JPH09113924A - Liquid crystal shutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain optimum light shielding, to perform fast switching from light view to dark view, to reduce the current consumption, and to secure safety even if a driving system is in trouble by placing a positive and a negative liquid crystal panel one over the other. SOLUTION: The negative liquid crystal panel 2 is constituted by sandwiching liquid crystal through spacers between glass substrates 4a and 4b having transparent electrodes formed in contact with the internal surfaces and forming polarizing plates 5 and 6 which have the same direction of polarization outside the glass substrates 4a and 4b in contact. The positive liquid crystal panel 3, on the other hand, is constituted by sandwiching liquid crystal through spacers between glass substrate 7a and 7b having transparent electrodes formed and forming polarizing plates 8 and 9 whose directions of polarization cross each other at right angles outside the glass substrates 7a and 7b. This liquid crystal shutter 1 is constituted by placing the negative liquid crystal panel 2 and positive liquid crystal panel 3 one over the other and when light view is automatically switched to dark view, the initial driving voltage to the positive liquid crystal panel 3 is set high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal shutter that protects the naked eye from light rays.

[0002]

2. Description of the Related Art Conventionally, welding work has always been required in construction work and the like. In the era when gas welding was the mainstream as before, simple protective glasses such as dark sunglasses were enough to protect the eyes from burner flames, but as in recent years, electric welding has become mainstream. Then, in order to protect the eyes from the light of a strong electric arc (hereinafter referred to as a welding arc), various problems must be dealt with.

FIG. 7 is a diagram comparing a welding arc with sunlight. Curve A shows the radiant energy distribution of the welding arc, and curve B shows the radiant energy distribution of sunlight. As shown in the figure, it can be seen that the spectrum of the welding arc is extremely strong not only in the visible region but also in the ultraviolet region and the infrared region as compared with sunlight. It is well known that direct viewing of the sun with the unaided eye damages the retina of the fundus and, in severe cases, blindness, but the welding arc emits even more intensely than the sunlight. In addition to strong visible light, radiation with wavelengths of 200 to 400 nm (nanometers) for ultraviolet rays and radiation with wavelengths of 780 nm or more for infrared rays are considered to be dangerous to the human eye. It is said that blindness is caused when exposed to. In welding work, it is not possible to completely block visible light because it is necessary to visually confirm the hand at work, but radiation in the invisible region is unnecessary for the eye. There is no hindrance. Therefore, the protective glasses for electric welding generally use a filter that almost completely blocks the above-mentioned ultraviolet rays and infrared rays, and a night-vision filter that appropriately blocks visible light.

As described above, since the welding arc is extremely strong, it is insufficient to protect only the direct viewing direction like sunglasses and gas welding glasses. Therefore, in the past, protective glasses for electric welding have a problem in work due to strong visible light that wraps around from the side due to reflection or the like and interferes with work, or damages the eyes with the above-mentioned dangerous radiation. In order to avoid this, the shape of the protective surface covering the entire face up to the base of the ear was used. This was held in one hand and the welding work was performed in the other hand. That is, when confirming the working position before starting welding, the operation is to avoid the protective surface aside and expose the face, and cover the face with the protective surface immediately before the welding rod is brought into contact with the working position to form an electric arc. Was also done.

Therefore, not only is this inconvenient because both hands are blocked, but since the protective surface is quite heavy to hold with one hand for a long time, the degree of work fatigue is accelerated. In recent years, liquid crystal light-shielding shutters have been developed with the improvement of liquid crystal technology, and goggles-type electric welding protective eyeglasses having a viewing window capable of automatically switching from clear vision to night vision have come to be used.

Liquid crystals were originally developed and used for display devices. Generally, in a liquid crystal display panel, transparent electrodes are formed on surfaces of two glass substrates facing each other.
In order to align (orient) liquid crystal molecules in a certain direction, a thin polymer film (usually 500Å to 1000) is placed on the transparent electrode.
Å) is formed. A directivity is contributed to the surface of the polymer thin film so that the liquid crystal molecules are twisted and aligned by exactly 90 degrees between the two glass substrates, and a polarizing plate is arranged outside the two glass substrates. By applying a voltage to the transparent electrode, the orientation of liquid crystal molecules is changed, and the light incident on the liquid crystal substrate is transmitted by tuning or rotating the one-dimensional polarization directions of the two polarizing plates respectively. Allow or block light. When no voltage is applied to the liquid crystal, the orientation of the liquid crystal is 90 degrees twisted.
Allows light to pass if the polarization directions of the polarizing plates are orthogonal,
The light is blocked if the polarization directions of the two polarizing plates are synchronized. When a voltage is applied to the liquid crystal, the orientation of the liquid crystal is released from the twisted state of 90 degrees, and becomes substantially vertical to the glass substrate. Therefore, if the polarization directions of the two polarizing plates are orthogonal to each other, the light is blocked, and if the polarization directions of the two polarizing plates are synchronized, the light is transmitted.

When a liquid crystal panel that transmits light when no voltage is applied and blocks light when voltage is applied is used as an optical shutter, this is called a positive type liquid crystal shutter, and light is applied when no voltage is applied. When a liquid crystal panel that cuts off and transmits light when a voltage is applied is used as an optical shutter, this is generally called a negative type liquid crystal shutter.

By the way, when not only the protective glasses for welding but also liquid crystal shutters are widely adopted in various fields,
It would be inconvenient in terms of material transactions and design if there is no standard for shutter functions. For this reason, JIS standard T8141 regarding light-shielding glasses exists.

FIG. 8 shows the JIS standard T8141 for light-shielding glasses.
Is a list of. The chart showing the transmittance of ultraviolet rays and infrared rays is omitted from the chart shown in the figure. As described above, the ultraviolet rays and the infrared rays are generally constantly eliminated by using, for example, a "green" filter or the like, and therefore they will not be specifically described below. As shown in the figure, according to the JIS standard,
There are standards from shade number 1.2 to shade number 16. Depending on the application in each field, these standards are referred to in order to maintain a certain light-shielding property when making light-shielding glasses.

When the above-mentioned liquid crystal shutter is used for electric welding, generally, the darkness of night vision of the welded portion during the work is 2
It is configured so that it can be switched to a stage.
In Japan, many negative type liquid crystal shutters are used in combination on protective glasses for electric welding so as to form two kinds of darkness. This type is always in the night-vision state, remove it from your eyes when not in use, turn on the power switch immediately before starting work to put it in the visible state and put it on your eyes. It is a structure that is cut off to enter the night-vision state. As described above, the power source is only energized only when the work position is confirmed immediately before the start of welding, and thus the power saving type is achieved.

On the other hand, in Europe and the United States, one type of liquid crystal shutter is used and two types of darkness are realized by controlling the voltage. This is a structure in which it is always in a clear-vision state, and when welding is started, the power is automatically turned on to become a night-vision state.
In this way, since it is always in a clear state, there is an advantage that it does not take time and trouble even if it is left in the eye in the workplace. Further, since switching from clear vision to night vision depends on the application of voltage, there is also an advantage that the switching speed can be controlled by voltage.

[0012] Normally, as a light-shielding characteristic of protective glasses for electric welding, the standard of light-shielding number 4 is optimal in terms of brightness when viewed clearly. Further, the darkness when performing night vision during the execution of the welding operation varies depending on the person, but the shade numbers 8 or 10 are switched and used, the shade numbers 9 and 11 are switched, and the shade numbers 10 and 12 are switched. It has been found statistically that the usage method of using or switching between the light blocking numbers 10 or 13 is often requested.

[0013]

However, the one using the negative type liquid crystal shutter, which is the mainstream in Japan, has a low light blocking characteristic of the negative type liquid crystal shutter, and therefore even if two sheets are stacked, the light blocking numbers 12 and 13 are used. There is a problem that the degree of shading cannot be realized. However, if three or more negative type liquid crystal shutters are stacked, there arises a problem that it is not possible to maintain the brightness of the light shielding number 4 at the time of clear vision. Further, since the switching from the clear vision to the night vision is performed by shutting off the applied voltage, the speed of the switching from the clear vision to the night vision (the fall of the voltage sensitivity of the liquid crystal) is naturally left constant. The switching speed is currently limited to 40 msec (millisecond) due to the characteristics of the liquid crystal.

By the way, it is said that the afterimage phenomenon does not occur if the eyes are turned to another within 200 msec even when the sun is mistakenly viewed directly. However, in the welding arc, the light intensity is extremely strong as described above. For this reason, it is said that if the switching from the clear vision to the night vision is not done within 30 msec, it will be temporarily blind due to the afterimage of the welding arc that is clearly visible, which is extremely dangerous in terms of work. However, in the negative type liquid crystal shutter, the switching from the clear vision to the night vision is constant at 40 msec as described above, and the above condition is not satisfied. In Japan, it seems that workers are responding by closing their eyes at the beginning of welding.

On the other hand, since the one using the positive type liquid crystal shutter which is predominant in Europe and the United States has a high positive type light shielding property when a voltage is applied, it is necessary to realize the light shielding degree of the light shielding numbers 12 and 13. You can However, on the other hand, there is a problem in that the power source voltage must be applied in order to maintain the night-vision state during long-term work, which is energy-consuming and inferior in economic efficiency. In addition, if the voltage applied to the liquid crystal is cut off during work due to an unexpected power failure, 40
It becomes a clear state in an almost instant of msec. Human reaction to such unforeseen circumstances is generally extremely slow, so even if an accident is noticed and the eyes are closed by the conditioned reflex, the worker can not see the welding arc for more than 100 milliseconds until that time. There is a danger that the person will look directly and become extremely dangerous.

An object of the present invention is to provide a liquid crystal shutter which has an optimum light-shielding degree during night vision, switches from clear vision to night vision at high speed, consumes less current, and can ensure safety even when a drive circuit system fails. Is to provide.

[0017]

The liquid crystal shutter of the present invention is constructed by stacking a positive type liquid crystal panel and a negative type liquid crystal panel.

Then, for example, when the power supply voltage for the positive type liquid crystal panel is turned off and the power supply voltage for the negative type liquid crystal panel is turned on, a visible light transmission with a constant brightness is provided. When the power supply voltages for the positive type liquid crystal panel and the negative type liquid crystal panel are both turned on, it has a first cutoff property of a certain darkness with respect to visible rays, and the power source voltage for the positive type liquid crystal panel is turned on and negative. When the power source voltage for the positive type liquid crystal panel is turned off, the second type has a second blocking property that is darker than the first blocking property for visible rays, and the power source voltage for the positive type liquid crystal panel and the negative type liquid crystal panel is When both are turned off, they have a third blocking property of a certain darkness with respect to visible rays.

The visible light transmissivity having the constant brightness is configured to form the visible light transmissivity of the light shielding degree number 4 of JIS standard T8141 as described in claim 3, for example.
Further, the first blocking property is, for example, as described in claim 4, the light shielding degree number 8, 9 or 10 of JIS standard T8141.
Is configured to form a visible light transmittance of. Further, the second cutoff property is defined by JI
Shading degree number 10, 11, 12 or 1 of S standard T8141
It is configured to form a visible light transmittance of 3. Also,
The third blocking property is configured so as to have a light blocking property sufficient to protect a human eye from visible rays of an electric arc, for example, as described in claim 6.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view schematically showing the structure of a liquid crystal shutter according to an embodiment. As shown in the figure, the liquid crystal shutter 1 is configured by stacking a negative liquid crystal panel 2 and a positive liquid crystal panel 3.

The negative type liquid crystal panel 2 includes two glass substrates 4a and 4b, and although not shown in the figure, a spacer for forming a space between the glass substrates 4a and 4b, and a glass substrate. 4a and 4b, two transparent electrodes formed in contact with the inner surfaces, liquid crystal contained in the above-mentioned voids, and two polarizing plates 5 and 6 formed in close contact with the outsides of the glass substrates 4a and 4b, respectively. To be done. Polarizing plates 5 and 6
The directions of the polarized lights of are the same as each other.

On the other hand, the positive type liquid crystal panel 3 has two glass substrates 7a and 7b, and although not shown in the figure, a gap is formed between the glass substrates 7a and 7b. The spacers, the two transparent electrodes formed in contact with the inner surfaces of the glass substrates 7a and 7b, the liquid crystal contained in the space, and the two polarizing plates 8 and 9 are closely attached to the outsides of the glass substrates 7a and 7b, respectively. It is similar to the negative liquid crystal panel 2 described above. However, the polarization directions of the polarizing plates 8 and 9 are configured to be orthogonal to each other. Further, the polarization directions of the polarizing plates 6 and 8 are configured to be the same.

In the figure, the glass substrates 4a and 4b and the glass substrates 7a and 7b are shown with different lengths in order to distinguish the negative type from the positive type at a glance. That is, the one having the shorter glass substrate on the right side of the drawing is the negative type liquid crystal panel 2, and the one having the shorter glass substrate on the left side is the positive type liquid crystal panel 3.

FIG. 2 shows the liquid crystal shutter 1 having the above structure.
The operation state of is shown in the figure. In general, in the clear viewing state of the liquid crystal shutter, light oscillating in the 360-degree direction is allowed to pass only in one oscillation direction even if there is a technically small width. Therefore, the light transmittance is about 5%. Is. However, it is possible to observe the outside with a lightness that does not cause a problem, although it feels a little dim to the human eye. Therefore, in the following description, this clear vision state is referred to as transparent. In addition, the night-vision state of the liquid crystal shutter has a certain range of polarization angle as described above, and the light itself also has a diffractive effect, so that even if the alignment axis of the liquid crystal and the polarization direction of the polarizing plate are orthogonal, The light is not blocked, and it is possible to dark-vision the strong light, but it is almost dark in the light of normal intensity. Therefore, in the following description, this night-vision state is referred to as light-shielding. In the figure, the upper part shows whether the applied voltage of the negative type liquid crystal panel 2 is on / off and whether it is transparent or light-shielded at that time, and the middle part shows whether the applied voltage of the positive type liquid crystal panel 3 is on / off and whether it is transparent at that time. The state of light shielding and the state of transparent or light shielding of the liquid crystal shutter 1 in each of the above cases are shown in the lower stage.

As shown in the vertical frame 11 in the figure, the state is transparent when the negative liquid crystal panel 2 is on, and the state is also transparent when the positive liquid crystal panel 3 is off. Therefore, the state of the liquid crystal shutter 1 is "transparent" as a whole.

Further, as shown in the vertical frame 12 in the figure, when the negative liquid crystal panel 2 is on and the state is transparent, and when the positive liquid crystal panel 3 is on, the state is light-shielded. As a whole, the state of the liquid crystal shutter 1 is “shading”
It is. This is the first blocking property against visible light.

Further, as shown by the vertical frame 13 in the figure, when the negative type liquid crystal panel 2 is in the voltage-off state and therefore its state is light-shielded, if the positive-type liquid crystal panel 3 is in the voltage state, that state is also Since it is light-shielding, the state of the liquid crystal shutter 1 as a whole is a stronger "light-shielding". This is the second blocking property against visible light.

Then, as shown in the vertical frame 14 of the figure, the negative liquid crystal panel 2 is off (therefore, the state is light-shielded), and the positive liquid crystal panel 3 is also off the voltage (there is a transparent state). The state of the liquid crystal shutter 1 as a whole is still "light-shielded". Generally, a positive type liquid crystal panel 3
Of the negative type liquid crystal panel 2 is weak, and therefore the light blocking of only one negative type liquid crystal panel 2 is not suitable for protection during welding work. However, when the power source for driving the liquid crystal shutter 1 is cut off during welding due to an unexpected accident such as a power source failure, the light blocking degree is still weak even though the light blocking degree is weak. It is much safer than looking directly at the welding arc in a see-through state. That is, the first blocking property (vertical frame 1 in FIG.
2)), if the voltage is cut off due to a power failure such as battery exhaustion, the fall of the liquid crystal (attenuation from the excited state) is the same for both the negative type and the positive type, so the positive type liquid crystal panel 3 decays. While gradually becoming transparent,
Simultaneously with this, the negative liquid crystal panel 2 gradually changes to the light-shielded state. Therefore, even if an unexpected voltage cut occurs, the protective glasses do not become transparent even for an instant. Similarly, when the voltage is cut off when the second cutoff property (see the vertical frame 13 in FIG. 2) is shown, in this case, the negative liquid crystal panel 2 is already in the light-shielding state.
Therefore, only the night-vision state of the negative liquid crystal panel 2 is changed from the dark-vision state of the dark side. In either case,
Since the field of view becomes brighter than before, the worker can easily know that the power cut accident has occurred. With this, without looking directly at the welding arc in the transparent state,
That is, such changes can be dealt with without causing an accident such as damage to the fundus retina.

If only the negative type liquid crystal panel is used for the protective glasses, as described above, the state transition from transparent to light shielding is such that the applied voltage is cut off, that is, the liquid crystal falls from the excited state, that is, the natural state. It depends on the decay. The speed of this spontaneous decay depends on the physical properties of the liquid crystal material and the thickness of the liquid crystal, and as described above, it is currently limited to 40 msec.

On the other hand, in the present embodiment, a negative type liquid crystal panel and a positive type liquid crystal panel are combined, and thereby the light blocking state which exhibits the first blocking property and the second blocking property are exhibited. Both the light blocking state and the light blocking state are blocked by the positive liquid crystal panel 3. That is, it depends on the excitation of the liquid crystal due to the voltage application. The rising speed (excitation of the liquid crystal) of the positive type liquid crystal panel 3 can be controlled by the applied voltage.

FIG. 3 is a diagram showing the relationship between the rising and falling speeds (response speed of liquid crystal) of the positive type liquid crystal panel and the applied voltage (liquid crystal panel drive voltage). In the same figure, the horizontal axis shows the applied voltage from 0V to 25V (V: volt) from left to right, and the vertical axis shows the elapsed time of state transition from bottom to top on a logarithmic scale from 0.1 msec to 100 msec. ing. And the circle mark (white circle and black circle) shown in the figure
Indicates the relationship between the applied voltage and the rise time of the positive type liquid crystal panel, and the triangular marks (white triangles and black triangles) also indicate the relationship between the applied voltage and the fall. Black circles and black triangles indicate 10% to 90% when the falling equilibrium state is "0" and the rising equilibrium state is "100".
Shows the rising time and the falling time from 90% to 10%. This is provided for reference in order to explain that the transition time of the first 10% and the transition time of the last 10% are extremely large in comparison with the transition time of 80% in the middle both at the rising edge and the falling edge.

In the case of protective glasses, the elapsed time from 0% in the falling equilibrium state to 100% in the rising equilibrium state poses a problem. As shown in the same figure, it can be seen that the elapsed time of the fall is almost independent of the magnitude of the applied voltage cut off and is constant. And 100%
In the case of the white triangle mark indicating the trailing edge, the constant elapsed time is approximately 40 msec as described above. On the other hand, the elapsed time of rising largely depends on the applied voltage, and as the applied voltage increases, the time decreases geometrically and converges to a constant value.

As shown by the white circles representing the 100% rise in the figure, the elapsed time is about 8 msec when the applied voltage is 5 V, the elapsed time is about 1.8 msec when the applied voltage is 10 V, and the applied voltage is 15 V. In case of, the elapsed time is about 0.8 msec, and the applied voltage is 20V.
In the case of, the elapsed time is known to be about 0.4 msec. Based on this, in the present embodiment, the transition elapsed time from the transparent state to the light blocking state of the positive type liquid crystal panel 3 is 3
The applied voltage is controlled to be 0 msec or less.

FIG. 4A shows a method of applying a voltage to the positive type liquid crystal panel 3 in this embodiment, and FIG. 4B shows a comparative diagram for explaining the result. As shown in (a) of the same figure, when the liquid crystal shutter 1 is automatically switched from transparent to light-shielded by detecting the occurrence of a welding arc, at the beginning of rising, the saturation voltage V1 after the rising equilibrium is kept for a period of time T0. Applied voltage V0 set to about 3 times higher
Is applied. The above period T0 is 10 from transparent to light shielding.
It corresponds to the elapsed time T that is appropriately selected such that the elapsed time for 0% transition is 30 msec or less.

As a result, as shown in FIG. 6B, as compared with the elapsed time T2 at which 100% transition from transparent to light shielding occurs when the same voltage V2 is continuously applied at the beginning of rising and after the excitation equilibrium, The elapsed time T of 100% transition from transparent to light shielding in the embodiment can be shortened to a fraction. As a result, the liquid crystal shutter 1 can be switched from the transparent state to the light shielding state in an instant sufficient to protect the fundus based on the generation of the welding arc.

By the way, it has already been stated that, when the degree of transparency and light shielding described above is examined on the basis of the demand of the worker at the welding work site, several kinds of constant conditions are summarized. In other words, as a request, it is preferable to combine the standard with the light-shielding number 4 for the brightness when viewed with the standard with the light-shielding number 8 or 10 for the darkness to be switched when the night-vision is performed. As a request, it is preferable to combine the standard with the light-shielding number 4 with the brightness for the clear viewing and the standard with the light-shielding number 9 or 11 for the darkness to be switched when the night viewing is performed. As a request, it is preferable to combine the standard with the light-shielding number 4 with the brightness for the clear viewing and the standard with the light-shielding number 10 or 12 for the darkness to be switched when the night viewing is performed. Then, as a request, it is desirable to combine a standard with a light-shielding number of 4 with a standard of light-shielding and a standard with a light-shielding number of 10 or 13 with a darkness to switch when night-vision is performed. .

FIG. 5A shows the results of the survey in a table. In the same figure (a), the above four types of requests ~
The combination of transparent and light-shielding corresponding to "# 4, # 8, # 10", "# 4, # 9, #" according to the JIS standard light-shielding number.
11 ","# 4, # 10, # 12 "and"# 4, # 1 "
0, # 13 ”.

FIG. 6B shows an example of a liquid crystal shutter configured in this embodiment so as to satisfy the conditions shown in the requests tabulated by the above survey. Figure (b) shows
The standard of the polarizing plate (see FIG. 1) constituting the liquid crystal shutter corresponding to the above requirements is shown. That is,
(b) shows the specifications of the outer polarizing plate 9 of the positive type liquid crystal shutter 3, the inner polarizing plate 8, the inner polarizing plate 6 of the negative liquid crystal shutter 2, and the outer polarizing plate 5 of the negative type liquid crystal shutter 2, respectively. ing. As shown in FIG. 3B, as a liquid crystal shutter configuration that satisfies the demand, it is appropriate to use D type, D type N type and XQ type polarizing plates for the polarizing plates 9, 8, 6 and 5. is there. As a structure of the liquid crystal shutter which satisfies the demand, it is suitable to use polarizing plates of H type, H type, E type and XL type as the polarizing plates 9, 8, 6 and 5. As a liquid crystal shutter configuration that satisfies the demand, it is suitable to use A type, A type, E type, and XL type polarizing plates. Then, as the structure of the liquid crystal shutter that satisfies the demand, it is suitable to use the A type, A type, A type and XE type polarizing plates.

FIG. 6 is a diagram showing the standard of the above-mentioned polarizing plate. The standard of the polarizing plate is set for the polarized light in the direction of 45 degrees and the polarized light in the direction of 135 degrees perpendicular to this.
The types (standards) of the 45 degree polarizing plate include A, C, D,
E, J, K, L, M, N, O, P, Q, B, F, G,
There are H and R. Also, the standard symbols of the 135-degree polarizing plate are XA, XC, XD, XE, XJ, XK, XL, X.
M, XN, XO, XP, XQ, XB, XF, XG, X
There are H and XR. FIG. 6 shows a standard A (1
1), D (12), E and XE (13), XL (1
4), N (15), XQ (16) and H (17) only are shown. The specified values are shown for the single-piece transmittance, the parallel transmittance, the orthogonal transmittance, and the hue, respectively, and further remarks are shown. In the remarks, the descriptions "Neutral" and "Blue" can be seen. "Blue" indicates that the welding position (the welded portion that melts at a high temperature of the welding arc) has a property of transmitting some of the blue spectrum which is said to be easily visible.

The liquid crystal shutter of the present embodiment is constructed by combining the negative type and positive type liquid crystal panels having such a constitution,
The initial voltage applied to the positive type liquid crystal panel is set higher than the equilibrium voltage (saturation voltage).

[0041]

As described above, according to the present invention,
Since the liquid crystal shutter is configured by combining the negative type liquid crystal panel and the positive type liquid crystal panel, the response speed for switching from clear vision to night vision can be controlled by voltage, and when a failure such as power interruption occurs in the drive circuit. A light blocking property can be imparted, and thus high safety can be provided. Further, since the positive type liquid crystal panel is used in combination, the response speed for switching to night vision can be controlled at high speed by the drive voltage, and therefore, the high light blocking property (low light transmittance) of the JIS standard can be easily achieved. It becomes possible to respond.
Moreover, since only the initial drive voltage is increased and the state transition of the liquid crystal to the light cutoff is completed, the equilibrium state is maintained by the saturation voltage of the liquid crystal, so the light cutoff response speed can be significantly increased and the current consumption is normally cut off. It can be suppressed almost as much as time,
Therefore, it is possible to provide an economical liquid crystal shutter.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a configuration of a liquid crystal shutter according to an embodiment.

FIG. 2 is a diagram illustrating an operating state of a liquid crystal shutter according to an embodiment.

FIG. 3 is a diagram showing a relationship between rising speed and falling speed of a positive type liquid crystal panel and an applied voltage.

FIG. 4A is a diagram showing a method of applying a voltage to a positive type liquid crystal panel in an example, and FIG. 4B is a comparative diagram for explaining the result.

FIG. 5A is a diagram showing a worker's request regarding the degree of transparency and light shielding at a welding work site, and FIG. 5B is a diagram showing a configuration example of a liquid crystal shutter that satisfies the request.

FIG. 6 is a table showing standards of polarizing plates used in Examples.

FIG. 7 is a diagram showing a comparison between radiant energy distributions of a welding arc and sunlight.

FIG. 8 is a chart showing a relationship between a light-shielding degree number and visible light transmittance in the JIS standard of light-shielding glasses.

[Explanation of symbols]

 1 Liquid Crystal Shutter 2 Negative Liquid Crystal Panel 3 Positive Liquid Crystal Panel 4a, 4b, 7a, 7b Glass Substrate 5, 6, 8, 9 Polarizing Plate

Claims (6)

[Claims] 1. A liquid crystal shutter comprising a positive type liquid crystal panel and a negative type liquid crystal panel which are superposed on each other. 2. A positive type liquid crystal panel and a negative type liquid crystal panel, which have visible light transmittance of a certain brightness when the power source voltage for the positive type liquid crystal panel is turned off and the power source voltage for the negative type liquid crystal panel is turned on. When the power supply voltage for both liquid crystal panels is turned on, it has a first cutoff property with a certain darkness for visible rays. The power supply voltage for the positive type liquid crystal panel is turned on and the power supply voltage for the negative type liquid crystal panel is turned off. Has a second blocking property that is darker than the first blocking property against visible rays, and becomes visible when both the power supply voltages for the positive type liquid crystal panel and the negative type liquid crystal panel are turned off. The liquid crystal shutter according to claim 1, wherein the liquid crystal shutter has a third blocking property with a constant darkness. 3. The visible light transparency of the constant brightness is J
The liquid crystal shutter according to claim 2, wherein a visible light transmittance having a light-shielding degree number 4 of IS standard T8141 is formed. 4. The first barrier property is JIS standard T81.
The liquid crystal shutter according to claim 2, wherein a visible light transmittance of 41, which is a light shielding degree of 41, is formed. 5. The second barrier property is a JIS standard T81.
The liquid crystal shutter according to claim 2, wherein a visible light transmittance of 41, which is a light blocking degree of 10, 11, 12, or 13 is formed. 6. The liquid crystal shutter according to claim 2, wherein the third blocking property has a light blocking property sufficient to protect a human eye from a visible ray of an electric arc.