is performed with a short display period, thereby shortening the time required for switching the inclination direction of the plate member 107a and securing a longer data transfer time. it can.

  FIG. 3 shows examples of drive waveforms. In FIG. 3, an alloy of aluminum and titanium having a 10 μm square and a thickness of 0.15 μm was used for the plate-like member 107a. The inclination angle of the plate-like member 107a was 15 °, and the maximum drive voltage was 30V. Then, as shown in FIG. 3, the drive voltage was decreased during the inclination.

  FIG. 3A shows a state where the plate-like member 107a is inclined in the first inclination direction. The electrode a of the electrode group 103a opposed to the plate member 107a in the first inclined direction and the electrode b of the conductive fulcrum member 106 that is in electrical contact with the plate member 107a are at the same potential. Electricity does not work. The potential difference between the electrode c and the electrode a of the electrode group 103b in the second tilt direction is 30V, and the plate member 107a starts tilting displacement in the second tilt direction.

  FIG. 3B shows a state in which the plate-like member 107 a is inclined and displaced to an angle parallel to the substrate 101. As the displacement of the electrode c and the plate-like member 107a is closer than the height of the fulcrum 106 in a state where the inclination displacement is advanced and parallel to the substrate 101, the electrostatic force further increases after this inclination angle.

  FIG. 3C shows a state in which the plate-like member 107a is further inclined in the second inclination direction. In this state, the absolute value of the driving voltage of the electrode c is reduced or is set to 0V. The moving speed of the plate-like member 107a is sufficiently high, and even if the speed in this state is slowed to some extent, the ratio of this period to the time for the entire tilt displacement is small. That is, the time required for the tilt displacement is slightly longer, but not so much.

  FIG. 3D shows a state in which the tilt displacement of the plate member 107a in the second tilt direction is completed. If the speed immediately before landing of the plate-shaped member 107a is large, the plate-shaped member 107a may bounce due to the impact of the collision. For this reason, it can prevent that the speed before the collision of the plate-shaped member 107a becomes excessive by weakening an electrostatic force in the period of FIG.3 (c). Further, by applying the driving voltage again after the plate-like member 107a has landed, the spring of the plate-like member 107a can be suppressed.

  By the way, a high potential of the semiconductor memory device is applied to the conductive fulcrum member 106, and the electrode group opposed to the plate member 107a is driven at such a potential that it is tilted in the first tilt direction, and then in the second tilt direction. The present applicant has already filed an application in Japanese Patent Application No. 2004-320821 as a series of driving methods for driving at a potential such that the current is tilted and applying the potential so as to maintain the tilt direction. In this case, if the address signal is transmitted while there is a residual vibration in which bounce occurs, an undesirable displacement of the plate-like member is caused. This is because, when the plate-like member 107a is tilted and is bounced by impact at the landing site in the second tilt direction, if a drive voltage for switching the tilt direction is applied, the potential difference of VH between the plate-like member 107a and the electrode b is applied. This is because the electrostatic force between the plate-like member 107a and the electrode c is weakened, and the tilt displacement may be started by the driving force that causes the tilt displacement.

  Therefore, as in the method of driving the optical deflector according to the present invention, when the residual vibration after the end of the tilt displacement is suppressed, the potential of the electrode that is in electrical contact with the plate member 107a is set to the operation of the semiconductor memory device. The plate-like member can be more effectively fastened to the inclined electrode at a high voltage potential. For this reason, it is possible to reduce the time for waiting for attenuation of the residual vibration with respect to the switching of the state 1, the state 2 and the state 3 described in the conventional Japanese Patent Application No. 2004-320821. For this reason, the gradation means can be further expanded by the projection method that expresses the gradation with the length of the display period. For example, the shortest display time can be shortened and the number of gradations can be increased.

This will be described with reference to FIG. FIG. 4 shows a case where the plate-like member 107a is displaced by tilting. FIG. 4A shows a state in which the plate member 107a is inclined in the first inclination direction, and the electrode b of the conductive fulcrum member 106 at the start of the inclination displacement of the plate member 107a has the same potential as the electrode a of the electrode group ( 0V) is applied and the electrostatic force does not work. The potential E (V) is applied to the plate-like member 107a and the far electrode c, and tilt displacement is started.
FIG. 4B shows a state in which the plate-like member 107a is about to start the tilt displacement with a delay. The tilt displacement is continued by the electrostatic force of the electrode c and the plate-like member 107a.
FIG. 4C shows a state where a waveform is applied by the driving method of the present invention. On the other hand, the plate-like member 107a having advanced the inclination displacement is becoming far from the inclined electrode, and the driving force for the inclination displacement is large and the inclination displacement continues.
FIG. 4D shows a state in which the tilt displacement is completed. The plate member 107a continues to be tilted and the tilting direction is switched from the first tilting direction to the second tilting direction.

FIG. 5 shows a case where the plate member 107a is not tilted and displaced.
FIG. 5A shows a state where the plate member 107a is inclined in the first inclination direction. The electrode a close to the plate-like member 107a at the start of the inclination displacement of the plate-like member 107a is given 0 V, and the electrode c far from the plate-like member 107a is given a potential E (V). The electrode b of the conductive fulcrum member 106 in contact with the plate member 107a is in a state where the H level potential VH is applied from the output of the semiconductor memory device. The electrostatic force due to the potential difference between the plate-like member 107a and the electrode a is set to be larger than the electrostatic force between the electrode c and the plate-like member far from the plate-like member 107a, and the plate-like member 107a originally does not cause a tilt displacement. . However, let us consider the situation where this electrostatic force is conquering.
FIG. 5B shows a state in which the plate-like member 107a is about to start tilting displacement with a delay. When the plate-like member 107a is slightly distant from the electrode due to the spring, the electrostatic force is lowered, the electrostatic force between the plate-like member 103c and the electrode 103c in the second inclination direction for inclining the plate-like member 107a is excellent, and the tilt displacement is reduced. Will start.
FIG. 5C shows a state in which a waveform according to the driving method of the present invention is applied. Since there is an electrostatic force due to the potential difference VH between the plate-like member 107a and the electrode a, the inclination displacement proceeds slowly. At this time, when the potential of the electrode a on the side on which the plate-like member 107a is inclined is increased to Er (V), the plate-like member 107a stops the inclination displacement and returns to the inclined side.
FIG. 5D shows a state in which the tilt displacement is completed. The plate member 107a stays in the first inclined direction on the electrode 103a side by an electrostatic force generated by the potential Er (V) of the electrode 103a and the potential VH of the plate member 107a.

In this way, by using the driving method of the present invention, the electrode on the side where the plate member 107a is inclined can be given a margin for fastening the plate member 107a, and it is also affected by disturbances such as residual vibration. It is difficult to widen the drive voltage range. In particular, when a voltage having a polarity opposite to that of the voltage applied to the plate member 107a is applied, the voltage does not pass through a point having the same potential as that of the plate member 107a.
(Second Embodiment)
Next, the configuration of the optical deflection apparatus that applies a potential to the plate member by electrostatic induction will be described. Japanese Patent Application Laid-Open No. 2004-78136 discloses an invention of an optical deflection device that uses a group of electrodes facing a plate-like member to generate a potential on the plate-like member by electrostatic induction. In this embodiment, in such electrostatic induction, an electrode for latching and latching the plate-like member on the inclined side is provided. That is, as shown in FIG. 6, the optical deflection apparatus has a plurality of electrode groups 103a, 103b, 103c, 103d, 104a, and 104b arranged on an insulating film 102 on a substrate 101 and covered with an insulating film (not shown). It has been broken. The plate-like member 107 a having a light reflection region has a conductor layer 107 b supported by a fulcrum member 106. The plate-like member 107a can be tilted (rotated) by a certain degree of swinging by the restricting member 108 disposed around the plate-like member 107a, but the movement is restricted so as not to jump out. The inclination angle of the plate-like member 107a is an angle obtained by sine arc sin of an inverse trigonometric function of 1/2 of the length of the plate-like member 107a and the height of the fulcrum member 106 in contact with the plate-like member 107a. The plate-like member 107a is rotated and tilted by comparing the electrostatic force generated by the conductor layer 107b and the electrodes 103a and 103b and the electrostatic force generated by the conductor layer 107b, the electrode 103c and the electrode 103d. Further, on the substrate 101, electrodes 104a and 104b for controlling the starting of the plate member 107a are arranged in addition to the electrodes for driving the plate member 107a. It is preferable to arrange the electrode group substantially symmetrically with respect to the fulcrum member 106. The electrode group may be configured as six electrodes instead of four electrodes.

  The electrode group is disposed to be inclined with respect to the substrate 101. Since the plate-like member 107a is driven by electrostatic force like the electrode 103a, the electrode 103b, the electrode 103c, and the electrode 104d, these are referred to as drive electrodes. The electrodes 104a and 104b are also provided for controlling starting, and are referred to as control electrodes.

  Next, a driving method for suppressing the residual vibration of the plate-like member 107a by the optical deflector shown in FIG. 6 will be described. It is assumed that 0 V is applied to the electrode 104a and VH (high potential of the operating voltage of the semiconductor memory device) is applied to the electrode 104b. The plate member 107a is in the process of being tilted and displaced from the first tilt direction shown in FIG. 7 to the second tilt direction.

  FIG. 7 shows an example of drive waveforms. In this embodiment, a 10 μm square, a thickness of 0.15 μm, and an aluminum alloy material are used as the plate-like member, and the maximum driving voltage is 30V. E = 30V. In FIG. 7, the electrodes 103a, 103b, 103c, 103d, 104a, and 104b are simply referred to as electrodes a, b, c, d, e, and f.

FIG. 7A shows a state where the plate-like member 107a is inclined in the first inclination direction. A potential is electrostatically induced in the plate member by the electrode group opposed to the plate member 107a in the first inclination direction, the electrode c and the electrode d in the figure. When E (V) is applied to the electrode c and −E (V) is applied to the electrode d, the potential of the plate-like member 107a becomes 0 (V). When the potential of the electrode a and the electrode b is 0 (V), no electrostatic force acts between them. The potential difference between the electrode group in the second tilt direction, the electrode c or electrode d in the figure, and the plate member 107a is 30 V, and the plate member 107a starts to be displaced in the second tilt direction.
FIG. 7B shows a state in which the plate member 107 a is tilted and displaced to an angle parallel to the substrate 101. This is a process in which the region where the distance between the electrode c or the electrode d and the plate-like member 107a is closer than the height of the fulcrum increases in the state where the tilt displacement advances and is parallel to the substrate 101, and the electrostatic force further increases after this tilt angle.
FIG. 7C shows a state in which the plate-like member 107a is further inclined in the second inclination direction. In this state, the potentials of the electrodes c and d on the second inclination direction side with respect to the electric potential of the plate-like member 107a are shown. Decrease the deviation or set it to 0V. The moving speed of the plate-like member 107a is fast, and even if the driving force is reduced in this way, the ratio of this period to the time taken for the entire tilt displacement is small. Even if the speed in this state is slowed to some extent, the time required for the tilt displacement is only slightly increased.
FIG. 7D shows a state in which the tilt displacement of the plate member 107a in the second direction is completed. If the speed immediately before landing of the plate-like member 107 is large, the plate-like member 107a may bounce due to the impact of the collision.

  For this reason, it can prevent that the speed before the collision of the plate-shaped member 107a becomes excessive by weakening an electrostatic force in the period of FIG.7 (c). Furthermore, the plate-like member 107a can repel the plate-like member by applying the drive voltage again after landing.

As described above, since the residual vibration after the end of the tilt displacement is suppressed by the driving method of the optical deflecting device according to the present invention, the potential of the electrode that is in electrical contact with the plate member 107a is set to the operating voltage of the semiconductor memory device. The plate-like member 107a can be more effectively fixed to the inclined electrode at a high potential. Further, it is possible to reduce the time for waiting for attenuation of the residual vibration in response to the switching of the state 1, state 2, and state 3 of the plate-like member described in Patent Document 1 (FIG. 12). With the projection method that expresses gradation with the length of the display period, the gradation means can be further expanded. For example, the shortest display time can be shortened and the number of gradations can be increased.
(Third embodiment)
Next, using FIG. 8, FIG. 9, and FIG. 10, when the plate member is not tilted and displaced, the optical deflection device is driven so that the plate member is not tilted and displaced by disturbance such as residual vibration of the plate member. A method will be described. FIG. 8A and FIG. 8B show the configuration of the optical deflection apparatus. Since this configuration adopts the same configuration as the optical deflecting device shown in FIG. 6, a detailed description thereof will be omitted, and a driving method will be described.

The case where the plate-like member 107a is tilted and displaced will be described with reference to FIG.
FIG. 9A shows a state in which the plate-like member 107a is inclined in the first inclination direction, and the same potential as the potential induced in the plate-like member 107a is applied to the control electrode e for starting the tilt displacement of the plate-like member 107a. Given, electrostatic force does not work. As shown in FIG. 8A, potential E (V) is applied to the plate member 107a and the far electrode c, and potential −E (V) is applied to the electrode d, and tilt displacement is started.
FIG. 9B shows a state in which the plate member 107a is about to start the tilt displacement with a delay, and the tilt displacement is continued by the electrostatic force between the electrodes c and d and the plate member 107a.
FIG. 9C shows a state in which a waveform according to the driving method of the present invention is applied. On the other hand, the plate-like member 107 having advanced the inclination displacement is becoming far from the inclined electrode, and the driving force for the inclination displacement is large and the inclination displacement continues.
FIG. 9D shows a state where the tilt displacement is completed. In this state, the plate-like member 107a continues to be inclined and the inclination direction is switched from the first inclination direction to the second inclination direction.

FIG. 10 shows a case where the plate member 107a is not tilted and displaced.
FIG. 10A shows 0V for the electrodes a and b close to the plate member 107a shown in FIG. 8, E (V) for the electrode c far from the plate member 107a, and −E (V) for the electrode d. Given. A high potential HV is applied to the electrode 104a from the output of the semiconductor memory device, and 0 (V) is applied to the electrode f. The electrostatic force due to the potential difference between the potential induced in the plate member 107a and the potential of the electrode a is set larger than the electrostatic force between the electrode c and the plate member far from the plate member 107, and the plate member 107a. Does not inherently cause tilt displacement. However, let us consider the situation where this electrostatic force is conquering.
FIG. 10B shows a case where the plate-like member 107a is slightly distant from the electrode due to a spring such as residual vibration. In such a case, the electrostatic force is lowered, and the second inclination for inclining the plate-like member 107a. The electrostatic force between the direction electrode and the plate-like member is excellent, and the tilt displacement starts.
In FIG. 10C, since there is an electrostatic force due to the potential difference VH between the plate-like member 107 and the electrode a, the inclination displacement proceeds slowly. At this time, when the potential of the electrode a on the side where the plate member 107a is inclined is increased to Er (V) and the potential of the electrode b is increased by -E (V), that is, the deviation from the potential of the plate member 107a is increased. The plate-like member 107a stops the tilt displacement and returns to the tilted side. In this case, since electrostatic induction occurs in the plate-like member 107a from the potentials of the electrodes a and b, the potential induced by these electrodes is preferably the same as the potential induced by the electrodes c and d. In this example, it is 0V.
In FIG. 10 (d), the plate member 107a is an electrostatic force generated by the potential Er (V) of the electrode a, -Er (V) of the electrode b, and the potential VH of the electrode e. Stay in the first tilt direction.

  Thus, by using the driving method of the present invention, the electrode on the side where the plate-like member 107a is inclined can be given a margin for fastening the plate-like member, and it is hardly affected by disturbance such as residual vibration. The driving voltage range can be expanded.

  Next, the configuration of a projection apparatus 800 serving as an image projection display apparatus using the apparatus driving method of the present invention will be described with reference to FIG. In FIG. 11, the projection device 800 irradiates the light deflecting device 801 of the present invention with light having a certain spread angle from a light source 802, for example, via a rotating color filter 805, and reflects it from the reflection region of the plate member 107a. Light is applied to the projection screen 810 through the projection lens 806 in the first tilt direction of the plate-like member. This is the on state. However, in the second tilt direction, the reflected light hits the light shielding member 804 that is a stop and does not output light to the projection screen 810. This is the off state. When the light deflection device 801 is arranged in a two-dimensional array, an image can be formed on the projection screen 810 by this on / off. For this reason, it can be used as an optical switch means of an image projection data display (that is, bright / dark display of pixels) device of the light deflection device 801. Therefore, pixel brightness control (ie, optical switch on / off control) is good, stray light (reflected light from adjacent elements generated when the reflection direction is disturbed) can be suppressed, high-speed operation is possible, and long-term operation is possible. High reliability, can be driven at a low voltage, and can improve the contrast ratio.

It is a block diagram which shows 1st Embodiment of the optical deflection apparatus to which this invention was applied. It is the top view which has arrange | positioned the optical deflection | deviation apparatus shown in FIG. 1 in the two-dimensional array state. It is a figure which shows the positional relationship of the applied voltage and plate-shaped member in a 1st form. It is process drawing in the case of carrying out the inclination displacement of the plate-shaped member of the optical deflection apparatus concerning the 1st form. It is process drawing in the case of not carrying out the inclination displacement of the plate-shaped member of the optical deflection apparatus concerning the 1st form. It is a block diagram which shows 2nd Embodiment of the optical deflection apparatus to which this invention was applied. It is a figure which shows the positional relationship of the applied voltage and plate-shaped member in a 2nd form. It is a block diagram which shows the 3rd form of the optical deflection apparatus to which this invention was applied. It is process drawing in the case of carrying out the inclination displacement of the plate-shaped member of the optical deflection apparatus concerning a 3rd form. It is process drawing in the case of not carrying out the inclination displacement of the plate-shaped member of the optical deflection apparatus concerning a 3rd form. It is a block diagram which shows schematic structure of the image projection display apparatus to which the light deflection apparatus of this invention was applied. It is a figure which shows the positional relationship of the applied voltage and plate-shaped member in the conventional optical deflection | deviation apparatus.

Explanation of symbols

101 Substrate 103a to 103d Multiple electrodes 104a to 104b Multiple electrodes 106 Support member 107a Plate member 107b Conductor layer 108 Multiple restricting members 108a Stopper 801 Optical deflecting device

Claims (9)

A plurality of regulating members provided at the end of the substrate and provided with stoppers on the top thereof;
A plate-like member which is provided with a light reflection region and a conductor layer on the upper surface and is movably disposed and supported in a space between the substrate, the fulcrum member and the stopper by a fulcrum member provided in the center of the substrate;
A plurality of electrodes provided on the substrate so as to face the plate-like member;
Means for establishing the potential of the plate-like member by electrostatic induction from an electrode or a plurality of electrodes that are in electrical contact with the conductor layer of the plate-like member to establish the potential;
The plate-like member is inclined and displaced from the first inclined direction to the second inclined direction around the fulcrum member by the electrostatic force between the plurality of electrodes and the conductive layer of the plate-like member, and is incident on the light reflecting region. An optical deflecting device that deflects light by changing the reflection direction of the luminous flux,
A driving method of an optical deflecting device, wherein the absolute value of the potentials of the plurality of electrodes in the second tilt direction is increased or decreased after the plate member starts tilt displacement. In the driving method of the optical deflection apparatus according to claim 1,
A method of driving an optical deflection apparatus, comprising: decreasing absolute values of potentials of a plurality of electrodes in a second tilt direction after the plate member starts tilt displacement. In the driving method of the optical deflection apparatus according to claim 1,
A driving method of an optical deflection apparatus, wherein after the plate-like member starts tilt displacement, the potentials of the plurality of electrodes in the second tilt direction are set to 0V. In the driving method of the optical deflection apparatus according to claim 1 or 2,
A driving method of an optical deflecting device, wherein the absolute value of the potentials of a plurality of electrodes on the second tilt direction side is increased just before the plate member is tilted toward the electrode located on the second tilt direction side. . In the driving method of the optical deflection apparatus according to claim 1,
A method of driving an optical deflecting device, wherein after the plate-like member starts tilt displacement, a deviation between the potential of the plurality of electrodes on the second tilt direction side with respect to the potential induced in the plate-like member is reduced. . In the driving method of the optical deflection apparatus according to claim 1,
After the plate-like member starts the tilt displacement, the deviation of the potential of the plurality of electrodes on the second tilt direction side from the potential induced in the plate-like member is set to 0V. Method. In the optical deflecting device in which the plate-like member having the light reflecting region rotates around the rotation axis or the fulcrum and performs the light deflecting operation by changing the reflection direction of the incident light beam.
The plate-like member has a conductor layer, has an electrode for applying a potential to the conductor layer by contact, fixation, or electrostatic induction, and has a plurality of electrode groups installed facing the plate-like member. The tilt direction of the plate-like member is switched from the first tilt direction to the second tilt direction by an electrostatic attractive force generated by a potential difference between an arbitrary electrode of the plurality of electrode groups and an electrode for applying a potential to the conductor layer. With
An absolute value of the potential of the plurality of electrodes on the first tilt direction side is increased at an arbitrary time after the potential of the plurality of electrodes on the second tilt direction side of the plate member is increased. Driving method. In the driving method of the optical deflection apparatus according to claim 7,
After the deviation between the potential of the plate member and the plurality of electrode potentials in the second tilt direction increases, the plate member starts tilt displacement, and then the plurality of electrodes on the first tilt direction side with respect to the potential of the plate member. A method of driving an optical deflection apparatus, characterized by increasing a deviation from the potential of the optical deflection apparatus.   An image projection display device using the method for driving an optical deflection device according to claim 1.

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