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    12.
    发明专利
    未知

    公开(公告)号：DE1487805A1

    公开(公告)日：1969-02-13

    申请号：DE1487805

    申请日：1966-07-13

    Applicant: XEROX CORP

    Inventor： DALE GREEN LELAND ,  WILLIAM REYNOLDS ROBERT ,  SAEGER WALDEMAR

    IPC: H04N1/17 ,  H04N1/04

    Abstract: 1,154,531. Facsimile systems; selective transistor amplifiers. XEROX CORP. 12 July, 1966 [14 July, 1965], No. 31351/66. Headings H3T and H4F. In a facsimile transmission system information bearing portions of the original are scanned at a slower rate than non-information bearing portions and video signals are transmitted only during the slower scan. The invention is described mainly in connection with the facsimile transmission of type-written or printed (black) information on paper (white) but an adaption suitable for the transmission of a wider range of tonal values, e.g. documents containing pictures &c., is also disclosed the object in both cases being to reduce the total transmission time required. In Fig. 1 the original to be transmitted is advanced via rollers 100, 102 driven by a stepping device 110 past a first detector switch 112 and then past a second detector switch 116 the latter being adjacent a slit 120 in a platen 104. Operation of switch 112 results, via the closure of associated contacts 114a, 114b in the connection of master synchronizing pulses (B) to the output 146 connected to the transmission line to bring remote receivers into synchronism and to the stepping device 110 which advances the original. When the latter reaches switch 116 the associated contacts 118a, 118b operate to open the two previously made circuits. In this position the orginal, which is illuminated via the slit with light from sources 122, is scanned in a line transverse to its length by means of a mirror 124 oscillated at the higher of the two scanning speeds by means of scan generator 136. The latter, the circuit of which is described in connection with Fig. 8, comprises a three stage active filter with a twin T network and operates to produce a 30 c.p.s. sine wave output in response to a 60 c.p.s. square wave input derived from a synchronizing arrangement (Fig. 2, not shown) which also supplies various other control signals (Fig. 3, not shown) to similarly identified terminals in Fig. 1. The original is thus scanned at the higher rate from right-to-left and from left-to-right the scanning mirror directing the light to a photo-electric device 130 which feeds a squaring amplifier 132 delivering a two level output corresponding to black or white portions of the original. The operation is then as follows. During the higher rate scan if no black areas (i.e. information bearing print &c.) are detected the white representative level of the output of amplifier 132 inhibits the transmission of video signals but causes the stepping device 110 to advance the original and also allows the transmission of advance control signals to step on associated receivers, such advance occurring at the end of each scan. When during the higher rate scan black areas are detected the second level output of amplifier 132 (1) inhibits the advance signals (2) gates off the higher speed scan generator 136 and gates on a slower speed saw-tooth scan generator 134 (3) initiates the transmission of a pre-video alterting signal (4) transmits video signals generated during the forward trace of the slower speed scan and (5) advances the original and transmits advance control signals but no video signals during the (rapid) retrace period of the slower speed scan. If black (information bearing) areas are detected during this retrace period a further slower speed scan is effected but if no such areas occur an advance operation is effected and the system reverts to the higher scan rate and advance operations until black areas are again detected. At a co-operating receiver (Fig. 4, not shown) the received video signals are supplied to a recording head 172 which is advanced via lead screw 178 driven by a stepping device 110 to mark a recording sheet carried by a drum 174 rotating in synchronism with the slower scan generator 134 of Fig. 1. When a wider range of tonal values is required the transmitter is modified by the addition of a linear amplifier (190, Fig. 5, not shown) an analog gate (192) and a linear adder (194) and the receiver is modified by the addition of an analog gate (196, Fig. 6, not shown). The slower scan saw-tooth wave generator may take the form depicted in Fig. 7 (not shown).

    16.
    发明专利
    未知

    公开(公告)号：DE1487816A1

    公开(公告)日：1969-04-03

    申请号：DE1487816

    申请日：1966-09-30

    Applicant: XEROX CORP

    Inventor： SAEGER WALDEMAR

    IPC: H02P5/46 ,  H02P5/50 ,  H04L7/00 ,  H04N1/36

    Abstract: 1,140,456. Automatic speed control. XEROX CORP. Sept.27, 1966 [Oct. 1, 1965], No. 43086/66. Heading G3R. [Also in Division H2] In a synchronizing system, oscillator 10 is connected to frequency divider 12 whose output is amplified and applied to motor 16 having a permanent magnet rotor so as to afford a fixed relationship between the position of the motor shaft and the phase of the applied voltage. The motor is geared to facsimile drum 20 to which is fixed a cam 26 for operating periodic contacts 27, 29, associated with low-voltage source 30. A circuit 34 separates a synchronous signal from incoming information signals applied to terminal 32, a differentiating capacitor 40 ensuring that AND gates 36, 38, respond only to the leading edge of the received synchronizing signal. The other input of gates 36, 38, are connected to contacts 29, 27, respectively. The reset input of flip-flop 42 receives a signal from gate 38 to indicate an out-of-synchronization condition, whereby amplifier 44 energizes lamp 46. When frequency divider 12 corresponds to a count of 60, gate 50 generates a signal which passes through gate 48, due to the simultaneous presence of the signal from flip-flop 42. The signal from gate 48 passes through OR gate 52 and capacitor 54 and is applied to the re-set terminals of stages 1, 2, 3, of divider 12 which now delivers a higher frequency signal to the motor. The drum catches up with the incoming synchronizing signals so that coincidence is detected by gate 36 between these signals and those from the contact 29. Flipflop 42 changes-over to extinguish lamp 46, pulses from gate 50 being prevented from passing through gate 48 thereby restoring the unit 12 to its normal dividing ratio. Pulses from the flip-flop 42 now coincide with the incoming synchronizing signals which are passed through gates 56, 52, to re-set the divider 12 to zero whereby the phase of the voltage applied to the motor is regulated within narrow limits. The system may be modified to operate as a combined transmitter and receiver, the units corresponding to the gates 48, 56, being disabled in the transmitter mode so that the divider 12 functions as an ordinary divider and motor 16 operates at a steady speed. A three-input AND gate detects coincidence between the outputs of stages 5 and 6 of the divider and the closure of contact 29, the output of the gate being a pulse occurring once per revolution of drum 20 and accurately timed with respect to the position of the drum. This pulse serves as a transmitter synchronizing signal and is combined with information signals in an OR gate, Fig. 2 (not shown).

    17.
    发明专利
    未知

    公开(公告)号：DE1487811A1

    公开(公告)日：1969-04-03

    申请号：DE1487811

    申请日：1966-09-29

    Applicant: XEROX CORP

    Inventor： SAEGER WALDEMAR ,  WILLIAM REYNOLDS ROBERT ,  DALE GREEN LELAND ,  RENE TANGUAY ARMAND ,  T SHIMABUKURO GEORGE

    IPC: H04N1/32 ,  H04N3/00

    Abstract: 1,159,403. Facsimile transmission. XEROX CORP. 27 Sept., 1966 [10 Oct., 1965], No. 43077/66. Heading H4F. A facsimile transceiver adapted to operate through a telephone network comprises logic means including a plurality of resettable bistable devices in a divider configuration for generating periodic timing pulse patterns, timing means responsive to selected ones of the timing pulses for generating a plurality of repetitive timing signals in phase with the timing pulses, Figs. 6 and 7 (not shown), selectively energizable facsimile transmitter scanning means responsive to the timing means, Fig. 8 (not shown), selectively energizable facsimile receiver printer means, Fig. 12 (not shown), first control means responsive to the detected presence of a document to be transmitted for energizing the transmitter scanning means, and second control means responsive to the detected absence of an original document to be transmitted and to received video signals for energizing the receiver printer means. The first control means includes a sensing switch and reset means responsive to the actuation of the switch for operating the divider at a fixed frequency, and the second control means synchronizes the divider in accordance with received synchronizing signals. To reduce transmission time the operation of the transceiver in the transmit mode is such that in the absence of black areas or other marks which a photomultiplier, for example, is designed to detect, the document to be transmitted is rapidly scanned alternately from left to right and from right to left. Althrough no video information is transmitted in this condition, characteristic advance signals are transmitted and also directed to the transistor stepping motor to advance the document one increment at the end of each scan. If a black area is detected during a fast scan then the document is not advanced any further, a document advance signal is not transmitted, and the scanning action reverts to a slow scan. When the scanning mechanism e.g. a galvanometer, reaches the time and position at which a slow scan is about to commence, a charateristic pre-video alerting signal is transmitted and thereafter video signals corresponding to the scan are transmitted. At the end of a slow scan the document is advanced one increment, a paper advance signal is transmitted, and the galvanometer executes a rapid retrace during which video signals are not transmitted. If information is detected during the retrace, then a further slow scan is made and further paper advances or advance signals are withheld until the end of the slow scan. If no information is detected during the fast scan retrace, then the document is advanced at the end of the retrace, an advanced signal is transmitted, and further rapid scans and advances are made until other back areas are detected. Thus every elemental line of the document which contains information is scanned twice, first with a rapid scan and then with a slow scan during which video signals are transmitted. Lines bearing no information are merely scanned rapidly over. To further reduce the transmission time only every alternate elemental line of the document may be scanned. When the transceiver is in the receive mode, as controlled by the absence of a document in the scanner, and the timing circuits are in synchronism with those of the remote transmitter, the printer stepping motor exactly follows the operation of the scanner stepping motor at the remote connected transmitter. An alarm is actuated to indicate, in the absence of an original document to be transmitted, loss of synchronization or loss of incoming control signals.

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