Balance with counting scale

The invention indicates a balance with counting scale in which the resolution of the balance with counting scale can be increased in the determination of the reference weight of light pieces without an additional switching key operated from the outside. To this end, a comparator (14) is present in the built-in electronic circuitry which is actuated when the transfer key (8) is pressed and which frees the transfer of the weight into the memory (16) and the determination of the average individual weight when a set threshold is exceeded, while, when this threshold is dropped below, it does not free the transfer of the weight into the memory and increases the resolution of the balance by a given factor.

BACKGROUND OF THE INVENTION 
The invention relates to a balance with counting scale with a tare key for 
setting the display to zero and with a transfer key which can bring about 
the transfer of the weight of a certain number of pieces for determination 
of the average individual weight into a memory of the built-in electronic 
circuitry. 
This type of balance with counting scale is generally known; e.g. DE-OS No. 
32 15 962 describing a special embodiment. 
Balances with counting scale generally require a very great resolution, 
since on the one hand great quantities are weighed and therewith counted 
on the balance, yet, on the other hand, very small loads must also be 
weighed sufficiently accurately in order to determine their individual 
weight. Therefore, dual-function balances are frequently used as balances 
with a counting scale. The determination of the individual weight is then 
performed in the more sensitive range and the determination of larger 
quantities in the coarse range, i.e. less sensitive. 
These dual-function balances with counting scale have the disadvantage that 
another key and another switch are required to switch from one function to 
the other, thus making the operating panel of the balance less compact. 
The invention therefore has the objective of improving a balance with 
counting scale of the type initially mentioned in such a manner that it is 
possible to change the balance resolution without the balance requiring a 
separate function switching key. 
SUMMARY OF THE INVENTION 
The invention achieves this as follows: A comparator is present in the 
built-in electronic circuitry which is actuated when the transfer key is 
pressed and which frees the transfer of the weight into the memory and the 
determination of the average individual weight when a set threshold is 
exceeded, while, when this threshold is dropped below, it does not free 
the transfer of the weight into the memory and increases the resolution, 
i.e. sensitivity of the balance by a given factor. 
Thus, the enlarging of the balance resolution occurs automatically as soon 
as the net value in the display drops below a certain, i.e. selected 
threshold when the transfer key is pressed. 
The change in the balance resolution is advantageously indicated to the 
user in the balance display panel. This can occur, for example, by causing 
an additional symbol to light up or by a blinking of the weight display. 
It is advantageous if the balance with counting scale comprises another 
comparator which switches the balance resolution to its normal value if 
another, larger threshold is exceeded, in order to avoid false weighings 
with the increased resolution in the case of large loads.

DETAILED DESCRIPTION OF THE INVENTION 
The balance with counting scale shown in FIG. 1 consists of housing 1, 
balance scale 2, display panel 3 and operating keys 7, 8 and 9. Display 
panel 3 includes digital display 6, display 5 of the measuring unit, e.g. 
"g" when weighing or "C" (=count) when counting, and panel 4 for 
displaying additional symbols. In FIG. 1 the additional symbol ".times.10" 
is being displayed. Operating key 7 is for taring, that is, for setting 
the display to zero, transfer key 8 is for transferring weight of a given, 
counted reference amount and the other key 9 is for switching as desired 
between counting and weighing. 
The operation of the balance with counting scale is apparent from the block 
diagram in FIG. 2 and the associated flow chart in FIG. 3. The gross 
measured value coming from measured value receiver 10 of the balance is 
digitized, if it is not already in digital form, in analog-to-digital 
converter 11 and supplied to taring unit 12. There, the stored value is 
subtracted in a known manner in tare memory 13 from the current measuring 
value and the net value is formed in this manner. Tare key 7 loads tare 
memory 13 thereby. The net value is supplied via lead 20 to arithmetic 
unit 15 and is passed unchanged from there, e.g. during the weighing 
operation, to display panel 3 and displayed as weight value 6 with the 
unit symbol 5 "g". The net value is supplied further via lead 21 to 
comparator 14, where it is compared with a set threshold of e.g. 20 
digits. After the given quantity (e.g. 10 pieces) has been placed on 
balance scale 2, comparator 14 is actuated by actuating transfer key 8. If 
the net value exceeds the set threshold thereby, a signal appears on 
output 22 of comparator 14. This signal controls unit symbol "C" in 
display panel 3 and also brings it about that in arithmetic unit 15 the 
net value is retrieved into memory 16, the average individual weight of 
the placed pieces is calculated therefrom and the net weight values 
supplied via lead 20 are divided by the average individual weight and 
passed on therewith as an indication of quantity to display panel 3. This 
terminates the customary initializing process of the balance with counting 
scale. 
If, however, the net value is smaller than the set threshold of e.g. 20 
digits when transfer key 8 is actuated, then no signal appears on output 
22 of comparator 14, but rather output 23 carries a signal. After this 
signal passes through AND gate 18, it causes additional symbol 
4".times.10" to be selected in display panel 3, analog-to-digital 
converter 11 to determine the current weight value with a resolution 
increased by a factor of 10, e.g. by extending the integration time by a 
factor of 10, and causes the tare value in tare memory 13 to be shifted 
correspondingly by a decade, so that the net value on the output of taring 
unit 12 is likewise available with a 10 times greater resolution. Output 
23 has a storing function thereby, i.e. the signal on output 23 remains 
until a new comparison with the set threshold occurs by pressing transfer 
key 8 again. 
Thus, the balance with counting scale of the invention automatically 
switches to a higher resolution when the weight of the pieces to be 
counted is too small. The operator recognizes this switching by the 
illumination of additional symbol 4 in display panel 3 and can let the 
average individual weight determined more precisely by a factor of 10 be 
transferred into memory 16 of arithmetic unit 15 by pressing transfer key 
8 again. It is assumed thereby that the net value exceeds the set 
threshold of e.g. 20 digits with 10 times greater resolution. If this is 
not the case, the resolution could be raised again by a factor of 10, if 
the construction of the balance permits, (with the display of the 
additional symbol ".times.100"), or the reference quantity assumed to be 
10 pieces in the example can be raised to be 20 pieces (indicated to the 
operator by an additional symbol "add 10", or the pieces to be counted are 
finally rejected as being too light for the balance with counting scale 
used (as is indicated in the flow chart of FIG. 3). Any expert can readily 
execute details of these embodiments. The second comparator 17 shown in 
FIG. 2 has the function, in conjunction with AND gate 18, of limiting a 
weighing with the increased resolution to small loads, e.g. 5% of the 
weighing range. The threshold in this comparator 17 is set at this 5% of 
the weighing range. Thus, the output only emits a signal in the case of 
net values below 5% of the weighing range, so that gate 18 remains open 
only in this range. 
The operating person can of course also press transfer key 8 when no 
reference pieces have been set, that is, when the net weight is zero, thus 
naturally also passing automatically into the operating mode with 
increased resolution. 
Various embodiments of the invention are naturally possible: Thus, for 
example, increased resolution can be indicated to the operating person by 
a blinking of the display instead of by the illumination of an additional 
signal. Or, the hardware components in FIG. 2 can be replaced by a 
microprocessor which comprises dotted area 19 and in which the individual 
operations are performed by software.