JP3134309B2 - Image recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus, and more specifically, to an image recording apparatus that records image signals photographed in a plurality of photographing modes on a recording medium.

2. Description of the Related Art There is known a technique for digitally recording an information signal such as an audio signal as a video signal on a magnetic tape stored in a small cassette. In such a magnetic recording / reproducing apparatus, while transmitting the information signal at a predetermined transmission rate to a transmission system in the apparatus,
Performs signal processing and recording / reproducing processing.

[Problem to be Solved by the Invention] In the magnetic recording and reproducing apparatus as described above, the signal transmission speed is set to, for example, about 768 bits / sec / = 2 (ch) * 32 (KHz) * 12.
(Bit) When set to as low as｝, image quality sufficient for recording and reproduction of a video signal can be secured. However, for one frame (3.
It takes about 4.8 seconds to record a video signal of 7 Mbit {= 640 (pixel) * 1.5 (Y + C)}.

Therefore, for example, when such a magnetic recording / reproducing device is incorporated in an electronic still camera and used, the timing of the shutter is greatly restricted, and the continuous shooting function, which is an important function as a still camera, is also significantly restricted. There are drawbacks.

In order to shorten the recording time, the above-mentioned transmission speed may be increased. However, if the tape running speed is constantly increased, the power consumption is increased, and the battery life of the electronic still camera which is a portable device is shortened. It is not preferable.

Therefore, an object of the present invention is to provide an image recording apparatus which has solved such a disadvantage.

[Means for Solving the Problems] An image recording apparatus according to the present invention converts an object image into an electric signal to generate an image signal, and sets a desired photographing mode from a plurality of photographing modes. A recording unit for compressing the image signal obtained by the imaging unit, adding an error correction code to the compressed image signal, and recording the compressed image signal on a recording medium, according to a shooting mode set by the setting unit. Control means for controlling the compression processing of the recording means, the amount of error correction code added, and the recording speed.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
10 is a photographing optical system, 12 is an imaging circuit for converting a subject image into an electric signal, 14 is a recording signal processing circuit for processing the output of the imaging circuit 12 for a recording signal, 16 is a head switch, and 18 and 20 are on the rotating drum 22. A magnetic head 24 mounted 180 ° opposite thereto is a drum motor for rotating the rotating drum 22. 26 is a magnetic tape as a recording medium, 28 is a capstan, and 30 is a capstan motor for rotating the capstan 28. The rotating drum 22 is attached so as to be inclined with respect to the longitudinal direction of the magnetic tape 26. Reference numeral 32 denotes a motor drive circuit for driving the motors 24 and 30; 34, a system control circuit for controlling the entire system; 36, a continuous shooting mode setting switch; and 38, a release switch.

The basic operation of FIG. 1 will be described. The imaging circuit 12 converts a subject image by the photographing optical system 10 into an electric signal, and outputs a video signal to a recording signal processing circuit 14. The recording signal processing circuit 14
It performs D / A conversion and, if necessary, data compression, adds an error correction code necessary for recording, performs recording modulation, and outputs the result to the switch 16. The switch 16 is controlled by a system control circuit 34, and the output of the recording signal processing circuit 14 is alternately applied to the magnetic head 18 or 20 at a predetermined timing. The system control circuit 34 also drives the drum motor 24 and the capstan motor 30 via the motor drive circuit 32, and rotates the rotating drum 24 and the capstan 28 at a predetermined speed, as will be described in detail later. The rotation of the capstan 28 causes the magnetic tape 26 to travel in its longitudinal direction, and at the same time, the rotary drum 22 rotates, and the magnetic heads 18 and 20 scan the magnetic tape in a direction inclined with respect to its longitudinal axis. So-called,
It is a helical scan method. Thus, oblique tracks 40 as shown in FIG. 1 are sequentially formed.

Next, referring to the flowchart shown in FIG.
The characteristic operation of the present embodiment will be described in more detail. When started, firstly, the operation of the release switch 38 is waited (S
1). When the release switch 38 is operated, whether the continuous shooting mode or the single shooting mode is determined from the state of the continuous shooting mode setting switch 36 (S2).

In the single shooting mode, the recording signal processing circuit 14 is set to an operation mode in which data compression is not performed, and the capstan 28
Then, the motor drive circuit 32 is set to rotate the rotating drum 22 at the normal speed (S3). In the continuous shooting mode,
The recording signal processing circuit 14 is set to an operation mode for compressing data, and the motor drive circuit 32 is set so that the capstan 28 and the rotating drum 22 are rotated at twice the normal speed (S4).

After the mode setting (S3, 4), recording starts (S
Five). That is, a video signal is output from the imaging circuit 12, and the recording signal processing circuit 14 temporarily stores this in an internal memory. For the continuous shooting mode, the recording signal processing circuit 14 sequentially reads out the image data stored in the internal memory, performs a predetermined compression process (for example, two-dimensional discrete cosine transform, etc.), adds an error correction code, The signal is modulated and output for recording, and is sequentially recorded on the magnetic tape 26. In the single-shot mode, of course, without data compression, error correction codes are added and recording modulation is performed.
The information is recorded on the magnetic tape 26.

In the continuous shooting mode, the additional amount of the error correction code may be increased.

When recording of one screen is completed (S6), the continuous shooting mode setting switch 36 is used (S7).
In the case of the continuous shooting mode, as long as the release switch 38 is on (S8), the process returns to S5 to repeat the recording.

In this embodiment, since the rotating drum 22 and the magnetic tape 26 run at twice the speed during continuous shooting, the transmission speed is doubled. When the transmission speed is doubled in this manner, one frame of the normal uncompressed image data is reduced to about 2.4 seconds (= 4.8 seconds *).
1/2). To reduce the continuous shooting speed to about 4 frames per second, data compression of about 1/10 is required, but such a compression rate can be sufficiently achieved by two-dimensional discrete cosine transform (CCITT Recommendation H .261). Also, by performing offset sampling for field capture during continuous shooting, compression can be reduced to about 1/4, and continuous shooting of about 2 frames per second can be achieved.

The compression ratio may be changed and set according to the continuous shooting speed.

In this embodiment, as shown by hatching in FIG.
Pilot signals of four frequencies fp1, fp2, fp3, fp4 are recorded in a part of the track 40, and recording of continuous shooting and recording of single shooting are performed, for example, fp1, fp2, fp3, f A case where recording is performed in the order of p4 and a case where recording is performed in the reverse order of fp4, fp3, fp2, fp1 may be distinguished.

Further, at the time of reproduction of single-shot recording, the signal can be reproduced without tracking control by increasing the rotation speed of the rotary head and scanning the same track a plurality of times. At the time of reproduction of continuous recording, the signal can be reproduced without tracking control by reducing the tape feed speed to half the recording speed and scanning the same track a plurality of times.

[Effects of the Invention] As can be easily understood from the above description, according to the present invention, the compression processing, the amount of addition of the error correction code, and the recording speed are controlled according to the shooting mode, so that the present invention is adapted to each shooting mode Image recording can be performed, and unnecessary power consumption can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a flowchart showing the operation thereof. 10: shooting optical system, 12: imaging circuit, 14: recording signal processing circuit, 1
6: head changeover switch, 18, 20: magnetic head, 22: rotating drum, 24: drum motor, 26: magnetic tape, 28: capstan, 30: capstan motor, 32: motor drive circuit, 34: system Control circuit, 36: Continuous shooting mode setting switch, 38: Release switch

Claims (1)

(57) [Claims] An imaging unit configured to convert a subject image into an electric signal to generate an image signal; a setting unit configured to set a desired imaging mode from a plurality of imaging modes; and a compression unit configured to compress the image signal obtained by the imaging unit. Process,
Recording means for adding an error correction code to the compressed image signal and recording the image signal on a recording medium; compression processing of the recording means according to a shooting mode set by the setting means; An image recording apparatus comprising: a control unit that controls a speed.