Photo-Resistor Based Programming Device for Cycled Processes Control The device is intended for application in the periodical and cyclic processes in which one or more parameters are time-dependent.

A pre-programmed function (curve) of the controlled parameter variation can be updated in the simplest way if necessary (e.g. the hydrolyze apparatus pressure in the agriculture waste treatment; the temperature in the steam-curing chamber, etc.).

Devices are known in which the programming is performed by using templates, sets of switched resistors or by entering the program into the processor memory.

In the intended device (Fig. 1), a photo-resistor matrix is installed in which the columns (vertical lines) of photo-resistors 2 are connected to the outlet load circuit via the corresponding thyristors connected to the pulse counter outlet. A parameter variation curve to be programmed is traced to the trace-paper.

The diagram 1 surface above that curve is blackened. The matrix is covered by the trace-paper. The power switches, e.g. thyristors 4 controlled by the pulses from decimal counter 5 connect those columns in turn to load circuit 3. The pulse generator 6 produces clock pulses for the counter. These pulses enter the counter input via frequency divider 7 that changes the duration of the program. The start pulse and the reset pulse are loaded into counter 5 from command device 8 that generates run, stop, program reload commands.

Stable voltage lamp 9 uniformly illuminates the matrix. The parameter control signal is read from resistor 3. This signal is proportional to the number of illuminated photo-resistors 2 in the column (vertical line) connected to the load circuit at any given time.

The intended device is efficient due to the following considerations. Various modifications of the controllers equipped with the built-in microprocessors are used in local technology process control systems.



Such switches are manufactured in different countries. They can be used with the sensors that have unified inputs and with the single- and multi-revolution electrical actuators.

The controllers are mainly devoted to process signals from the programming device and one or more sensors and to form output commands in correspondence with the control mode for a given object. All these functions are performed by a microprocessor of the controller, the microprocessor being updated during the object adjustment.

As a rule, the command device is built-in to the same controller. It sets a parameter value (e.g. temperature or pressure) to be maintained by the control circuit. The stabilizing control is the most common application of the controllers in infinite processes. But in periodical, periodic-infinite and several other processes not only the maintenance of one value of the parameter is needed but time changing it as well. The changing mode depends on the starting material (e. g., in the hydrolyze process the pressure is to be adjusted in correspondence with the load of the sunflower-seed hull, cabbage stump, cotton husk, etc. ). The separate command device for setting up the changing mode is connected to the corresponding input of the controller.

In conventional devices a command signal can be formed and sent to the controller using various tools: templates, rewound chart strips with a servo micro drive, sets of replaced resistors. In all these cases the replacement of the program medium is a time-consuming procedure, it requires a skilled personnel.

Even if the command device with a microprocessor is used then changing the program requires a time and a skilled personnel.

These solutions have several disadvantages in the operative conditions. Local control systems are used at small enterprises where the skilled electronic specialist does not work 24 hours every day. The operator is not usually authorized to perform comparatively complicated operations.

The intended device does not have these disadvantages. A set of templates for all possible starting materials are pre-prepared. As soon as the operator receives the information about loading a new portion of the starting material into one of the hydrolyze apparatuses he simply replaces the template on the photo-matrix by the template that corresponds to that new portion. Such a replacement does not require special skill or much time. Besides, the intended device is simple, cost- saving and small in the dimensions.