Mechanism for securing recorded contents of recording medium cassette

A recorded data securing mechanism secures data recorded on a recording medium cassette provided with a memory and a data recording enable/disable tab at a predetermined position on the cassette. Breaking the recording enable/disable tab provided on the memory-based recording medium cassette prevents data recorded on the cassette from being written over and ensures that there will be no mismatch between the recording information stored in the memory of the cassette and the data recorded on the recording medium of the cassette. In one embodiment, rewriting is enabled but a memory mismatch flag is set if rewriting results in a mismatch.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a mechanism for securing recorded contents 
of a recording medium cassette whether or not it has a memory and, more 
particularly, to a mechanism for ensuring that recording information 
stored in the memory of the recording medium cassette always matches 
contents recorded on a recording medium of a recording medium cassette. 
2. Description of the Prior Art 
A variety of recording medium cassettes having memory have been proposed. 
See for example a patent to Staar U.S. Pat. No. 4,338,644 for "Magnetic 
Tape Cassettes Provided with Memory Circuits for Storing Information," 
issued Jul. 6, 1982. Such cassettes are often referred to as MIC cassettes 
(MIC is an acronym for "memory in cassette"). If these memory-based 
recording medium cassettes are put in the market, there will be both types 
of recording medium cassettes at the same time: memory-based type and 
non-memory type. 
At the same time, there will be both types of recording/reproducing 
apparatus: one compatible with a memory-based recording medium cassette 
and the other incompatible with a memory-based recording medium cassette. 
Possible combinations of these cassettes and recording/reproducing 
apparatus will be as shown in Table 1. 
TABLE 1 
______________________________________ 
Recording/reproducing apparatus 
Recording medium 
cassette For memory Not for memory 
______________________________________ 
With memory A B 
Without memory C C 
______________________________________ 
The memory installed on a recording medium cassette stores character 
information about contents recorded on the cassette as well as other 
information such as recording time and date. It is therefore essential 
that there exist a correlation between the information stored in the 
memory and the contents recorded on the cassette. However, in a situation 
where there are a recording/reproducing apparatus suitable for a 
memory-based recording medium cassette and a recording/reproducing 
apparatus not suitable for such a cassette at the same time as shown in 
Table 1 above, there is a possibility, as described below, that the 
contents recorded on the cassette will not correspond to the recording 
information stored in the memory. 
"A" in Table 1 is the combination of a memory-based recording medium 
cassette and a recording/reproducing apparatus suitable for such a 
cassette. As FIG. 14 shows, there exists a complete match between contents 
15a, 15b, 15c, 15d and 15e recorded on a recording medium 15 of the 
recording medium cassette and information 16a, 16b, 16c, 16d and 16e 
stored in a memory 16 of the recording medium cassette. Thus, there is no 
problem in retrieving desired data. 
"B" in Table 1 is a combination between a memory-based recording medium 
cassette and a recording/reproducing apparatus incompatible with such a 
cassette. Referring to FIG. 15, there may not be a complete correlation 
between contents 17a, 17b, 17c, 17f and 17g recorded on a recording medium 
17 and the information 16a, 16b, 16c, 16d and 16e stored in the memory 16. 
That is, since this recording/reproducing apparatus is incompatible with 
the memory, recorded contents 17f and 17g do not match the information 16d 
and 16e stored in the memory. 
"C" in Table 1 is the combination of a recording medium cassette without a 
memory and a recording/reproducing apparatus compatible with a memory or a 
recording/reproducing apparatus incompatible with a memory. In this case, 
there is no problem of a mismatch between recorded contents and recording 
information. As FIG. 16 shows, since no memory is provided, the 
recording/reproducing apparatus does not know the start point of 18e. 
Thus, if a recording medium cassette with a memory and a recording medium 
cassette without a memory exist together and, additionally, a 
recording/reproducing apparatus compatible with the recording medium 
cassette with the memory and a recording/reproducing apparatus 
incompatible with such a cassette exist together, there is always a chance 
of a mismatch between the information stored in the memory of a recording 
medium cassette and the contents recorded on the recording medium of a 
recording medium cassette. In that case, if a recording medium cassette 
having such a mismatch is used on the memory-compatible 
recording/reproducing apparatus and the contents in the memory are read, 
the mismatch causes confusion in a data retrieval operation, and the value 
added by the memory is lost. 
Besides, there are two conventional types of mechanisms for protecting 
information recorded on a video tape cassette. One, employed on video tape 
cassettes of VHS type and Beta type, uses a protection tab removably 
attached on the rear or bottom side of the cassette. Normally, a write 
protect opening provided on the rear or bottom side of the cassette is 
closed with this tab, enabling the writing of data on the magnetic tape. 
When this tab is removed, the write protect opening is exposed to prevent 
a data write operation. 
The other, employed on a video tape cassette of 8-mm type, uses a slidable 
tab on the rear side of the cassette. The tab slides over a write protect 
opening provided in the bottom of the cassette to close the opening, 
thereby enabling a write operation. When the tab slides in the other 
direction, it exposes the opening and protects recorded data from being 
erased or overwritten. 
OBJECTS AND SUMMARY OF THE INVENTION 
An object of the present invention is to provide a mechanism for securing 
contents recorded on a recording medium cassette having a memory and a 
recording medium cassette having no memory and, particularly, a mechanism 
for ensuring a correlation between information stored in the memory and 
contents recorded on a recording medium of the cassette. 
In the above-mentioned mechanism, if a recording medium cassette with a 
memory and a recording medium cassette without a memory exist together 
and, additionally, a recording/reproducing apparatus compatible with the 
memory-based recording medium cassette and a recording/reproducing 
apparatus incompatible with it exist together, there is always a 
correlation between the recording information stored in the memory of the 
recording medium cassette and data recorded on the recording medium of the 
recording medium cassette. 
In implementing the above-mentioned mechanism, the present invention is 
practiced as two groups of preferred embodiments. 
In one group of preferred embodiments, when a memory-based recording medium 
cassette has been loaded in a recording/reproducing apparatus incompatible 
with such a cassette, data recording is forcibly disabled. 
In the other group of preferred embodiments, when the memory-based 
recording medium cassette has been loaded in the recording/reproduced 
apparatus incompatible with such a cassette, data recording is enabled but 
a flag is stored in the memory to indicate that there is a mismatch 
between the recording information stored in the memory and the data 
recorded on the cassette.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A mechanism for securing the contents recorded on a recording medium 
cassette according to this invention is described below with reference to 
the drawings. 
In a first embodiment of the invention, a write protect hole of the 
recording medium cassette is used for implementing the recorded content 
securing mechanism. As shown in Table 2 below, a recording medium cassette 
with memory and a recording medium cassette without memory are different 
with respect to the construction of a tab that covers the write protect 
hole provided on each of these cassettes. In addition, they are different 
with respect to the recorded content securing mechanism depending on 
whether or not a recording/reproducing apparatus on which they are 
operated is compatible with the memory-based cassette. The securing 
mechanism is described below with reference to Table 2 for each 
combination of recording medium cassette and recording/reproducing 
apparatus. 
TABLE 2 
______________________________________ 
Recording/reproducing apparatus 
Recording medium 
cassette For memory Not for memory 
______________________________________ 
With memory Removable tab 
Removable tab + memory 
Without memory 
Slidable tab 
Slidable tab 
______________________________________ 
(1) MIC cassette with memory in combination with VCR deck for MIC 
FIG. 1(a) shows, a recording/reproducing apparatus 4a compatible with a 
memory-based recording medium cassette la and comprising a recorder 8a for 
recording data on a recording medium of the recording medium cassette 1a 
by means of a head 9a, an interface 5 for supplying power to a memory 3 in 
the recording medium cassette 1a, a microcomputer 6a for reading/writing 
information on the memory 3, and a detector 7a for determining the state 
of a write protect hole 2 provided on the recording medium cassette 1a. 
The recording medium cassette has terminals for communication with the 
recording/reproducing apparatus 4a. 
(2) MIC cassette in combination with VCR deck for IDB 
FIG. 1 (b) shows a recording/reproducing apparatus 4b incompatible with the 
memory-based recording medium cassette 1a and comprising a recorder 8b for 
recording data on a recording medium of the recording medium cassette 1a 
by means of a head 9b, a detector 7b for determining the state of the 
write protect hole, and a microcomputer 6b for controlling recording means 
based on a detection result obtained from the detector 7b. 
As FIGS. 1(a) and 1(b) show, the memory-based recording medium cassette la 
comprises the memory 3 for storing information about the contents recorded 
on the recording medium of the recording medium cassette and the write 
protect hole 2 for ensuring protection of data recording. 
As FIG. 2 shows, the write protect hole 2 of the memory-based recording 
medium cassette la is opened or exposed from the beginning: i.e., when the 
cassette is shipped from the factory. 
When the memory-based recording medium cassette 1a is loaded in the 
recording/reproducing apparatus 4a compatible with memory, the 
microcomputer 6a is activated to determine whether or not the recording 
medium cassette is provided with memory. If the cassette is found to have 
a memory, then the microcomputer 6a reads information from the memory. The 
memory stores a flag for enabling/disabling data recording. From the state 
of the flag, the microcomputer 6a determines whether or not data can be 
recorded on the recording medium of the cassette. Thus, a part of the 
recording medium can be write-protected while other parts are enabled for 
data writing. 
Meanwhile, when the recording medium cassette 1a having a memory is loaded 
in the recording/reproducing apparatus 4b incompatible with memory, the 
microcomputer 6b determines whether or not the recording medium cassette 
is provided with memory. If the cassette is found to have a memory, then 
the microcomputer 6b detects the write protect hole of the cassette by 
means of the detector 7b. Since the write protect hole is open, the 
microcomputer 6b determines that the cassette is write-protected. 
(3) IDB cassette in combination with VCR deck for MIC 
FIG. 3 shows a recording medium cassette 1b provided with no memory and 
having a slidable lug 9 in a corner of a side of a cassette case 
accommodating the recording medium and a write-protect hole 10 covered 
with a slidable tab 10a operatively associated with the slidable lug 9. 
When the recording medium cassette 1b provided with no memory is loaded in 
the recording/reproducing apparatus 4a compatible with the memory-based 
cassette or the recording/reproducing apparatus 4b incompatible with the 
memory-based cassette, the microcomputer detects the state of the slidable 
tab 10a, that is, whether or not it covers the write-protect hole, to 
determine whether or not the cassette is write-protected. 
To be specific, when the write-protect hole is closed with the slidable lug 
9 at the position of the slidable tab 10a, recording is enabled; when the 
write-protect hole is open, recording is disabled. 
Thus, the method of enabling/disabling the writing of data on the recording 
medium differs depending on whether (a) the recording medium cassette 1a 
(FIG. 2) provided with memory is loaded into the recording/reproducing 
apparatus 4a compatible with a memory-based cassette or into the 
recording/reproducing apparatus 4b incompatible with the memory-based 
cassette, or (b) the recording medium cassette 1b (FIG. 3) lacking memory 
is loaded into one of these apparatuses. 
That is, as FIG. 4(a) shows, the recording/reproducing apparatus 4a 
compatible with the memory-based cassette first determines whether or not 
a loaded cassette has memory (step S1). The determination is made for 
example by sending a data read instruction. If data is returned in 
response to the instruction, it is determined that the recording medium 
cassette is provided with memory. If no data is returned, it is determined 
that the cassette is provided with no memory. If the cassette is the 
recording medium cassette 1 provided with memory, the 
recording/reproducing apparatus 4a extracts from the memory a recording 
disable/enable flag (step S2). If the flag is found to disable data 
recording, the recording/reproducing apparatus 4a determines that the 
recording of data on the cassette is disabled (step S5); if the flag is 
found enabling, the apparatus determines that the recording of data on the 
cassette is enabled (step S3). 
If the cassette is found to have no memory, the recording/reproducing 
apparatus 4a checks whether or not the write-protect hole has been 
detected (step S4). If the write-protect hole has been found, data 
recording is disabled (step S5); otherwise, data recording is enabled 
(step S3). 
In FIG. 4(b), the recording/reproducing apparatus 4b incompatible with the 
memory-based recording medium cassette checks a loaded cassette for memory 
(step S6) and checks a state of the write-protect hole of the cassette 
(step S9). If the loaded cassette is found having no memory and its 
write-protect hole is found open, data writing is disabled (step S8); if 
the write-protect hole is found closed, data recording is enabled (step 
S10). In the case of a memory-based recording medium cassette (a "yes" 
answer at step S6), its write-protect hole is open (step S7), so that data 
recording is automatically disabled (step S8). Consequently, there is 
always a correlation between the contents recorded on the recording medium 
of the cassette and the recording information stored in its memory. 
In a second embodiment of the invention, means for determining whether a 
recording medium cassette is provided with memory or not is provided 
separately. For ease of understanding, elements shown in the first 
embodiment are assigned the same reference numerals. 
In FIG. 5(a), a recording medium cassette 1c provided with memory has a 
memory 3, a write-protect hole 2, and a memory detection hole 11. 
Description of features described above in connection with the 
above-mentioned first embodiment will be omitted. 
Unlike the write-protect hole 2 of the first embodiment, the memory 
detection hole 11 serves to indicate whether or not the recording medium 
cassette is provided with memory. 
To be specific, in FIG. 6, the memory detection hole 11 of the recording 
medium cassette 1c provided with memory is disposed near the write-protect 
hole 2 of the recording medium cassette 1 for example. The memory 
detection hole 11, which is open from the beginning, indicates that the 
cassette is provided with memory. The write-protect hole 2 is provided 
with a slidable tab, in contrast to the write-protect hole of the first 
embodiment. 
In FIG. 7, a memory detection hole 11 of a recording medium cassette 1d 
provided with no memory is closed with a tab 11a from the beginning. This 
closure indicates that the cassette is provided with no memory. A 
write-protect hole 10 of this cassette is provided with a slidable tab 
like the write-protect hole of the first embodiment. 
Meanwhile, as FIG. 5(a) shows, a recording/reproducing apparatus 4c 
comprises a microcomputer 6c, a detector 7c for detecting whether a 
recording medium cassette is enabled or disabled for recording, a recorder 
8c for recording through a head 9c, a memory detector 13a, and an 
interface 5 for communication with memory. 
The memory detector 13a detects the state of the memory detection hole 11, 
or determines whether or not the recording medium cassette is provided 
with memory. This memory detector 13a is provided separately from the 
detector 7c for determining whether recording of data is enabled or 
disabled. 
A recording/reproducing apparatus 4d incompatible with the memory-based 
recording medium cassette comprises a microcomputer 6d, a detector 7d for 
detecting whether a recording medium cassette is enabled or disabled for 
recording, a recorder 8d for recording through a head 9d, and a memory 
detector 13b. 
In FIG. 8, when the recording medium cassette 1c provided with memory or 
the recording medium cassette 1d provided with no memory is loaded in the 
recording/reproducing apparatus 4d incompatible with memory, the memory 
detection hole 11 is first detected (step S11). If the recording medium 
cassette is found to have memory, the recording/reproducing apparatus 
unconditionally disables data recording regardless of the state of 
write-protect holes 2 and 10 of the recording medium cassette (step S14). 
When the recording medium cassette 1d provided with no memory is loaded, 
the recording/reproducing apparatus disables or enables data recording 
according to the state of the write-protect hole. That is, if the 
write-protect hole is found at step S12, recording is disabled (step S14); 
if the write-protect hole is not found at step S12, recording is enabled 
(step S13). 
The recording/reproducing apparatus 4c compatible with the memory-based 
recording medium cassette can also check for the memory as mentioned above 
without using the memory detection hole 11. That is, the 
recording/reproducing apparatus sends a data read instruction to the 
cassette. Then, if data are returned in response to the instruction, the 
apparatus determines that the cassette has the memory; if data are not 
returned, the apparatus determines that the cassette has no memory. 
In FIG. 9, the recording/reproducing apparatus 4c compatible with the 
memory-based recording medium cassette first checks the recording medium 
cassette for memory (step S15). If the cassette is found to have memory, 
the recording/reproducing apparatus detects the state of the write-protect 
hole 2 of the recording medium cassette 1c (step S18). If the state of the 
write-protect hole 2 is found in the recording enabled state, the 
recording/reproducing apparatus reads recording information from the 
memory 3 of the cassette 1 to determine whether a recording flag is 
enabled or disabled for recording (step S19). 
If the recording flag is found enabling, it is ready to record data on the 
recording medium of the cassette 1 (step S20). If the recording flag is 
found disabling, recording is disabled at step S17 despite the 
determination of the state of the write-protect hole 2 at step S18. 
Meanwhile, if the write-protect hole 2 is not detected at step S18, the 
recording/reproducing apparatus determines that recording is disabled, 
unconditionally putting the cassette in the recording disabled state at 
step S17. In contrast to the first embodiment, the determination of the 
state of the write-protect hole is preferred to the recording 
disable/enable flag. 
If step S15 if the cassette is found to have no memory, or the recording 
medium cassette 1d provided with no memory has been loaded, the 
recording/reproducing apparatus checks the state of the write-protect hole 
(step S16). If the write-protect hole is found disabling, the 
recording/reproducing apparatus puts the cassette in the recording 
disabled state (step S17); if not, the recording/reproducing apparatus 
puts the cassette in the recording enabled state (step S20). 
In the cases described so far, loading the memory-based recording medium 
cassette into the recording/reproducing apparatus incompatible with the 
memory-based recording medium cassette automatically disables data 
recording. A third embodiment of this invention, however, is provided with 
means for storing data (a tape content rewrite flag) in the memory of the 
recording medium cassette 1. This data indicates, when the memory-based 
recording medium has been loaded in the recording/reproducing apparatus 
incompatible with such a cassette, that there is a mismatch between 
recording information stored in the memory and data recorded on the 
recording medium of the cassette. 
In the third embodiment, shown in FIG. 11, the memory-based recording 
medium cassette and the recording medium cassette having no memory have 
the same constitution; that is, each comprises a cassette case 21, a 
write-protect hole 22, a slidable lug 30, and a tab 29 operatively 
associated with the slidable lug 30. 
In FIG. 10, a recording/reproducing apparatus compatible with the 
memory-based recording medium cassette and a recording/reproducing 
apparatus incompatible with the memory-based cassette have the same 
constitution; that is, each comprises an interface 25, a detector 27, a 
recorder 28 that records through a head 28a, and a microcomputer 26. 
However, in the recording/reproducing apparatus incompatible with the 
memory-based cassette, the microcomputer 26 is provided with a capability 
for rewriting a particular area in the memory of the memory-based 
cassette. In the recording/reproducing apparatus compatible with the 
memory-based cassette, the microcomputer 26 is provided with a capability 
for rewriting the entire memory area of the memory-based cassette. 
In FIG. 12, when the memory-based cassette is loaded in the 
recording/reproducing apparatus incompatible with such a cassette, the 
recording/reproducing apparatus first checks the cassette for memory (step 
S21). The determination whether or not the cassette is provided with 
memory is done in the same way as in the second embodiment and therefore 
need not be described again. 
If the cassette is found to have memory, the recording/reproducing 
apparatus checks the write-protect hole 22 (step S22) of the cassette to 
determine its state. If the write-protect hole 22 is detected or is found 
open, it indicates that the recording of data on the cassette is disabled, 
and the cassette is put in the recording disabled state (step S25). If, on 
the other hand, the write-protect hole 22 is not detected or is found 
closed, it indicates that data recording is enabled. In this case, the 
recording/reproducing apparatus at step S23 sets the tape content rewrite 
flag which indicates a mismatch between recording information stored in a 
memory 23 of the memory-based recording medium cassette 1 and data 
recorded on the recording medium of the cassette and then puts the 
cassette in the recording enabled state (step S26). 
If at step S21 the cassette is found to have no memory, the 
recording/reproducing apparatus checks the write-protect hole 22 of the 
recording medium cassette to determine its state (step S24). If the 
write-protect hole 22 is not detected, it indicates that data recording is 
enabled, putting the cassette in the recording enabled state (step S26). 
If the write-protect hole 22 is detected, it indicates that data recording 
is disabled, putting the cassette in the recording disabled state (step 
S25). 
Thus, even the recording/reproducing apparatus incompatible with the 
memory-based recording medium cassette can record data on the recording 
medium of the memory-based recording medium cassette. By setting the tape 
content rewrite flag in the memory, a mismatch, if any, between the data 
recorded on the recording medium and the recording information stored in 
the memory can be identified later. 
That is, when the recording medium cassette provided with the memory 
containing such a mismatching information is later loaded in the 
recording/reproducing apparatus compatible with the memory-based recording 
medium cassette, the tape content rewrite flag indicating the mismatch is 
first read and displayed, informing a user thereof very easily. 
To be more specific, in FIG. 13, if at step S27 the tape content rewrite 
flag indicates rewritten data, it shows that there is no correlation 
between the recording information stored in the memory and the data 
recorded on the recording medium, and the recording/reproducing apparatus 
asks the user whether the recorded data is to be erased (step S29). If the 
recorded data is to be erased, the cassette containing it becomes 
recordable as an unrecorded cassette (step S31). If the recorded data is 
not to be erased, the cassette may be reproduced to correct the 
information in the memory (step S30). If at step S27 it is determined that 
the tape content rewrite flag is not set, the recording/reproducing 
apparatus realizes that there is no mismatch between the recording 
information stored in the memory of the recording medium cassette and the 
data recorded on its recording medium and enters a normal memory-based 
recording/reproducing mode (step S28). 
Accordingly, previously breaking the recording enable/disable tab provided 
on the memory-based recording medium cassette prevents data recorded on 
the cassette from being written over and ensures that there will be no 
mismatch between the recording information stored in the memory of the 
cassette and the data recorded on the recording medium of the cassette. 
Providing the recording medium cassette having no memory with the slidable 
recording enable/disable tab disallows easy rewriting of recorded data 
when the recording medium cassette having no memory is loaded in the 
recording/reproducing apparatus compatible with the memory-based recording 
medium cassette. 
Providing a write-protected data area in the memory of the memory-based 
recording medium cassette and disabling data writing based on the data in 
the write-protected data area makes it possible to partially rewrite the 
recorded data by disabling data recording even if data recording is 
enabled by the detection hole. 
Providing a recording medium cassette with detecting means for checking the 
cassette for memory prevents an inadvertent recording even on the 
recording/reproducing apparatus incompatible with the memory-based 
recording medium cassette. 
Providing the memory of the memory-based recording medium cassette with an 
area in which to save the flag indicating a mismatch between the recording 
information stored in the memory and the data recorded on the recording 
medium of the cassette facilitates detection of the mismatch. 
While the preferred embodiments of the invention have been described using 
specific terms, such description is for illustrative purpose only, and it 
is to be understood that changes and variations may be made without 
departing from the spirit or scope of the appended claims.