JPH05166338A - Cassette tape recorder - Google Patents

Abstract

PURPOSE:To detect the existence of a cassette without providing a special means by identifying no existence of the cassette by a light receiving element for detecting the start and end of winding a tape when light beam from a light emitting element is detected. CONSTITUTION:When a cassette 12 is not inserted into a mechanism case 11, infrared rays from a bi-directional light emitting element 17 reaches both a BOT sensor 18 for detecting the start of winding the tape and an EOT sensor 19 for detecting the end of winding the tape. Thus, a phototransistor 22 is turned ON, voltage and current flows to a grounding terminal 23, outputs from the sensors 18 and 19 become 'L' and no insertion of the cassette 12 is detected. Because of this constitution, a push switch for detecting the existence of the cassette 12 is eliminated, a dedicated microcomputer port is made unnecessary and the cassette tape recorder is provided capable of detecting the existence of the cassette 12 highly accurately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cassette tape recorder, and more particularly to a cassette tape recorder equipped with a sensor for detecting the start and end of winding of a tape using a light emitting element and two light receiving elements.

[0002]

2. Description of the Related Art Conventional tape recorders such as VTRs and DATs have means for detecting the presence / absence of a cassette and means for detecting the beginning and end of winding of a cassette tape. This type of cassette tape recorder detects the presence or absence of a cassette based on whether or not the cassette itself pushes a push switch inside the machine body, and also detects the beginning of tape winding with a BOT (Bigin Of Tape) sensor. The end of winding is detected by an EOT (End Of Tape) sensor.

In this type of cassette tape recorder, in order to bring the tape into close contact with the head, the cassette is moved into the apparatus by the cassette loading operation, and the tape is pulled out from the cassette by the tape loading operation. A flowchart of this operation is shown in FIG. As shown in FIG. 3, first, it is determined whether or not the cassette-in switch is pressed (step 1). Then, when the cassette-in switch is pressed, the motor etc. is driven and the cassette is loaded into the device (step 2), and then the cassette-in detection switch is touched by hand or pushed by a foreign object. Assuming an abnormal condition such as a failure, "whether there is a cassette?" Is determined to determine whether or not a cassette is loaded (step 3). The presence / absence of the cassette is determined by pressing a push switch in which the cassette itself is built. If it is determined in step 3 that there is a cassette, a tape loading operation for bringing the tape into close contact with the head is performed (step 4).

On the other hand, if the push switch is not pressed and it is determined in step 3 that there is no cassette, the operation proceeds to cassette unloading operation (step 5) and the process returns to step 1.

[0005]

In the above-mentioned cassette tape recorder, a push switch is used to judge whether or not the cassette is correctly inserted. However, the cassette itself does not have a structure for pushing the push switch. Therefore, there has been a problem that mechanical precision is required for the stroke or mounting of the push switch.

Further, since the push switch is a single sensor, there is a problem that a dedicated microcomputer port is required when the information is taken into the microcomputer.

The present invention has been invented in view of the above problems, and does not require a push switch and a dedicated microcomputer port for detecting the presence / absence of a cassette, and further detects the presence / absence of a cassette with high accuracy. It is an object of the present invention to provide a cassette tape recorder that can be used.

[0008]

In order to achieve the above object, a cassette tape recorder according to the present invention comprises a sensor for detecting the start or end of winding of a tape using a light emitting element and two light receiving elements. The provided cassette tape recorder is characterized by comprising cassette presence / absence detection means for determining that there is no cassette when both of the light receiving elements detect a light beam from the light emitting element.

[0009]

According to the above construction, in the cassette tape recorder provided with the sensor for detecting the winding start and the winding end of the tape using the light emitting element and the two light receiving elements, both of the light receiving elements are the above. Since there is a cassette presence / absence detection unit that determines that there is no cassette when the light beam from the light emitting element is detected, the presence / absence of a cassette is detected by a sensor that detects the start of winding of the tape and the end of winding of the tape without providing special means. Can also be determined.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cassette tape recorder according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic plan view showing a cassette tape recorder according to an embodiment. In FIG. 1, reference numeral 11 shows a mechanism case, and a cassette 12 is arranged in the mechanism case 11. A take-up side reel 13 and a supply side reel 14 are formed in the cassette 12, and the take up side reel 13 and the supply side reel 1
A tape 20 is wound between the four. The rotary head 1 that reads the contents of the tape 20 while the tape 20 is being sent from the supply-side reel 14 to the take-up-side reel 13.
5 is arranged at a position facing the cassette 12, and the tape 20 is guided to the rotary head 15,
The mechanical guides 16 for guiding the inside of the cassette 12 into the cassette 12 are provided at four positions. Further, a bidirectional light emitting element 17 is arranged at a substantially central portion of the cassette 12, and a BOT sensor 18 and an EOT sensor 19 which are light receiving elements for receiving infrared rays from the bidirectional light emitting element 17 are provided in the cassette 1.
It is arranged on both outer sides of 2.

FIG. 2 shows the BOT sensor 18 and EO described above.
FIG. 6 is a circuit diagram showing the mechanism of the T sensor 19, in which a load resistor 21 and a phototransistor 22 are connected in series, a reference voltage is applied to one end of the load resistor 21, and one end of the phototransistor 22 is grounded. .. Then, the output is provided between the load resistor 21 and the phototransistor 22. When the infrared rays emitted from the bidirectional light emitting element 17 reach the BOT sensor 18 (or the EOT sensor 19), the phototransistor 22 is turned on.
Since the voltage current flows through the load resistor 21 and the phototransistor 22 to the ground terminal 23 side, the output level becomes low level (hereinafter referred to as L). When the infrared rays do not reach the BOT sensor 18 or the EOT sensor 19, the phototransistor 22 is turned off, and the voltage / current flows to the output side through the load resistor 21, so that the output level becomes a high level (hereinafter referred to as H). ..

The cassette tape recorder having the above-mentioned structure is operated by the cassette loading operation.
When the tape is inserted into the mechanism case 11, the tape 20 is brought into close contact with the rotary head 15 by the tape loading operation, and the tape 20 wound around the supply-side reel 14 is taken up via the mechanical guide 16 and the rotary head 15. It is sent to the side reel 13. In addition, the bidirectional light receiving element 17
Infrared rays are emitted from the infrared rays, and the presence or absence of the cassette 12 is detected depending on whether or not the infrared rays reach the BOT sensor 18 or the EOT sensor 19.

Usually, there is a leader tape which is a transparent portion at the beginning and the end of the winding of the tape 20. At the beginning of the winding, the leader tape passes the infrared rays emitted from the bidirectional light receiving element 17 to the BOT sensor 18, and thus the BOT. Sensor 18
The output from is L. On the other hand, since the EOT sensor 19 side is not a leader tape, infrared rays are blocked, and the output from the EOT sensor 19 becomes H. On the other hand, when the winding is completed, the infrared rays emitted from the bidirectional light receiving element 17 do not reach the BOT sensor 18, the output from the BOT sensor 18 becomes H, reaches the EOT sensor 19, and reaches the EOT sensor 19 The output from is L. Further, when the winding is not started or ended, that is, when the winding of the tape 20 is in the middle, the infrared rays from the bidirectional light receiving element 17 to the BOT sensor 18 and the EOT sensor 19 are both blocked. become. Therefore, the output from the BOT sensor 18 and the output from the EOT sensor 19 both become H. On the other hand, when the cassette 12 is not inserted into the mechanism case 11, infrared rays from the bidirectional light emitting element 17 reach both the BOT sensor 18 and the EOT sensor 19. Therefore, the output from the BOT sensor 18 and the output from the EOT sensor 19 are both L. Therefore,
According to this aspect, it can be detected that the cassette 12 is not inserted.

Table 1 shows these modes.

[0016]

[Table 1]

Based on the embodiment of Table 1 above, the cassette 1
When the presence or absence of 2 is detected, B
The outputs of the OT sensor 18 and the EOT sensor 19 are detected, and in any of the above modes 1 to 3, it is determined that there is a cassette, and in the above mode 4, it is determined that there is no cassette. Set on the side. By this, the presence or absence of the cassette 12 can be easily
In addition, it is possible to detect accurately. Therefore, usually, the presence or absence of the cassette can be detected by the means for detecting the winding start and the winding end of the tape 20, the conventional dedicated push switch can be eliminated, and the microcomputer dedicated port can be eliminated.

[0018]

As described above in detail, in the cassette tape recorder according to the present invention, the light emitting element and the two light receiving elements are used to provide a sensor for detecting the start or end of winding of the tape. The cassette tape recorder is provided with cassette presence / absence detection means for determining that there is no cassette when both of the light receiving elements detect a light beam from the light emitting element. It is also possible to judge the presence / absence of a cassette by a sensor that detects the start of winding and the end of winding of the tape. Therefore, it is possible to accurately detect the presence or absence of the cassette without requiring a dedicated microcomputer port such as the push switch.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing an embodiment of a cassette tape recorder according to the present invention.

FIG. 2 is a circuit diagram showing an output of a light receiving element.

FIG. 3 is a flowchart showing an operation up to a tape loading operation of a conventional cassette tape recorder.

[Explanation of symbols]

 17 Bidirectional light emitting element 18 BOT sensor (light receiving element) 19 EOT sensor (light receiving element) 20 Tape

Claims (1)

[Claims] 1. A cassette tape recorder provided with a sensor for detecting the start and end of winding of a tape by using a light emitting element and two light receiving elements, wherein both of the light receiving elements are light rays from the light emitting element. A cassette tape recorder, characterized by comprising cassette presence / absence detection means for determining that there is no cassette when detecting.