JP2866431B2 - Electronic equipment for mounting on moving objects and tide meter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electronic device equipped with a color CRT and mounted on a moving body such as a ship or a vehicle, and particularly to a tidal current meter equipped with a color CRT.

(B) Prior Art In general, in a color CRT display device, a cathode ray tube is magnetically shielded so that the electron beam is not affected by terrestrial magnetism to cause color shift or color unevenness. Further, a degaussing coil and a degaussing circuit for supplying an AC decay current to the degaussing coil so that the iron plate for magnetic shield is not magnetized are incorporated. Usually, this degaussing circuit is configured to operate only for a certain period of time when the power of the device is turned on or turned off so as not to affect the actual display screen. Therefore, normally, once convergence is performed, correct color display without color shift or color unevenness is maintained. However, when a color CRT is used as a display of an electronic device mounted on a moving object such as a ship or a vehicle, the direction of the color CRT changes during use of the device, that is, during display, so that it is strongly affected by geomagnetism. The shield plate is easily magnetized. In order to avoid such magnetization during display, conventionally, for example, a degaussing circuit is operated to degauss during a vertical retrace period of a raster scan.

(C) Problems to be Solved by the Invention However, in the above-described method of performing degaussing during display, a large current is required for degaussing, not only increasing power consumption, but also noise generated due to this. Adversely affect electronic devices and other electronic devices.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic device mounted on a moving body and a tidal current meter which eliminates the above-mentioned conventional problems by automatically degaussing only when degaussing is required.

(D) Means for Solving the Problems Color misregistration and color unevenness of the color CRT are caused by a change in the direction (azimuth) of the color CRT, thereby changing the degree of the influence of geomagnetism. Therefore, demagnetization only needs to be performed when the azimuth is changed so that color shift or color unevenness occurs in the color CRT. The present invention focuses on this point.

The electronic device for mounting on a moving object according to claim 1 of the present invention includes:
An electronic device mounted on a moving body including a color CRT and a degaussing circuit for degaussing the color CRT, an azimuth change detecting unit for detecting an azimuth change of the electronic device;
A degaussing instruction signal generating means for generating a degaussing instruction signal to the degaussing circuit when the detected change in azimuth exceeds a certain amount is provided.

The tidal current meter according to claim 2 of the present invention is a color CRT.
And a degaussing circuit to degauss the color CRT, input a heading signal from an external device, measure the tidal current at a predetermined depth, and determine the current direction and current velocity of the color CRT.
In the tidal current meter displayed in (1), a degaussing instruction signal generating means for generating a degaussing instruction signal to the degaussing circuit when detecting that the heading has changed by a certain angle or more is provided.

(E) Action In the mobile-mounted electronic device according to claim 1, the azimuth detecting means such as a gyro compass or a magnetic compass detects a change in the azimuth of the electronic device, and the degaussing instruction signal generating means determines that the azimuth change is a fixed amount. Activate the degaussing circuit when it exceeds.
Therefore, degaussing is performed only when the azimuth of a moving body such as a ship or a vehicle on which the electronic device is mounted changes by a certain angle.
Although the degaussing is not performed while the azimuth change of the electronic device is small since the previous degaussing, the color shift and the color unevenness do not usually occur during this period. As described above, since the degaussing is performed only at a necessary point in time while the electronic apparatus is mounted on a moving body, useless power consumption and generation of noise are suppressed.

In the tide meter according to claim 2, when the degaussing instruction signal generating means detects that the heading has changed by a certain angle or more,
Activate the degaussing circuit. Originally, a tide meter inputs a heading signal based on the north from an external device such as a gyro compass or a magnetic compass to measure the trend and flow rate of a tide at a predetermined depth. Therefore, color measurement of the tidal current
In the tide meter displayed on the CRT, the tide meter having the automatic demagnetization function can be configured without newly connecting a device for detecting a change in heading.

(F) Embodiment A block diagram of a tidal current meter according to an embodiment of the present invention and a processing procedure thereof are shown in FIG. 1 and FIG.

In FIG. 1, a CPU 1 is connected to a bus line, and each unit described below controls the entire tide meter. RO
A program to be executed by the CPU 1 is written in M2 in advance. The RAM 3 is used as a working area for storing the heading at the time of the previous demagnetization and calculating the amount of change in the heading. VRAM4 is a display memory for storing display data, and video output circuit 5 converts the output signal of VRAM4 into a video signal and outputs it to CRT6. The display control circuit 7 specifies a read address of the VRAM 4 according to the raster scan of the CRT. The degaussing circuit 9 is a circuit for supplying a degaussing current to a degaussing coil incorporated in the CRT 6, and the CPU 1 gives a degaussing instruction signal via the interface 8. The tidal current measuring device 11 measures the Doppler shift of the returning wave reflected at a predetermined depth, using an ultrasonic transducer that transmits and receives ultrasonic pulses at a constant depression angle, with the horizontal pointing directions different from each other by 120 degrees, and The ship speed, the direction of movement of the ship, and the direction and velocity of the tidal current in each layer are obtained. The CPU 1 reads the measured power flow data via the interface 10. Compass 13
Is a gyrocompass or magnetic compass, and calculates the heading azimuth with reference to the north. CPU1 is the interface
Read that data via 12. The key input device 15 includes a key switch for instructing forcible degaussing, a key switch for setting a threshold value of azimuth change for performing automatic degaussing, and the like. The CPU 1 reads the key operation contents via the interface 14. The interface 16 is an interface for outputting the ship speed and true heading measured by the tidal current measuring device 1, the heading measured by the compass 13, and the like to an external device.

The tide meter performs the processing in the procedure shown in FIG. First,
Immediately after the power is turned on, a degaussing instruction signal is forcibly given to the degaussing circuit 9 (n1). After that, the presence or absence of key operation is detected,
If there is any key operation, the operated key is read (identified) (n2 → n3). Subsequently, processing corresponding to the operated key is performed. For example, in the case of a key operation for setting a threshold value S for azimuth change when performing automatic demagnetization described later, the operated value is read and stored (n4). If a key operation for forcibly degaussing is performed, a degaussing instruction signal is sent to the degaussing circuit 9.
Output to (n5).

When it is time to measure while waiting for key input,
First, the heading θo is read from the compass 13 (n6 → n
7). Subsequently, the difference between the current heading θo and the heading θ1 at the time of previous degaussing is determined as Δθ (n8). Then, it is determined whether or not the azimuth change Δθ has exceeded the threshold value S (n9). If the threshold value S is exceeded, the current heading θo is stored as θ1 and a degaussing instruction signal is output to the degaussing circuit 9 (n10 → n11). After that, the speed of the ground, the moving direction (true direction) of the ship, and the tidal current (flow velocity and current direction) of each layer are read from the tidal current measuring device 11 (n12 → n13). Further, these data are displayed on the color CRT 6 by writing them in the VRAM 4 as graphic data and character data (n14). The change in heading Δθ
Is not greater than the threshold value S, no demagnetization is performed (n9 → n12
・ ・).

In the above-described embodiment, the tide meter is used as an example.However, a color scanning sonar that performs underwater detection over a wide area in the circumferential direction of the ship, a color radar that displays radar images in color along with the wake, or a fish species is used. The present invention can be similarly applied to an electronic device mounted on a moving body equipped with a color CRT such as a fish finder that performs color display.

(G) Effects of the Invention According to the present invention, the degaussing is performed automatically only when the azimuth of the CRT is changed to the extent that color misregistration or color unevenness may occur in the color CRT. Unless the frequency changes frequently, the power consumption required for degaussing is significantly reduced. In addition, the occurrence of noise is small, and there is no adverse effect on the device body and other electronic devices.

[Brief description of the drawings]

FIG. 1 is a block diagram of a tidal current meter according to an embodiment of the present invention;
FIG. 2 is a flowchart showing a processing procedure of the tidal current meter.

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Claims (2)

(57) [Claims] An electronic device mounted on a moving body including a color CRT and a degaussing circuit for degaussing the color CRT, an azimuth change detecting means for detecting an azimuth change of the electronic device, and a azimuth change detected by a predetermined amount. And a demagnetization instruction signal generating means for generating a demagnetization instruction signal to the degaussing circuit when the distance exceeds the limit. 2. A color CRT and a degaussing circuit for degaussing the color CRT. A heading signal is input from an external device, and a tidal current at a predetermined depth is measured. When the displayed tide meter detects that the heading has changed by more than a certain angle,
A power flow meter comprising a degaussing instruction signal generating means for generating a degaussing instruction signal for the degaussing circuit.