JPH04192101A - Automatic regulating circuit for sound recording bias of cassette tape recorder - Google Patents

Abstract

PURPOSE:To ensure convenience when there is no time to operate automatic regulation of sound recording bias by resetting a memory circuit where a different kind of magnetic tape from the magnetic tape for data stored in the memory circuit is mounted in the playing position. CONSTITUTION:When the magnetic tape is replaced with one of different kind, a reset signal in H-level is outputted to a reset signal output terminal 18 of a control circuit 15 since the magnetic tape of different kind from the one for the data stored in the memory circuit 16 is mounted. When such a reset signal is outputted, reset operation of the memory circuit 16 is performed to reset it to the data of a reference bias value which is set to the magnetic tape mounted for the data. Consequently, when the sound recording operation is performed in such a state, a bias current of the reference value being set to each magnetic tape is supplied to a sound recording head, then the sound recording operation can be performed without trouble.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a cassette tape recorder using a cassette tape, and more particularly to an automatic recording bias adjustment circuit.

(b) Prior Art Cassette-type tape recorders that use a cassette tape in which a magnetic tape is housed in a container called a cassette have become widespread. Such a cassette tape recorder is configured to record signals on a magnetic tape by supplying a bias current to a recording head. There are three types of magnetic tape used in such cassette type tape recorders: normal tape, chrome tape, and metal tape, and the structure is such that the magnitude of the bias current can be switched according to the characteristics of each tape. has been done. Furthermore, even among magnetic tapes of the same type, the characteristics differ slightly between magnetic tapes made by different companies, so in order to make the most of the characteristics of each magnetic tape, it is necessary to adjust the bias current value. In popular cassette tape recorders, this bias current value is set according to the type of magnetic tape, but in high-end cassette tape recorders, the bias current value is variably adjusted to match the characteristics of each magnetic tape. It has the ability to.

There are two methods for adjusting the bias current: a manual method and an automatic method, but the automatic method has better operability. A technique for automatically adjusting the magnitude of such bias current is disclosed in, for example, Japanese Patent Laid-Open No. 61-39203.

(c) Problems to be Solved by the Invention The automatic adjustment operation of the bias current is performed by the technology disclosed in the above-mentioned publication, but the bias value set in this way is In this case, it is necessary to perform a new automatic adjustment operation or reset the set bias value to return to each reference value. Generally, a reset switch is provided for resetting the bias value, but it is inconvenient to perform the reset operation and there are cases where the user forgets to perform the reset operation. The present invention aims to provide an automatic recording bias adjustment circuit that is improved in this respect.

(d) Means for Solving the Problems The automatic recording bias adjustment circuit of the present invention has a memory circuit that stores bias value setting data at the end of the automatic bias adjustment operation, and a magnetic tape due to the difference in the shape of the cassette tape. A tape type detection circuit that detects the type, and a control that is switched when a cassette tape is inserted and the cassette holder, which is displaceable between the loading/unloading position and the playing position, is moved from the loading/unloading position to the playing position. and a switch, and in a state in which bias value setting data based on the bias automatic adjustment operation is stored in the memory circuit, a magnetic tape of a different type from the magnetic tape of the data stored in the memory circuit is mounted at the performance position. The memory circuit is reset when this happens.

(E) Function The present invention is capable of storing information in a memory circuit when a cassette tape is inserted and a cassette holder is displaceable between an attachment/detachment position and a performance position. The memory circuit is reset when a magnetic tape of a different type from the magnetic tape containing data is detected.

(f) Embodiment The illustrated circuit is an embodiment of the recording bias automatic adjustment circuit of the present invention. In the figure, (1) is an input terminal to which a recording signal is applied, (2) is a preamplifier circuit that amplifies the recording signal input from the input terminal (1), and its output terminal is a selector switch ( 3) is connected to the first terminal (3a). (4) is activated when an H (high) level signal is applied to the control terminal (4a), and the first and second signals at different frequencies, for example, 400H2 and 10KHz,
This is a reference signal generation circuit that generates a reference signal, and its output terminal is connected to the second terminal (3b) of the changeover switch (3). (5) is a switch circuit that switches the changeover switch (3) to the opposite side from the state shown in the figure when an H level signal is applied to the control terminal (5a); (6)
(7) is a recording amplifier circuit whose input terminal is connected to the movable terminal (3C) of the changeover switch (3); (7) is a recording amplifier circuit to which a signal amplified by the recording amplifier circuit (6) is applied; Recording head (8) for recording on magnetic tape.
) is a bias oscillation circuit that supplies a bias current to the recording head (7), (9) is a playback head that plays back the signal recorded on the magnetic tape, and (10) is a signal that is played back by the playback head (9). This is a reproducing amplifier circuit which receives a signal input thereto and amplifies the signal, and its output signal is connected so as to be applied to a 72-ter amplifier circuit (not shown). (11) becomes operational during automatic bias adjustment, detects the level difference between the first and second reference signals that are amplified and input by the reproducing amplifier circuit (10), and eliminates the level difference. This is a bias adjustment circuit that adjusts the magnitude of the bias current output from the bias oscillation circuit (8). (12) is a cassette holder into which a cassette tape is inserted and which is movable between an attachment/detachment position and a playing position;
(13) a control switch that is closed when in the playing position;
(14) is a bias adjustment operation switch that is pressed and closed when automatically adjusting the recording bias, and (14) is a tape type that detects the type of magnetic tape from the difference in shape when the cassette tape is installed in the performance position. Detection circuit, (1
5) is a control circuit that controls each operation of the tape recorder including the automatic bias adjustment operation, and (16) is a memory that stores the bias value setting data by the bias adjustment circuit (11) when the automatic bias adjustment operation is completed. When an H level reset signal is applied to the reset terminal (16a), the data is reset to the standard bias value set for each type of magnetic tape. (17) outputs an H level control signal when the bias adjustment operation switch (13) is pressed and closed, and outputs an L (low) level control signal when the bias adjustment circuit (11) completes the adjustment operation. This is a control signal output terminal to which a signal is output, and is connected to the control terminal (4a) of the reference signal generation circuit (4) and the control terminal (5a) of the switch circuit (5). (1
8) is different from the magnetic tape stored in the memory circuit (16) due to the automatic bias adjustment operation when the control switch (12) is closed due to the displacement of the cassette holder to the playing position accompanying the replacement of the cassette tape. This is a reset signal output terminal that outputs an H-level reset signal when a type of magnetic tape is loaded, and is connected to the reset terminal (16a) of the memory circuit (16).

The recording bias automatic adjustment circuit of the present invention is constructed as described above, and the operation of this circuit will now be described.

When the bias adjustment operation switch (13) is pressed and closed, an H level signal is output to the control signal output terminal (17) provided in the control circuit (15), and a signal that puts the tape recorder into the recording state is output. The signal is output and the tape recorder is put into recording mode. The H level signal output to the control signal output terminal (17) is applied to the control terminal (4a) of the reference signal generation circuit (4) and the control terminal (5a) of the switch circuit (5). When an H level signal is applied to the control terminal (4a) of the reference signal generation circuit (4), the reference signal generation circuit (4) becomes operational, and the first and second signals of 400)(z and 10KHz) It also outputs the reference signal of the switch circuit (5).
When an H level signal is applied to 5a), the selector switch (
3) is switched to the opposite side from the illustrated state, so that the first and second reference signals output from the reference signal generation circuit (4) are input to the recording amplifier circuit (6). The first and second reference signals input to the recording amplifier circuit (6) are amplified and then sent to the bias oscillation circuit (8).
It is applied to the recording head (7) along with a bias current from the recording head (7), and recording is performed on the magnetic tape by the recording head (7). The first and second reference signals recorded on the magnetic tape are reproduced by a reproduction head (9) and then input to a reproduction amplifier circuit (10) where they are amplified. The first and second reference signals amplified by the reproduction amplifier circuit (10) are input to a bias adjustment circuit (11). As a result, the bias adjustment circuit (11) outputs to the bias oscillation circuit (8) a signal that varies the value of the bias current so that the level difference between the reference signals is eliminated.

When the bias current output from the bias oscillation circuit (8) is varied, the level of the signal recorded on the magnetic tape changes, and the difference between the first reference signal and the second reference signal reproduced by the playback head (9) changes. The level difference between the signals gradually becomes smaller, and as the variable operation further progresses, the level difference between the signals disappears. When the level difference between the reference signals disappears, the bias adjustment circuit (1
1), the bias variable operation for the bias oscillation circuit (8) is no longer performed, and the control signal output terminal (1)
The output signal of 7) is inverted from H level to L level. Further, when such an adjustment operation is performed, data corresponding to the bias value set by the bias adjustment circuit (11) is stored in the memory circuit (16). When the output signal of the control signal output terminal (17) becomes L level, the reference signal generation circuit (4) becomes inactive and the changeover switch (3) is switched to the state shown. In this manner, the recording bias adjustment operation is completed, but the bias current value supplied from the bias oscillation circuit (8) to the recording head (7) is set in accordance with the characteristics of the magnetic tape. Therefore, by performing the recording operation after rewinding the magnetic tape to the bias adjustment start position, the recording signal inputted from the input terminal (1) can be recorded on the magnetic tape with the best characteristics.

As described above, the automatic bias adjustment operation is performed.Next, the operation when the cassette holder is moved from the performance position to the attachment/detachment position and then to the performance position again will be described. When such an operation of the cassette holder is performed, the control switch (12) is opened and then opened. When the recording operation on the A side of the cassette tape is completed, the cassette tape is turned over in order to record on the B side. When such an operation is performed, the control switch (12) is opened and closed, and the tape type detection circuit (14) performs a detection operation. In this case, the memory circuit (16)
Since a magnetic tape of the same type as the data stored in is loaded, an H-level reset signal is not output to the reset signal output terminal (18) of the control circuit (15). Therefore, if a recording operation is performed, it is possible to record the B side using the same bias current value as when recording the A side. In this way, recording operations are performed on sides A and B of the same cassette tape.Next, a case will be described in which recording operations are performed using magnetic tapes of the same type but different types. When replacing the cassette tape with the same type of cassette tape, the same type of magnetic tape as the data stored in the memory circuit (16) will be loaded, so an H level signal will be sent to the reset signal output terminal (18) of the control circuit (15). A reset signal is never output. Therefore,
In this case, the recording operation will be performed using a bias value set based on the data stored in the memory circuit (16). If the recording operation is performed in this manner, the characteristics of the magnetic tape cannot be fully utilized, but the recording operation on the magnetic tape can be performed without any problems.

As described above, when the bias value data adjusted by the bias automatic adjustment operation is stored in the memory circuit (16), the same type of magnetic tape as the data stored in the memory circuit (16) is stored. The operation will be performed when replacing with magnetic tape, but we will explain the operation when replacing with the next type of magnetic tape = When replacing with a different type of magnetic tape, the memory circuit (1
Since a magnetic tape of a different type from the data stored in the controller 6) is loaded, an H level reset signal is output to the reset signal output terminal (18) of the control circuit (15). When such a reset signal is output, the memory circuit (1
The reset operation 6) is performed, and the data is reset to the reference bias value set on the mounted magnetic tape. Therefore, when a recording operation is performed in such a state, a bias current having a reference value set for each magnetic tape is supplied to the recording head, and the recording operation can be performed without any trouble.

The bias adjustment circuit (11), tape type detection circuit (14), control circuit (15), memory circuit (16), etc. in this embodiment can be constructed by a microcomputer.

(g) Effects of the Invention The automatic recording bias adjustment circuit of the present invention allows the cassette holder, which is provided to be movable between the loading/unloading position and the playing position, to be displaced from the loading/unloading position to the playing position when a cassette tape is inserted. If a different type of magnetic tape is detected than the magnetic tape containing the data stored in the memory circuit, the memory circuit is reset, so if there is no time to automatically adjust the recording bias. It is very convenient.

[Brief explanation of the drawing]

The illustrated circuit is an embodiment of the recording bias automatic adjustment circuit of the present invention. Explanation of main drawing numbers (3)...Choice switch, (4)...Reference signal generation circuit, (5)...Switch circuit, (6)...
Recording amplifier circuit, (7)...recording head, (8)
...bias oscillation circuit, (9)...playback head,
(10)... Reproduction amplifier circuit, (11)... Bias adjustment circuit, (12)... Control switch,
(14)...Tape type detection circuit, (15)...
Control circuit, (16)...Memory circuit.

Claims (1)

[Claims] (1) Two reference signals with different frequencies are recorded on a magnetic tape by a recording head, and the reference signal recorded on the magnetic tape is played back by a playback head, and a recording bias is based on the level difference between the played reference signals. In a cassette tape recorder configured to automatically adjust the current, the memory circuit that stores the bias value setting data at the end of the automatic bias adjustment operation and the type of magnetic tape due to the difference in the shape of the cassette tape. A tape type detection circuit for detecting the tape type, and a control switch that is switched when a cassette tape is inserted and a cassette holder, which is provided so as to be movable between an attachment/detachment position and a performance position, is moved from an attachment/detachment position to a performance position. When a magnetic tape of a different type from the magnetic tape of the data stored in the memory circuit is attached to the performance position in a state in which the bias value setting data by the bias automatic adjustment operation is stored in the memory circuit. An automatic recording bias adjustment circuit for a cassette tape recorder, characterized in that the memory circuit is reset.