JPH05274827A - Head location controller for electronic still camera - Google Patents

Abstract

PURPOSE:To perform the positioning of a magnetic head even if the peak value of an envelope does not exist based on average displacement amount or a reference location. CONSTITUTION:When a magnetic head A is moved step by step in a disk radial direction within a search range R, the output of an envelope detection circuit 43 in each location or the envelope value of a recording signal is obtained. At the location of this peak value M, the positioning is performed for the magnetic head A (auto tracking). The SN ratio of a reproduction signal is maximum at the location of the peak value M in each track T and a clear image or voice is obtained. From the positioning and the present displacement, amount, the formation of novel average displacement amount is performed, or from old and new displacement amount, the formation of the novel average displacement amount is performed. As the present displacement amount, the number of moving steppings corresponding to the interval of a reference location B and the detection location of the peak value M in the track T is used, for instance, and the old average displacement amount is replaced by the new average displacement amount and it is stored in a memory within a system control circuit 10.

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 fork mats 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. In the case of frame recording, the audio signal is the same as the field recording, but the image signal is recorded on two tracks in which the first field and the second field are different. When reproducing such a recording signal,
In order to obtain a clear image or sound, the magnetic head is conventionally positioned on a predetermined track by automatic 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, there are cases where the peak value of the envelope detection output cannot be obtained. 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 the envelope detection output of a reproduction signal by moving the head within a predetermined range of a track, and the peak of the envelope detection output. When a value is detected, the reproduction position of the head is determined based on the peak value, the first positioning means for holding the displacement amount formed based on the movement amount of the head, and the peak value of the envelope detection output. When it is not possible to obtain, the second positioning means for determining the reproducing position of the head based on the displacement amount or the reference position is provided.

[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. Inside the system control circuit 10, various memories (not shown) are provided. This memory holds data such as the number of searches described below, the number of steps as the movement amount of the magnetic head A, and the average displacement amount.

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 PG pulse for each rotation of the magnetic disk D. Spindle motor 1
From 1 onward, a predetermined number of FGs are generated for each rotation of the magnetic disk D.
A pulse is output. 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 and phase. 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. Tracking drive circuit 13
Are 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 recorded on a predetermined track on the magnetic disk D via the amplifier 28 and the magnetic head A.

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 is connected between the head amplifier 31 and the AGC amplifier 32. The envelope detection circuit 43 is connected to the system control circuit 10. 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.

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 at the time of recording or reproduction, during reproduction, the reference position B of the desired track is the center. It is necessary to search the reproducing head position at least in the range E in which the error is taken into consideration in the left-right direction. However, considering an error due to expansion and contraction of the magnetic disk D due to temperature change, it is preferable to set the search range R to be wider than the range E. 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 B. Note that, for example, when the movement amount per step is 5 μm and 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 R. It becomes a point.

When the magnetic head A is moved step by step in the disk radius direction within the search range R, the output signal of the envelope detection circuit 43, that is, the envelope value of the recording signal is obtained at each position. 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 a position where this peak value M is reached [hereinafter referred to as auto-tracking. ]. That is, in each track T, the SN ratio of the reproduction signal becomes maximum at the position of the peak value M, and the clearest image or sound is output for that track.

In the search range R, when the peak value M is detected in the envelope value, the magnetic head A is positioned at the position where the peak value M is detected. At the same time, the current displacement amount is obtained, and a new average displacement amount is formed from the current displacement amount. Alternatively, a new average displacement amount is formed from the previously determined average displacement amount and the current displacement amount. As an example of the current displacement amount described above, the number of movement steps corresponding to the interval between the reference position B and the position where the peak value M is detected in each track T can be used. The new average displacement amount is replaced with the previously determined average displacement amount, and a memory (not shown) in the system control circuit 10 is used.
Held in.

On the other hand, when the peak value M of the envelope does not exist within the search range R, the magnetic head A is positioned based on the previously calculated average displacement amount. If there is no average displacement, the magnetic head A is positioned based on the reference position B.

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 in FIG. 2, for example, it is displaced rightward by a movement amount corresponding to 1 step. 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 "EV2" at the reference position and the envelope value "EV1" at the position displaced by +1 step are compared.

When the envelope value "EV1" is equal to or greater than "EV2" in step 106, step 107 is executed to determine whether the magnetic head A has moved to the upper limit of the search range R (the right end portion in FIG. 2). To be done. If the envelope value “EV1” is less than or equal to “EV2”, the process proceeds to step 110.

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. During this search, when the envelope value continues to increase and the head position reaches the upper limit of the search range R, step 13 described later is performed to position the magnetic head through step 107.
One or less is executed.

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 of the envelope value is detected by executing steps 104 to 108, step 110 is executed after the magnetic head A has moved +2 steps or more from the reference position. 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. After this, the process proceeds to step 121.

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 B by -1 step is replaced with "EV1". Step 1
In 15, the envelope value “EV2” at the reference position
And the envelope value "EV1" at the position displaced by -1 step are compared. If the envelope value "EV1" at the position displaced by -1 step is equal to or greater than "EV2", step 116 is executed and the envelope value "E"
When “V1” is equal to or smaller than “EV2”, the process proceeds to step 119.

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.
During this time, the envelope value continues to increase and no peak value exists, and when the head position reaches the lower limit of the search range R, step 131 and later described below are executed to position the magnetic head via step 116.

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. After this, the process proceeds to step 131.

In steps 121 to 126, processing is performed after the peak of the envelope value is detected and the magnetic head A is positioned. In step 121, the number of searches is counted and the count value is held in the memory in the system control circuit 10. The number of searches means the number of times of auto-tracking performed on the magnetic disk D. For example, when auto-tracking is performed on another track in the past, the count value is already “1” and When the head positioning on the track is completed, the count value becomes "2". Then, the process proceeds to step 122.

At step 122, the current displacement amount is obtained, and this displacement amount is held in the memory in the system control circuit 10. This displacement amount is obtained as the number of movement steps of the magnetic head A at the position where the peak value M of the envelope value is detected from the reference position B shown in FIG. After this, the process proceeds to step 123.

At step 123, a judgment is made as to the number of searches. When the number of searches is 1, that is, when the search operation is performed first, the count value is (+
1), the process proceeds to step 124, and if the search operation is the second time or later, the process proceeds to step 125.

Since step 124 is the first search operation, the current displacement amount obtained in step 122 is set as the average displacement amount, and the average displacement amount is held in the memory in the system control circuit 10. This ends the program.

In step 125, it is determined whether or not the target track T has already been auto-tracked. If auto-tracking has already been performed, the previously calculated average displacement amount is maintained and the program ends. If automatic tracking is not performed, step 126
Proceed to.

In step 126, a new average displacement amount is calculated by the following equation based on the current displacement amount on the target track T and the previously calculated average displacement amount. Average displacement amount = (average displacement amount + current displacement amount) / 2 The average displacement amount previously obtained by this is replaced with the new average displacement amount, and the new average displacement amount is stored in the system control circuit 10. Retained in memory. This ends the program.

In steps 131 to 133, the magnetic head A is positioned when the peak envelope value is not detected. In step 131, step 12
The determination regarding the number of searches described above in 1 is made.
When the number of searches is 1, that is, when it is the first search operation, the process proceeds to step 132, and the search operation is 2
If it is after the first time, the process proceeds to step 133.

In step 132, the magnetic head A is moved based on the average displacement amount previously obtained and held. This ends the program.
Further, in step 133, the magnetic head A is moved to the reference position B.
Be moved to. That is, when the average displacement amount is not obtained, 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 is used.
At the time of determining the reproduction position of, the peak value of the envelope detection output in each track T is detected. When the peak value is detected, the magnetic head A is positioned at the position where the peak value is obtained. Along with this, a new average displacement amount formed based on the current displacement amount or a new average displacement amount formed based on the current displacement amount and the previously determined average displacement amount is held. .. When the peak value cannot be detected, the magnetic head A is positioned based on the average displacement amount previously obtained and held, or based on the reference position B.

Therefore, even when the peak value of the envelope detection output cannot be obtained, the auto-tracking operation of the magnetic head A becomes possible and the image signal or the audio signal can be reproduced.

[0040]

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 block 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 flowchart for explaining positioning of a magnetic head based on an envelope value.

FIG. 5 is a flowchart for explaining positioning of a magnetic head based on an envelope value.

FIG. 6 is a flowchart for explaining an average displacement amount calculation process performed when a peak envelope value is detected.

FIG. 7 is a flowchart for explaining the positioning of the magnetic head that is performed when the peak value of the envelope value is not detected.

[Explanation of symbols]

 A magnetic head D magnetic disk

Claims (1)

[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, the reproduction signal being obtained by moving the head within a predetermined range of the track. When the envelope detection output of is detected and the peak value of the envelope detection output is detected, the reproduction position of the head is determined based on the peak value, and the displacement amount formed based on the movement amount of the head is determined. And a second positioning means for holding the reproducing position of the head based on the displacement amount or the reference position when the peak value of the envelope detection output is not obtained. A head position control device for a characteristic electronic still camera.