JPH06100493B2 - Vibration analyzer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vibration analysis device for analyzing the vibration of an object.

[Prior Art] Conventionally, as a vibration analyzer for analyzing the vibration of an object, a strobe light is caused to emit light by synchronizing the emission frequency of the strobe light with the frequency of the object to be measured or by setting a minute difference. Is used.

By using such a strobe light, the motion of an object vibrating at high speed can be stopped or viewed as a continuous photograph, so that the vibration can be easily analyzed.

[Problems to be Solved by the Invention] However, although the strobe light has limited brightness and can be used in a dark room or at night, it is a very large object or an object that moves in a very wide range. However, there is a problem that the intensity of the light of the strobe light is insufficient and the analysis cannot be used for the analysis described above or the analysis that requires measurement outdoors under sunlight.

Therefore, there has been a demand for a vibration analysis device that can be used in a wide area and under strong sunlight.

[Means for Solving the Problem] The present invention has been made to solve the above problems, and includes a liquid crystal shutter and an oscillator for turning on and off the liquid crystal shutter, illuminates an object to be measured, and ON in synchronization with the vibration of the measured object or with a slight cycle difference,
A vibration analysis device for analyzing vibration of an object to be measured by observing the object to be measured through the liquid crystal shutter that is turned off, wherein the liquid crystal shutter has a relationship d between a pitch p of a nematic liquid crystal and a substrate gap d. / p is greater than 0.5 × n and 0.5+
It is smaller than 0.5 × n (n is an integer of 1 or more), and the voltage applied between both transparent electrodes is turned on and off sequentially, so that the liquid crystal molecules are almost 90 ° + 180 ° when the voltage is off.
It takes a twisted state of × n, the liquid crystal molecules take a vertical alignment state when the voltage is turned on, and when the voltage is turned off for a short time after the voltage is turned on, the liquid crystal molecules are in a state of relaxation to a twisted state when the voltage is turned off. × m (m represents an integer of 0 ≦ m <n)
The vertical alignment state of the liquid crystal molecules when the voltage is turned on and the liquid crystal molecule when the voltage is turned off are approximately 90 ° + 180 ° × m
The present invention provides a vibration analysis device characterized in that the light transmittance can be changed by utilizing two states, that is, a twisted state and a twisted state.

The present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of the basic configuration of the present invention.

FIG. 1 shows an example of analyzing vibration of a loudspeaker as an object to be measured. 1 is a high-speed response liquid crystal display element, 2 is an oscillator for driving the high-speed response liquid crystal display element, and 3 is a Frequency counter, 4 is the output waveform of the oscillator, 5
Is a loudspeaker which is the object to be measured, 6 is a light source for illumination,
7 is an observer.

In this case, the high-speed response liquid crystal display element in which the shutter opens when the output of the oscillator is on is used, but it goes without saying that the opposite case can also be used.

As the DUT capable of analyzing the vibration in the present invention,
In addition to the above loudspeakers, there are various musical instruments, cushioning materials, various structural materials, buildings, rotating bodies, etc., which can be used to analyze the frequency, vibration mode, rotational speed of the rotating body, surface wobbling, shaft wobbling, etc. .

Since the present invention can also use sunlight as a light source for illumination,
It can also be used as a large measured object to analyze the vibration of various buildings, suspension bridges, iron bridges, rails, towers and large machines.

It can also be used to track an object that moves in one direction.

Further, the observer may directly see the image, or the camera may be directly attached to the optical shutter and the image may be taken by the camera. Conventionally, it has been proposed to use a liquid crystal display element as a shutter of a camera, but it is not used substantially because a sufficient shutter degree cannot be obtained or a response speed is slow. In the present invention, a high-speed response liquid crystal display element is used instead of the conventional low-speed liquid crystal display element.

In the present invention, this high-speed response liquid crystal display device is configured to transmit light repeatedly at a certain fixed period, and therefore has the following configuration.

That is, a pair of transparent substrates with transparent electrodes are arranged so that the transparent electrodes face each other, the periphery is sealed with a sealing material, a nematic liquid crystal is sealed inside, and a pair of polarizing films is placed outside the nematic liquid crystal layer. The respective transparent substrates are horizontally aligned, and the transparent substrates are arranged so that their horizontal alignment directions are substantially orthogonal to each other. Arranged so as to be substantially parallel to or orthogonal to the orientation direction of molecules, the relationship d / p between the pitch p of the nematic liquid crystal and the substrate gap d is larger than 0.5 × n and smaller than 0.5 + 0.5 × n. (N represents an integer of 1 or more), and by sequentially turning on and off the voltage applied between both transparent electrodes, the liquid crystal molecules are almost
The twisted state is 90 ° + 180 ° × n, and when the voltage is on, the liquid crystal molecules are in a vertical alignment state, and when the voltage is off for a short time after the voltage is turned on, the liquid crystal molecules are in a state of relaxation to a twisted state when the voltage is off. The twisted state is 90 ° + 180 ° × m (m is an integer of 0 ≦ m <n), and the vertical alignment state of the liquid crystal molecules when the voltage is on and almost 90 ° of the liquid crystal molecules when the voltage is off
It is a high-speed response liquid crystal display element capable of changing the light transmittance by utilizing two states of a twisted state of + 180 ° × m.

This fast response liquid crystal display element does not change the light transmittance by utilizing only two stable states of the liquid crystal, which are used in a normal liquid crystal, that is, when the voltage is on and when it is off. When turned off, it is twisted more than a normal liquid crystal, and light is transmitted using two states: a stable state when the voltage is turned on and a metastable state where the voltage is turned off and then relaxed to a completely off state. It changes the rate, and the metastable state does not last that long, but like the present invention, it is a few ms.
It is suitable for applications where the liquid crystal is repeatedly turned on and off at short intervals of ec to several seconds, and provides high contrast and high response.

FIG. 2 is a sectional view showing the basic structure of this high-speed response liquid crystal display element.

In FIG. 2, 11A and 11B are transparent substrates made of glass, plastic, etc., and transparent electrodes 12A, 12B made of tin oxide, indium oxide-tin oxide, etc. are patterned in a desired pattern on the inner surface thereof. Has been formed. The surface of the transparent electrode is subjected to a horizontal alignment process such as rubbing or oblique vapor deposition so that the liquid crystal molecules are horizontally aligned in one direction. And a nematic liquid crystal 14 is enclosed inside to form a liquid crystal cell. On the outer surface of this liquid crystal cell, a pair of polarizing films 15A, 1
5B is arranged such that the polarization axes of the respective polarization films are substantially parallel to or substantially orthogonal to the alignment direction of the liquid crystal molecules on the respective substrate surfaces, and the polarization axes of the pair of polarization films are substantially parallel or It is provided so as to be orthogonal to each other.

In addition to this, other applications such as those used in general liquid crystal display devices, for example, forming metal leads on transparent electrodes,
Electroless Ni plating, except for the part that changes the light transmittance
An opaque mask is formed by Cr vapor deposition, a color filter is formed, an overcoat for an alignment film of polyimide, polyamide, silica, alumina, etc. is formed on the transparent electrode, and a substrate gap is formed in the liquid crystal cell. Spacers such as glass fibers, alumina particles, and plastic particles for maintaining the accuracy may be sprinkled or a sealing material containing these spacers may be spotted.

It suffices that the orientation treatment directions of the high-speed response liquid crystal display element are orthogonal to both substrates, and the polarization axis direction of the polarizing film may be arranged to be parallel or orthogonal to the respective orientation treatment directions.

For example, when the polarization axis directions of both polarizing films are arranged in parallel, light is transmitted when turned on and is not transmitted when turned off.

In this high-speed response liquid crystal display element, liquid crystal molecules are almost 90 ° + 180 ° × n when the voltage is off, as in a normal liquid crystal display device.
The first stable state, which is the twisted state, and the second stable state, which is the vertical alignment state when the voltage is turned on, are taken. The process up to this point is the same as in the conventional liquid crystal display device.

However, in this fast response liquid crystal display element, since the twist angle of the liquid crystal molecules is large, when the voltage is turned off after the vertical alignment state which is the second stable state in which the voltage is on, in addition to the two stable states, Twist of about 90 ° × 180 ° × m (m represents an integer of 0 ≦ m <n) which is a relaxation state to the first stable state, that is, the twisted state when the voltage is completely turned off for a short time At least one metastable state that is a state is taken. This metastable state has a strong tendency to twist the liquid crystal itself, so it is extremely fast from the second stable state, that is, the vertical alignment state, and specifically reaches at a high speed of 1 to several msec at room temperature.
It is held for some time and reaches the next metastable state or the first stable state. In this high-speed response liquid crystal display element,
It can be driven between two states of the second stable state and at least one metastable state at the time of this voltage ion, and can be turned on and off at an extremely high speed.

Since this metastable state is not stable for a long time, it sequentially transitions to the next stable state or the first stable state. However, since both of them are determined by the orientation direction, the twist between them is 180 ° Will be increased. Therefore, the change in light transmittance between the metastable state and the metastable state and the change in light transmittance between the metastable state and the first stable state are relatively small. Especially, the change between the metastable states of 90 ° and 270 ° is small, and the change of state is hardly recognized.

In this case, the relationship between the pitch p of the nematic liquid crystal and the substrate gap d may be 0.5 × n <d / p <0.5 + 0.5 × n (n represents an integer of 1 or more). As a result, when the horizontal alignment directions on both substrates are orthogonal to each other, the liquid crystal molecules take a twisted state of 90 ° + 180 ° × n when the voltage is turned off. This is the first stable state.

Here, when a voltage is applied, the liquid crystal molecules rise, become almost vertical, and become vertically aligned. This is the second stable state.

Then, when the voltage is turned off, the liquid crystal molecules tend to be in a twisted state, and the liquid crystal molecules try to align in the alignment direction of the substrate. In this case, in this fast response liquid crystal display element, the liquid crystal molecules are in the first stable state of 90 ° + 180 ° × n when the voltage is completely turned off.
The twisted state of 270 °, that is, 270 °, 450 °, 630 °, and so on, the liquid crystal molecules do not immediately change to this state even when the voltage is turned off, and first become 90 °, then The twist gradually expands to 270 °, 450 °, and so on, resulting in a metastable state of 1 or more.

Moreover, in this case, the alignment state of the liquid crystal molecules is almost 90 ° + 180.
In a twisted state of ° × m (m is an integer of 0 ≦ m <n), the pretilt angle is aligned with the horizontal alignment treatment, that is, the helical pitch of liquid crystal molecules is the same at both ends of the molecule. By doing so, this particular metastable state tends to last much longer than other metastable states, and can last for a few seconds or more. Therefore, it is preferable to determine the alignment treatment direction in consideration of the spiral direction of the liquid crystal. 180 ° more than the first stable state
It is preferable that the metastable state in which the twisting is small is matched so that the metastable state is easily stabilized.

For this purpose, for example, when a liquid crystal having a left helix with a twist of 450 ° is used, the transparent substrate 11A on the front side in FIG.
Then, the rubbing direction may be set from the lower left to the upper right when viewed from the front side of the cell, and the transparent substrate 11B on the back side may be rubbed from the lower right to the upper left.

In this way, the liquid crystal is adjusted so that the first stable state is 450 °, that is, the liquid crystal with 1 <d / p <1.5 is used, the metastable state is 270 °, and the alignment state is 270 °. It is preferable that

This is because the larger the d / p of the liquid crystal and the stronger the twisting force of the liquid crystal molecules, the faster the speed at which the first metastable state of 90 ° is reached, and the first stable state becomes 270 °. This is because a faster response is possible in the case of 450 ° than in the case of. The difference between the case where the first stable state is 270 ° and the case where the first stable state is 450 ° is larger than the difference between the case of 450 ° and the case of 630 °. This is because the first stable state is 270 ° and the metastable state is only 90 °.
It is considerably faster than the conventional liquid crystal display device that is °,
The first stable state at 450 ° is even faster. Further, this fast response liquid crystal display element is turned on and off between the second stable state when the voltage is turned on and the metastable state immediately after the voltage is turned off. Is preferred and the first stable state is 450 °. In particular, the first stable state is set to 450 ° and 270
By setting the alignment state of the liquid crystal molecules and the pretilt in the metastable state of °, the switching can be repeated for several seconds.

Although the response speed of the transition to the metastable state tends to improve as the twist angle increases, setting a twist angle of 630 ° or more depends on whether the first stable state is 270 ° or 450 °. The difference is not so large, on the contrary, the driving voltage is increased, the circular polarization is increased, the light transmittance is decreased, and the contrast is decreased. Also,
When the twist angle is increased, the retardation color tends to be strong, which may cause an unfavorable color.

[Operation] In this fast response liquid crystal display element, the light beam emitted from the illumination light source is incident on the object to be measured, and a part of the reflected light beam is directed to the fast response liquid crystal display element.

When the shutter of the high-speed response liquid crystal display element is opened by the transmitter, the incident light beam selectively reaches the observer.
According to this principle, when the frequency of the object to be measured and the shutter frequency of the high-speed response liquid crystal display element are synchronized, the object to be measured appears to be stationary.

In this case, the synchronized frequency can be known by the frequency counter, and thus the vibration frequency of the measured object can be known.

Also, by setting the frequencies so that they are not completely synchronized and slightly shifted, it is possible to observe that the DUT vibrates at the frequency of the difference.

[Example] Example 1 A vibration analyzer for analyzing vibration of a loudspeaker as shown in Fig. 1 was prepared. This high-speed response liquid crystal display element was manufactured as follows.

Rubbing a glass substrate with a solid transparent electrode on which a polyimide alignment film is formed, and arranging the two substrates with their electrode surfaces facing each other so that the rubbing directions are orthogonal and aligned at 270 °, A cell was formed by sealing with a sealing material excluding the injection port and injecting liquid crystal from the injection port. The cell gap of this cell was 4.6 μm.

As this liquid crystal, liquid crystal "ZLI-1565" manufactured by Merck & Co., which has a refractive index anisotropy Δn of 0.13, is cholesteryl nonanate as a chiral component so that its helical pitch is 3.7 μm.
A liquid crystal added with 5.5 wt% was used.

A pair of polarizing films were arranged on the front and back of this cell so that their polarization axes were parallel to each other.

In the high-speed response liquid crystal display device manufactured in this manner, the liquid crystal molecules were twisted by 450 ° when no voltage was applied, which was the first stable state. In this state, the light travels along the twist of the liquid crystal molecules in the liquid crystal cell.
The light is twisted by 0 °, and the light entering the liquid crystal optical switch device is not transmitted because the polarization axes of the pair of polarizing films are parallel to each other.

Next, a pulsed voltage is applied at a certain frequency. While this voltage is applied, the liquid crystal molecules are in a vertical alignment state,
A second stable state has been reached. In this state, the liquid crystal cell was isotropic with respect to the light, and the light incident on the liquid crystal optical switch device was transmitted because the polarization axes of the pair of polarizing films were parallel to each other.

Next, when the voltage is turned off, the liquid crystal molecules in the cell are instantly twisted by 90 ° into the first metastable state, and the incident light that has passed through the front side polarizing film has its polarization component in the cell according to the twisted structure of the liquid crystal. It is twisted 90 degrees and cannot pass through the back side polarizing film,
The light was blocked.

Since the first metastable state is a mismatched state and is not so stable, the liquid crystal molecules are further twisted in a relatively short time and become the second metastable state having a 270 ° twist structure. Even in this state, the incident light was blocked as in the 90 ° twist structure, and the change in contrast due to this change was slight. This 270 ° twisted structure is relatively stable because the alignment state of the liquid crystal molecules matches the pretilt angle due to the horizontal alignment treatment, and it is relatively stable because it is in the aligned state. It lasted for a few seconds. When left for a longer period of time, the structure changed to a 450 ° twist structure.

In this example, in order to observe the vibration of the loudspeaker, a low-speed pulse such as several seconds is not used, and a few hundreds of pulses are applied per second. It turned on and off with respect to the first stable state of vertical orientation, high-speed and high-contrast switching was possible, and the vibration of the loudspeaker was well discriminated.

Example 2 The rotation of the turbine used under sunlight was observed using the same vibration analyzer as in Example 1.

Despite being used in sunlight, the rotation status can be determined because a high-speed response liquid crystal display element is used, and if it synchronizes with rotation, it appears to stop, and if the synchronization is slightly shifted, it becomes slow. It looked like it was spinning at.

EFFECTS OF THE INVENTION Since the vibration analysis device of the present invention uses the high-speed response liquid crystal display element, it is possible to analyze vibrations under sunlight that cannot be used in conventional strobe lights, vibrations of light-emitting objects, or It is possible to analyze the vibration of a large object.

Further, since a high-speed response liquid crystal display element is used, power consumption is small even when it is turned on and off at high speed, it can be driven by a battery, and the device itself is inexpensive and can be miniaturized.

The vibration analysis device of the present invention can be applied in various ways without impairing the effects of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a vibration analysis device of the present invention. FIG. 2 is a cross-sectional view of an example of a fast response liquid crystal display element used in the vibration analysis device of the present invention. 1 is a high-speed response liquid crystal display element, 2 is a driving oscillator, 3 is a frequency counter, 4 is an output waveform of the oscillator, 5 is a loudspeaker, 6 is a light source for illumination, and 7 is an observer.

Claims (3)

[Claims] 1. A liquid crystal shutter comprising: a liquid crystal shutter; and an oscillator for turning the liquid crystal shutter on and off, illuminating an object to be measured, and turning on and off in synchronization with vibration of the object to be measured or with a slight cycle difference. A vibration analysis device for analyzing vibration of an object to be measured by observing the object to be measured through a liquid crystal shutter, wherein the liquid crystal shutter has a relationship d / p between a pitch p of a nematic liquid crystal and a substrate gap d of 0.5 ×. greater than n and 0.5+
It is smaller than 0.5 × n (n is an integer of 1 or more), and the voltage applied between both transparent electrodes is turned on and off sequentially, so that the liquid crystal molecules are almost 90 ° + 180 ° when the voltage is off.
It takes a twisted state of × n, the liquid crystal molecules take a vertical alignment state when the voltage is turned on, and when the voltage is turned off for a short time after the voltage is turned on, the liquid crystal molecules are in a state of relaxation to a twisted state when the voltage is turned off. × m (m represents an integer of 0 ≦ m <n)
The vertical alignment state of the liquid crystal molecules when the voltage is turned on and the liquid crystal molecule when the voltage is turned off are approximately 90 ° + 180 ° × m
The vibration analysis device is characterized in that the light transmittance can be changed by utilizing two states, that is, a twisted state. 2. The vibration analysis device according to claim 1, wherein the alignment treatment direction of the liquid crystal shutter is adapted to be matched in a metastable state in which a twist of 180 ° is smaller than that in a stable state when the voltage is off. 3. The liquid crystal shutter has a 450 ° twist, and
The vibration analysis device according to claim 2, wherein the vibration analysis device is adapted to be matched in a metastable state with a twist of 70 °.