Patent GB-1485439-A (GB)
Title: Line skip system for facsimile device
IPC: H04N1/38
Filed: 1974-10-15
Abstract: 1485439 Facsimile system RICOH CO Ltd 15 Oct 1974 [1 Nov 1973] 44575/74 Heading H4F A facsimile system, Fig. 1, incorporates means for skipping a scan path containing no data and ignoring the presence along that path of ruled lines, such as margins or borders occurring in predetermined positions, comprising: a generator for producing a gating signal which may be nullified at predetermined intervals corresponding to the position of the ruled lines to be ignored; a pre-scanning head which scans a path for data content prior to re-scanning for transmission by a second head in the event of the path containing data; a detector for detecting the simultaneous presence of the gating signal and a non-null (i.e. black) picture signal indicating the presence of data to be transmitted along the path; and a scanner position control unit 24 for skipping the proscanned path in the event of it containing no data so as to avoid transmission of blank lines. The system consists of a rotating document carrying drum 10 having a synchronizing bar 14 occurring at the beginning of the main scan path. A scanning head assembly 22 moves along the drum to produce the side scan. The scanning heads 26 scan two adjacent paths, if the path scanned by the pre-scan head contains data it is subsequently re-scanned by the transmission scan head otherwise it will not be re-scanned. An example of a document to be scanned, Fig. 2, comprises a ruled border in the form of lines 32, 34, 36 and 38. The picture signal corresponding to a blank scan path above or below lines 36 and 38 respectively is shown by A, Fig. 3, the square pulses being produced by the sync. bar on the drum, that corresponding to a path containing no data between those lines is shown by B the additional pulses corresponding to ruled lines 32 and 34, Fig. 2. Signals C and D, Fig. 3, represent respectively a set pulse and a reset pulse for a bi-stable element generated in response to the trailing edge of the sync. pulse, and E represents the gating signal generated by the bi-stable element. The set and reset pulses are arranged so that their trailing edges, which actuate the bi-stable element, occur after the pre-scan head passes line 32, Fig. 2, and before it reaches line 34 so that the gating signal is only non-null in the interval between and not including those lines. The set pulse C, Fig. 3, is inverted D, Fig. 4, and differentiated E. A pulse F is generated in response to the positive spike in signal E, generated in turn by the trailing edge of the set pulse C, and is used to set the bi-stable element which is reset in a similar manner. Fig. 5 shows a circuit for producing the gating signal and detecting, by means of a comparator 62, the blackness level signal of data. These two signals are input to an AND gate 64, the output of which is connected to the position control unit. The circuit comprises a sync. pulse generator 50, set 52 and reset 54 signal generators or multivibrators triggered by the trailing edge of the sync. pulse, pulse shapers 56 and 58 for generating the set and reset pulses in response to the set and reset signal trailing edges and gating signal generator 60. Details of the pulse shaper circuitry appear in Fig. 6 (not shown). In another embodiment, Fig. 7 (not shown), the device is modified to suppress the gating signal once only along each scan path corresponding to a single ruled vertical line. In a further embodiment, Fig. 8 (not shown), the device is modified to suppress the gating signal in three places corresponding to three ruled vertical lines, a correspondingly modified gating signal generator, Fig. 9 (not shown), is required, this generator may also be used to accommodate the single line case, and may be further modified to cope with any number of lines perpendicular to the main scan direction.