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公开(公告)号：DE2206761A1
公开(公告)日：1973-08-02
申请号：DE2206761
申请日：1972-02-12
Applicant: IBM
Inventor： HART GARY ALLEN , WILSON MELVIN GEORGE
Abstract: Small current signals (0.5 ua and less) such as the output of a photodiode are direct current coupled to a preamplifier which also passes an impedance reducing injection current to a pair of amplifiers. A voltage output proportional to the logarithm of the signal current is produced by passing the amplified current through a log producing junction of a transistor. However, to produce the logarithm function accurately, the injected or impedance reducing current is precisionally removed so that only a very minute portion (one part out of 5000) passes through the log producing junction.
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公开(公告)号：DE1272378B
公开(公告)日：1968-07-11
申请号：DE1272378
申请日：1966-10-04
Applicant: IBM
Inventor： WILSON MELVIN GEORGE
Abstract: 1,144,808. Transistor amplifying circuits. INTERNATIONAL BUSINESS MACHINES CORP. 22 Sept., 1966 [6 Oct., 1965], No. 42279/66. Heading H3T. A transistor amplifier comprises a first differential stage, - as shown comprising transistors T 1 with common emitter circuit resistor R 1 , the input being applied to one transistor over resistor RIN. The output is taken from the collector circuit of the other transistor and applied to the base of a second stage, transistor T 2 which has negative feedback between collector and base, provided by resistor R 2 and a rolloff network C 2 , Ra. The collector of transistor T 2 is coupled to the emitter of a third stage, comprising transistor T 3 in common base connection, which in turn drives an emitter follower output stage : this comprises transistor T 4 with the base and collector of transistor T 5 connected to its collector and emitter respectively. Overall negative feedback is provided by resistor RF. A second roll-off circuit is also provided; this may comprise a series R, C circuit across resistor R 4 (Fig. 1, not shown), or inductances L 1 , L 2 in the emitter circuits of the stage T 1 , together with resistor R 8 . Series connected inductors L 1 , La and L 2 , Lb of respectively large and small value are used to increase the effective resonance frequency. The arrangement is more particularly intended to provide an amplifier which is insensitive to changes in power supply, and the Specification gives a relationship between the resistors which should hold if this is to occur.
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公开(公告)号：DE2966861D1
公开(公告)日：1984-05-03
申请号：DE2966861
申请日：1979-12-04
Applicant: IBM
Inventor： HERALD ROBERT FREDERICK , WILSON MELVIN GEORGE
Abstract: Control apparatus for an electrical stepping motor having its rotor mechanically connected to drive a transducer carriage of a magnetic disk drive machine, includes a transistor which is responsive to the voltage across the stator coils of the stepping motor and initiates the controlled discharging of a capacitor. The charge on the capacitor is effective through transistor control circuits when the capacitor has discharged to a predetermined level to short all of the stator coils, except the one to which an energizing voltage is applied to attract and hold the rotor in its target position, so as to brake the rotor as the rotor approaches its target position on a return movement after the rotor initially passes across its target position.
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公开(公告)号：DE2532358A1
公开(公告)日：1976-02-19
申请号：DE2532358
申请日：1975-07-19
Applicant: IBM
Inventor： WILSON MELVIN GEORGE
IPC: C08F10/00 , C08F8/00 , G06K7/00 , G06K7/10 , H03K5/08 , H04L25/03 , H04N1/403 , G06K7/14 , H04N1/38
Abstract: 1468624 Bar code reader and decoder INTERNATIONAL BUSINESS MACHINES CORP 18 July 1975 [9 Aug 1974] 30185/75 Heading G4M [Also in Division H3] A circuit for producing a digital output from an analogue input signal, e.g. a bar code on a label comprises: a circuit for producing peak signals representing the peak values of the input signal in opposite directions; means for producing a threshold level dependent on the instantaneous values of the peak signals; means for producing a control signal dependent on a predetermined relationship between the instantaneous values of the input signal and a delayed, amplitude shifted, version of said input signal in which the threshold level is changed towards the instantaneous input signal level in dependence on the control signal. A signal derived from a bar code scanner for Universal Product Code symbols 211, Fig. 2, is fed to input 307, Fig. 3, of a circuit comprising two differential amplifiers Q31, Q32, Q33, Q34, Q35, for peak white and Q36, Q37, Q38, Q39, for peak black. When the input signal is rising towards peak white the voltage 221 across capacitor C21 follows it and subsequently decays through a time constant circuit connected across it. During the periods 213, 214, 215 when the input signal 211 exceeds the delayed, level shifted signal 212 a comparator Q41, Q42, Q43, Fig. 4, applies an enabling signal to the base of transistor Q47. If during this period the instantaneous input signal 211 is lower than the peak signal 221, e.g. during period 214, a second comparator Q45, Q46, Q48 applies an enabling signal to the emitter of Q47 so that Q47 turns on, feeding current to current mirror Q49, Q410. Q49 then provides a low resistance path through which capacitor C31 discharges rapidly until the peak value signal reaches the level of the input signal, 277. The circuits Q36 . .. Q39, C32 and Fig. 5 function in a similar way for peak black level.
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