Video signal recording apparatus having overlap function

Abstract: A video signal recording apparatus has an overlap function of gradually switching a video signal read from a memory capable of storing a one-picture portion of an input video signal to another video signal during a first predetermined time period. The apparatus can effectively utilize the overlap function with a simple operation by operating a manual operation member for setting the apparatus to an overlap mode for operating the overlap function when a recording operation is not performed, and thereby confirming an image stored in the memory. When the apparatus is in an interval recording mode in which a recording means periodically operates during every second predetermined time period, the first and second predetermined time periods are determined so that the second predetermined time period is longer than the first predetermined time period when the apparatus is set to the overlap mode. Recording of an imperfect image is thereby prevented.

Description: 1. Field of the Invention This invention relates to a video signal recording apparatus, and more particularly, to a video signal recording apparatus having an overlap function and provided with a memory capable of storing a video signal for one picture frame. 2. Description of the Related Art Recently, a memory capable of storing a video signal for one picture frame, a so-called field memory or frame memory, has been used in many apparatuses for commercial use. On the other hand, a technique of providing a video signal with various kinds of special effects using a memory has been practiced in apparatuses for television broadcast. In providing an apparatus for commercial use with such special effects, however, there exist problems, such as limitation in the capacity of a memory, incapability of providing a complicated operation control unit, and the like. Hence, there is a limitation in providing such special effects. JP-A-248 878 discloses a video signal recording apparatus, comprising a memory (18) capable of storing a one-picture portion of an input video signal, overlapping means (20, 22, 24) for gradually switching a video signal read from said memory to another video signal during a first predetermined time period, recording means (34) for recording an output signal from said overlapping means as a video siqnal, and a first manual operation member (42) for setting said apparatus to an overlap mode for operating said overlapping means in response to a start of recording by said recording means. Furthermore, the US-A-4 271 437 describes a controller for a video signal recording apparatus, which provides an interval recording mode in order to play the apparatus at a predetermined frequency. However, complicated operation controls and high memory capacities are required in the above prior art apparatuses in order to obtain various kinds of special effects. It is therefore an object of the present invention to provide a video signal recording apparatus by means of which special effects can be obtained with a simple operation. This object is achieved by a video signal recording apparatus according to the new claim 1. Accordingly, by performing the overlap operation when the apparatus shifts from the recording pause state to the recording state during interval recording and setting the interval recording time to be longer than the overlap time, an entirely new type of recording can be realized without misoperation. The foregoing and other objects and features of the present invention will become more apparent from the following detailed description of the preferred embodiment taken in connection with the accompanying drawings. FIG. 1 is a block diagram showing the schematic configuration of a camcorder (a video cassette recorder formed integral with a camera) according to an embodiment of the present invention; FIG. 2 is a flowchart illustrating the operation of a system controller for switching modes in the camcorder shown in FIG. 1; and FIG. 3 is a flowchart illustrating the operation of an overlap mode in the camcorder shown in FIG. 1. An explanation will now be provided of an embodiment in which the present invention is applied to a camcorder. FIG. 1 is a block diagram showing the schematic configuration of a camcorder according to an embodiment of the present invention. In FIG. 1, there are shown an operation unit 36 of the camcorder, a power-supply switch PWR, a trigger key TRG, a picture-recording key REC, a stop key STP, a playback key PLY, an overlap key OVR, a clear key CLR, an interval-recording key INT, a plus key PLS, and a minus key MNS. A system controller 34 controls respective units of the apparatus by the operation of the operation unit 36. An explanation will now be provided of the operation of the camcorder with reference to a flowchart showing the operation of the system controller 34. FIG. 2 is a flowchart illustrating the operation of the system controller 34 for switching modes in the camcorder shown in FIG. 1. When the power-supply switch PWR has been switched on (step S20), the apparatus is in a state of temporarily stopping recording (a recording pause state) (step S21). In this state, the system controller 34 connects a switch 8 to side R. Hence, a video signal from a camera unit 6 is supplied to an electronic view finder (EVF) 20 via the switch 8 and an adder 16, and an image of an object being photographed by the camera unit 6 can be monitored by the EVF 20. On the other hand, by the control of the system controller 34, a drum rotation control circuit 38 rotates a rotating drum 28 mounting a rotating magnetic head 26 at the same speed as in a recording operation, and a capstan rotation control circuit 40 sets a capstan 42 to a stop state. If the trigger key TRG is operated in this recording pause state (step S22), the apparatus is in a recording state (step S26). In the recording state, a video signal provided in the form of a signal suitable for magnetic recording by a video signal recording processing circuit 18, and an audio signal picked up by a microphone 2 and provided in the form of a signal suitable for magnetic recording by an audio signal recording processing circuit 4 are added together in an adder 22, and the resultant signal is supplied to the magnetic head 26 via an R-side terminal of a switch 24. By the control of the system controller 34, the drum rotation control circuit 38 rotates the drum 28 at a predetermined speed, and the capstan rotation control circuit 40 rotates the capstan 42 at a predetermined speed. The output signal of the adder 22 is thereby recorded on a magnetic tape T by the rotating magnetic head 26 while sequentially forming helical tracks. If the trigger key TRG is operated in the recording state (step S30), the apparatus returns to the above-described recording pause state. If the interval-recording key INT is operated in the recording pause state or the recording state (step S23 or S27), the process proceeds to step S19 for interval recording. In step S19, a recording interval TA and a recording time TB of each recording are set by operating the plus key PLS and the minus key MNS. When the apparatus has shifted to an interval recording state, the lapse of the recording interval TA is awaited (step S31), and the apparatus proceeds to a recording mode (step S33). When the recording time TB has lapsed after shifting to the recording mode (step S34), the apparatus shifts to the recording pause state (step S36). Subsequently, interval recording is performed by repeating steps S31, S33, S34 and S36. About 60 seconds and about 0.5 seconds are suitable for the recording interval TA and the recording time TB, respectively. In the present embodiment, TA and TB can be set between 30 seconds - 2 minutes, and between 0.1 seconds - 10 seconds, respectively, by operating the above-described plus key PLS and minus key MNS. If the stop key STP is operated in the recording pause state, the recording state or the interval recording state (steps S24, S28, S32 or S35), the apparatus shifts to the stop state (step S37). That is, the system controller 34 stops the drum 28 and the capstan 42 via the drum rotation control circuit 38 and the capstan rotation control circuit 40, respectively. If the picture-recording key REC is operated in the stop state (step S40), the apparatus shifts again to the recording pause state. If the playback key PLY is operated in the stop state (step S38), the apparatus is set to a playback state. In the playback state, the system controller 34 connects the switches 8 and 24 to sides P, and rotates the drum 28 and the capstan 42 at the same speeds as in the recording operation via the drum rotation control circuit 38 and the capstan rotation control circuit 40, respectively. The rotating head 26 thereby reproduces a recorded signal. The reproduced signal is supplied to a reproduced video signal processing circuit 44 and a reproduced audio signal processing circuit 46. An audio signal reproduced by the reproduced audio signal processing circuit 46 is output to the outside from a sound output terminal 50. A video signal reproduced by the reproduced video signal processing circuit 44 is output to the outside from an image output terminal 48. The reproduced video signal is also input to a field memory 10 and the adder 16 via side P of the switch 8, and is converted into an image on the EVF 20. If the stop key STP is operated in the playback state (step S43), the apparatus shifts to the above-described stop state. If the power-supply key PWR is operated in the recording pause state, the recording state, the stop state or the playback state (steps S25, S29, S39 or S44), the system controller 34 stops the control of respective units, and terminates the processing. The mode shifting operation of the camcorder in the present embodiment has been explained. An explanation will now be provided of an operation relating to an overlap mode, which is a feature of the present invention, with reference to the flowchart shown in FIG. 3. When the overlap key OVR has been operated and the apparatus has been set in the overlap mode (step S1), the system controller 34 sets the above-described recording time TB (a second predetermined time period) in the interval recording mode to the same value as a time TR (a first predetermined time period) necessary for an overlap operation (step S2). In the present embodiment, since 3 seconds are postulated for the overlap time TR, the recording time TB in the interval recording mode is forcibly set to 3 seconds. If the apparatus is in the stop state when the overlap key OVR has been operated (step S3), the system controller 34 supplies the field memory 10 with a write enable pulse for a period of one field via a memory controller 30 so as to write a one-field portion of a video signal supplied to the field memory 10 at that time (step S4), and the process proceeds to step S6. If the apparatus is in the recording pause state when the overlap key OVR has been operated (step S5), the process proceeds to step S6. In step S6, the system controller 34 sets the coefficient K of a coefficient unit 14 to K = 1 via a coefficient control circuit 32. In this case, the video signal from the switch 8 is offset in the adder 16. Hence, the video signal read from the field memory 10 is output from the adder 16. Since the output of the adder 16 is supplied to the EVF 20, an image stored in the memory 10 can be confirmed on the EVF 20. If the operation of the overlap key OVR is subsequently released (step S7), the coefficient K of the coefficient unit 14 is changed from 1 to 0 during the above-described overlap time TR by controlling the coefficient control circuit 32. If the coefficient K of the coefficient unit 14 is K = 0, the video signal from the switch 8 is output to the adder 16 without being modified. Hence, by changing the coefficient K from 1 to 0, the signal output from the adder 16 is switched (while overlapping) from the video signal read from the field memory 10 to the video signal from the switch 8 during the predetermined time period TR. Even if the operation of the overlap key OVR is released, the apparatus is maintained in the overlap mode. Such an operation is convenient in the recording pause state for the preparation of overlap recording to be performed, and the effect of overlap recording can be confirmed in the stop state. No particular dedicated key is used in such preparatory and confirming operations, but these operations are performed only by operating the conventional interval-recording key INT and overlap key OVR. Since such new functions can be provided with a very simple operation, the configuration of the present embodiment is suitable for providing an apparatus for commercial use with an overlap recording function. If the apparatus shifts from the recording pause state to the recording state by the operation of the trigger key TRG, that is, if recording is started, when the apparatus is in the overlap mode via steps S1 - S8 (step S9), the coefficient K of the coefficient unit 14 is changed from 1 to 0 during the above-described overlap period TR (step S10). The video signal to be recorded is thereby switched while being overlapped from an image stored in the memory at the timing of the start of recording to an image being photographed by the camera unit 6. If the apparatus shifts to the recording pause state by the operation of the trigger key TRG in the recording state, that is, if recording is stopped (step S11), the system controller 34 sets the memory 10 to a write enable state during a period of one field via the memory controller 30. A photographing signal from the camera unit 6 at that time is thereby written in the memory 6 for a period of one field (step S12). When recording is resumed, the picture stored in step S12 is recorded while being overlapped with the next picture to be recorded during the predetermined time period TR. This overlap operation is also performed when the apparatus shifts from the recording pause state to the recording state during interval recording. Moreover, since the overlap time period TR and the interval recording time TB are set to be equal, it has become possible to automatically perform interval recording utilizing the overlap function. Accordingly, a new type of recording wherein pictures momentarily changing during a few seconds are sequentially subjected to overlap recording can be performed with a very simple operation without misoperation. Hence, the above-described configuration is very useful for applying this new mode to an apparatus for commercial use. If the clear key CLR is operated while the above-described overlap mode is set (step S13), the interval recording time TB adjusted to the overlap time TR is released and set to the original TB, for example, 0.5 seconds (step S14), and the overlap processing is terminated. As explained above, in the camcorder of the present embodiment, the practical use of the overlap function, and new functions utilizing the overlap function are realized with a very simple operation. Hence, the configuration of the present embodiment is very useful when the overlap function is applied to an apparatus for commercial use. Although, in the above-described embodiment, the interval recording time TB and the overlap time TR are set to be equal, the interval recording time TB may be set to be longer than the overlap time TR. In such a case, an entirely new type of recording, wherein pictures momentarily changing during a few seconds can be sequentially subjected to overlap recording, can be realized without misoperation. An explanation has been provided illustrating an operation of gradually switching the entire image stored in the memory to an image being photographed, i.e., so-called "cross fade" as the overlap function in the present embodiment. However, the present invention may also be applied to an operation of gradually changing the ratio of the area occupied by an image stored in the memory to the area occupied by an image being photographed from 1:0 to 0:1, i.e., so-called "wipe", serving as the overlap function. The individual components shown in outline or designated by blocks in the Drawings are all well-known in the video signal processing arts and their specific construction and operation are not critical to the operation or best mode for carrying out the invention. While the present invention has been described with respect to what is presently considered to be the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment. A video signal recording apparatus has an overlap function of gradually switching a video signal read from a memory capable of storing a one-picture portion of an input video signal to another video signal during a first predetermined time period. The apparatus can effectively utilize the overlap function with a simple operation by operating a manual operation member for setting the apparatus to an overlap mode for operating the overlap function when a recording operation is not performed, and thereby confirming an image stored in the memory. When the apparatus is in an interval recording mode in which a recording means periodically operates during every second predetermined time period, the first and second predetermined time periods are determined so that the second predetermined time period is longer than the first predetermined time period when the apparatus is set to the overlap mode. Recording of an imperfect image is thereby prevented.

Claims: A video signal recording apparatus, comprising: a) a memory (10) capable of storing a one-picture portion of an input video signal; b) overlapping means (14, 16, 32) for gradually switching a video signal read from said memory to another video signal during a first predetermined time period (TR) ; c) recording means (26) for recording an output signal from said overlapping means (14, 16, 32) as a video signal; and d) a first manual operation member (OVR) for setting said apparatus to an overlap mode for operating said overlapping means in response to a start of recording by said recording means; characterized in that e) a second manual operation member (INT) is provided for setting said apparatus to an interval recording mode for periodically operating said recording means during every second predetermined time period (TB) ; and that f) said overlapping means (14, 16, 32) and said recording means (26) are controlled in the overlap mode so as to simultaneously operate and the first and second predetermined time periods (TR, TB) are determined such that the second predetermined time period (TB) is longer than said first predetermined time period (TR) when said apparatus is in said overlap mode and in said interval recording mode. A video signal recording apparatus according to claim 1, characterized by determining means (34) for setting said second predetermined time period (TB) to be longer than said first predetermined time period (TR) by changing said second predetermined time period (TB) . A video signal recording apparatus according to claim 2, characterized in that said determining means (34) can set said second predetermined time period (TB) to be shorter than said first predetermined time period (TR) when the apparatus is not in said overlap mode. A video signal recording apparatus according to claim 1, characterized in that said determining means (34) is adapted to set said second predetermined time period (TB) to be longer than said first predetermined time period (TR) by changing one of said first and second predetermined time periods (TR, TB) according to an operation of said first manual operation member (OVR) . A video signal recording apparatus according to any one of the preceding claims, characterized by image pick-up means (6) for forming a video signal from light from an object, a video signal output from said image pick-up means (6) being input to said overlapping means (14, 16, 32) as said another video signal.

Inventors: NAGASAWA KENICHI, SATO CHIKARA, TAKAHASHI KOJI, NAGASAWA, KENICHI, SATO, CHIKARA, TAKAHASHI, KOJI, Nagasawa, Kenichi, c/o Canon Kabushiki Kaisha, SATO, CHIKARA, C/O CANON KABUSHIKI KAISHA, Takahashi, Koji, c/o CANON KABUSHIKI KAISHA
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1991
Main classification: G11B27
IPC codes: H04N5, H04N9, G11B27, G11B20