Abstract: An electronic device (10) comprises an array of pixels (12), arranged in rows and columns (14,16) with row and column address lines (18,20) for addressing each pixel (12). Each row and column address line is connected to two discharge lines (30,32) through a discharge circuit (38). The circuit allows the, passage of charge between the address line and the first discharge line (30) when the address line is at a potential below that of the first discharge line, and allows the passage of charge between the address line and the second discharge line (32) when the address line is at a potential above that of the second discharge line. This provides electrostatic discharge protection against an increase or decrease in voltage on the row or column address lines during manufacture of the device. By providing suitable voltages on the two discharge lines during operation of the manufactured device, it is possible to prevent the discharge circuit from operating, thereby saving power.

Abstract: A cholesteric liquid crystal display has pixel address circuits (84) with an input (12) for receiving a data signal and a plurality of outputs, wherein each output is for applying a pixel drive signal to a respective portion of the liquid crystal material (20), and wherein the pixel drive signal for each output is independently switchable by the pixel address circuit to each output. This provides spatially-separated sub-pixels, and a number of the sub-pixels can be addressed in order to provide a grey scale output for each pixel. Each pixel drive signal can however be a two-level digital signal.

Abstract: An image sensor comprises rows and columns of pixels. Each pixel comprises an image sensing element (26) and a switching device (32, 34). The switching device (32, 34) enables a signal of the image sensing element (26) to be provided to the associated column conductor (30). The switching device has two inputs—a first input defined by the row conductor (22), and a second input. Two adjacent columns of pixels are associated with each column conductor (30), and the two columns of pixels (P1, P2; P3, P4; P5,P6) between adjacent column conductors are associated with a respective shared control line (CS0;CS1;CS2;CS3) providing the second input.

Abstract: An active matrix electroluminescent display device has an array of current-driven electroluminescent display elements (20), for example comprising organic electroluminescent material, whose operations are each controlled by an associated switching means (10) to which a drive signal for determining a desired light output is supplied in a respective address period and which is arranged to drive the display element according to the drive signal following the address period. Each switching means comprises a current mirror circuit (24, 25, 30, 32) which samples and stores the drive signal with one transistor (24) of the circuit controlling the drive current through the display element (20) and having its gate connected to a storage capacitance (30) on which a voltage determined by the drive signal is stored. Through the use of current mirror circuits improved uniformity of light outputs from the display elements in the array is obtained.

Abstract: A display uses column address circuitry having a plurality of multiplexing switching arrangements (50), each of which is associated with two buffers (46a;46b) for providing selected pixel drive signals. The two buffers provide respective pixel drive signals simultaneously to two adjacent columns, such that the pixel drive signal for one column starts before the end of the pixel drive signal for the column driven previously, and ends after the end of the pixel drive signal for the column driven previously. This enables a reduction in the number of buffers required and reduces the cross talk between column signals for adjacent columns within the group of columns shared by each multiplexing arrangement. This is achieved by ensuring that any capacitive coupling between first and second columns is charged to a static level before the signal on one of the columns is switched off.

Abstract: A display has circuitry (50) which generates all possible pixel drive signal levels on separate signal level lines. A buffer (54) is associated with each signal level line. The outputs of the buffers are selectably switchable onto the columns. The signal levels for each column are stored in a memory (72) and the buffers are controlled in dependence on the stored signal levels. The response of the buffers is heavily dependent on the output load, and there is a very large variation in the output load of the buffers (54), as a function of the number of columns to which the buffer output is to be provided. The buffers are controlled in dependence on stored signal levels to ensure stability of the buffers for any output load.

Abstract: A bistable chiral nematic liquid crystal display has pixel address circuits which comprise a first switching device (14) for switching a supply voltage to the remainder of the pixel address circuit and which is controlled by a row address line (10) and a second switching device (16) for allowing or preventing the supply voltage to be provided to the respective portion of the liquid crystal material (18), and controlled by a column select line (32). This pixel layout enables a transition to the H state to be avoided when the material is to remain in the P or FC states, so that the black addressing bar artifact can be avoided.

Abstract: An active matrix electroluminescent display device has an array of current-driven electroluminescent display elements (20), for example comprising organic electroluminescent material, whose operations are each controlled by an associated switching means (10) to which a drive signal for determining a desired light output is supplied in a respective address period and which is arranged to drive the display element according to the drive signal following the address period. Each switching means comprises a current mirror circuit (30, 32, 38) in which the same transistor (30) is used to both sense and produce the required drive current for the display element (20) with the gate of the transistor being connected to a storage capacitance (30) on which a voltage determined by the drive signal is stored. This allows variations in transistor characteristics over the array to be compensated and improved uniformity of light outputs from the display elements to be obtained.

Abstract: An active matrix electroluminescent display device has an array of current—driven electroluminescent display elements (20), for example comprising organic electroluminescent material, whose operations are each controlled by an associated switching means (10) to which a drive signal for determining a desired light output is supplied in a respective address period and which is arranged to drive the display element according to the drive signal following the address period. Each switching means comprises a current mirror circuit (24, 25, 30, 32) which samples and stores the drive signal with one transistor (24) of the circuit controlling the drive current through the display element (20) and having its gate connected to a storage capacitance (30) on which a voltage determined by the drive signal is stored. Through the use of current mirror circuits improved uniformity of light outputs from the display elements in the array is obtained.

Abstract: A display device has row driver circuitry (30) providing row address signals and column address circuitry (32) providing pixel drive signals. The row address signals comprise a plurality of voltage levels (V1- V4) to implement a desired drive scheme. The column address circuitry comprises circuitry (70) for generating low voltage representations of at least some of the row address signals. The row address circuitry comprises a conversion circuit (72) for converting the representations into the row address signal levels, at least one of has a high voltage magnitude. The invention provides an architecture which partitions different sections of the row voltage supply circuitry optimally between the row and column drivers. This enables a simplified power supply to be provided which can be made more power efficient.

Abstract: An image sensor (10) comprises an array having an image sensing portion (12) and a control portion (14). Pixels (18) of the image sensing portion and devices (20) of the control circuitry portion each comprise a diode stack (34) of a back-to-back switching diode (36, 38, 40) and a photodiode (42, 44, 46). The photodiodes of the devices (20) are constantly illuminated in use so that they act as current sources in series with the switching diode. This provides a circuit device which has characteristics enabling its use in control circuitry.

Abstract: A portable electronic device (1) has a keypad for entering alphanumeric characters. Some of the keys include a fingerprint sensor (2) and for each of these keys a different character may be selected for entry by using a different finger. The device is provided with a reference set of fingerprints of the authorised user or users, so unauthorised users cannot enter characters. A high resolution fingerprint sensor may be used for validating a user for secure transactions, while a lower resolution sensor may be used for differentiating between a small number of fingerprints. Size and interconnection complexity can be minimised by providing fingerprint sensors that are smaller than a fingerprint, and entering a fingerprint by wiping a finger across the sensor.

Abstract: An image sensor comprising an array of pixels 2, each pixel 2 including a pin or nip photodiode P.

Abstract: A multiplexer circuit is disclosed for switching a selected one of a plurality of current inputs carried by respective input lines (2;101) to a common output. The circuit comprises, for each input line, a diode clamp (5;104) and isolation means (10;109) provided between each input line and the common terminal The diode clamp (5;104) is operable in a first mode in which voltages are applied to the clamp terminals such that the diodes (8,9;107,108) of the diode clamp are forward biased and hold the input line (2;101) at a first voltage which prevents the passage of current from the input line to the common output, and a second mode in which the voltages are applied to the clamp terminals such that the diodes of the diode clamp are reverse biased and the passage of the current from the input line to the common output is allowed. Only two connections, for the diode clamp, are needed to control the switching of the current input, and the switch introduces no current offset to the output.

Abstract: A display device has current-addressed pixels, with the currents being supplied by driver circuitry which comprises a transistor (10) for applying a charging voltage to a switched capacitor arrangement (Ci, S1, S2) arranged to selectively charge and discharge the capacitor (Ci) at a predetermined rate to a charging voltage. A transistor control voltage (Vref) is applied to a control terminal of the transistor which is adjusted depending on the transistor threshold voltage to ensure that the capacitor (Ci) is charged to the charging voltage irrespectively of the value of the threshold voltage. This enables an accurately controllable current to be provided which is used to drive the current-addressed pixels.

Abstract: A fingerprint sensing device comprises an array of sense elements (12) which each include a sense electrode (33), providing in combination with an overlying fingerprint part a capacitance (35), and first and second diode devices (30, 31) connected respectively between the sense electrode and associated ones (18, 20) of first and second sets (e.g. row and column) address conductors. An address circuit (22, 24) connected to the address conductors biases the diode devices in a respective address period such that a potential is applied via the first address conductor and the first diode device to the sense electrode and thereafter stored charge, indicative of the capacitance, is transferred via the second diode device to the second address conductor. The device offers fast, reliable, scanning and can conveniently be implemented using thin film technology for low cost and compactness.

Abstract: A multiplexer circuit includes switches 26 or 260 each having a hold portion 120 or 1200 and driving portion 110 or 1100 for providing a hold voltage or a select voltage to an output 14. If all control inputs 28A or 280A are at a first level, then the output has the select voltage, whereas if one input 28A is at a second level, the output has the hold voltage. The switches 26 may be integrated onto the substrate of a diode-based array of electrical elements, for example image sensing pixels. In this case, the output 14 includes a row conductor for a row of such pixels.

Abstract: An image sensor comprising an array of pixels 2, each pixel 2 including a pin or nip photodiode P. At least the intrinsic semiconductor layer of the photodiodes of a group of pixels is shared between those pixels and acts as a barrier to reduce edge leakage currents. A group of pixels may be a row of pixels, or may be all pixels of the array.

Abstract: A compressed hay bale cutting and stacking system includes a compressed bale cutter and a stacker arranged to stack half-cut or quarter-cut bales in multi-tier stacks while maintaining slices of the bales in substantial alignment. The bale cutter is oriented to discharge the half-cut or quarter-cut bales as a unit at a predetermined elevation. The stacker has a table assembly and a pushoff assembly positioned to receive each bale as a unit from the bale cutter and automatically form a stack of at least 2 bale by 2 bale tiers. The table assembly has an elongate first platform movable vertically on the stacker frame between a raised position aligned with the bale cutter discharge to form a first row of bales and a lowered position for receiving a second row of bales, to accumulate a tier of stacked bales while maintaining the bales substantially aligned along their vertical sides.

Abstract: The array comprises an insulating substrate with diode-capacitor pixels disposed over conductors on the substrate. A single mask is used to etch the pixel stacks, and each pixel stack is wider than the conductor beneath. As a result, the mask alignment does not influence the pixel characteristics.