JPS58225360A - Apparatus for detecting disconnection of lamp - Google Patents

Abstract

PURPOSE:To automatically carry out the detection in the disconnection of a lamp at the time of ignition switch manipulation, by providing a sequence circuit for successively lighting plural lamps in a state divided into plural times for a short time directly after an engine is started. CONSTITUTION:A relay circuit 37 is provided in the voltage regulator charging display lamp circuit in an automobile and closed when an ignition switch 20 is turned OFF or an engine is stopped. In this state, when the ignition switch 20 is turned off, the plus side inlet terminals of comparators 43-45 are held to zero potential but the potential of a condenser 41 is added at the same time when a switch 37 is turned OFF by the start of the engine and gradually lowered as discharge is advanced. According to the lowering of potential, inverters 34-36 are successively operated by a logical circuit constituted by the comparators 43-45 and gates 46-48 and the automatic disconnection check of a lamp is carried out for every definite time by disconnection detecting circuits 24-26.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a lamp breakage detection device.

Generally, automobiles use many types of incandescent light bulbs (hereinafter referred to as lamps), such as a single headlight, a parking light, a stop light, and a license light. Since many of these lamps are intended to ensure driving safety, driving without lights due to a broken lamp is dangerous, and early detection is desirable. Therefore, various types of lamp breakage detection devices have been proposed in the past that automatically detect lamp breakage and notify the driver, and several types of devices are actually installed in automobiles.

However, all conventional devices of this type can detect lamp breakage only when the lamp to be detected is turned on (light switch on), and cannot detect lamp breakage unless the light switch is operated. This makes it difficult to check for lamp breakage in advance, and cannot be considered a perfect warning device for lamps that are not turned on until nightfall (such as taillights).

The present invention corrects these conventional drawbacks,
The object of the present invention is to provide a lamp breakage detection device that automatically performs a preliminary check for lamp breakage during a vehicle start-up inspection. Examples will be described in detail below.

FIG. 1 is a block diagram of main parts of an apparatus according to an embodiment of the present invention.
0 is a car battery, 11-13 are ride relays, 1
4-16 are light switches, 17a, 17h.

18α, 18A, 19α, and 19h are lamps to be detected, 20 is an ignition switch, 21 to 23 are current detection resistors, 24 to 26 are disconnection detection circuits, and 27 is a warning lamp. When the light switches 14 to 16 are turned on, the contacts of the ride relays 11 to 13 are closed, and lighting current is supplied from the battery 10 through these contacts to light the detected lamps 17α to 195. The magnitude of the lighting current is converted into a voltage drop by a current detection resistor, and the presence or absence of lamp breakage is detected by the breakage detection circuits 24 to 26 based on the magnitude of the voltage drop.

FIG. 2 is a block diagram showing an embodiment of the disconnection detection circuits 24 to 26, in which the power supply side terminal of the current detection resistor 21 is connected to one input terminal of the comparator 71 via the reference voltage generator 70, and the The detection lamp side terminal is connected to the other input terminal of the comparator 71, so that the comparator 71 detects a change in the voltage drop occurring across the current detection resistor 21. The reference voltage generation circuit 7o generates a reference voltage corresponding to when all the lamps are in normal condition. For example, when all the lamps are in normal condition, a voltage that is slightly higher than the voltage drop from the power supply side terminal voltage at the current detection resistor 21 (power supply terminal voltage) is generated. generates a voltage that is lower than the power supply terminal voltage when viewed from the side. Note that the reference voltage generator 70 is configured so that this relationship is maintained even during a transitional period such as immediately after power is turned on, and in a range of changes in battery voltage. Since the input signal of the comparator 71 is set as described above, when the current flowing through the current detection resistor 21 decreases from the normal state due to a burnout of the lamp, the voltage drop across the current detection resistor 21 decreases and the reference voltage generator 7
0, and the output of the comparator 71 is inverted. Comparator 71 is inverted)1
;ic! (j! 151 way 72 V-iW * 8
k・10 "1 force゛゛1°)'#-+.

The warning lamp drive circuit 75 is activated and the warning lamp is activated.
Lamp 27 is turned on. Note that it is desirable to provide a noise removal circuit 74 such as a delay circuit before the storage circuit 72.

Also, in the diagram @1, 50 is a constant voltage circuit, 31 is a time control circuit, 32 is an inhibition circuit, 65 is a sequential circuit, 34 to 36
is a ride relay drive circuit, 37 is a relay circuit, 3B is an oscillator, 59 is a Zener diode, 4i is a transistor,
41 is a capacitor, 42 is a diode, 45 to 45 are comparators, 46 to 4 are gate circuits, and 49 to 56 are resistors. The operation equivalent to turning on the light switches 14 to 16 one after another for a short period of time is automatically performed as follows.

The relay circuit 37 is provided in the voltage regulator charge indicator lamp circuit of the automobile, and its contacts open when the Niresin starts and the alternator output exceeds a certain value, and its contacts open when the ignition switch 20 is turned off or the engine is stopped. Closed. Further, the capacitor 41 is discharging through the resistor 49, and the terminal voltage thereof is approximately zero.

When the ignition switch 20 is turned on in this state, current flows through the contacts of the relay circuit 57 due to the constant voltage generated by the constant voltage circuit 30, and the transistor 40 is turned on. When the transistor 40 is turned on, the current from the constant voltage circuit 30 flows through the capacitor 41, and the capacitor f41 is rapidly charged to a certain voltage. The terminal voltage of this capacitor 41 is applied to the positive (+) input terminals of the comparators 43 to 45 through the resistor 50, but while the contact of the relay circuit 57 is closed, the positive input terminal is applied through the diode 42. Since the comparators 43 to 45 are grounded, the positive input terminal voltages of the comparators 43 to 45 are held at approximately zero potential during that period.

FIG. 6 is a diagram showing an example of the signal waveforms of each part of the sequential circuit 33 and the output waveform of the ride relay drive circuit in C when the first illustrated device is operated, and shows the positive input terminals of the five comparators 43 to 45. The voltage rises at the same time as the ignition switch contact is turned on, as shown by curve 80 in FIG.
become. Thereafter, when the engine is started and the contact 67 is opened, the transistor 40 is turned off, charging is stopped, and the capacitor 41 starts discharging through the resistor 49, so that the voltage gradually decreases.

The minus (-) side terminals of the comparators 46 to 45 are connected to standards such as those shown in straight lines 81 to 83 in FIG. Voltage V
1 to V is applied, and the comparators 43 to 45 compare this reference voltage with the voltage applied to the positive input terminal, and calculate the positive input terminal voltage as shown in FIG. 3 CB) to (D). is greater than the reference voltage V1~VS, its output VG1
' Set VGS to high level.

The outputs VG1 to VG3 of the comparators 43 to 45 are applied to the gate circuits 46 to 4 in the logical relationship shown in FIG. VD & is, for example, Figure 6 CE) ~ (G) l
: As shown, the level becomes low for a certain period of time. The outputs of the ride relay drive circuits '54 to 36 are connected to the drive coils of the ride relays 11 to 13, so the above-mentioned operation (secondary contact of the ride relays 11 to 16 is 11.
The lamps are closed for a certain period of time in the order of 12.13, and lighting current is passed from the battery 10 to the detected lamps 17α to 19h. If any of the lamps is disconnected at this time, it is detected by the disconnection detection circuits 24 to 26 described above, and the memory circuit 72 stores the fact that the lamp is disconnected, and the lighting state of the warning lamp 27 is maintained. Ru. In addition, it is desirable that the low level period of the outputs of the ride relay drive circuits 54 to 36 be made as low as possible so that it is difficult to visually recognize that the lamp is lit.

As described above, immediately after the ignition switch 20 is turned on, the presence or absence of a lamp breakage is automatically checked. still,
After the accumulated charge in the capacitor 41 is discharged, normal light switch operation is performed.

Further, in this embodiment, an oscillator 58 is provided which generates a pulse signal that turns on the transistor 40 for a certain period of time (this period only needs to be enough time to charge the capacitor 41 to a predetermined voltage). Therefore, the above-described lamp breakage check operation immediately after the engine is started is repeated at every interval after the engine is started.

In the above embodiment, a sequential circuit was provided to sequentially turn on the ride relays 11 to 1'5 for a certain period of time, but this was done in consideration of the fact that turning on all the lamps at once would place too much load on the battery. This is what I did. Therefore, if the battery capacity allows, it is also possible to configure two or more of the ride relays 11 to 13 to operate simultaneously. Further, in this example, a six lamp system consisting of two lamps per system has been described, but the number of lamps per system and the number of systems can be determined freely. Further, although current detection type circuits are used as the disconnection detection circuits 24 to 26, it goes without saying that other types may be used as long as they have a memory circuit.

The above operation is performed when the alternator voltage increases after the engine starts, but it is also possible to operate immediately after the ignition switch is turned on, even if the battery capacity increases.

As explained above, the present invention provides a lamp disconnection detection device having a disconnection detection circuit that detects disconnection of a plurality of lamps that are crossed while the light switch is on.
This system is equipped with a sequential circuit that lights up the plurality of lamps one after another for a short period of time immediately after the engine starts, and lamp breakage is automatically detected when the ignition switch is operated, making it extremely easy to detect lamp breakage. It becomes possible to perform a preliminary check. In addition, by adding a control means that turns on the plurality of lamps in sequence for a short time at certain intervals after the engine starts, it becomes possible to check for lamp breakage intermittently and quickly detect burnout. Become.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main part of the device according to the embodiment of the present invention, FIG. 2 is a block diagram of the main part showing the embodiment of the disconnection detection device, and FIG. 3 is a sequential circuit when the device shown in the first figure is operated! +3
This is a line diagram showing an example of signal waveforms of each part. 10 is a battery, 11-13 are ride relays, 14-1
6 is a light switch, 17α to 19h are detected lamps,
20 is an ignition switch, 21 to 23 are current detection resistors, 24 to 26 are disconnection detection circuits, 27 is a warning lamp, 30 is a constant voltage circuit, 31 is a time control circuit, 52
is an inhibition circuit, '56 is a sequential circuit, 54 to 56 are ride relay drive circuits, 67 is a relay circuit, and 38 is an oscillator. Patent applicant Fujitsu Ten Ltd.

Claims (2)

[Claims] (1) In a lamp disconnection detection device having a disconnection detection circuit that detects disconnection of a plurality of lamps installed in an automobile while the light switch is on, the plurality of lamps are sequentially turned on for a short time in multiple times immediately after the engine is started. 1. A lamp breakage detection device characterized by comprising a sequential circuit. (2) In a lamp disconnection detection device having a disconnection detection circuit that detects disconnection of a plurality of lamps installed in an automobile while the light switch is on, the plurality of lamps are sequentially turned on for a short period of time in a plurality of times immediately after the engine is started. 1. A lamp breakage detection device comprising: a sequential circuit for lighting the plurality of lamps sequentially for a short period of time at certain intervals after the engine is started;