JP2004109276A - Liquid crystal shutter controller and method for controlling liquid crystal shutter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal shutter controller with which light outgoing from a display device is efficiently projected onto a screen by effectively using a time period during which an electronic shutter of an imaging apparatus is closed. <P>SOLUTION: The liquid crystal shutter controller 1 is provided with a vertical synchronized signal separating means 10 to separate a vertical synchronized signal from a synchronized signal of the imaging apparatus, a reference driving signal generating means 20 to generate a reference driving signal which is to be a fundamental signal of a liquid crystal shutter driving signal synchronized to the vertical synchronized signal and a compensating driving signal generating and outputting means 30 to generate a compensating signal to compensate the reference driving signal, to generate a compensating driving signal from the compensating signal and the reference driving signal and to output the compensating driving signal to the liquid crystal shutter. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal shutter control device, and more particularly, to a liquid crystal shutter control device that provides light from a light source as intermittent light by opening and closing a liquid crystal shutter at a desired timing.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in a video production in a television studio or the like, a video composing method for composing a performer and a subject such as a person or a background which constitutes a screen is often used. When performing video production using these video synthesis methods, the subject, which is a video to be synthesized with the performer, does not exist in the same space as the performer, and shooting of the performer to be synthesized with the video is It is performed in a situation (such as a blue screen) where no one other than the performer is photographed. For this reason, there is a problem that the performer cannot perform while watching the subject, which is the video to be synthesized, and the image becomes unnatural such that the eyes are not directed toward the subject. In order to improve this problem, an information providing technique using intermittent light which is visually recognized by a person and is not reflected in a video imaged by an imaging device is used.
[0003]
Here, an information providing technique based on intermittent light that is visually recognized by a person and is not reflected in a video imaged by an imaging device will be described with reference to the drawings. FIG. 9 is a schematic diagram of a television studio for explaining an information providing technique using intermittent light that is visually recognized by a person and is not reflected in a video imaged by an imaging device. FIG. 10 is a time chart for explaining the principle of the information providing technique. In FIG. 9, an imaging device 51 takes an image with an electronic shutter (not shown), and when the liquid crystal shutter 52 of the display device 53 is opened while the electronic shutter is closed, light emitted from the display device 53 is emitted. Only when the electronic shutter of the imaging device 51 is closed, the image is projected on the screen 54 and is visible to the performer 55, but is not photographed by the imaging device 51. In this state, by using the display device 53 and projecting an image to be actually synthesized on a screen 54 placed at an appropriate position in the background of the performer, the performer 55 can obtain the projected image, It is possible to perform while watching the digitized subject to be synthesized. As a result, the performance burden of the performer 55 is reduced, and retakes due to failure in the performance are reduced, and the viewpoint of the performer 55 becomes natural.
[0004]
Further, the relationship between the signals of the electronic shutter of the imaging device 51 and the liquid crystal shutter 52 will be described with reference to FIG. The vertical synchronizing signal is a vertical synchronizing signal separated from the synchronizing signal (composite synchronizing signal composed of the vertical synchronizing signal and the horizontal synchronizing signal) of the imaging device 51, and the shutter signal controls opening and closing of an electronic shutter (not shown) of the imaging device 51. The driving signal and the driving signal are signals for controlling the opening and closing of the liquid crystal shutter 52. One field is one transmission period in the interlacing process of transmitting an image twice, Ton is a period when the electronic shutter of the imaging device 51 is open, and Toff is a period when the electronic shutter of the imaging device 51 is closed. It is.
[0005]
Here, in the information providing technology based on intermittent light that is visually recognized by a person and is not reflected in the image captured by the imaging device, light emitted from the display device 53 is transmitted only during a period Toff during which the electronic shutter of the imaging device 51 is closed. In this case, it is necessary to effectively use Toff during this period to increase the visibility under studio lighting conditions. That is, in order to efficiently project the light emitted from the display device 53 onto the screen 54, it is desirable to open the liquid crystal shutter 52 over the entire period in which the electronic shutter of the imaging device 51 for capturing an image is closed.
[0006]
Next, the liquid crystal shutter 52 will be described with reference to the drawings. FIG. 12 is a configuration diagram of the liquid crystal shutter 52. As shown in FIG. 12, the liquid crystal shutter 52 includes a transparent electrode 57 attached to a transparent substrate 56 such as glass, a liquid crystal layer 58 (thickness of several microns to several tens of microns) sandwiched between the transparent electrodes 57, And a power supply 59 capable of generating a voltage having polarity. The liquid crystal material used for the liquid crystal layer 58 includes a nematic liquid crystal (a liquid crystal having a property in which molecules are oriented in a substantially constant direction) and a cholesteric liquid crystal (a liquid crystal having a twisted structure in addition to the characteristics of the nematic liquid crystal). ) And smectic liquid crystal (a type of liquid crystal in which molecules are oriented in the same direction and are further arranged in layers). These liquid crystal molecules can be arranged vertically, horizontally, or obliquely to the substrate by the action of an alignment film (such as a friction-treated polyimide resin) provided on the transparent electrode, and can also be twisted. . In order to obtain high-speed light modulation, a low-viscosity liquid crystal material or a ferroelectric liquid crystal having spontaneous polarization is advantageous.
[0007]
The incident light incident on these liquid crystals changes the polarization state by the birefringence effect according to the molecular orientation of the liquid crystals (light modulation). Further, the molecular orientation of the liquid crystal changes depending on the applied voltage. This makes it possible to control the incident light by controlling the voltage applied between the liquid crystal sandwiched between two orthogonal polarizing plates. However, the incident light from the projection device is unpolarized light, and half of it is lost by being polarized by the polarizing plate. In order to avoid this, a light scattering effect of a composite film in which a fine polymer structure (eg, an acrylic resin or a phthalene resin) is formed in a liquid crystal that does not require a polarizing plate may be used.
[0008]
When this composite film of liquid crystal and polymer is used, the unpolarized incident light is scattered when the voltage is not applied between the transparent electrodes because the molecular orientation of the liquid crystal is random, and the straight light disappears (off state), and the transparent light is turned off. When a sufficiently high voltage is applied between the electrodes, the liquid crystal molecules are arranged in the direction of the electric field, so that there is no light scattering and the liquid crystal molecules are transmitted as they are (ON state). By this effect (light scattering effect), unpolarized incident light can be turned on and off without being polarized by the polarizing plate. Examples of a method for forming a composite film using a liquid crystal and a polymer include a phase separation method using photopolymerization, thermal polymerization, and liquid medium evaporation, and an impregnation method in which liquid crystal is impregnated into a porous resin.
[0009]
Conventionally, with respect to this liquid crystal shutter control technique, in a liquid crystal display device of an active matrix type or the like, a decrease in brightness caused by a rounded waveform of a video signal is prevented by superimposing a correction signal on an output buffer signal of the video signal. Liquid crystal display devices have been proposed. As a method of driving an optical device, there has been proposed a method of removing charges accumulated in an alignment film by applying a reset pulse before driving a liquid crystal. (See Patent Document 2)
[0010]
[Patent Document 1]
JP 2001-66572 A (pages 13 to 15, FIG. 1)
[Patent Document 2]
JP-A-7-7705 (pages 7-11, FIG. 1)
[0011]
[Problems to be solved by the invention]
However, in an information providing technique using intermittent light that is visually recognized by a person and is not reflected in an image captured by an imaging device, a liquid crystal shutter 52 actually used includes a liquid crystal shutter 52 as illustrated in FIG. 10 (and FIG. 11). Since the change in the amount of light passing through the liquid crystal shutter 52 (see FIG. 9), which is the amount of light passing through the liquid crystal shutter 52 (see FIG. 9) with respect to the on / off of the drive signal for driving the liquid crystal, is slow, the ideal effect is obtained. There is a problem that light emitted from the display device cannot be efficiently projected on the screen by effectively using the closed period. The details will be described below.
[0012]
FIG. 11 shows a relationship between a shutter signal of the imaging device 51 (see FIG. 9), a drive signal of the liquid crystal shutter 52, and a passing light amount which is an amount of light from a light source passing through the liquid crystal shutter 52. As shown in FIG. 11, the response delay at the rise of the drive signal (ie, the period T1 until the liquid crystal shutter 52 is completely turned on) is not so large, but the response delay at the fall of the drive signal (ie, the liquid crystal). It can be seen that the period T2) until the shutter 52 is completely turned off is very long.
[0013]
(Response delay when falling)
The cause of the delay of the response at the time of falling is that when a voltage is applied to the liquid crystal shutter 52 for a relatively long time, ions 60 in the liquid crystal are adsorbed on the electrode surface as shown in FIG. It is considered that the charge is only gradually attenuated. In addition, when the liquid crystal shutter 52 is used for an information presentation technique using intermittent light that is visually recognized by a person and is not reflected in a video imaged by the imaging device due to the delay in response at the time of falling, as illustrated in FIG. In addition, the pulse width PW of the drive signal of the liquid crystal shutter 52 must be narrowed by a period until the liquid crystal shutter 52 of the display device 53 (see FIG. 9) is completely turned off (that is, a response delay T2 at the time of falling). However, there is a problem that the amount of light passing therethrough is reduced and the brightness of the projected image is reduced.
[0014]
(Response delay at startup)
Further, the cause of the delay in the response at the time of rising may be caused by the capacitance of the liquid crystal, and may be caused by a period until the charge due to the driving impedance or the internal resistance is charged. Due to this delay in response, when the liquid crystal shutter is used in an information presentation technique using intermittent light which is visually recognized by a person and is not reflected in the image captured by the imaging device, as shown in FIG. However, there is a problem that the amount of light passing through the response delay T1 is reduced and the brightness of the projected image is reduced.
[0015]
The present invention has been made in view of the above-described problems, and in an information presentation technology using intermittent light that is visually recognized by a person and is not reflected in a video imaged by the imaging device, an electronic shutter of the imaging device is used. An object of the present invention is to provide a liquid crystal shutter control device and a liquid crystal shutter control method capable of efficiently transmitting light from a display device during a closed period and making a projected image brighter.
[0016]
[Means for Solving the Problems]
The present invention has been devised in order to achieve the above object, and a liquid crystal shutter control device according to claim 1 is a liquid crystal shutter control device for opening and closing a liquid crystal shutter, wherein a liquid crystal shutter control device is provided based on a synchronization signal of an imaging device. Vertical synchronizing signal separating means for separating a vertical synchronizing signal; reference driving signal generating means for generating a reference driving signal serving as an original signal of a liquid crystal shutter driving signal synchronized with the vertical synchronizing signal; and a response characteristic of the liquid crystal shutter. And a correction driving signal generating and outputting means for generating a correction driving signal based on the correction signal and the reference driving signal and outputting the correction driving signal to the liquid crystal shutter.
[0017]
According to this configuration, the liquid crystal shutter control device separates the vertical synchronization signal from the synchronization signal of the imaging device by the vertical synchronization signal separation unit. Further, the reference drive signal generation means generates a reference drive signal which is an original signal of the drive signal of the liquid crystal shutter synchronized with the vertical synchronization signal from the vertical synchronization signal. Then, the correction drive signal generation / output unit generates a correction drive signal obtained by correcting the reference drive signal with the correction signal, and outputs the corrected drive signal as a drive signal for the liquid crystal shutter. Driving the liquid crystal shutter with this correction drive signal changes the response characteristics of the liquid crystal shutter.
[0018]
In the liquid crystal shutter control device according to a second aspect, in the liquid crystal shutter device according to the first aspect, the correction drive signal generation and output means includes a predetermined drive synchronized with a fall (or rise) timing of the reference drive signal. A correction signal generating circuit for generating a correction signal having a pulse width of:, a switch circuit for converting the reference drive signal and the correction signal to a predetermined voltage level, and the reference circuit converted to a predetermined voltage level by the switch circuit. A drive signal and the correction signal are added, a waveform that becomes a positive voltage in a predetermined period from a rise of the reference drive signal in synchronization with the reference drive signal, and a negative voltage in a predetermined period from a fall of the reference drive signal. And an adder circuit for generating at least one of the following waveforms and outputting the generated waveform to the liquid crystal shutter. .
[0019]
According to this configuration, the liquid crystal shutter control device uses the correction drive signal generation and output means to generate a positive voltage waveform in a predetermined period from the rise of the reference drive signal and a negative voltage in a predetermined period from the fall of the reference drive signal. A correction drive signal that is at least one of the waveforms is output. As a result, when the drive voltage of the liquid crystal shutter rises, an overvoltage is applied, the liquid crystal is rapidly charged, and the response of the light output to the rise of the drive signal of the liquid crystal shutter caused by the capacitance of the liquid crystal delays ( That is, the period until the liquid crystal shutter is completely turned on) is shortened. Further, when the drive voltage of the liquid crystal shutter falls, a voltage having a polarity opposite to the voltage applied up to that time is applied for a certain period of time, so that ions adsorbed on the electrode of the liquid crystal shutter are removed, The delay of the response of the light output to the fall of the drive signal of the liquid crystal shutter (that is, the period until the liquid crystal shutter is completely turned off) becomes earlier.
[0020]
In the liquid crystal shutter control device according to a third aspect, in the liquid crystal shutter device according to the first aspect, the correction drive signal generation and output unit sets the reference drive signal or the reference drive signal to a predetermined voltage level. A waveform differentiating circuit for generating a correction signal obtained by performing a waveform differentiation on the converted reference drive signal; a switch circuit for converting the reference drive signal and the correction signal to a predetermined voltage level; and a switch circuit for converting the reference drive signal and the correction signal to a predetermined voltage level. The reference drive signal and the correction signal are added, and a waveform that becomes a positive voltage in a predetermined period from the rise of the reference drive signal in synchronization with the reference drive signal, and in a predetermined period from the fall of the reference drive signal And an adder circuit for generating at least one of the negative voltage waveforms and outputting the generated waveform to the liquid crystal shutter. It was.
[0021]
According to this configuration, the liquid crystal shutter control device applies an overvoltage when the drive signal of the liquid crystal shutter rises by the correction drive signal generation and output means, and the liquid crystal is rapidly charged. As a result, when the drive signal of the liquid crystal shutter rises, an overvoltage is applied, the liquid crystal is rapidly charged, and the response of the light output to the rise of the drive signal of the liquid crystal shutter caused by the capacitance of the liquid crystal delays ( That is, the period until the liquid crystal shutter is completely turned on) is shortened. In addition, when the drive signal of the liquid crystal shutter falls, a voltage having a polarity opposite to the voltage applied up to that time is applied for a certain period of time, and the ions adsorbed on the electrode of the liquid crystal shutter are removed. The delay of the response of the light output to the fall of the drive signal of the liquid crystal shutter (that is, the period until the liquid crystal shutter is completely turned off) becomes earlier.
[0022]
Further, in the liquid crystal shutter control device according to a fourth aspect, in the liquid crystal shutter device according to the first aspect, the correction drive signal generation and output unit sets a cycle shorter than the reference drive signal in synchronization with the vertical synchronization signal. A synchronous oscillating circuit that generates a correction signal that is a continuous square waveform, a gate circuit that outputs the correction signal only while the reference drive signal is at a high level, and the correction signal that is output from the gate circuit swings positive or negative. And a switch circuit that converts the signal into a signal and outputs the signal to the liquid crystal shutter.
[0023]
According to this configuration, the liquid crystal shutter control device drives the liquid crystal with a continuous square waveform that swings positive and negative by the correction drive signal generation and output means, and the potential of the electrode is inverted before ions are adsorbed on the electrode. The ions no longer adsorb to the electrodes. As a result, the delay of the response of the optical output to the fall of the drive signal of the liquid crystal shutter (that is, the period until the liquid crystal shutter is completely turned off) is increased.
[0024]
6. A liquid crystal shutter control method according to claim 5, wherein the liquid crystal shutter is opened and closed by a vertical synchronization signal separating step of separating a vertical synchronization signal from a synchronization signal of an imaging device; A reference drive signal generating step of generating a reference drive signal serving as an original signal of the drive signal of the liquid crystal shutter, a correction signal generating step of changing a response characteristic of the liquid crystal shutter, and the correction signal and the reference drive signal. Generating a correction drive signal and outputting the correction drive signal to the liquid crystal shutter.
[0025]
According to this configuration, the liquid crystal shutter control device separates the vertical synchronization signal from the synchronization signal of the imaging device in the vertical synchronization signal separation step. Further, in the reference drive signal generation step, a reference drive signal serving as an original signal of the drive signal of the liquid crystal shutter synchronized with the vertical synchronization signal is generated from the vertical synchronization signal. Then, in a correction drive signal generation and output step, a correction drive signal obtained by correcting the reference drive signal with the correction signal is generated and output as a drive signal for the liquid crystal shutter. As a result, a correction drive signal which is a drive signal of the liquid crystal shutter obtained by adding a correction for improving the response characteristic of the light output to the drive signal of the liquid crystal shutter is output.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
The configuration and functions of the liquid crystal shutter control device 1 according to the first embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a liquid crystal shutter control device 1 according to a first embodiment of the present invention. A liquid crystal shutter control device 1 shown in FIG. 1 is a liquid crystal shutter control device that opens and closes a liquid crystal shutter. The liquid crystal shutter control device 1 separates a vertical synchronization signal from a synchronization signal of an imaging device. A reference drive signal generating means for generating a reference drive signal serving as an original signal of the drive signal of the synchronized liquid crystal shutter; a correction signal synchronized with the vertical synchronizing signal by the reference drive signal; And a correction driving signal generation / output unit 30 for generating a correction driving signal from the driving signal and outputting the correction driving signal to the liquid crystal shutter.
[0027]
The vertical synchronizing signal separating means 10 receives the synchronizing signal (composite synchronizing signal composed of the vertical synchronizing signal and the horizontal synchronizing signal) of the imaging device 51, separates the vertical synchronizing signal from the synchronizing signal, and outputs the reference driving signal generating means 20. Is output to
[0028]
The reference drive signal generation means 20 receives the vertical synchronization signal separated by the vertical synchronization signal separation means 10 and synchronizes the liquid crystal from the period in which the electronic shutter of the imaging device 51 is closed in synchronization with the falling timing of the vertical synchronization signal. A reference drive signal having a pulse width corresponding to a period obtained by subtracting a shutter response delay is generated and output to the correction drive signal generation / output means 30.
[0029]
The correction drive signal generation and output means 30 includes a correction signal generation circuit 31, a switch circuit 32, a switch circuit 33, and an addition circuit 34, and receives the reference drive signal generated by the reference drive signal generation means 20, The generation circuit 31 generates a correction signal having a predetermined pulse width (depending on the liquid crystal shutter) synchronized with the falling timing of the reference drive signal, and outputs the correction signal to the switch circuit 33. The reference drive signal a converted to a predetermined voltage level is added by an adder circuit 34 and output as a corrected drive signal to the liquid crystal shutter.
[0030]
It is to be noted that the switch circuit 32 outputs 0 volts when the input voltage is at a low level and a predetermined positive voltage (depends on the liquid crystal shutter 52) when the input voltage is at a high level. In this case, the voltage level is converted so as to be 0 volt, and when it is at the high level, a predetermined negative voltage (depending on the liquid crystal shutter 52).
[0031]
The predetermined positive voltage here corresponds to a voltage for turning on the liquid crystal shutter, and its value is determined by the input specification of the liquid crystal shutter to be used. (For example, +200 V) The predetermined negative voltage refers to a delay in the response of the light output to the fall of the drive signal of the liquid crystal shutter (that is, a period until the liquid crystal shutter is completely turned off). This voltage is a reverse voltage for removing ions adsorbed on the electrode, and its value depends on the characteristics of the liquid crystal shutter to be used and is determined by simulation, experiment, or the like. (For example, -200V)
[0032]
The liquid crystal shutter control device 1 having the above-described configuration and function is capable of intermittent light that is visible to a person from light from a light source (for example, an image projected by a display device) and is not reflected in an image captured by an imaging device. Provide as.
[0033]
Further, the operation of the liquid crystal shutter control device 1 according to the first embodiment will be described with reference to FIG. 1, FIG. 4, FIG. 5, and FIG. FIG. 13 is a flowchart showing the operation of the liquid crystal shutter control device 1.
[0034]
[Vertical sync signal separation step]
The liquid crystal shutter control device 1 inputs a synchronizing signal (composite synchronizing signal composed of a vertical synchronizing signal and a horizontal synchronizing signal) of the imaging device to the vertical synchronizing signal separating means 10 and, as shown in FIG. The signal is separated, and the separated vertical synchronization signal is output to the reference drive signal generation means 20. (Step S1)
[0035]
[Reference drive signal generation step]
The reference drive signal generating means 20 that has received the vertical synchronization signal starts from the period (Toff in FIG. 10) in which the electronic shutter of the imaging device is closed in synchronization with the falling timing of the vertical synchronization signal as shown in FIG. A reference drive signal having a pulse width PW1 corresponding to a period obtained by subtracting the response delay of the liquid crystal shutter (T2 in FIG. 10) is generated and output to the correction drive signal generation / output means 30. (Step S2)
[0036]
[Correction drive signal generation step]
When the reference drive signal is input, the correction drive signal generation / output means 30 uses the switch circuit 32 to output 0 volts when the reference drive signal is low and the positive voltage V1 when the drive signal is high as shown in FIG. The reference drive signal a whose voltage level has been converted so as to be output to the adder circuit 34. (Step S3)
[0037]
Here, the positive voltage V1 is a voltage corresponding to the above-mentioned predetermined positive voltage, and its value is determined by the input specification of the liquid crystal shutter to be used. (For example, 200V)
[0038]
[Correction signal generation step]
The correction signal generation circuit 31 generates a correction signal having a predetermined pulse width PW2 in synchronization with the falling timing of the reference drive signal as shown in FIG. (Step S4)
[0039]
[Correction drive signal generation step]
The switch circuit 33 to which the correction signal is input is a correction signal b whose voltage level is converted so that the voltage becomes 0 volt when the correction signal is low level and becomes the negative voltage V2 when the correction signal is high level as shown in FIG. Is output to the adding circuit 34. (Step S5)
[0040]
Here, the negative voltage V2 is a voltage corresponding to the above-mentioned predetermined negative voltage, and the predetermined pulse width PW2 is a period during which the negative voltage V2 is applied to the liquid crystal shutter. Is determined by the characteristics of the liquid crystal shutter to be used. (For example, PW2 = 0.1 msec, V2 = 200 V)
[0041]
[Correction drive signal generation step]
The adder circuit 34, which has received the correction signal b and the reference drive signal a from the switch circuit 32, adds them and outputs a correction drive signal serving as a drive signal for controlling ON / OFF of the liquid crystal shutter to the liquid crystal shutter. (Step S6)
[0042]
In this embodiment, the driving signal of the liquid crystal shutter is corrected so that a voltage having a polarity opposite to the voltage applied up to that time when the driving voltage of the liquid crystal shutter falls is applied for a certain period of time. As shown in FIG. Here, 50% of the peak value (Td50) is a period in which the liquid crystal operation waveform (corresponding to the amount of passing light) falls to 50% when the liquid crystal shutter ON is set to 100%. According to the results shown in FIG. 8, by implementing the present embodiment, Td50 is reduced from 1.50 msec to 0.90 msec (−0.60 msec: improvement rate 40.0%). That is, it can be seen that the delay of the response of the light output to the fall of the drive signal of the liquid crystal shutter (that is, the period until the liquid crystal shutter is completely turned off) is improved.
[0043]
As described above, the liquid crystal shutter control device 1 has been described based on one embodiment, but the present invention is not limited to this. For example, the correction driving signal generation / output unit 30 generates a correction signal having a predetermined pulse width in synchronization with the rising timing of the reference driving signal, and outputs a voltage higher than the voltage applied up to that time when the reference driving signal a rises. May be generated for a fixed period of time and output to the liquid crystal shutter as a correction drive signal.
[0044]
Further, the correction drive signal generation / output means 30 outputs a signal having a predetermined pulse width in synchronization with the rising timing of the reference drive signal and a signal having a predetermined pulse width in synchronization with the fall timing of the reference drive signal. Is used as a correction signal, a signal obtained by applying a voltage higher than the voltage applied so far at the rise of the reference drive signal a of the liquid crystal shutter for a certain period of time, and a voltage having the opposite polarity to the voltage applied so far at the fall. It is also possible to generate a composite signal with a signal added only for a certain period and output it to the liquid crystal shutter as a correction drive signal.
[0045]
(Second embodiment)
Next, the configuration and functions of a liquid crystal shutter control device 1B according to a second embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing a configuration of a liquid crystal shutter control device 1B according to a second embodiment of the present invention. The liquid crystal shutter control device 1B shown in FIG. 2 is a liquid crystal shutter control device that opens and closes a liquid crystal shutter. The liquid crystal shutter control device 1B separates a vertical synchronization signal from a synchronization signal of an imaging device. A reference drive signal generating means 20 for generating a reference drive signal serving as an original signal of the drive signal of the synchronized liquid crystal shutter, and a correction signal synchronized with the vertical synchronization signal from the reference drive signal; And a correction drive signal generation / output means 30B for generating a correction drive signal B based on the drive signal and outputting the correction drive signal B to the liquid crystal shutter.
Here, the components other than the correction drive signal generation / output means 30B (waveform differentiating circuit 31B) are the same as those of the liquid crystal shutter control device 1 (FIG. 1), and thus the same reference numerals are given and the description is omitted.
[0046]
The correction drive signal generation and output means 30B has a waveform differentiation circuit 31B, a switch circuit 32, and an addition circuit 34, and converts the reference drive signal from the reference drive signal generation means to a predetermined voltage level by the switch circuit 32, The correction signal B, the waveform of which is differentiated by the waveform differentiating circuit 31B, and the reference drive signal a are added by the adder circuit 34 and output as a corrected drive signal B to the liquid crystal shutter.
[0047]
The liquid crystal shutter control device 1 </ b> B having the above configuration and function is capable of visually recognizing light from a light source (for example, an image projected on a display device) by a person and not appearing on an image captured by an imaging device. Provide as.
[0048]
Further, the operation of the liquid crystal shutter control device 1B according to the second embodiment will be described with reference to FIGS. The switch circuit 32 that has received the reference drive signal from the reference drive signal generation means outputs a reference drive signal a obtained by converting the reference drive signal to a predetermined voltage level to the waveform differentiating circuit 31B. The waveform differentiating circuit 31B to which the reference driving signal a has been input outputs a correction signal B obtained by differentiating the reference driving signal a to the adding circuit 34, as shown in FIG.
[0049]
The adder circuit 34, which has received the correction signal B and the reference drive signal a, adds the signals and outputs a correction drive signal B serving as a drive signal for controlling ON / OFF of the liquid crystal shutter to the liquid crystal shutter.
[0050]
In FIG. 6, the differential signal (correction signal B) is a signal generated from both a waveform obtained by differentiating the rising edge of the reference drive signal and a waveform obtained by differentiating the falling edge. Alternatively, a control signal (not shown) may be generated in accordance with the falling timing, and the waveform differentiating circuit 31B may be controlled to generate a signal generated by either of them.
[0051]
(Third embodiment)
Next, the configuration and functions of a liquid crystal shutter control device 1C according to a third embodiment will be described with reference to FIG. FIG. 3 is a block diagram showing a configuration of a liquid crystal shutter control device 1C according to a third embodiment of the present invention. A liquid crystal shutter control device 1C shown in FIG. 3 is a liquid crystal shutter control device that opens and closes a liquid crystal shutter. The liquid crystal shutter control device 1C separates a vertical synchronization signal from a synchronization signal of an imaging device, and a vertical synchronization signal separation unit 10; A reference drive signal generating means 20 for generating a reference drive signal serving as an original signal of the drive signal of the synchronized liquid crystal shutter, and a correction drive signal C synchronized with the vertical synchronization signal from the reference drive signal and output to the liquid crystal shutter And a correction drive signal generation / output unit 30C. Here, since the components other than the correction drive signal generation / output means 30C (the synchronous oscillation circuit 31C, the gate circuit 32C, and the switch circuit 33C) are the same as those of the liquid crystal shutter control device 1 (FIG. 1), they are denoted by the same reference numerals. Explanation is omitted.
[0052]
The correction drive signal generation and output means 30C includes a synchronous oscillation circuit 31C, a gate circuit 32C, and a switch circuit 33C. The vertical drive signal generated by the vertical sync separation means 10 and the reference drive signal generated by the reference drive signal generation means 20 are provided. A drive signal is input, converted to a drive voltage level signal that swings positive and negative at a predetermined voltage, and output as a corrected drive signal C to the liquid crystal shutter.
[0053]
The gate circuit 32C generates and outputs a signal obtained by modulating the correction signal C with the reference drive signal (a signal obtained by calculating the logical product of the correction signal C and the reference drive signal). The switch circuit 33C has two inputs (inputs a and b), outputs a predetermined negative voltage when the input b is at a low level during a period when the input a is at a high level, and outputs a predetermined negative voltage when the input b is at a high level. In this case, a predetermined positive voltage is output, and during the period when the input a is at a low level, 0 volt is output regardless of the level of the input b.
[0054]
The liquid crystal shutter control device 1C having the above-described configuration and function is capable of intermittent light which is visible to a human and receives light from a light source (for example, an image projected on a display device) and is not reflected on an image captured by an imaging device. Provide as.
[0055]
Further, the operation of the liquid crystal shutter control device 1C according to the third embodiment will be described with reference to FIGS. The reference drive signal generation means 30C, which has received the vertical synchronization signal from the vertical synchronization signal separation means 10, generates a continuous square waveform having a shorter cycle than the reference drive signal by the synchronization oscillation circuit 31C, and generates a gate circuit 41C as a correction signal C. Output to
[0056]
The gate circuit 32C to which the correction signal C and the reference drive signal generated by the reference drive signal generation means 20 are input is used as a signal c (the correction signal C and the reference signal C) obtained by modulating the correction signal C shown in FIG. A signal obtained by taking a logical product with the drive signal) is generated and output to the switch circuit 33C.
[0057]
The switch circuit 33C, which inputs the signal c to the input b and inputs the reference drive signal generated by the reference drive signal generation means 20 to the input a, turns on and off the liquid crystal shutter swinging positive and negative at a predetermined voltage shown in FIG. A correction drive signal C which is a drive signal to be controlled is generated and output to the liquid crystal shutter.
[0058]
【The invention's effect】
As described above, the liquid crystal shutter control device and the liquid crystal shutter control method according to the present invention have the following excellent effects.
[0059]
According to the first or fifth aspect of the present invention, it is possible to output a correction drive signal which is a drive signal of the liquid crystal shutter obtained by adding a correction for improving the response characteristic of the liquid crystal shutter to the liquid crystal shutter. The delay of the response of the light output to the rise of the drive signal (that is, the period until the liquid crystal shutter is completely turned on) and the delay of the response of the light output to the fall of the drive signal (that is, the period until the liquid crystal shutter is completely turned off) are earlier. can do. Thus, the illumination and the liquid crystal shutter of the display device can be opened by effectively using the period in which the electronic shutter of the imaging device is closed, and the light from the display device can be transmitted efficiently to make the projected image brighter. it can.
[0060]
According to the second or third aspect of the present invention, by applying an overvoltage when the drive voltage of the liquid crystal shutter rises, the liquid crystal is rapidly charged, and the rise of the drive signal of the liquid crystal shutter caused by the capacitance of the liquid crystal. (Ie, the period until the liquid crystal shutter is completely turned on) becomes faster. Also, by applying a voltage having a polarity opposite to the voltage applied up to that time when the driving signal of the liquid crystal shutter falls for a certain period of time, the ions adsorbed on the electrodes of the liquid crystal shutter are removed, and the driving of the liquid crystal shutter is performed. The delay of the response of the light output to the falling of the signal (that is, the period until the liquid crystal shutter is completely turned off) becomes earlier. Thus, the illumination and the liquid crystal shutter of the display device can be opened by effectively using the period in which the electronic shutter of the imaging device is closed, and the light from the display device can be transmitted efficiently to make the projected image brighter. it can.
[0061]
According to the fourth aspect of the present invention, by driving the liquid crystal with a continuous square waveform that swings positively and negatively, the potential of the electrode is inverted before the ions are adsorbed on the electrodes. The delay in the response of the light output to the fall of the shutter drive signal (that is, the period until the liquid crystal shutter is completely turned off) is increased. Accordingly, the liquid crystal shutter of the display device can be opened by effectively using the period in which the electronic shutter of the imaging device is closed, and the light from the display device can be transmitted efficiently and the projected image can be made brighter.
[0062]
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of a liquid crystal shutter control device according to a first embodiment of the present invention.
FIG. 2 is a block diagram illustrating an overall configuration of a liquid crystal shutter control device according to a second embodiment of the present invention.
FIG. 3 is a block diagram showing an overall configuration of a liquid crystal shutter control device according to a third embodiment of the present invention.
FIG. 4 is a time chart showing a relationship between a synchronization signal and a vertical synchronization signal of the liquid crystal shutter control device according to the first embodiment of the present invention.
FIG. 5 is a time chart showing a relationship among a vertical synchronization signal, a reference drive signal, a correction signal, and a correction drive signal of the liquid crystal shutter control device according to the first embodiment of the present invention.
FIG. 6 is a time chart illustrating a relationship among a drive signal, a differential signal, and a correction drive signal of the liquid crystal shutter control device according to the second embodiment of the present invention.
FIG. 7 is a time chart illustrating a relationship among a vertical synchronization signal, a reference drive signal, a correction signal, and a correction drive signal of the liquid crystal shutter control device according to the third embodiment of the present invention.
FIG. 8 is a waveform chart and a comparison table showing an actual improvement example of the liquid crystal shutter control device according to the first embodiment of the present invention.
FIG. 9 is a schematic diagram for explaining an information providing technique using intermittent light that is visually recognized by a person and is not reflected in a video imaged by an imaging device.
FIG. 10 is a time chart illustrating a relationship between a vertical synchronization signal and a shutter signal of the imaging apparatus, a driving signal of a liquid crystal shutter, and a passing light amount.
FIG. 11 is a time chart showing a relationship between a shutter signal of the imaging apparatus, a driving signal of a liquid crystal shutter, and a passing light amount.
FIG. 12 is an explanatory diagram for explaining a liquid crystal shutter.
FIG. 13 is a flowchart showing an operation of the liquid crystal shutter control device according to the first embodiment of the present invention.
[Explanation of symbols]
1, 1B, 1C ... liquid crystal shutter control device
10 Vertical sync separation means
20: Reference drive signal generating means
30, 30B, 30C... Correction drive signal generation and output means
31 ... Correction signal generation circuit
31B …… Waveform differentiation circuit
31C …… Synchronous oscillation circuit
32, 32C, 33, 33C ... Switch circuit
34 Addition circuit
51 ... Imaging device
52 ... LCD shutter
53 Display device
54 ... Screen
55 …… Performers
56 ... Transparent substrate
57 …… Transparent electrode
58: Liquid crystal layer
59 …… DC power supply
60 ...... Ion

Claims (5)

A liquid crystal shutter control device that opens and closes a liquid crystal shutter,
Vertical synchronization signal separation means for separating the vertical synchronization signal from the synchronization signal of the imaging device,
Reference drive signal generation means for generating a reference drive signal serving as an original signal of the drive signal of the liquid crystal shutter synchronized with the vertical synchronization signal;
A correction drive signal generation / output unit that generates a correction signal for changing a response characteristic of the liquid crystal shutter, generates a correction drive signal based on the correction signal and the reference drive signal, and outputs the correction drive signal to the liquid crystal shutter;
A liquid crystal shutter control device comprising: The correction drive signal generation and output means, a correction signal generation circuit that generates a correction signal having a predetermined pulse width synchronized with the fall timing of the reference drive signal,
A switch circuit that converts the reference drive signal and the correction signal to a predetermined voltage level,
Adding the reference drive signal and the correction signal converted to a predetermined voltage level by the switch circuit, synchronizing with the reference drive signal, a waveform that becomes a positive voltage in a predetermined period from a rise of the reference drive signal, and An adder circuit that generates at least one waveform of a waveform that becomes a negative voltage in a predetermined period from the fall of the reference drive signal and outputs the waveform to the liquid crystal shutter;
The liquid crystal shutter control device according to claim 1, further comprising: A switch circuit for converting the reference drive signal to a predetermined voltage level,
A waveform differentiation circuit that generates a correction signal that is a differentiation signal obtained by performing waveform differentiation on the reference drive signal obtained by converting the reference drive signal to a predetermined voltage level;
The reference drive signal converted to a predetermined voltage level by the switch circuit and the correction signal are added, and a waveform that becomes a positive voltage in a predetermined period from a rise of the reference drive signal in synchronization with the reference drive signal, and An adder circuit that generates at least one of a waveform that becomes a negative voltage in a predetermined period from a fall of the reference drive signal and outputs the waveform to the liquid crystal shutter;
The liquid crystal shutter control device according to claim 1, further comprising: A synchronous oscillation circuit that generates a correction signal that is a continuous square waveform having a shorter cycle than the reference drive signal in synchronization with the vertical synchronization signal;
A gate circuit that outputs the correction signal only during a period in which the reference drive signal is at a high level;
A switch circuit that converts the correction signal output from the gate circuit into a signal that swings positive and negative and outputs the signal to the liquid crystal shutter;
The liquid crystal shutter control device according to claim 1, further comprising: A liquid crystal shutter control method for opening and closing a liquid crystal shutter, comprising:
A vertical synchronization signal separating step of separating a vertical synchronization signal from a synchronization signal of the imaging device;
A reference drive signal generating step of generating a reference drive signal serving as an original signal of the drive signal of the liquid crystal shutter synchronized with the vertical synchronization signal;
A correction signal generating step of generating a correction signal for changing a response characteristic of the liquid crystal shutter;
Generating a correction drive signal based on the correction signal and the reference drive signal and outputting the correction drive signal to the liquid crystal shutter;
A liquid crystal shutter control method, comprising:

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