CN1182221A - Two-dimensional position measurer based on linear CCD array - Google Patents

Abstract

The present invention belongs to technological field of position sensor design. The said two-dimensional position measurer includes coaxially arranged main spherical lens, spherical lens and spectroscopic prism. In the two perpendicular optical axles of said spectroscopic prism, are arranged separately two cylindrical lenses with perpendicular cylinder axles and two linear CCD arrays. The interval between the main spherical lens and spherical lens is equal to the sum of the image distance of the main spherical lens and the focal length of the spherical lens. The said measurer also includes CCD driver circuit, CCD signal processing circuit, and computer.

Description

A kind of two-dimensional position measurer based on linear array charge-coupled picture pick-up device

The invention belongs to the position transducer design field, particularly the noncontact two-dimensional position measurer that adopts linear CCD array to constitute.

Charge coup (CCD) has wide practical use at aspects such as non-cpntact measurement, image sensing and storages.CCD is divided into two big classes: linear CCD array device and face formation CCD device.Linear CCD array has characteristics such as the pixel number is many, speed is fast, splicing is ripe, price is low, 5000 CCD as Toshiba Corp, frequency of operation 20MHz, 5732 CCD of U.S. Shiloh gram company, frequency of operation 32MHz, the CCD21-40 type CCD pixel of Britain EV company can reach 12288, frequency of operation 4MHz.Because These characteristics, linear CCD array is easy to realize the high-acruracy survey and the positioning system of one dimension size.Face formation CCD can be directly used in two dimensional size measurement and positioning system, but (U.S. Tektronix company has produced 2048*2048 pixel face formation CCD because face formation CCD pixel is few, domestic at present multipotency has been bought 1024*1024 pixel face formation CCD, and price is high.), thereby can't realize the high precision position measurement.In addition, face formation CCD image processing complexity, signal Processing cycle are long, need special-purpose image card and software.

The objective of the invention is to by designing special optical system, adopt two linear CCD arrays to constitute two-dimensional position measurer for overcoming the weak point of prior art.Make its have simple in structure, price is low, the precision advantages of higher.

A kind of two-dimensional position measurer that the present invention proposes based on linear CCD array, it is characterized in that comprising the main spherical mirror of coaxial setting, spherical mirror and Amici prism, two cylindrical mirrors and two linear CCD array devices are set respectively on two mutually perpendicular optical axis that said Amici prism is told, the cylinder axis of said two cylindrical mirrors is orthogonal, distance between said main spherical mirror and the spherical mirror equals the image distance of main spherical mirror and the focal length sum of spherical mirror, also comprises the CCD driving circuit, ccd signal treatment circuit and this signal processing circuit output signal calculated, the computing machine of display result.

The said spherical mirror of the present invention and two cylindrical mirrors can stick on respectively on the optical input surface and two light gasing surfaces of said Amici prism, make its becoming one structure.

Principle of work of the present invention is described below:

At first introduce the characteristic of spherical mirror one cylindrical mirror combination in conjunction with Fig. 1, it constitutes the basis of this CCD optical imaging system.In Fig. 1, the focal length of spherical mirror 11 is f ₁, the focal length of cylindrical mirror 12 is f ₂, they coaxial and between distance respectively less than f ₁And f ₂O is the focus of spherical mirror 11, and the xoy plane is the focal plane of spherical mirror 11.M be on the focal plane on the x axle a bit, be a branch of directional light by spherical mirror 1 back, directional light pools straight line through cylindrical mirror 12.Be imaged as straight line a by globe lens one cylindrical mirror combination m point like this, straight line a is positioned on the focal plane of cylindrical mirror 12 and is parallel with the cylinder axis direction of cylindrical mirror 12.In like manner, cross on the straight line that m point is parallel to the y axle arbitrarily some picture of one-tenth all be straight line a.Like this, a x coordinate of ordering to the corresponding m of the distance of z axle.If a is b to the distance of z axle, draw as formula by lens: $\frac{\mathrm{<figure-callout\; id="2"\; label="b\; f"\; filenames="A9711645700082.png"\; state="\{\{state\}\}">b</figure-callout>}}{f_{}}=\frac{\mathrm{om}}{f_1}----\left(1\right)$ If get f ₁=f ₂, then a is b=om to the distance of z axle.

Optical system principle of work of the present invention is described as follows in conjunction with Fig. 2: complete optical system is made up of one group of optical element, comprises main spherical mirror 21, spherical mirror 22, Amici prism 23, two 241,242 and two linear CCD arrays 251,252 of cylindrical mirror.Main spherical mirror 11, spherical mirror 12 and Amici prism 23 are coaxial, and Amici prism is told two orthogonal optical axis z, z ₁, on two optical path axis, adding cylindrical mirror 241,242 respectively, the cylinder axis direction of cylindrical mirror 251,252 is vertical mutually.Like this, the introducing of Amici prism has constituted two groups of spherical mirror one cylindrical mirror combinations, and they measure x axle and the axial position of y respectively.For convenience of description, we choose and have the same focal length f ₁Spherical mirror and cylindrical mirror.

In Fig. 2, the focal length of main spherical mirror 21 is f, m be on the xoy of plane more arbitrarily, its coordinate be (x, y), object distance d ₀The m point is by main spherical mirror imaging n point, and the n point is at plane x ₁o ₁y ₁On, image distance d ₁Coordinate (the x that n is ordered ₁, y ₁) draw by following formula: $\frac{1}{f}=\frac{1}{d_0}+\frac{1}{d_1}----\left(2\right)$ $\frac{d_0}{d_1}=\frac{x}{x_1}=\frac{y}{y_1}----\left(3\right)$ Distance between main spherical mirror 21 and the spherical mirror 22 is d ₁+ f ₁, picture point n is positioned on the focal plane of spherical mirror like this.By the characteristic of spherical mirror one cylindrical mirror combination as can be known, the n point is two straight line a and b by spherical mirror, Amici prism and two imagery of cylindrical mirror, straight line a be positioned on the focal plane of cylindrical mirror 241 and with the distance of z axle be x ₁, straight line b is positioned on the focal plane of cylindrical mirror 242 and and z ₁The distance of axle is y ₁On the focal plane of cylindrical mirror, cross z and z respectively ₁The parallel placement linear CCD array of axle with the cylindrical mirror bending direction.Like this, as line a and b respectively with CCD251,252 vertical and intersect, CCD measures the position x of straight line a and b ₁And y ₁, by formula (3) can obtain the coordinate that m orders (x, y).

The present invention has following characteristics:

One. the principle of the invention is simple, realizes reliable.The invention belongs to non-contacting position and measure, this method is utilized the characteristic of spherical mirror-cylindrical mirror group, by special light path design, has realized the high-precision two-dimensional position measurement with two line array CCDs.

Two. response speed is fast.The signal Processing cycle of this covering device can reach a millisecond magnitude, makes it can be used for dynamic object real-time follow-up and industrial on-line measurement.

Three. 2-d position measurement precision height.When the line array CCD of selecting 5000 pixels for use, this covering device Measurement Resolution can reach or near five per milles.

Four. cost is low.Because the price of linear CCD array is significantly less than face formation CCD, and the pixel number makes this covering device have the very high ratio of performance to price far away more than face formation CCD on the one dimension direction.

Brief Description Of Drawings:

Fig. 1 is combined into image pattern for spherical mirror one cylindrical mirror

Fig. 2 is a 2-d position measurement optical system schematic diagram of the present invention

Fig. 3 is a high-precision two-dimensional position-measurement device example structure synoptic diagram of the present invention

Fig. 4 is the ccd signal treatment circuit figure of present embodiment

Fig. 5 is present embodiment signal processing flow figure

The present invention proposes a kind ofly to implement based on the linear CCD array two-dimensional position measurer, its general structure as shown in Figure 3, it can detect the position that the m of random motion is ordered on the target surface in real time.This device is made of three parts, is respectively zoom lens 31, CCD imaging moiety 32 and peripheral circuit 33, and PC computing machine 34.

The effect of zoom lens is that the m point is imaged on the front focal plane of spherical mirror of back, the purpose of selecting zoom lens for use be by regulate image distance CCD is gone up produce clearly as; Zoom lens also has the effect of the working range of modifier in addition, i.e. the detection distance and the sensing range of modifier by the focal length of regulating camera lens.What provide among Fig. 3 is that the zoom lens focal length is the situation of 50mm, at this moment this Device Testing distance is 1000mm, sensing range is the square of length of side 530mm, and the variation range of setting the zoom lens focal length is 40～60mm, the running parameter when providing focal length in the table one and getting boundary value.

Table one

	Focal length	Detect distance	Image distance	Sensing range
					Parameter	????40mm	??1500mm	????41.1mm	??1022×1022mm 2
????60mm	??500mm	????68.2mm	??205×205mm 2

The CCD imaging moiety is integrated, by spherical mirror 321, Amici prism 322, two cylindrical mirrors 3231,3232 and two linear CCD arrays 3241,3242 form, spherical mirror and cylindrical mirror are plano-convex lens, focal length is 100mm, divide and two linear CCD arrays 3241,3242 form, spherical mirror and cylindrical mirror are plano-convex lens, focal length is 100mm, (knowing spherical mirror for expression among the figure separates it and Amici prism to be bonded at the front of Amici prism and two sides by direction as shown respectively, in fact should stick together in Amici prism), the center of two cylindrical mirrors is respectively on two optical axises that Amici prism is told, and their cylinder axis direction is orthogonal, CCD vertically places by optical axis, and its direction is vertical with the cylindrical mirror cylinder axis respectively.Provide the position relation between each parts among Fig. 3, the unit millimeter, wherein Amici prism is of a size of 35 * 35 * 35mm ³, the aperture of spherical mirror is 35mm, cylindrical mirror is of a size of 35 * 35mm ²CCD is the TCD102C type line array CCD that Toshiba Corp produces, and has 2048 pixels, photosensitive face length 28.67mm.

Peripheral circuit is made up of driving circuit and the signal processing circuit of CCD.The CCD driving circuit all has detailed introduction on various CCD application data, here not in narration, it is to be noted that TCD102C type CCD has the output sampling and keeps function, and what promptly CCD exported is the full sized pules vision signal of removing dark pulse.The ccd signal treatment circuit mainly comprises, potentiometer U ₁, voltage comparator U ₂, with the door U ₃, Z80-CTC counter U ₄, sequential circuit U ₅With PC computing machine U ₆, its major function is the digital signal that the vision signal of CCD output is processed into the reception of calculating function.

The structure and the course of work of ccd signal treatment circuit are described: according to the fixed threshold method principle of deboost amplitude size, regulator potentiometer U below in conjunction with Fig. 4, Fig. 5 ₁Provide threshold level, the vision signal φ 1 of CCD output is by voltage comparator U ₂Convert to and have only high level and low level binary signal φ 2.The full sized pules that φ 2 and CCD driving circuit provide by with door U ₃With.Synchronization pulse φ 3 backs of COMPUTER DETECTION CCD start the Z-80CTC counter works, begin to count N1 simultaneously.After treating that two-value signal is opened the counter pulse door, time clock enters the Z-80CTC counting channel.Vision signal finish time by sequential circuit U ₅Send and gathered signal, COMPUTER DETECTION stops the Z-80CTC counter works, and takes data N2 away from the Z-80CTC counter behind this signal, stops to count N1 simultaneously.Like this, obtain object space count value N1 and size count value N2.If CCD output clock frequency is p, unit wires is of a size of d, and the counting clock frequency of counter is K, and then the center c of object can be expressed from the next: $c=((N1-\frac{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="A9711645700082.png"\; state="\{\{state\}\}">N</figure-callout>}2}{2})\&times;\frac{p}{K})d----\left(4\right)$ PC computing machine U ₅Finish the computing to (4) formula, the testee position then can accurately be presented on the computer screen.In addition, also can finish the function of PC computing machine with 51 or 98 series monolithic systems.

Claims (2)

1, a kind of two-dimensional position measurer based on linear CCD array, it is characterized in that comprising the main spherical mirror of coaxial setting, spherical mirror and Amici prism, two cylindrical mirrors and two linear CCD array devices are set respectively on two mutually perpendicular optical axis that said Amici prism is told, the cylinder axis of said two cylindrical mirrors is orthogonal, distance between said main spherical mirror and the spherical mirror equals the image distance of main spherical mirror and the focal length sum of spherical mirror, also comprises the CCD driving circuit, ccd signal treatment circuit and this signal processing circuit output signal calculated, the computing machine of display result.

2, device as claimed in claim 1 is characterized in that said spherical mirror and two cylindrical mirrors can stick on respectively on the optical input surface and two light gasing surfaces of said Amici prism, make its becoming one structure.

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