JPS6045481B2 - magnetic recording and reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing apparatus that automatically sets an equalizer to an optimum value according to a magnetic tape.

The magnetic properties of magnetic tapes used in magnetic recording and reproducing devices such as cassette decks are influenced by chemical factors such as the properties of the magnetic material constituting the magnetic tape, and physical factors such as thickness orientation. For this reason, magnetic tapes are roughly classified into three types based on their magnetic properties: normal type, chrome type, and ferrichrome type. It is a well-known fact that the optimum equalizer differs depending on these magnetic tapes, but it is also a well-known fact that even among the same type, there are variations depending on the manufacturer and rod. For this reason, various devices have recently been proposed for automatically setting the optimum equalizer for each magnetic tape used, with the aim of obtaining even frequency characteristics. The device previously submitted by the inventors is shown in FIG. 1 is an input terminal, 2 is a reference signal oscillation circuit, 3 is a control circuit composed of a microcomputer, etc., 4 is a variable equalizer circuit, 5 is a fixed equalizer circuit, 6 is a recording head, 7 is a magnetic tape, and 8 is a playback head, 9 is a reproduction equalizer circuit,
10 is an A/D converter, 11 to 13 are tape selectors for selecting the type of magnetic tape 7, and 11' to 13' are tape instruction signals.

Next, to explain its operation, first, tape selector 11~
13, the type of magnetic tape is selected and inputted to the control circuit 3, and the control circuit 3 sends tape instruction signals 11' to 13' corresponding to the tape selectors 11 to 13 to the fixed equalizer circuit 5, and the fixed equalizer circuit 5 It is fixed to an equalizer compatible with the magnetic tape 7. Next, control circuit 3 or J
Under these controls, the reference signal oscillation circuit 2 outputs a reference signal of 1KH2, and this reference signal is recorded on the magnetic tape 7 via the variable equalizer circuit 4, the fixed equalizer circuit 5, and the recording head 6. At this time, the variable equalizer/I sensor circuit 4 is varied by a control signal from the control circuit 3. For example, if the control signal is 4 bits, Lj change of one degree is possible. Now, the reference signal recorded on the magnetic tape 7 is detected by the playback head 8, passed through the playback equalizer circuit 9, converted to a digital signal by the A/D converter 10 at the next stage, and inputted to the control circuit 3 to be used as the reference signal. A comparison operation is performed with the value, and the control circuit 3 further controls the variable equalizer circuit 4 based on the operation result. Thus, when the reference signal matches the reference value, the control circuit 3 sets and holds the variable equalizer circuit 4 as the optimum equalizer. The above describes the setting of the 1KHz equalizer, which is relatively low, but in the same way, the middle range equalizer is set to the optimum value at 7K pressure, and the high range equalizer is set to the optimum value at 14KHz. In this device, as mentioned before, in order to effectively utilize the control signal from the control circuit 3 to vary the variable equalizer circuit 4 (as mentioned above, 4 bits = 1 level),
The equalizer is fixed in advance in a fixed equalizer circuit 5 according to the type of magnetic tape 7.

Therefore, if the tape selectors 11 to 13 are changed due to an erroneous operation while the equalizer is being varied, the fixed equalizer will also be changed, and the overall equalizer and variable range will be changed.
As a result, there is a drawback that the output value of the A/D converter 10 may not match the reference value during the equalizer adjustment after the change, and the optimum equalizer may not be set. SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording and reproducing apparatus that eliminates the above-mentioned drawbacks and can smoothly and automatically measure an optimal equalizer.

In order to achieve the above object, in the present invention, switching of the tape type is prohibited while the equalizer is being varied.

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 2 shows the main parts of the magnetic recording and reproducing apparatus according to the present invention. The feature in FIG. 2 is that a logic circuit composed of N1 gates A1 to A3 is added. In FIG. 2, the tape selectors 11 to 13 are operated by two people at the
-A3 are connected to one input terminal of each, and a tape control signal 14, which is an output signal from the control circuit 3, is connected to the other input terminal of each of AND gates A1 to A3. Now, in FIG. 2, the tape selector 13 is closed,
The AND gate connected to this is logically 1 (H
(Since the logic circuit 3 is composed of a MOS transistor that applies a negative voltage, the ground level is logically 1).

The tape control signal 14 is a signal that is logically 1 before and after the equalizer is changed, and becomes 0 during the equalizer change. This signal is not a new signal especially provided for the present invention, but for example, it can be used to control a display circuit that indicates that the equalizer is being set, or to output the recording signal that is being applied to the input terminal 1 during the equalizer setting to the reference signal oscillation circuit. This signal is originally used for switching to the reference signal from 2. Now, before the equalizer is changed, this is the case. Since the tape control signal 14 is 1, only the inputs of the AND gate A3 are all 1, only the outputs of the AND gates are 1, and the information of the tape selector 13 is held from the control circuit 3 with only the tape instruction signal 13'' being 1. is transmitted to the fixed equalizer circuit 5. Next, when a start switch (not shown) is operated, the tape control signal 1 is transmitted to the fixed equalizer circuit 5.
Since 4 is logically 0, the outputs of the AND gates A1 to A3 are all 0. Therefore, even if the tape selectors 11 to 12 are selected by mistake while the equalizer is being varied, the tape instruction signals 1" to 13" are maintained at the previous state and will not be switched. Also tape selector 1
Even if 3 is operated again, it will not be reset and the equalizer will not be changed again from the beginning. As described above, according to the present invention, by preventing erroneous operation of the tape selector while the equalizer is being varied, it is possible to prevent the inability to find the optimum equalizer due to switching of the fixed equalizer circuit, and to smoothly select the optimum equalizer. This is convenient because it can provide a magnetic recording and reproducing device that sets

[Brief explanation of the drawing]

Figure 1 is a main configuration diagram of the magnetic recording and reproducing device proposed earlier.
FIG. 2 is a main configuration diagram showing an embodiment of a magnetic recording/reproducing apparatus according to the present invention. 3...Control circuit, 4...Variable equalizer circuit, 5...Fixed equalizer circuit, 11-13...
...Tape selector, 14...Tape control signal, A1-A3...AND gate.

Claims (1)

[Claims] 1. In a magnetic recording/reproducing device that sets a fixed value in an equalizer by a signal instructing the type of magnetic tape, and then automatically sets an optimum equalizer by varying the equalizer by a control signal from a control circuit, the type of the magnetic tape is determined. 1. A magnetic recording and reproducing apparatus, comprising a means for performing a logical operation on a signal instructing the equalizer and a control signal, and prohibiting the type of magnetic tape from being changed while the equalizer is being varied.