JPH0348614B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a slit mechanism used in a mass spectrometer, and more particularly to a slit mechanism whose slit width can be changed from outside a vacuum chamber.

(Prior Art) Most of the conventional slit mechanisms used in analytical devices, especially devices that perform analysis in vacuum, are mechanical variable width slits or fixed width slits.

Mechanical variable width slits are movable by introducing a shaft into the vacuum chamber via a vacuum seal mechanism that moves linearly by rotating a knob outside the vacuum chamber, and attaching one of a pair of slit pieces to the tip of the shaft. A slit is formed between the shaft and the other fixed slit piece, and the width of the slit is changed by turning a knob to move the shaft linearly.

A fixed width slit is one in which a plurality of slits with different widths are prepared in a vacuum chamber, and the slit with the optimum width is selected and moved to a predetermined position by an electric actuator outside the vacuum chamber.

(Problems to be Solved by the Invention) Mechanical variable-width slits and fixed-width slits require vacuum seals for movable parts and a mechanism for converting rotational motion into linear motion, resulting in complicated structures.

In addition, mechanically variable width slits pose an obstacle to promoting automation of analytical equipment.

It is an object of the present invention to provide a slit mechanism that is capable of sending only an electric signal from the outside of the vacuum chamber to the inside of the vacuum chamber, and that is capable of controlling the slit width within the vacuum chamber using the electric signal, and that has a simple structure. be.

(Means for solving the problem) In the slit mechanism of the present invention, at least one of the pair of slit pieces is movable, and the movable slit piece (hereinafter referred to as the slit movable piece) is located at the tip of the bimorph piezoelectric element. The base end of the bimorph piezoelectric element is fixed to the support, and the slit width of the pair of slit pieces is changed by applying a voltage to the bimorph piezoelectric element.

(Function) Since the bimorph piezoelectric element is displaced in accordance with the applied electric field, the movable slit piece attached to the piezoelectric element is also displaced, and the other movable slit piece that faces the movable slit piece and forms the slit. The relative distance between the slit piece and the slit piece, that is, the slit width, depends on the applied electric field.

(Embodiment) FIG. 1 shows an embodiment using a bimorph piezoelectric element, and FIG. 1A, FIG. 1B, and FIG. 1C are a plan view, a front view, and a side view, respectively.

Reference numeral 2 denotes a fixed slit piece (hereinafter referred to as a slit fixing piece) which is one of a pair of slit pieces forming the slit S, and is fixed to the metal support 4. Reference numeral 6 denotes a movable slit piece which is the other of the pair of slit pieces constituting the slit S. A groove 8 is provided in a part of the movable slit piece, and the tip of the bimorph piezoelectric element 10 is fitted into this groove 8 and fixed with adhesive. As a result, the movable slit piece 6 is attached to the tip of the bimorph piezoelectric element 10. The base end of the bimorph piezoelectric element 10 is fixed to the support 4 by a metal clamper 12 so that the slit movable piece 6 and the slit fixed piece 2 face each other to form a slit S.

The bimorph piezoelectric element 10 is constructed by bonding two piezoelectric elements polarized in the same direction with an intermediate electrode in between, and a metal support 4 and a clamper 12 are used as one electrode common to both piezoelectric elements. A predetermined electric field is applied between the electrode and the intermediate electrode.

A photointerrupter 14 serves as a position sensor for detecting the position of the movable slit piece 6, and is fixed to the support 4. A part 18 of the movable slit piece 6 is located in the gap 16 between the light emitting part and the light receiving part that face each other. is inserted, and the position of the movable slit piece 6 is detected by the portion 18 blocking light from the light emitting section to the light receiving section.

FIG. 2 shows an example of the slit width control system used in this embodiment.

20 inputs the slit width setting signal and the position signal from the position sensor 14, compares both signals, and generates a DC voltage (hereinafter referred to as control voltage) that is the basis of the optimal DC voltage to be applied to the bimorph piezoelectric element 10. Although this control circuit includes a proportional element with a high amplification factor, it may further include an integral element if it is necessary to completely eliminate the offset. 22 is a DC voltage generation circuit, and control circuit 2
Bimorph type piezoelectric element 10 receives a signal from 0
A high DC voltage necessary to drive the bimorph piezoelectric element 10 is generated and applied to the bimorph piezoelectric element 10.

The operation of this embodiment will be explained with reference to FIGS. 1 and 2. Assuming that the slit movable piece 6 is now in the state shown by the solid line in FIG. 1, when a corresponding slit width setting signal is input to the control circuit 20 in order to change the slit width to another desired constant width, the control circuit At 20, the slit width setting signal and the signal from the position sensor 14 are compared, and a predetermined DC voltage is applied from the DC voltage generation circuit 22 to the bimorph piezoelectric element 10.
is displaced, for example, to the state shown by the chain line in FIG. 1, and the slit movable piece 6 is also displaced. The position of the movable slit piece 6 is detected by a position sensor 14, and the detection signal is fed back to the control circuit 20, whereby the position of the movable slit piece 6 is accurately controlled to a desired set position.

Examples of the DC voltage generating circuit in FIG. 2 are shown in FIGS. 3 to 5.

The example in Figure 3 is the oscillation IC 24 and the voltage multiplier circuit 2.
It consists of 6. The DC control voltage, which is the output signal of the control circuit 20, is input as the power supply voltage of the oscillation IC 24 to create a low-voltage AC signal, and the AC output signal is input to the voltage multiplier circuit 26, where it is boosted and rectified. Smooth.

Here, as the oscillation IC 24, one that can handle a DC power supply voltage over a wide range (for example, about 5 to 15 V) is suitable. Furthermore, the voltage multiplier circuit 26 can be used in multiple stages.

In the example shown in FIG. 4, a low voltage AC signal from an oscillating IC 24 is boosted by a transformer 28 and then converted to a DC voltage by a rectifier and smoothing circuit 30.

Also, the example in Figure 5 is the same as in Figure 4, where the oscillation IC
After the low voltage alternating current signal from 24 is boosted by a transformer 28, it is further boosted by a voltage multiplier circuit 26 and rectified and smoothed.

In these examples of DC voltage generation circuits, using an oscillation IC has the advantage of simplifying the configuration of the control system and making it more compact. A configured oscillator circuit may also be used.

Returning to FIG. 1 again, in this embodiment, one of the pair of slit pieces is movable and the other is fixed, but both slit pieces are supported by two bimorph piezoelectric elements so that both slit pieces are movable. You can do it like this. In this case, there is an advantage that the voltage applied to the bimorph piezoelectric element can be reduced to about 1/2 in order to produce the same amount of change in slit width as in the embodiment shown in FIG.

Although a photointerrupter is used as the position sensor 14 in the embodiment of FIG. 1, other position sensors may be used. The use of the position sensor 14 has the advantage that the slit width can be controlled with high accuracy. However, if coarse slit width control is acceptable, the position sensor can be omitted. In that case, the control circuit 20 may be configured to generate a control voltage by inputting only the slit width setting value.

In addition, in FIG. 1, if the voltage applied to the bimorph piezoelectric element 10 affects the beam passing through the slit, for example, the bimorph piezoelectric element 1
It is sufficient to apply conductive paint to the entire outer periphery of 0 and ground it.

(Effects of the Invention) The slit of the present invention is effective in automating the device because the slit width can be controlled only by electrical signals. Since the slit piece is directly moved by the bimorph type piezoelectric element, the structure is simple and the slit width can be changed with a low applied voltage.

Since it is only necessary to send an electric signal from the outside to the inside of the vacuum chamber, the vacuum seal portion can be used as a connector for sending and receiving electric signals, and the structure is simplified in this respect as well.

[Brief explanation of drawings]

1A, B and C are respectively a plan view, a front view and a side view showing one embodiment of the present invention, FIG. 2 is a block diagram showing a slit width control system of the same embodiment, and FIG. 5 through 5 are block diagrams showing examples of the DC voltage generating circuit shown in FIG. 2, respectively. 2...Slit fixed piece, 6...Slit movable piece, 10...Bimorph type piezoelectric element.

Claims (1)

[Claims] 1. In a mechanism in which at least one slit piece is movable and a pair of slit pieces form a slit, the movable slit piece is attached to the tip of a bimorph piezoelectric element, and the movable slit piece is attached to a base end of the bimorph piezoelectric element. is fixed to a support body, and the slit width of the pair of slit pieces is changed by applying a voltage to the bimorph piezoelectric element.