Sheet feeding or delivering – Feeding – Separators
Patent
1996-05-03
1998-01-20
Skaggs, H. Grant
Sheet feeding or delivering
Feeding
Separators
271106, 235 98R, B65H 308
Patent
active
057093784
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a sheet counter, and in particular to a counter intended to count the number of sheets in a stack by operating on a corner region of that stack.
A known form of sheet counter has an elongate element usually in the form of a blade, and an elongate member arranged with its axis substantially parallel to that of the element and mounted to orbit around the element. During this orbiting movement, the element performs a synchronised essentially-rocking movement. The element has at least one port in its outer surface through which air is drawn by a low pressure source. Counting is performed by positioning the element at the corner region of one end of the stack of sheets to be counted, drawing air through the port and then driving the pin to orbit round the element whilst simultaneously rocking the element, thereby transferring sheets from one side of the element to the other. Such a sheet counter will hereinafter be referred to as a "sheet counter of the kind described".
In a sheet counter of the kind described, it is usual to generate a count signal by monitoring the pressure in a duct connected to the port in the elongate element. Each time a sheet corner is pulled onto the element by the air being drawn through the port, that port is covered and the pressure in the duct will drop. This drop in pressure can be detected and used to produce a count signal. A reduction in erroneous counts may be achieved by including a position sensor for the elongate member, whereby a count signal may be regarded as valid only if it is generated at the time a sheet to be counted may be expected to lie over the port.
Usually, in a sheet counter of the kind described, the elongate member is in the form of a pin. Often, the elongate element is in the form of a blade since this allows the easy insertion thereof into the corner region of a stack of sheets to be counted. In order to minimise the separation of sheets to each side of the counter in a stack, it is desirable for the motion of the pin closely to follow the surface of the blade, which latter usually performs a rocking motion. In this case, the motion of the pin around the blade has to be complex and various mechanisms have been designed to achieve this.
One design of such a mechanism is disclosed in GB-1,426,523-A. This mechanism aims at having the pin more closely follow the outer periphery of the blade whilst that blade itself performs a rocking movement, in order to minimise the required separation of sheets in the corner region of a stack. In GB-1,455,109-A a more complex mechanism is disclosed, and yet another mechanism is disclosed in GB-2,106,871-A. Here, the rocking movement of the blade has been increased in order to enhance the sheet-separation characteristics of the counter and so to reduce the likelihood of erroneous counts, but the required mechanism to have the pin closely follow the movement of the blade is necessarily complex.
In all the prior art designs, the mechanisms are complex and relatively large. The complexity gives rise to lower reliability and the appropriate adjustment of the mechanisms can be difficult to set accurately. The physical size of the prior designs does not allow for the production of a compact unit, which therefore leads to further difficulties in controlling the vertical movement of the counter and its positioning closely adjacent a corner region of a stack of sheets to be counted.
The present invention results from attempts to reduce the complexity and physical size of the linkage required to cause the pin to perform an orbit around the outer surface of a blade, whilst at the same time allowing that blade to perform a relatively large rocking movement to enhance sheet separation.
According to the present invention, there is provided a sheet transfer mechanism comprising an elongate element adapted for insertion into the corner region of a stack of sheets, an elongate member arranged to extend substantially parallel to the elongate element, and means mounting the elongate member to orbit around the elongate
REFERENCES:
patent: 3801777 (1974-04-01), Onoe et al.
patent: 5133540 (1992-07-01), Suzuki et al.
Pelcombe Limited
Skaggs H. Grant
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