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Description  |
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BACKGROUND OF THE INVENTION
This invention relates to tachographs for motor vehicles, and particularly
to tachographs for use on motor vehicles, such as trucks driven by
professional drivers, for the purpose of recording data such as the time
of day, the date, the driver's service hours, the driver's driving times,
the driver's standby times, the driver's rest times, the distance driven,
and the speed driven.
The invention is particularly directed to such tachographs using various
signal transmitters for obtaining the data, and a microprocessor for
utilizing the data to determine other data such as distance and speed.
Tachographs of this type are often legally prescribed for various types of
motor vehicles to acquire data describing the transport services being
performed in such a way that the data satisfactorily takes into account
the interest of the drivers, their employers, and the regulatory agencies
involved. The required data should offer the drivers proof of service or
work time which is easily readable at any time, that is, readable at any
time without technical input, preferably in the form of "hard", i.e.
printed, copy. The data should enable those in charge of a carpark or
garage to easily monitor the business use of the vehicles, and the
organizational consequences resulting from such use. The data should
permit the official regulatory agencies a quick overview of the driver
behavior and adherence to work time guidelines, safety regulations, and
what is called in some jurisdictions "social regulations". This
information should be available to the agencies during their examinations,
which are generally conducted as random samplings or spot checks.
This type of information has in the past been gathered with so-called disk
graphs (sometimes called tachograph charts or record charts) in the form
of polar-coordinate hard copy disks which utilize the angular displacement
as time. An analog radial displacement is indicative of such data as
speed, distance, fuel consumption, engine rotation rates, etc. Such disk
graphs have dispensed with the troublesome keeping of driving logs, and
allow consistent recording of data such as speed, distance, fuel
consumption, engine rotation rates, work-time data, driving time, ready
periods, and rest times. These are accomplished on a real time or clock
time basis in analog form. Such disk graphs or diaphragm disks are, per
se, documents with high density information which is easy to handle,
easily capable of being filed, and visually readable at all times. They
are capable of mechanical evaluation, although at considerable cost. Such
data carriers or data copies in the form of disk graphs are also
distinguished by the fact that all driving data of a transportation
commission, a shift, or a work day, can be overseen at a glance.
Furthermore, in identifying each data carrier with a person or driver, the
disk graphs are adapted in a particular manner to the requirements of the
practice of motor vehicle transportation with respect to changes of driver
in vehicle.
The weaknesses of systems using diaphragm disk or disk graph data carriers
reside chiefly in the recordings themselves. The weaknesses are revealed
during random spot checks of such data as rest periods to be observed,
when one wishes to gather numerical information from the drive data
recording in analog form on the disk graphs. These analog numbers are
reliable to some extent. Any resulting errors can be prevented only with a
substantial expenditure of time and evaluation experience. However, the
reconstruction of the speed history of a vehicle before an accident
situation is practically impossible. This is because the usual disk speed
of one revolution per twenty-four hours, furnishes a relatively low
resolution of the speed recordings, and requires considerable evaluation
experience, and costly measuring instruments.
This compromise of fixing the recording time horizon, i.e. the overall
recording time of a disk graph, at twenty-four hours is understandable for
practical reasons. However, many jurisdictions have a legal requirement
that the disks of the two preceding days must be available for inspection
by the driving personnel, must be taken into account as a further
disadvantage.
Moreover, acquiring drive data from a disk graph, fails to correspond to
modern ideas concerning the handling of hard copy data. Thus, it is also
understandable from this viewpoint, if the drivers have little affection
for the tachograph in general. Aside from the fact that the driver must
enter his personal data, and possibly other data, by hand before mounting
the disk graph onto the tachograph, the tachograph must be opened, the
disk graph must be threaded into the centering and carrying spindle, and
the cover of the tachograph must be closed again. This assumes that the
tachograph is equipped with a disk graph fastening arrangement which
becomes effective automatically when the cover is closed. Otherwise, the
fastening operation must be performed manually. If the vehicle's driver
has a co-driver or "partner", as required depending upon regulations based
on the tonnage or the distance to be driven, the insertion of the two
required disk graphs becomes a relatively arduous and expensive procedure.
It is a rather troublesome duty carried out in the morning in the cold,
and usually poorly lighted driver cab. In addition, some care is required
for handling of diagram disks because they must accommodate very fine
speed recording traces, and are therefore equipped with a special
recording layer which has the disadvantage of being sensitive to scratches
and pressure.
SUMMARY OF THE INVENTION
An object of the invention is to provide an improved tachograph.
Another object of the invention is to avoid the aforementioned
deficiencies.
Still another object of the invention is furnish a tachograph that to
avoids the deficiencies of diaphragm disk recording, but which can receive
driver-directed data carriers enabling changes of driver and vehicle in a
manner analogous to previously conventional driving data acquisition
devices, and which at all times permits a correct clock time or real time
drive data output which is particularly useful to drivers and
administrative agencies, without requiring additional technical evaluation
expenditure for its interpretation.
According to a feature of this invention, the tachograph is equipped with a
printing device, and a semiconductor memory with the driver's
identification card serves as a memory, while the work-time data and drive
data are written into defined memory areas of the data memory along with
specific data relating to the driver which is already entered when the
data card is inserted into the tachograph, and readout of the data memory
and print out of a tabular drive record are triggered by feeding a
sheet-type paper into the feed slot in the front of the tachograph.
According to a preferred embodiment of the invention, each operating change
entered into the tachograph, either from the vehicle's drive train or by
hand, transfers the values of the working time data occurring at that
moment into the data memory in correct clock time or real time, and an
additional memory area in the data memory continuously records at least
speed measurement values in intervals of one second, in accordance with
the order of magnitude, while a predetermined quantity of work-time data
records filed in the data memory generates a request for triggering a
driving record printout. The printout provides a substantially rectangular
paper or print carrier that carries the drive record with two equally wide
adjoining table sections that include work-time data records, and a speed
profile chart, and a table section containing speed measurement values and
having a total height equal to the height of the two other table sections.
According to a feature of the invention, the front face of the tachograph
includes a keyboard for receiving data.
The invention satisfactorily achieves it objects with surprisingly low
expenditures, particularly by requiring only one drive data acquisition
and drive record output device which, because of the keyboard, and the
front feed slots for the print carrier and cards, is particularly flat and
accordingly, well suited for installation in a dashboard. In addition, the
invention provides the advantage of preserving the drive data acquisition,
which is customary per se, with mobile driver-related carriers. Hence, no
noteworthy expenditure on adaptation to a new system is required, aside
from the obvious handling changes.
These and other features of the invention are pointed out in the claims.
Other objects and advantages of the invention will become evident from the
following detailed description when read in light of the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective drawing of a tachograph embodying the invention;
FIG. 2 is a view of a data card of FIG. 1;
FIG. 3 is a block diagram showing the different structural components of
the tachograph; and
FIG. 4 is an illustration showing a drive record.
FIG. 5 is a schematic representation of memory areas in a memory of FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown by FIG. 1, the tachograph according to the invention has an
installation housing 1 which is suitable for mounting in the dashboard of
a vehicle. The front of the housing forms the opening of a front feed slot
2 for receiving a sheet-type print carrier 3, openings of receiving slots
4 and 5 which accept the insertion of the drivers' data cards 6 and 7
constructed, for example, according to FIG. 2, as well as a display device
8 in the form of a line display. In addition, keys 9 and 10 are assigned
to respective drivers to feed in the work states "ready period" and "rest
time". The tachograph automatically recognizes the driving periods. By
actuating a key 12 or 13 corresponding the driver's or co-driver's
activity at the moment, each driver can have a drive record printed out by
a keyboard 11 when he (or she) introduces a print carrier 3 into the front
feed slot 2 and/or when he actuates a key 14 provided with a drive time
symbol. In addition, the driver can obtain a display for the length of
time he has already driven the vehicle or the time the driver can drive
until the next drive period interruption is due. On the other hand, if the
driver actuates a key 15 provided with the reset period symbol he can
display, for example, how much work time remains until the daily or
periodic rest period must be observed. The keys 16 and 17 are used for
selection and visualization of the work time data records written into the
data cards 6 and 7.
Preferably, the system program of the tachograph is structured such that
the tachograph guides the driver and promptly furnishes the driver with a
visual display, and an acoustical prompt, that signals the driver to avoid
violations against the safety regulations and work rules. For example, the
signals may inform the driver that it is time to take a break after a
four-hour uninterrupted drive, that the work time is concluded, that the
maximum allowable driving distance has been reached and a change of
drivers is due or, in order to ensure a consistent documentation of the
drive data, that a print-out of a drive record must be made.
FIG. 1 shows the latter state, i.e. the driver 1, who has driven or will
drive the vehicle, is required in plain language to insert a print carrier
3 which is drawn in by the tachograph and imprinted with the drive record.
The usual symbols display that ready time, which is evaluated as work
time, for driver 1, and rest time for driver 2, the co-driver, are entered
or written in the data memory of the respective data cards 6 and 7 when
the data cards 6 or 7 are removed from the tachograph or when the
tachograph receives information that the work time has changed. The latter
information is applied by actuating the keys or automatically, i.e. in
dependence on the drive, with a drive time symbol being displayed for
driver 1.
The block diagram, FIG. 3, shows that the different functional assemblies
of the tachograph, according to the invention, are connected with one
another via a bus system composed of a data bus 18, an address bus 19, and
a control bus 20. In particular, the tachograph includes a microprocessor
23 comprising a ROM 21 in which the system program is loaded, and
comprising a RAM 22, which serves as a work-time memory and is preferably
maintained by means of a maintaining battery, not shown. The maintaining
battery serves to maintain a voltage supply for the RAM, and thus make it
non-volatile. A clock or time data transmitter is designated 24. A display
device 25 produces an alphanumeric display and which is connected with the
bus system 18, 19, 20 via a multiplexing driver 26. A printing driver 27
preferably of the thermal printing type is series connected to an
interface circuit 28 and includes a switch 29 which is actuatable by means
of a print carrier (hard-copy) 3. An interface circuit 30 couples various
transmitters of quantities to be measured, for example, the rate of engine
rotation, the fuel consumption and the distance covered. An interface
circuit 31 connects static transmitters, particularly the keyboard 11 and
the keys 9 and 10, with the bus system 18, 19, and 20. Coupling devices 32
and 33 receive the data cards 6 and 7.
Preferably, data cards 6 and 7 each include an EEPROM, as a data memory 34,
and microprocessor 35 assigned to the latter. Data card 6 and 7, which are
shown in FIG. 2, include a handling-direction arrow, the name and birth
date and signature of the driver, and his officially registered driver
number. In contrast with a battery maintained RAM, this system dispenses
with buffer action. Although done at the cost of a limited operation
duration, discussed in more detail in the following, this system permits
serial data transmission between the bus system and the data memory 34.
Accordingly, it avoids an otherwise required multiplicity of plug contacts
which are susceptible to wear. A plug contact 13 is shown at 36. In
addition, the microprocessor 35 contains program sequences which serve for
data encoding, and it can be used for the purpose of transferring
functions of the microprocessor 23 into the data card 6 and 7.
As can be seen from FIG. 4, the tabular print-out of the data of the drive
record is applied onto the rectangular print carrier 3 substantially
within a simultaneously produced network or field 37 which, aside from a
heading section 38, in which designations of the date are printed out,
forms three table sections. Two equally wide table sections 39 and 40,
which adjoin one another in the vertical format, serve for receiving the
work-time data records on the one hand, and a speed profile diagram on the
other hand. A table section 41, which corresponds to the total height of
the two table sections 39 and 40 and is located at the side of the latter,
shows speed measurement values. In addition, the drive record is composed
of two title lines, not designated in more detail, which include the
record number, the output date, name and birth date of the driver and his
drivers license. It is also composed of a free space below, for
handwritten documentation and remarks regarding specially characterized
data, e.g. relevant for salary calculation, the free space being provided
with the references "location", "date", and "signature".
During the print-out of the drive record, the personal data of the driver
are requested from a defined memory area of the data memory 34 of the data
cards 6 or 7, the identification memory. An index or modifier memory area
also fixed in the data memory 34 of the data card 6, 7, includes a record
counter which is increased by "1" after every drive record print-out,
while the formal designations and the measurements of the network or field
37 are filed in the ROM 21 of the tachograph as background data, possibly
in different variants.
It is noted here that the operating memory assigned to the microprocessor
23, the RAM 22, serves particularly to update the long term data
concerning the vehicle, such as fuel consumption, kilometers or miles
driven, excesses of the engine rate of rotation, and also other data
important for the servicing of the vehicle. In addition, the kilometers
already driven or starting mileage, and the actual clock time at every
change of work shift is fixed in this memory in order that the differences
with respect to the then current data states can be calculated during a
subsequent change of the work state in the microprocessor 23. Moreover,
the distance-dependent pulses supplied by the microprocessor 23 during the
drive time, for example speed values measured with a time base of 1
second, are continuously written into the RAM 22. Various
simultaneously-calculated mean speed values are entered for time
compressions of different scales. In addition, the microprocessor 23 also
serves to determine the information already mentioned, such as "rest
driving period", "start of the daily rest period" from the work-time data
stored in the data memory 34 of the data cards 6 and 7.
The work-time data records shown in the table section 39 are written into a
work-time memory, an additional memory area of the data memory 34 of the
data card 6 or 7. A complete work-time data record is filed in the
work-time memory, in each instance, when the work state or shift changes.
That is, the microprocessor 23 determines factors such as the time
difference between the start of a drive, which is detected through the
occurrence of "path" pulses, and leads to the formation of an address
which is typical of the driving period, and the standstill of the vehicle,
as well as the distance covered in so doing. After a certain waiting
period, which is usually not evaluated as a driving period interruption in
order to suppress stopping periods at traffic lights and in traffic jams,
the microprocessor supplements the partial data record composed of clock
time and device number, which is already written in at the start of the
drive, to form a complete work-time data record composed of clock time,
driving period, distance covered, and device number, and simultaneously
stores the partial data record for the following work state or shift. The
partial data record is generated for the stopping time point and includes
clock time and device number.
During the acquisition of the remaining work-time data, that is the ready
periods and the rest periods, the system furnishes a time delay for the
supplementing process, and accordingly completion of a work-time data
record and a writing in of a new partial data record in the work-time
memory. This prevents the limited print area in the drive record provided
for the work-time data record, table section 39, from receiving voids or
false work-time data records that may result, for example, from incorrect
key actuations. Only removal of a data card 6 or 7 effects completion of
the running work-time data record directly by actuation of the removal
switch 42. According to an embodiment of the invention, a mechanical timer
delays removal of the data cards 6 and 7 to ensure a positive conclusion
of the data transmission.
Furthermore, additional memory locations are reserved in the modifier or
index memory to fix the quantity of work-time data records written into
the work-time memory since the last drive record print-out, and a demand
for the print-out of the drive record is generated promptly before
reaching the maximum possible number of print lines in the table section
39. This overcomes the limited number of print lines in the table section
39 of the drive record and allows the system to meet legal or other
requirements that complete work time documentation must be available for
proof. According to an aspect of the invention, when the demand for
print-out occurs, locking facilitates lock the data cards 6 and 7 the
drive record can only be removed from the tachograph when the print-out is
effected. Preferably, additional memory locations are held open in the
modifier or index memory to serve as an hour counter. This would satisfy
another conceivable requirement that the drive records are to be produced
after a certain time segment.
According to the above, the following can be seen from the work-time data
records of the drive record according to FIG. 4, which was produced on
1/22/1985. This includes only the absolutely necessary data, since fuel
consumption, speeding and diverse references, e.g. to non-compliance with
a print-out demand, are not printed out.
The most recent complete work-time data record contains a km indication of
189.7. At time 04:58 hours (on a 24 hour time scale, e.g. 4:58 A.M.) the
vehicle with tachograph No. 76 was set in motion, and driven for 3 hours
and 42 minutes until it stopped at 08.40 hours (i.e. 8:40 A.M.). The
previous work-time data record shows that the driver had been ready since
01:20 hours and hence, presumably active as co-driver (or the driver's
partner) 3 hours and 38 minutes, and that he had previously observed a
rest period of 1 hour and 30 minutes beginning at 23:50 hours or 11:50
P.M. of the preceding day. The previous work-time data record is in turn
generated for a drive which began at 19:05 hours or 7:05 P.M., and during
which 152.9 kilometers were covered. The uninterrupted driving period of
4.45 hours determined for this drive clearly exceeds the 4 hour limit,
i.e., there is a violation of work time guidelines.
Before the drive, the driver had a rest period of 15 minutes from 08:50
hours to 19:05 hours, and before this he was obviously active as co-driver
for 3 hours and 15 minutes beginning at 1500 hours or 3 P.M. During this
time, a drive record was retrieved, possibly in the course of a police
check or that of another authority, which is characterized by an empty
line provided with a dotted line 43. The older work time data are
accordingly already printed out on the drive record No. 78 of 1/21/1985.
They show that before resuming his duty on 1/21/1985 at 1500 hours or 3
P.M., the driver left another vehicle with the tachograph device number 91
25 hours ago on 1/20/1985 at 1400 hours or 2 P.M. In this vehicle, he was
in transit on 1/20/1985 from 09:10 or 9:110 A.M. to 13:10 hours or 1:10
P.M. for four hours, covered 184.2 km, and then carried out another
activity for 50 minutes before he removed his data card from the
tachograph and left his "vehicle" work area.
The interpretation of the work-time data records will cease here in order
to avoid repetition, but it is still a matter of interest to know whether
the driver observed the legally prescribed daily rest period in the time
period interpreted; this poses a decisive question for the control or
safety agencies, and can be separately removed from the driving record.
Some jurisdictions set up three daily rest period categories according to
the type of conveyance and vehicle equipment. In one case, there must be
10 consecutive hours of rest time within 24 hours before starting work; in
another case there must also be 10 hours of uninterrupted rest time within
27 hours, and in the third case 8 hours uninterrupted rest time within 30
hours.
Starting from the stop time of the vehicle at 08:40 hours, it can be seen
that the driver would not violate the regulation only if he drives a
vehicle of the latter category, which is occupied by two drivers, and must
be equipped with a sleeping compartment.
With respect to the formation of the driving record, it is noted that empty
lines can be provided, particularly after longer rest periods, between the
work-time data records in which handwritten comments can be entered, for
example, vacation, absences due to illness or work times which could not
be detected by the tachograph.
A profile memory area is provided in the data memory 34 of the data card 6
or 7. The profile memory receives the values of eight predetermined speed
groups. The values serve to form a speed profile, and are determined
according to a specific computational mode of the microprocessor 23. The
speed profile shown in the table section 40, and received over a time
period of 8 hours, gives information on types of streets which were
traveled, and accordingly, on the use of the vehicle. The rest period
above shows that the vehicle is a heavy transport vehicle rather than a
bus, and that the driver drove at excess speeds (bars 44). This factor is
one which should not be overlooked.
Another memory area of the data memory 34 of the data card 6 or 7, the
speed memory serves to continuously write in the speed values which are
simultaneously stored in the RAM 22. That is, it serves for the real time
storage of the actual speed measurement values, wherein the measurement
base of one second (1 S) is a sufficient resolution for the driven speed.
It also serves for accident evaluation. The storage of average speed
values with a time base of, e.g., 10 seconds, which is already a
considerably enlarged time based on horizon, is still relatively high in
comparison to the visual evaluating ability of analogous prior art diagram
disk recordings. It also provides a storage of average speed values with a
time base of, e.g. 5 minutes, which allows detection of at least the
driver's daily allowable driving time.
In order for the drive record to show time horizons or time bases which are
as wide as possible, the table section 41 provided for the speed display
corresponds to the maximum possible length in the drive record. For the
sake of simplicity, only two columns of speed values are printed out in
FIG. 4. Column 45 shows the actual measured speed values, column 46 shows
the mean values corresponding to a time base of 10 seconds. The speeds
shown are the most recent performed by the vehicle.
It can be seen from column 45 that the driver braked relatively sharply at
08:40 hours, approximately 15 seconds before the final stop, and
afterwards performed two braking pumping movements with the vehicle. It is
also conceivable that emergency braking was necessary because the wheels
locked and the vehicle could only be brought to a standstill after two
additional applications of the brakes.
This speed information, which is decisive for a possible accident
evaluation, and for which neither special devices nor specialists are
required, should, of course, not be erased from the speed memory by
generating additional 00 speed values. Therefore, the system interrupts
the reading in of 00 speed values after, e.g. five 00 speed values, i.e.
when the standstill of the vehicle can clearly be assumed, and the start
time is again read into the speed memory when the vehicle is started
again.
For the sake of completeness, it should be noted that the real time storage
of the speed measurement values every second in the data memory 34, for
realization of a satisfactory time base, requires in a considerable
memory. However, this is only available tentatively because of the rest of
the memory tasks and the limited total memory capacity of 2K bytes. On the
other hand, the operating memory duration of EEPROMs is limited, namely,
by a predetermined quantity of erasures and memory locations. Hence, with
a give memory location, a compromise must be found between the operating
duration of the data cards 6 and 7 and the time base of the real time
storage of the speed measurement values, i.e. the accuracy of the speed
measurement. The latter is of considerable importance with respect to a
reliable accident evaluation.
The following rough estimate shows the relations:
______________________________________
Assuming 48 hours
the driving time/week
then, per year, it would amount to
45 .times. 48 = 2,160
hours
The quantity of the erasure cycles/
50,000.
memory locations can be
assume today at
The desired operating duration of
3 years.
the data card 6, 7 should amount to
at least
As a result, a time horizon (base) is to be realized on the
##STR1##
card amounting to 466 seconds
With a measuring clock of one
466 .times. 8 bits.
cycle per second, this time base
requires a memory of
______________________________________
This memory requirement can be easily realized on the data card so that an
operating duration of 4 years can also be available, all things remaining
the same.
This computation example further shows that the operating duration of the
data cards 6 and 7, or the data memory 34, and the time horizon to be
realized are directly proportional. If, for example, a higher measuring
accuracy is desired, either the expectations of the operating duration are
curtailed, or more memory locations must be provided. In other words, the
limited memory capacity of the data cards 6 and 7 results in a limited
operating duration, and this magnitude must be monitored in a suitable
manner. The total driving time, which is cumulative with respect to hours
and for which the required memory location must be held ready in the
modifier memory, is available as a measurement for this. However, the
operating duration of the data cards 6 and 7 with the data memory 34 is
determined by means of the contact elements for which, at this time, a
quantity of 5,000 connections or insertions are indicated. In order to
monitor this, the system makes sufficient memory locations available in
the modifier or index memory.
Accordingly, memory locations are to be held ready at least in the modifier
or index memory for the cumulative total driving time and the quantity of
card connections or insertions. These serve as characteristic magnitudes
for the operating duration of the data cards 6 and 7 on the one hand. On
the other hand, the quantity of work-time data records, the quantity of
printed out drive records, and the time after the last drive record
print-out serve as characterizing magnitudes for a continuous work time
documentation.
As stated, the EEPROMS of cards 6 and 7, permit only a limited number of
overwriting operations, and have a relatively small memory capacity, i.e.
there exists an operating duration problem in the EEPROM data memory
implanted in the data cards 6 and 7. Hence, it is advisable that the data
of the modifier or index memory, and preferably the data of the profile
memory, not be updated in the data memory 34 of the data cards 6 and 7,
but rather, that the work memory of the tachograph, the RAM 22, be used
for this. According to an embodiment of the invention the RAM 22 is used
for this purpose. The respective actual data states are only written into
the memory areas of the data memory 34 of the data cards 6 and 7, which
are held ready, when the data cards 6 and 7 are to be removed from the
tachograph. This is signaled by actuating the removal switch 42. On the
other hand, when a data card 6 or 7 is again introduced into the same or
another tachograph, the data of the modifier or index memory and of the
profile memory, is loaded back into its work memory and is updated or
newly provided there.
According to the invention, the drive record is reproducible at all times
in plain language, as well as in machine readable form. The record is
optimized in terms of the interest of the driving personnel, the business
in charge of the garage, and the official regulatory agencies, with
respect to the presentation of data and the availability to all. In
particular, it provides an easily readable proof of work time and service.
Also, it offers the possibility of determining the speed picture before an
accident or a near accident situation. It offers those in charge of the
carpark or garage an overview of the driving behavior of the driver, and
the workload or use periods of the vehicles. This overview is immediate,
and often sufficient because of the enlarged time base or horizon compared
to that of conventional disk graphs. It offers the official regulatory
agencies the possibilities of reconstructing the force of speeds before an
accident, and of producing a duplicate of the driver record without
requiring additional technical auxiliary means for this purpose. Moreover,
the drive record, which is constructed in a particular manner so as to
suitable for monitoring or checking, makes it easier for the regulatory
agencies to check that safety and social regulations as well speed limits
are observed.
In addition, it is noted that the previous danger of manipulation and loss
of driving records is extensively reduced by a continuous numbering of the
drive record which is possible without special expenditure, and can be
supplemented by official registration of the data cards. Another advantage
of the invention resides in that the driver in every vehicle equipped with
the corresponding tachograph is not only automatically guided by means of
the display device assigned to the tachograph, but can himself also
request preventive information at any time. This preventive information
can, for example, be the specially critical work-time data, daily driving
time, daily rest time, and uninterrupted driving time.
In addition, a data card with a semiconductor memory, when compared with a
magnetic memory data card or the like, has a greater memory capacity, and
is more secure from disturbance and counterfeiting. Aside from the plug
contacts, it is not burdened by the problem of abrasion and resistance. On
the other hand, it requires no movable converter for writing and reading
data. Superimposed writing caused by impact in case of an accident,
something that often makes exact evaluation of diaphragm disks or disk
graphs impossible, are eliminated.
Furthermore, currently available data cards with 2K byte data memories make
the time base or horizon of the storable work-time data and speed values
considerably greater than can be shown, or should be shown for the sake of
clarity, with a handwritten driving record. Because of the discovered data
optimization, these means allow the data card also to be used as a data
carrier for the carpark or garage organization, when, for example,
different data relating specifically to the vehicle, e.g., the actual
mileage state, the fuel consumption, and the like, is additionally written
in when the data card is removed from the tachograph. The data carrier can
be read, for example, at weekly intervals at a central garage with an
electronic data processor and can be evaluated together with transport
documents according to the viewpoint relating to the organization of the
garage.
FIG. 5 is a schematic representation of various memory areas in the memory
34. The latter includes the index memory area 50, the record counter 52,
the personal data area 54, the work-time memory area 56, the profile
memory area 58, and the speed memory area 60. It should be noted that this
showing is schematic only and does not represent the spatial distribution
of these areas.
While embodiments of the invention have been described in detail, it will
be evident to those skilled in the art that the invention may be embodied
otherwise without departing from its spirit and scope.
* * * * *
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