Control system for controlling an indicator

The present invention relates to a VFD / LED / LCD display control system.

Known displays are widely used in electrical devices and serve, inter alia, to indicate time or temperature. The electronic cooker systems have displays to show the set cooking or baking status or other functions, such as an alarm. Digital displays for time indication are known which are implemented by a 7-segment display.

Various VFD / LED / LCD control systems are known. In the VFD vacuum fluorescent display, a filament cathode is placed behind the indicated digits. The segments of the 7-segment digits are each connected in parallel and form the anodes. Grids are placed between the filament cathodes and the anode segments, each extending over the digit area. The segment displays a specific digit when not only the anode but also the grid corresponding to the digit have a positive voltage. Thus, by the multiple control of the segments and the figures, each segment of each figure is controlled separately.

In a display with LEDs, the segments of the digits are each formed by the light-emitting diodes. Segments of different digits are connected in parallel to each other and form the cathode, while the different digits form the anodes. Each segment is actuated separately by multiple control.

The difference in control between a VFD and an LED is that for a VFD a positive voltage or no voltage is applied to the terminals and a positive voltage for digits or negative for segments or no voltage is applied to the terminals of the LED display. In addition, the VFD display operates at a relatively high voltage of 16 to 30 V but a low current of 0.1 to 2 mA, while the LED display requires only a low voltage of about 2 V but a high current of 2 to 20 mA.

On the other hand, the control of the display on liquid LCD crystals is quite different. It is based on the use of passive elements which are introduced onto the substrate controlled by the ambient light. When an electrical voltage is applied to such an element, the crystals contained therein align, so that ambient light is absorbed at that point and the element is dark. In order to maintain this effect for a longer period of time, the element must in fact be continuously recharged approximately every 100 ms. In order to effect the alignment of the crystals, the voltage that is applied to the element must exceed a predetermined minimum value.

The LCD display is now constructed in such a way that up to 3 elements are connected in parallel to each other and form a single electrode. The second electrode is formed by three reverse electrodes which are each assigned to one of the three elements connected in parallel with each other. In this way, multiple control is possible. In fact, not only two voltage values ​​are applied to the display terminals, i.e. positive or negative or zero, but also the intermediate voltage values, in the described case 1/3 and 2/3 of the voltage, so that it is possible to purposefully charge individual elements without affecting the other items. While the control of the VFD and the LED display is similar and is feasible with a sufficiently wide dimensioning range of the control system components, a different control system is required to control the LCD display.

The VFD / LED / LCD control system of the invention is characterized in that a ROM with multiplex modes for controlling the excitation of VFDs, LEDs or LCDs is operatively coupled to the control logic.

Preferably, the system comprises three control blocks, a first block for an LCD display, a second block for a VFD display, and a third block for an LED display.

Preferably, the circuit comprises a plurality of memory elements, each assigned to a control block for the LCD and the VFD / LED or to a control block for the LCD, VFD and LED.

Preferably, the actuator unit has several actuators and each actuator is coupled to a VFD, LED or LCD display terminal.

Preferably, each actuator is coupled to each actuation control block of one of the VFD, LED or LCD terminals.

Preferably, the control blocks are coupled to the means for actuating the actual terminal of the VFD, LED or LCD.

PL 198 894 B1

Preferably, the control logic, at least one memory element, and control blocks are digital and the actuator is analog.

Preferably, the data receiver, control logic, memory element, control blocks, actuator and ROM constitute an integrated control circuit.

An advantage of the invention is to provide a control system that is easy to apply to VFD, LED and LCD displays, resulting in increased standardization of components, reduced logistics and storage efforts, as well as responsiveness to customer requests. The invention provides a control system that is capable of controlling not only VFD and LED displays, but also an LCD display.

The subject of the invention is shown in the drawing, in which fig. 1 shows the control system according to the invention in a block diagram, fig. 2a - luminous segments of a VFD or LED display, fig. 2b - time course of control signals for a VFD or LED display, Fig. 3a shows the light segments of the LCD display, Fig. 3b shows the time course of the control signals for the LCD display, and Fig. 4 shows the circuit diagram of the actuator.

Figure 1 shows a control system 1 for a VFD, LED or LCD display 2 that includes a data receiver 3 for receiving display control data from a microprocessor 4 that powers the data receiver 3 from a clock 4.1. The data receiver 3 forwards the received data to control logic 5 which examines the received data and decodes it, thereby extracting addresses, control words and instructions from the received data. The orders contain display data which are transferred to the data memory 6 and stored there. They remain stored unchanged as long as the display needs to be changed. The new display data is then stored in the data memory 6.

Control logic 5 is coupled to the first control block 7 for generating LCD control signals and to the second control block 8 for producing VFD or LED control signals. A control state is set via control blocks 7 and 8, for example a 5x, 6x, or 7x multiplication for a VFD / LED display, 3x multiplication for an LCD display, night dip or load relief as described below. The selected state is stored in ROM 9 which is operationally connected to the control logic 5.

Depending on whether the control state for the LCD or the VFD / LED display is set, control block 7 or control block 8 is active. Based on the display data supplied to it from data memory 6, the active control block 7 or 8 generates as explained below way control signals COM 1-3, S 1-13 for LCD display or control signals G 1-7 and S 1-9 for each 2 VFD / LED display.

The control signals from the control block 8 still pass through a level shifter in which, when using the control state of the VFD, the level of the control signals is increased from the usual 3.3V level to the 30V level needed for the VFD. In the case of LED display control state, this level increase is unnecessary. The set control state information is received by the level shifter 10 as well as control blocks 7 and 8 from control logic 5.

The control signals of the control units 7 and 8 then reach the actuator 11, which has the actuators 11.1-11.16, which each receive the control signals from the control blocks 7 or 8, process them and then send them to the display 2 in the appropriate form. of the actuators 11.1 - 11.16 is each connected to one display terminal 2.

Otherwise, it is also possible for both control blocks 7 and 8 to be active at all times, regardless of the set control state. In this case, however, it is necessary that the actuators 11.1 - 11.16 receive control signals depending on the set control state of the LCD or VFD / LED display from only one of the control blocks 7 and 8. The actuators 11.1 - 11.6 receive information directly from the control logic 5.

Thereafter, the control logic controls the switching circuit 12 connected to the microprocessor 4, the alarm circuit 13 connected to the alarm 14, and the excitation generator 15 for controlling the relays 16 and 17. The voltage supply to the individual components of the control circuit 1 is not shown for the sake of simplicity as it is done in a similar manner.

Figure 2a shows the lighting segments of the VFD or LED display. Segments a are connected in parallel with each other and with the end S1, and the segments b with the end S2, and so on. The terminals G1 to G7 are each connected with a grid extending over the digit, or with symbols placed next to it.

PL 198 894 B1

Figure 2b explains the display control by showing the time course of the signal applied to terminals S1 to S9 and G1 to G7. During a period of time t1, a signal, i.e. a voltage, is applied to both pin S1 and pin G1. As a result, the segment lights up a digit that belongs to the grid connected to G1. During the period t2, the grid belonging to the terminal G2 is controlled, however, no segments are controlled, so that the digit belonging to the terminal G2 remains dark.

The symbols a and b in the grid connected to the terminal G3 light up again because a signal is applied to the terminals S1 and S2 during the time period t3 in each case.

In the example shown, seven grids are controlled so that the cycle duration consists of times t1 to t7. Thus, a 7-fold multiplication occurs. If the meshes belonging to the terminals G6 and G7 are omitted, the cycle time is correspondingly shortened and then a 5-fold multiplication is applied.

The control of the LED display is essentially the same as just described, except that a negative voltage is applied to the terminals S1 to S9 instead of a positive voltage.

Figure 3a shows the elements of an LED display. In each case, up to 3 display elements are connected in parallel to each other and connected to the terminals S1 to S13. The reverse electrodes of these three elements are each connected to the terminals COM 1, COM 2 or COM 3.

Figure 3b shows the time course of the signals applied to the terminals COM 1, COM 2 or COM 3, as well as to the terminal S12, which relates to the standard method of controlling an LCD display. The signals fed to the pins S1 to S13 have the opposite polarity to the signals fed to the pins COM 1, COM 2 or COM 3, so that, for example, the upper element S12 of the display is supplied with a voltage corresponding to the voltage at the COM 1 pin minus the voltage at the S12 pin, a voltage corresponding to the voltage at terminal S12 is applied to the center display component S12 minus the voltage at terminal S12, and a voltage corresponding to the voltage at terminal S12 is applied to the lower display component S12. The voltage differences that occur on the upper element, corresponding to the voltage at terminal COM 1 minus the voltage at terminal S12, are too small for the crystals to align. So there is no indication there. There are, however, large voltage differences of 2U on the middle and lower display elements, so that there is an alignment of the crystals and thus an indication.

FIG. 4 shows the basic wiring diagram of the actuators 11.1-11.16 in each case for generating control signals for the displays 2. In the display control state VFD or LED, switches are controlled from the control block 8 via the digital signals W4 and WO. If a signal, i.e. a voltage, should be applied to the output A, i.e. the corresponding display terminal 2, then switch 18 is closed by digital signal W4, while switch 19 as well as switches 20, 21 and 22 remain open. When using a VFD display, the voltage U 'supplied to output A is 30 V, and when using an LED display only about 2 V. If no signal, i.e. no voltage, is to be applied to the output, switch 18 is opened and switch 19 is closed by the digital signal WO. Thus, a signal for a VFD or LED display element is produced by the switches 18 and 19. Information as to whether a voltage U 'of 30 V or only 2 V is applicable, corresponding to the control of the VFD or the LED, is obtained directly each time by the actuator 11.1-11.16 from the level shifter 10 or from the control logic 5 according to Fig. 1.

Switches 19, 20, 21 and 22 are used to control the LCD element. By closing the switch via a digital signal WO, W1, W2 or W3 coming from the control block 7, the voltage at output A is regulated to 1/3 U, 2 / 3 U or U, with U typically being 3.3 V.

Thus , by controlling the switches via digital signals WO, W1, W2, W3 and W4 from control blocks 7 and 8, through one and the same output or terminal A, not only the LCD display element but also the VFD display element are controlled. and LED.

The control logic 5, the memory element 6 and the control units 7 and 8 of the control 1 are digital, while the actuator 11 with the actuators 11.1-11.6 are analogous. The entire control circuit 1 is implemented as an integrated circuit. Also included in this IC are the indexing circuit 12, the alarm circuit 13, and the excitation generator 15.

PL 198 894 B1