JPS6039816Y2 - speedometer - Google Patents

Description

[Detailed description of the invention] The present invention relates to a speedometer, and in particular, in a car-mounted speedometer, etc., it detects the level change of a speed signal in a low speed state within a eugenic period after the car has started, and detects the speed. configured to display
It is an object of the present invention to provide a speedometer having an extremely simple circuit configuration.

Conventionally, various types of speedometers have been known as in-vehicle speedometers that display the speed of vehicles. Speedometers with a circuit configuration that performs this function are generally in widespread use, but in such speedometers, when the car is in a low speed state for a short period of time after starting, the speed can be adjusted in response to a speed signal. Due to the delay characteristics caused by the circuit configuration that performs the display, no speed display will appear on the speedometer even if the car is moving, and the speedometer display will start after a predetermined period of time. Therefore, there was a drawback that accurate speed display as a speedometer could not be performed.

The present invention is intended to eliminate the above-mentioned drawbacks, and will be described in detail based on the embodiments shown in the drawings.

The drawing shows a circuit configuration diagram of a speedometer with a bar graph display, which is an embodiment of the present invention. )-FFl to [)-FF3, the frequency is divided into a predetermined frequency by each T-type flip-flop circuit formed by converting from A clock pulse is provided.

The output from the counter circuit 1 is supplied to a bar graph display 4 via a data latch circuit 2 and a decoder driver circuit 3.

Further, the speed signal mentioned above is directly supplied to one terminal of an exclusive OR circuit (exclusive OR circuit) EX-OR, and the speed signal is supplied to the other terminal of the exclusive OR circuit EX-OR. A speed signal delayed by a certain predetermined period is supplied through a delay circuit 5 consisting of a resistor and a capacitor.

The output of the exclusive OR circuit EX-OR, which serves as a detection circuit for detecting level changes in the speed signal, is supplied to one terminal of an OR circuit (logical sum circuit), and the other terminal of the OR circuit OR is connected to the decoder driver circuit. 3 is supplied, and the output of the OR circuit OR is supplied to the bar graph display 4.

To explain the operating mode of a speedometer having such a circuit configuration, a speed signal is directly supplied to one terminal of the exclusive OR circuit EX-OR, and a speed signal is supplied to the other terminal for a predetermined period by the delay circuit 5. Since the delayed speed signal is supplied, these two
When a level change occurs between two speed signals, a phase shift occurs between the two speed signals, resulting in an exclusive OR circuit EX forming an anti-coincidence circuit.
The output of -OR becomes "H" level, and this output passes through the OR circuit OR to control the operation of the bar graph display 4. Therefore, on the bar graph display 4, the first The segment bar will be displayed lit.

The bar graph configuration of the bar graph display 4 mentioned above is
Assuming that one step is 2 kWt/h as a speed display, even if the speed is 2 km/h and the data signal is input to the bar graph display 4, it will take about 2.8 kWt/h. It requires a period of seconds.

Therefore, conventionally, the bar graph on the bar graph display 4 is still displayed as ``0'' when the car is initially accelerating or when the speed is 2 km/h or less, and the speed display is similar to that of the actual car. However, the speedometer of the present invention can now accurately display the speed even at the initial stage of the vehicle starting and driving, as described above. .

According to actual test results, with the speedometer of the present invention, the time from when the car starts until the first segment bar lights up on the bar graph display 4 is shorter than with conventional speedometers of this type. It has been confirmed that the speed is about 178 or less.

Note that the present invention is not limited to the above-mentioned speedometer, but can also be fully applied to a tachometer that displays the number of revolutions.

In a speedometer that displays a bar graph according to the speed using a speed signal and a clock pulse for speed counting, this detection detects the level change of the speed signal and the signal that has passed through the speed signal delay circuit. Since the circuit is configured to supply the detection signal output from the detection circuit to the bar corresponding to the low speed of the bar graph and display this bar, the speed can be displayed using the speed signal and the clock pulse for speed counting. By simply equipping this type of speedometer described above with an additional device having a simple circuit configuration,
For example, it can be used as a speedometer that can extremely accurately display the speed of the car from the moment the car starts moving.
Particularly, the present invention is particularly effective when applied to a bar graph display speedometer for use in an automobile.

[Brief explanation of the drawing]

The drawing shows a circuit configuration diagram of a speedometer that is an embodiment of the present invention. 1... Counter circuit, 2... Data latch circuit, 3... Decoder driver circuit, 4...
... Bar graph display, 5 ... Delay circuit, EX-OR ... Exclusive OR circuit, OR ... OR circuit, D-FFl to [)
-FF3...D type flip-flop circuit.

Claims (1)

[Scope of utility model registration request] In a speed meter that displays a bar graph according to the speed using a speed signal and a clock pulse for speed counting, a change in the level of the speed signal is detected from the speed signal and the signal that has passed through a delay circuit for the speed signal. A speedometer comprising a detection circuit configured to display the bar by supplying a detection signal output from the detection circuit to a bar corresponding to a low speed of the bar graph.