JPH05274829A - Head location control device of electronic still camera - Google Patents

Abstract

PURPOSE:To reproduce a recorded signal even if a peak value does not exist in envelope detection output by providing a means detecting the dropout of a signal in a reproduced signal and a means determining the reproduction loca tion of a head based on this detection output. CONSTITUTION:A magnetic head A is moved within the search range of a track and the envelope detection output of a reproduced signal is detected by an envelope detection circuit 43. When arc envelope value decreases by the move of a head, a peak value M exists and a head is returned to this location. When the peak value does not exist, the positioning is performed for the head based on the dropout frequency. When the peak value M does not exist, the head A is moved to a reference location and the integral value of a dropout detection circuit 44 is determined. When the integral value becomes more than a prescribed value, this location is defined as a reproduced location. When the reproduced location of the head A is not possible to be determined even if the dropout signal is used, the positioning is performed for the head A at the center location (reference location) of a track.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic still camera, and more particularly to a device for controlling the position of a head when reproducing an image signal of a recording medium.

[0002]

2. Description of the Related Art Usually, an electronic still camera uses a magnetic disk as a recording medium. There are two types of recording formats for magnetic disks: field recording and frame recording. In the case of field recording, an image signal or audio signal is recorded for each track of the magnetic disk, that is, an image signal or audio signal corresponding to one screen is recorded on one track. For frame recording,
The audio signal is the same as in field recording, but the image signal is recorded in different tracks in the first and second fields. In order to obtain a clear image or sound at the time of reproducing such a recording signal, the magnetic head is conventionally positioned on a predetermined track by auto tracking control. That is, the envelope detection output of the reproduction signal is detected while moving the magnetic head along the width direction of the reproduction track, and the magnetic head is set at a position where the envelope detection output has a peak value.

[0003]

However, in such an auto-tracking operation, the peak value of the envelope detection output may not be obtained in some cases, and in this case, there is a problem that the image signal or the like is not reproduced. SUMMARY OF THE INVENTION It is an object of the present invention to provide a head position control device for an electronic still camera capable of reproducing a signal recorded on the track even when a peak value does not exist in the envelope detection output in the auto tracking operation. It was made as.

[0004]

A head position control device for an electronic still camera according to the present invention detects a dropout of a signal in a reproduction signal, and reproduces a head based on the output of the dropout detection means. And a positioning means for determining the position.

[0005]

The present invention will be described below with reference to the illustrated embodiments. FIG. 1 shows a circuit of an electronic still camera including a head position control device according to an embodiment of the present invention. This electronic still camera uses a magnetic disk D as a recording medium. The system control circuit 10 is a microcomputer that controls the entire apparatus. Under the control of the system control circuit 10, a captured image or sound is recorded on the magnetic disk D, and an image signal or the like on the magnetic disk D is reproduced. To be done.

The magnetic disk D is rotated by a spindle motor 11, and the spindle motor 11 is drive-controlled by a spindle control circuit 12. A magnetic coil F is provided near the magnetic disk D. The magnetic coil F detects the PG yoke portion PGY provided on the magnetic disk D, and outputs one pulse for each rotation of the magnetic disk D. The spindle motor 11 outputs a predetermined number of FG pulses for each rotation of the magnetic disk D. The system control circuit 10 controls the rotation of the spindle motor 11 based on these pulse signals to rotate the magnetic disk D at a predetermined speed. A magnetic head A is provided for recording and reproducing image signals and the like on the magnetic disk D. The position of the magnetic head A is controlled to a predetermined track of the magnetic disk D by the tracking drive circuit 13. The tracking drive circuit 13 is controlled by the system control circuit 10.

An operation unit 14 and a display unit 15 are connected to the system control circuit 10. The operation unit 14 is provided for operating the present electronic still camera, and has, for example, a switch for selecting a track of the magnetic disk D to be reproduced. The display unit 15 has a liquid crystal panel, for example, and displays the track number of the magnetic disk D being processed at that time.

A structure for recording an image signal on the magnetic disk D will be described. The image pickup unit 20 has a solid-state image pickup device (CCD) and the like, and is controlled by the system control circuit 10 to form an image on the CCD and separate the image into a luminance signal and a color signal for output. The luminance signal and the color signal are the luminance signal FM modulation circuit 21 and the color signal F, respectively.
FM modulation is performed by the M modulation circuit 22. Each of the FM modulation circuits 21 and 22 is connected to the adder 23. Therefore, the FM-modulated luminance signal and the chrominance signal are mutually combined by the adder 23, thereby generating an image signal corresponding to one still image. To be done.

An adder 24 is connected to the adder 23. The adder 24 has a function of superimposing the DPSK signal on the image signal output from the adder 23, and is connected to the DPSK modulation circuit 25. It The DPSK modulation circuit 25 DPSK-modulates the carrier supplied from the carrier generation circuit 26 based on the ID data including the track number of the magnetic disk D, the shooting date, etc. supplied from the system control circuit 10 to generate a DPSK signal. To generate.
The carrier output from the carrier generating circuit 26 is formed based on the signal output from the reference clock generating circuit 27.

The adder 24 is connected to a recording side terminal R of a switch 29 via a recording amplifier 28. The switch 29 is switched and controlled by the system control circuit 10, and when recording an image signal or the like on the magnetic disk D, it is switched to the recording side position R and when reproducing the image signal or the like on the magnetic disk D,
The position is switched to the reproduction side position PB. Therefore, at the time of recording, the image signal superposed by the adder 24 and the DPSK
The signal is sent to the magnetic head D via the amplifier 28 and the magnetic head A.
It is recorded on the predetermined track above.

Next, the structure for reproducing the image signal recorded on the magnetic disk D will be described. Switch 29
The reproducing side terminal PB is connected to the head amplifier 31, and the head amplifier 31 is connected to the automatic gain control (AGC) amplifier 32. The AGC amplifier 32 is connected to a luminance signal FM demodulation circuit 34 via a high pass filter 33, a color signal FM demodulation circuit 36 via a low pass filter 35, and a band pass filter 37.
Are respectively connected to the DPSK demodulation circuit 38 via.
Luminance signal FM demodulation circuit 34 and color signal FM demodulation circuit 36
Are respectively connected to the encoder 41. The encoder 41 generates a video signal based on the luminance signal and the color difference signal input from the FM demodulation circuits 34 and 36. On the other hand, the DPSK demodulation circuit 38 is the system control circuit 10
Therefore, the ID data is input to the system control circuit 10 via the DPSK demodulation circuit 38.

Luminance signal FM demodulation circuit 34 and encoder 4
A synchronization signal separation circuit 42 is connected between 1 and 2. The sync signal separation circuit 42 extracts the horizontal sync signal Hsync and the vertical sync signal Hsync from the luminance signal. These horizontal sync signal Hsync and vertical sync signal Hsync are input to the system control circuit 10 and used for various timing controls. It

An envelope detection circuit 43 and a dropout detection circuit 44 are connected between the head amplifier 31 and the AGC amplifier 32. The envelope detection circuit 43 is connected to the system control circuit 10, and the dropout detection circuit 44 is connected to the system control circuit 10 via an integrator 45. The envelope detection circuit 43 envelope-detects the reproduction signal, and the output signal subjected to the envelope detection is input to the system control circuit 10. As will be described later, the system control circuit 10 positions the magnetic head A with respect to the track based on the envelope detection output signal. When the position control of the magnetic head A cannot be performed by the envelope detection output signal, the output signal of the dropout detection circuit 44 is integrated by the integrator 45, and the system control circuit 10 determines the magnetic head A based on the integrated value. Perform positioning.

Next, the positioning control of the magnetic head A at the time of reproducing a recording signal such as an image signal recorded on the magnetic disk D will be described. The track T and the search range R set on the magnetic disk D will be described with reference to FIG. A reference position B is defined for each predetermined pitch from the center (not shown) of the magnetic disk D, and a track width W of a predetermined width is set on both sides of the reference position B as a center. Normally, the magnetic head A records at the reference position B, but since there is an error in the positioning of the magnetic head A during recording or reproduction, at the time of reproduction, at least the reference position B of the desired track is the center. It is necessary to search the reproducing head position within the range E in which the error is taken into consideration in the horizontal direction. However, considering the error due to expansion and contraction of the magnetic disk due to temperature change,
It is preferable to set a range wider than the range E as the search range R. In this embodiment, the search range R is set to be the same as the track width W to simplify the description. The search range R is not limited to this, and may be set appropriately.

The magnetic head A is moved step by step in a search range R centered on the reference position B. The system control circuit 10 counts the number of movement steps from the reference position B and recognizes the count value as the amount of displacement from the reference position. Note that, for example, when the movement amount per step is 5 μm and the width of the search range R is 0.06 mm, the position moved by ± 6 steps from the reference position B (that is, the displacement amount +6 or −6) is the upper limit or the lower limit of the search range. It becomes a point.

Within the search range R, the magnetic head A is moved step by step in the disk radial direction, and at each position,
The output signal of the envelope detection circuit 43, that is, the envelope value of the recording signal is obtained. This envelope value normally takes a peak value M at any position within the search range R as shown in FIG. 3, and the magnetic head A is positioned at the position where the peak value M is reached. That is, the SN ratio of the reproduction signal is maximized at this position, and the clearest image or sound is output for that track.

When the envelope peak value M does not exist within the search range R, the magnetic head A is positioned based on the dropout signal as shown in FIG. The dropout signals X1 and X2 are output from the dropout detection circuit 44 and become a high (H) signal when the output signal of the head amplifier 31 includes a valid reproduction signal, and a low signal when a dropout is included. (L) signal. That is, the symbols Y1 and Y2 correspond to valid reproduction signals, and the symbols Z1 and Z2 correspond to dropouts.
The dropout signal X1 shown on the upper side of the figure has a smaller dropout Z2 and a larger SN ratio of the reproduced signal than the dropout signal X2 shown on the lower side. In this embodiment, as will be described later, this dropout signal X
The magnetic head A is positioned at a position where the integrated value of 1 and X2 becomes larger than a predetermined value.

When the integrated value of such a dropout signal does not exceed a predetermined value over the entire search range R (FIG. 2), the magnetic head A is located at the reference position B which is the center of the track T, as will be described later. Is positioned.

Next, the positioning control of the magnetic head A will be described with reference to the flow charts shown in FIGS. In step 101, the magnetic head A is moved to the reference position B (FIG. 2) of the target track, that is, the track to be reproduced. In step 102, the recording signal is reproduced at this reference position, and the envelope value output from the envelope detection circuit 43 is set as the "EV reference value". This “EV reference value” is obtained in step 103.
Is replaced with "EV2".

In step 104, the magnetic head A is moved by +1 step and is displaced by 5 μm to the right in FIG. 2, for example. The envelope value is again detected at this head position, and this envelope value is replaced with "EV1" in step 105. In step 106, the envelope value "E
V1 "and the envelope value" EV2 "at the position displaced by +1 step are compared.

The envelope value "EV" at the reference position
If "1" is larger, step 107 is executed and it is determined whether or not the magnetic head A has moved to the upper limit of the search range R (the right end in FIG. 2). If the envelope value “EV1” is smaller, step 110
Proceed to.

Immediately after the start of this positioning control, the magnetic head A has not reached the upper limit yet. Therefore, after "EV1" is replaced with "EV2" in step 108, the process returns to step 104 and the above-described operation is repeated.

As described above, when the envelope value continues to increase while the magnetic head A is moved step by step, steps 104 to 108 are repeatedly executed. If the envelope value continues to increase during this search and the peak value does not exist, it is determined in step 107 that the position of the magnetic head A has reached the upper limit of the search range R.
In this case, the subsequent steps 121 and subsequent steps are executed to position the magnetic head based on the dropout signal.

On the other hand, if it is determined in step 106 that "EV1" is smaller than "EV2", that is, if the envelope value is decreased by the movement of the magnetic head A, step 110 is executed and the magnetic head A is moved from the reference position. It is determined whether or not the position is moved by +1 step. As shown in FIG. 3, when the peak value M is detected in the envelope value by executing steps 104 to 108, step 110 is executed after the magnetic head A has moved from the reference position by +2 steps or more. Therefore, in step 110, it is not determined that the magnetic head A is displaced from the reference position by +1 step, and step 111 is executed, and the magnetic head A moves by -1 step and the envelope value becomes the peak value. Returned to position. In this way, the magnetic head A is positioned, and this program ends.

On the other hand, if the envelope value is reduced by only moving the magnetic head A by +1 step from the reference position by the first execution of step 104, step 1
In 10, it is determined that the magnetic head A is at the position displaced by +1 step. Therefore, in this case, step 112 and subsequent steps are executed next. First, in step 112,
The magnetic head A is moved from the reference position by -1 step, that is, in the direction opposite to step 104. In step 113, the envelope value at the reference position, that is, the "EV reference value" is replaced with "EV2".

In step 114, the envelope value at the position where the magnetic head A has moved from the reference position by -1 step is replaced with "EV1". Step 11
5, the envelope value "EV2" at the reference position and the envelope value "E" at the position displaced by -1 step
V1 "is compared. If the envelope value "EV1" at the position displaced by -1 step is larger, step 116 is executed, and if the envelope value "EV1" is smaller, step 119 is proceeded to.

At step 116, it is judged if the magnetic head A has moved to the lower limit of the search range R (the left end in FIG. 2). When the step 116 is executed for the first time, the magnetic head A has not reached the lower limit yet. Therefore, next in step 117, "EV1" changes to "EV1".
2 ”and the magnetic head A is moved -1 step in step 118, and then step 11
Returning to step 4, the above operation is repeated.

In this way, when the envelope value continues to increase while the magnetic head A is moved by -1 step, steps 114 to 118 are repeatedly executed.
If the envelope value continues to increase and the peak value does not exist during this period, it is determined in step 116 that the position of the magnetic head A has reached the lower limit of the search range R. In this case, the subsequent steps 121 and subsequent steps are executed to position the magnetic head based on the dropout signal.

On the other hand, when "EV1" is judged to be smaller than "EV2" in step 115, that is, when the envelope value is decreased by the movement of the magnetic head A, the peak value M exists in the envelope value, and therefore step 119 In, the magnetic head A moves by +1 step and is returned to the position where the envelope value becomes the peak value. In this way, the magnetic head A is positioned,
This ends the program.

If there is no peak value in the envelope value and it is determined in step 107 or step 116 that the magnetic head A has moved to the upper limit or the lower limit of the search range, the magnetic head A drops out in step 121 and thereafter. Positioned based on frequency. First, in step 121, the magnetic head A is moved to the reference position. In step 122, the integrated value (area value of the hatched portion in FIG. 4) of the output signal of the dropout detection circuit 44 (X1, X2 in FIG. 4) is obtained. The larger the SN ratio of the reproduction signal, the smaller the dropout and the larger the integrated value. In step 123, it is determined whether or not this integrated value is greater than or equal to a predetermined value, and when the integrated value is greater than or equal to the predetermined value, this program ends immediately. That is, in the magnetic head A, the position when the integrated value of the dropout signal becomes equal to or larger than the predetermined value is determined as the reproduction position.

When it is determined in step 123 that the integrated value of the dropout signal is not greater than the predetermined value, it is determined in step 124 whether the magnetic head A has moved to the upper limit of the search range. If the magnetic head A has not reached the upper limit yet, step 125 is executed and the magnetic head A is moved by +1 step.
Then, the process returns to step 122, and steps 122 to 125
Is repeatedly executed. During this time, when the magnetic head A reaches the upper limit of the search range without the integrated value reaching the predetermined value or more in step 123, step 124
To step 131.

The operation of steps 131 to 135 is basically the same as the operation of steps 121 to 125. That is, the magnetic head A is moved from the reference position in the opposite direction to the conventional one. First, in step 131, the magnetic head A is moved by -1 step from the reference position,
In step 132, the integrated value of the dropout signal is obtained. When it is determined in step 133 that this integrated value is equal to or greater than the predetermined value, this program is immediately terminated, and the magnetic head A is set at that position.

When it is determined in step 133 that the integrated value of the dropout signal is not equal to or greater than the predetermined value, it is determined in step 134 whether the magnetic head A has moved to the lower limit of the search range. If the magnetic head A has not yet reached the lower limit, step 135 is executed to move the magnetic head A by -1 step, and steps 132 to 135 are repeatedly executed.

During the execution of steps 132 to 135, when the magnetic head A reaches the lower limit of the search range without reaching the predetermined value or more in step 133, the magnetic head A moves to the reference position in step 136. Be punished. That is, when the reproduction position of the magnetic head A cannot be determined by using the dropout signal, the magnetic head A is set at the center position (reference position B) of the track T.

As described above, in this embodiment, the magnetic head A
When determining the reproduction position of, the peak value of the envelope detection output is first detected, and the magnetic head A is positioned at the position where this peak value is obtained. When this peak value cannot be obtained,
The magnetic head A is moved step by step to obtain an integrated value of the output of the dropout detection circuit, the magnetic head A is positioned at a position where the integrated value becomes a predetermined value or more, and the dropout signal also causes the magnetic head A to move. When the positioning cannot be performed, the magnetic head A is positioned at the reference position B.
Therefore, even when the peak value of the envelope detection output cannot be obtained, the output of the dropout detection circuit 44 can be used to reproduce the image signal or the audio signal having a good SN ratio.

Although the magnetic head A is positioned by using the integrated value of the dropout signal in the above embodiment, instead of this, the number of dropouts is detected, and when this number is less than the predetermined value. The magnetic head A may be positioned at the position.

[0037]

As described above, according to the present invention, even when the peak value does not exist in the envelope detection output in the auto-tracking operation, the signal recorded on the track can be reproduced. can get.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an electronic still camera having a head position detecting device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a search range in a track of a magnetic disk.

FIG. 3 is a diagram showing an example of changes in an envelope value with respect to a head position.

FIG. 4 is a diagram showing an example of a dropout signal.

FIG. 5 is a flowchart of the first half of a program for positioning the magnetic head based on the envelope value.

FIG. 6 is a flowchart of the latter half of the program for positioning the magnetic head based on the envelope value.

FIG. 7 is a flowchart of a program for positioning a magnetic head according to a dropout signal.

[Explanation of symbols]

 A magnetic head D magnetic disk

Claims (4)

[Claims] 1. A head position control device for determining a reproduction position of a head on a track for reproducing a signal recorded on a track of a recording medium, and means for detecting a dropout of a signal in the reproduction signal. A head position control device for an electronic still camera, comprising: positioning means for determining a reproduction position of the head based on the output of the dropout detection means. 2. The electronic still device according to claim 1, wherein the positioning means detects an integrated value of the dropout signal and determines a position of the head as a reproduction position when the integrated value is equal to or more than a predetermined value. Camera head position control device. 3. A second positioning means for setting the head at a predetermined reference position when the integrated value of the dropout signal is not more than a predetermined value.
Head position control device for electronic still camera. 4. The head is moved within a predetermined range of a track to detect the envelope detection output of a reproduction signal, and the reproduction position of the head is determined based on the peak value of the envelope detection output obtained within this range. The head position control device for an electronic still camera according to claim 1, further comprising a third positioning means.