Methods of and apparatus for reproducing recorded video signals

Claim 3

A method according to claim 1 which also includes the steps of detecting image data on the video tape (1) from a field other than the field from which image data is being stored and accessing another field memory (13,14,15) not currently in use for storage or retrieval for storage of the image data of said other field.

Claim 4

A method according to claim 1 wherein said given period is variable depending upon the scanning condition of a rotary head (2), in such a manner that, when the rotary head (2) is scanning a single field, the given period may be shorter than when the rotary head (2) is scanning more than one field.

Claim 5

A method according to claim 1 wherein said switching between said field memories (12,13,14) or disablement thereof is triggered by a pulse signal produced each time the scanning of one record area is completed.

Claim 6

A method according to claim 3 wherein said switching between the field memories (13,14,15) or disablement thereof is triggered by a pulse signal produced each time the scanning of one record area is completed.

Claim 9

Apparatus according to claim 6 wherein said memory condition detecting means (52,54) detects image data on the video tape (1) from a field other than the field from which image data is being stored and said retrieval control means (18,21) is responsive to said image data other than the field from which image data is being stored for accessing another memory (13,14,15) not currently in use for storage or retrieval for storage of the image data of said other field.

Claim 10

Apparatus according to claim 6 wherein said memory switching disabling means (53) derives said given period on the basis of a memory selection condition detected by said memory condition detecting means (52,54).

Claim 11

Apparatus according to claim 8 wherein said memory switching disabling means (53) derives a first shorter period when a single said memory (13,14,15) is selected for storing image data for a single field and a second longer period when two said memories (13,14,15) are selected for storing image data for two fields.

Claim 12

Apparatus according to claim 1 wherein said memory condition detecting means (52,54) includes a pulse generator which produces a pulse signal each time the scanning of one field of image data is completed.

Claim 13

Apparatus according to claim 10 wherein said disabling period starts in response to reversal of the tape drive and ends in response to a pulse signal produced by a pulse generator, said period varying according to the memory selection conditions detected by the memory condition detecting means (52,54).

Claim 14

Apparatus for reproducing a video signal recorded on a recording medium (1) in the form of a plurality of tracks, comprising: a memory means (16) including at least three memories (13,14,15), each capable of holding all of the image data for one field picked up from the recording tracks of the recording medium (1) by a reproduction head (2); characterised by: storage control means (18,17) for selecting one of said memories in said memory means for storage of the image data from the field currently being picked up by said head (2), said storage control means (18,17) selecting the memories (13,14,15) in a given order and detecting inclusion of image data from more than one field in an input video signal from said head (2) and selecting more than one memory (13,14,15) for storage of image data for each field separately; retrieval control means (18,21) for selecting one of said memories (13,14,15) currently holding one field of image data in a predetermined sequence for retrieval of the stored image data as an output video signal; a memory condition detecting means (52,54) for monitoring the selection condition of said memory (16); a drive direction detecting means (53) for detecting reversal of the tape drive direction; and a memory switching disabling means (53), responsive to reversal of the tape drive direction, for disabling selection of a different memory (13,14,15) for retrieval and supply of the stored data for a period of time related to the memory selection conditions detected by said memory condition detecting means (52,54).

Claim 15

Apparatus for reproducing a video signal recorded on a recording medium (1) in the form of a plurality of tracks, comprising: a memory means (16) including at least three memories (13,14,15), each capable of holding all of the image data for one field picked up from the recording tracks of the recording medium (1) by a reproduction head (2); characterised by: storage control means (18,17) for selecting one of said memories in said memory means for storage of the image data from the field currently being picked up by said head (2), said storage control means (18,17) selecting the memories (13,14,15) in a given order and detecting inclusion of image data from more than one field in an input video signal from said head (2) and selecting more than one memory (13,14,15) for storage of image data for each field separately; retrieval control means (18,21) for selecting one of said memories (13,14,15) currently holding one field of image data in a predetermined sequence for retrieval of the stored image data as an output video signal; a memory condition detecting means (52,54) for monitoring the selection condition of said memory (16); a drive direction detecting means (53) for detecting reversal of the tape drive direction; and a memory switching disabling means (53), responsive to reversal of the tape drive direction, for disabling selection of a different memory (13,14,15) for retrieval and supply of the stored data for a period of time related to the memory selection conditions detected by said memory condition detecting means (52,54).

Claim 16

Apparatus according to claim 12 wherein said memory condition detecting means (52,54) includes a signal generator (52a) which produces a memory switching demand each time the scanning of one field of image data is completed.

Claim 17

Apparatus according to claim 12 wherein said storage control means (18,17) include a counter means (17) for counting said memory switching demand for deriving a binary code, and a look-up table (54a) to be looked up in terms of said binary code for deriving a memory selection control signal which identifies said memories (13,14,15) for writing said image data.

Claim 18

Apparatus according to claim 13 wherein said retrieval control means (18,21) is also responsive to said memory selection control signal for selecting one of memories (13,14,15) for retrieval and supply of the stored image data.

Claim 19

Apparatus according to claim 12 wherein said memory condition detecting means (52,54) is arranged to detect the selection condition of said memory (16) between a first condition in which a single memory (13,14,15) is selected for storing one field of image data, and a second condition in which two memories (13,14,15) are selected for storing two fields of image data.

Claim 20

Apparatus according to claim 15 wherein said memory switching disabling means (53) derives said disabling period of time in such a manner that, when said memory condition detecting means (52,54) detects said first condition, a first shorter period is derived, and when said memory condition detecting means (52,54) detects said second condition, a second longer period is derived.

Claim 21

Apparatus according to claim 16 wherein said first period corresponds to a period of time in which one memory switching demand is supplied, and said second period corresponds to a period of time in which two of said memory switching demands are supplied.

Claim 22

Apparatus according to claim 13 wherein said memory condition detecting means (52,54) is arranged to detect the selection condition of said memory (16) between a first condition in which a single memory (13,14,15) is selected for storing one field of image data, and a second condition in which two memories (13,14,15) are selected for storing two fields of image data.

Claim 23

Apparatus according to claim 18 wherein said memory switching disabling means (53) derives said disabling period of time in such a manner that, when said memory condition detecting means (52,54) detects said first condition, a first shorter period is derived, and when said memory condition detecting means (52,54) detects said second condition, a second longer period is derived.

Claim 24

Apparatus according to claim 19 wherein said first period corresponds to a period of time in which one memory switching demand is supplied, and said second period corresponds to a period of time in which two of said memory switching demands are supplied.

Claim 25

Apparatus according to claim 20 wherein said counter means (17) is arranged to count up said memory switching demands to increment said binary code by one at every occurrence of a said memory switching demand while said drive direction detecting means (53) detects driving of the video tape (1) in a first direction, and to count down said memory switching demand to decrement said binary code by one at every occurrence of said memory switching demand while said drive direction detecting means (53) detects driving of said video tape (1) in a second direction opposite to said first direction.

Claim 26

Apparatus according to claim 21 wherein said signal generator (52a) includes a detector for detecting the rotary head position scanning at least one of a leading and a trailing boundary of a record area constituted by a plurality of tracks for generating said memory switching demand.