Rotating in the way of job of type of photograph of ancient bronze mirror of transformer, the horn of phasic difference θ between inductive signal VB and excitation signal VK, can detect through circuitry of appropriative phase discriminator come out and express as corresponding voltage signal, set) of the θ that it is U(, through measuring this voltage signal, can get θ secondhand to be worth. But because VB is the periodic function about θ , u(θ ) be to pass the cost that compares VB and VK to obtain, consequently it also is the periodic function about θ , namely U(θ ) 2 π of =U(n × + θ ) (N=1, 2, 3, ... ) (4, 9) reason is in actual application, not only should measure θ giving U() size, and measure θ giving U(even) N of periodic change frequency, perhaps will be measured limitation of horn of angular displacement θ is in ± π . Rotating the ancient bronze mirror of transformer in type job way, the amplitude of VB is set for VBm, by type (4- - 8) is knowable (4, 10) it also is the periodic function about θ , in applying actually, same need is θ horn limitation in ± π . Below this kind of circumstance, if stipulate with limitation α horn can be in only [- π , π ] inside take a cost, use formula (4-10) , can decide the value of θ exclusively truly. Otherwise, be like) of π of ＞ of 2(of ／ of θ =3 π , at this moment, ／ of α =3 π 2 with ／ of α =- π 2 can make VBm=0, make θ horn cannot decide exclusively thereby, cause detect result mistake. By afore-mentioned knowing, no matter be to rotate,the type of photograph of ancient bronze mirror of transformer works means, still be ancient bronze mirror type job way, need to will be measured demarcate of horn of angular displacement θ is in ± π , want θ to be in ± π only, can be detected to come out by correct ground. In fact, to be being measured angular displacement is more than π or be less than - the circumstance of π , if use,rotate transformer detects the circumstance of corner of machine tool guide screw, although θ of total corner of machine tool guide screw is likely very big, be head and shoulders above limits of definitive ± π , but it is machine tool guide screw however had turned a certain number of second the sum of I of small angle θ , namely (4, 11) and θ I is very small, do not exceed 3 ° commonly on numerical control machine tool, accord with - the requirement of π of ≤ of I of π ≤ θ , rotate transformer and line of its signal processing can in time the ground detects them one by one come out, output the result. Accordingly, this kind detects means belongs to trends to follow detect and increment type detects. CNC Milling