| 释义 |
planar, a.|ˈpleɪnə(r)|
[ad. L. plānār-is (Mart. Cap.), f. plān-um plane: cf. linear.]
a. Belonging to, situated in, or related in some way to, a plane.
1850Cayley Coll. Math. Papers I. 505, I propose to term the family of developables treated of in this paper, ‘planar developables’... The developable which is the envelope of such a system [of n different planes] may be termed a ‘multiplanar developable’, and in the particular case of n being equal to unity, we have a planar developable. 1931Proc. Nat. Acad. Sci. XVII. 127 A topological graph is called planar if it can be mapped in a 1–1 continuous manner on a plane (or sphere). 1942M. P. Billings Structural Geol. xvi. 307 A clear distinction between primary and secondary planar and linear structures is essential for a correct interpretation of the tectonics of plutons. 1969W. R. R. Park Plastics Film Technol. ii. 28 Biaxial or planar orientation occurs when a film or sheet is drawn in more than one direction. 1972J. G. Dennis Structural Geol. xx. 459 Other criteria of high-pressure shock origin include sets of closely spaced planes in quartz crystals... These planar features are known in quartz that has been subjected to nuclear explosions. 1972R. J. Wilson Introd. Graph Theory v. 58 A planar graph is one which is isomorphic to a plane graph. 1973Sci. Amer. Jan. 100/3 Probably the commonest single habit is the planar dendrite, a flat crystal with delicate branches that is often regarded as the typical snowflake.
b. Electronics. Of a thermionic valve: having plane-parallel electrodes usu. close together.
1956A. L. Albert Electronics & Electron Devices viii. 307 Tubes for handling a few watts or less at very high frequencies commonly use parallel electrodes and sometimes are called planar tubes. 1965Gewartowski & Watson Princ. Electron Tubes iv. 120 If the linear dimensions of a planar diode are increased by a factor k, the same current flows to the anode for the same applied voltage. 1975D. G. Fink Electronics Engineers' Handbk. ix. 26 Grid design is very important in planar triodes.
c. Electronics. Of a solid-state device: having boundaries of a number of different n- and p-type regions lying in a single plane. Also applied to the process by which such devices are made, involving the introduction of impurities into a semiconductor substrate through gaps in a thin masking layer.
1965Wireless World July 325/1 Tr 1 and Tr 2 are low noise, high gain silicon planar transistors. 1967A. S. Grove Physics & Technol. Semiconductor Devices 3 The planar technology..combines the advantages of junction formation by solid-state diffusion and the masking property of silicon dioxide for precise definition of device geometry. 1975D. G. Fink Electronics Engineers' Handbk. vii. 37 The significance of the planar process is that the pn junctions are terminated and protected beneath a silicon oxide layer. Thus many of the surface problems associated with other types of transistor fabrication techniques, i.e., high leakage currents and poor low-current dc gain, are eliminated.
Hence planarity |-ˈærɪtɪ|, the quality of being planar.
1850Cayley Coll. Math. Papers I. 505 It would be very desirable to have some means of ascertaining from the equation of a developable what the degree of its ‘planarity’ is. 1956Nature 7 Jan. 37/2 The dimensions of the amide group accord closely with those given by Corey and Pauling, and it is in the trans configuration. It shows, however, a significant departure from planarity, since the carbonyl oxygen is 0·5 A. out of the plane containing the remaining atoms of the amide group. 1972Sci. Amer. Dec. 54/3 Running tow or individual fibers between heated sprockets or gear teeth imparts a zigzag and more or less planar crimp... A disadvantage of the planarity is that it yields yarns of less bulk and stretchability than yarns produced by methods that impart a three-dimensional crimp. |