JPH0315887A - Laser output securing device for laser drawing device - Google Patents

Abstract

PURPOSE:To eliminate danger to a human body due to the excessive light emission of a laser light emitting element and prevent a drawn surface from damaging by reducing or stopping laser output automatically when detecting the detection output of a photodetector being outside a permissible range. CONSTITUTION:This device is provided with the photodetector 6 which detects the laser output of the laser light emitting element 3 and a laser level detecting circuit 7 which detects whether or not the detection output of the photodetector 6 being outside the permissible range and when the laser level detecting circuit 7 detects the output being outside the permissible range, the automatic power control circuit 2 of the laser light emitting element 3 controls a driving signal for reducing or stopping the laser output preferentially to a control signal. Consequently, the laser light emitting element is prevented from emitting light excessively to eliminate the danger of the excessive light emission to the human body and prevent the drawn surface from damaging.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a laser drawing device that creates an image by varying laser output according to the output of a video signal,
The present invention relates to a laser output guarantee device that guarantees the laser output.

[Summary of the invention]

The first invention includes a photodetector that detects the laser output of a laser emitting element, a laser level detection circuit that detects whether the detection output of the photodetector is outside the tolerance range, and the laser level detection circuit detects whether the detection output of the photodetector is outside the tolerance range. When detecting this, the automatic power control circuit of the laser emitting element controls the drive signal to reduce or stop the laser output with priority over the control signal, thereby preventing the laser emitting element from emitting excessive light, This is to prevent danger to the human body and damage to the drawing surface due to excessive light emission.

A second invention provides a power supply voltage detection circuit that detects whether the power supply voltage that drives the automatic power control circuit is outside the proper range, and when the power supply voltage detection circuit detects that the power supply voltage is outside the proper range, the automatic power control circuit By controlling the drive signal so that the circuit gives priority to the control signal and reduces or stops the laser output, excessive light emission of the laser emitting element is prevented, resulting in danger to the human body and
This is to prevent damage to the cat screen.

The third invention includes a photodetector that detects the laser output of the laser emitting element, a laser level detection circuit that detects whether the detection output of the photodetector is outside the allowable range, and a power supply voltage that drives the automatic power control circuit. A power supply voltage detection circuit is provided to detect whether the laser level is outside the permissible range, and when the laser level detection circuit detects that the laser level is outside the permissible range, or when the power supply voltage detection circuit detects that it is outside the permissible range, the automatic By controlling the drive signal so that the power control circuit reduces or stops the laser output with priority over the control signal, excessive light emission of the laser emitting element is prevented, resulting in danger to the human body and
This is to prevent damage to the drawing surface.

[Conventional technology]

The laser drawing apparatus has a video signal processing circuit that detects the level of a manually input video signal and sends a control signal corresponding to this level to an automatic power control circuit. This automatic power control circuit outputs a drive signal based on the control signal to the laser emitting element,
This laser emitting element outputs laser light. The optical path of this laser beam is controlled by an optical path changing means, and the laser beam is irradiated onto a desired position on a film, screen, or the like, which is the surface to be drawn.

[Problem to be solved by the invention]

However, conventional laser drawing apparatuses do not have safety measures against excessive light emission from laser light emitting elements. Therefore, if the video signal processing circuit or automatic power control circuit malfunctions and the laser light emitting element emits excessive light, problems such as danger to the human body and damage to the surface to be drawn will occur. Further, problems similar to those described above may occur when the automatic power control circuit malfunctions due to fluctuations in the power supply voltage that drives the automatic power control circuit.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a laser output guaranteeing device for a laser drawing apparatus that eliminates various problems caused by excessive light emission by preventing excessive light emission of a laser light emitting element.

[Means for Solving the Problems] A laser output guarantee device for a laser drawing device according to a first invention for achieving the above object supplies a control signal according to the level of a video signal to an automatic power control circuit,
A laser drawing device in which this automatic power control circuit outputs a drive signal based on a control signal to a laser emitting element is provided with a photodetector that detects the laser output of the laser emitting element, and whether the detected output of the photodetector is outside the allowable range or not. A laser level detection circuit is provided to detect whether the laser level is outside the allowable range, and when the laser level detection circuit detects that the laser level is outside the permissible range, the automatic power control circuit reduces or stops the laser output with priority over the control signal. It controls the

Further, a laser output guarantee device for a laser drawing device according to a second aspect of the invention for achieving the above object supplies a control signal according to the level of a video signal to an automatic power control circuit, and the automatic power control circuit controls the In a laser drawing device that outputs a drive signal based on a signal to a laser emitting element, a power supply voltage detection circuit is provided to detect whether the power supply voltage for driving the automatic power control circuit is outside the appropriate range, and whether the power supply voltage detection circuit is within the appropriate range or not. When detecting that it is outside the range, the automatic power control circuit controls the drive signal to reduce or stop the laser output, giving priority to the control signal.

Furthermore, a laser output guarantee device for a laser drawing device according to a third aspect of the invention for achieving the above object supplies a control signal according to the level of a video signal to an automatic power control circuit, and the automatic power control circuit controls the In a laser drawing device that outputs a drive signal based on a signal to a laser emitting element, a photodetector is provided to detect the laser output of the laser emitting element, and a laser level detection circuit is provided to detect whether the detected output of the photodetector is outside a permissible range. In addition, a power supply voltage detection circuit is provided to detect whether the power supply voltage for driving the automatic power control circuit is outside the appropriate range. When the voltage detection circuit detects that the voltage is outside the proper range, the automatic power control circuit controls the drive signal to reduce or stop the laser output in priority to the control signal.

When the laser level detection circuit detects that the laser output to be output is outside the permissible range, or when the power supply voltage detection circuit detects that the power supply voltage is outside the proper range, the automatic power control circuit uses a control signal to The control is stopped and the drive signal is forcibly controlled to reduce or stop the laser output.

[Effect]

According to the first invention, when the laser level detection circuit detects that the laser output detected by the photodetector is outside the permissible range, the automatic power control circuit stops the control by the control signal and forcibly controls the drive signal. to reduce or stop the laser output.

According to the second invention, when the power supply voltage detection circuit detects that the power supply voltage is outside the appropriate range, the automatic power control circuit stops controlling the control signal and forcibly controls the drive signal to control the laser output. reduce or stop.

According to the third invention, the photodetector detects (Example) Examples of the present invention will be described below with reference to the drawings.

1 and 2 show a first embodiment to which the first invention is applied. FIG. 1 shows a circuit block diagram of a laser drawing device. In Figure 1, a stable power source E
The power supply voltage is supplied to the following circuits etc. via the power switch SW.

A video signal is input to the video signal processing circuit I, and the video signal processing circuit I outputs a control signal according to the signal level to an automatic power control circuit (APC) 2. A drive signal according to the output voltage is outputted by feedback control to a laser diode (LD) 3, which is a laser light emitting element.The laser light from this laser diode 3 is sent to a beam splitter 5 via a collimator lens 4.This beam splitter The ivy 5 sends most of the incident laser light to the main optical path and changes the optical path of a part to the photodetector 6 side.The optical path of the laser light sent to the main optical path is controlled by an optical path changing means (not shown), and the optical path is changed to the drawing surface. It is irradiated onto a film, screen, etc.

The optical path changing means is controlled based on a synchronization signal of the video signal.

The output of the photodetector 6 is sent to laser level detection means 7. This laser level detection means 7 detects whether the detection output of the photodetector 6 is outside the permissible range or not, and outputs an abnormal signal to the automatic power control circuit 2 if it is outside the permissible range. Whether or not the detection output of the photodetector 6 is outside the permissible range can be determined by checking the photodetector 6 in advance.
It is determined by measuring the laser light output of the main optical path with respect to the detection output of and taking into consideration the influence on the human body, the surface to be drawn, etc. When the automatic power control circuit 2 receives an abnormal signal, it stops controlling the video signal processing circuit 1 using the control signal and controls the drive signal to forcibly reduce or stop the laser beam. Therefore, in this embodiment, the photodetector 6, the laser level detection circuit 7, and the automatic power control circuit 2 constitute a laser output guarantee device.

FIG. 2 shows a circuit diagram showing an example of the laser level detection circuit 7. In FIG. In FIG. 2, the output of the photodetector 6 is inputted to the input terminal of the converter 9 via the amplifier 8. The single input terminal of comparator 9 is variable resistor VR. A movable element is connected, and a partial voltage of the power supply voltage is input as a reference value V to the single power terminal. This reference value V1 is varied by changing the position of the movable element. The output of this converter 9 is input to the mono multi-bi break IO, and when the converter 9 outputs the H signal, the mono multi-bi break IO outputs the H signal as an abnormal signal to the automatic power control circuit 2 for a predetermined period of time.

In the above configuration, when the power switch SW is turned on and a video signal is input to the video signal processing circuit 1, a control signal corresponding to the signal level is sent to the automatic power control circuit 2.
is output to. The automatic power control circuit 2 supplies a drive signal based on the control signal to the laser diode 3, and the laser diode 3 outputs a laser beam with a predetermined output. This laser output Ichiro is detected by the photodetector 6,
This detection output is amplified by amplifier 8 and then input to comparator 9. If this detection output is less than the reference value V1, the output of the comparator 9 is in the L state, so no abnormal signal is output from the mono multivibrator IO, and the automatic power control circuit 2 performs control based on the control signal. .

If the video signal processing circuit 1, the automatic power control circuit 2, or the laser diode 3 breaks down and the laser output exceeds the safe value, the detection output of the photodetector 6 will exceed the reference value V. Then, the output of the comparator 9 becomes an H state, and the monomultiviprator 10 outputs an abnormal signal to the automatic power control circuit 2. The automatic power control circuit 2 stops the control by the control signal of the video signal processing circuit 1 and forcibly controls the drive signal to reduce the laser output (to a stable and safe value) or stop it.

3 and 4 show a second embodiment to which the second invention is applied. FIG. 3 shows a circuit block diagram of the laser drawing device. In FIG. 3, the power supply voltage of a power supply whose stability is not guaranteed is supplied to the circuits described below. Video signal processing circuit! , the automatic power control circuit 2 and the laser diode 3 are the same as in the first embodiment, so the same reference numerals as above will be used in the drawings and the explanation thereof will be omitted. All of the laser light from the laser diode 3 is guided to the surface to be drawn via a collimator lens 4. The power supply voltage detection circuit 11 is designed to operate at a voltage wider than the normal operating power supply voltage of the automatic power control circuit 2, and if the power supply voltage is outside the appropriate range for driving the power control circuit 2 or the laser diode 3. Detect whether or not. If it is outside the proper range, is it the automatic power converter? An abnormal signal is output to the roll circuit 2. When the automatic power control circuit 2 receives an abnormal signal, it performs the same operation as in the first embodiment. Therefore, in this embodiment, the power supply voltage detection circuit 11 and the automatic power control circuit 2 constitute a laser level guarantee device.

Figure 4 shows the power supply voltage detection circuit! A circuit diagram illustrating an example of one integrated circuit is shown. In FIG. 4, the power supply voltage is supplied to a power supply stabilizing circuit 12, and this power supply stabilizing circuit 12 has a simple structure that removes ripples in the input voltage. The output of this power supply stabilizing circuit 12 is used as driving power for the two comparators 13 and I4, and is also connected to each comparator 13 via each variable resistor VR.
, l4 are supplied to the ten-input terminal and one-power terminal, respectively. Specifically, each variable resistor V R t, V R
The movable element a is connected to the ten-input terminal and one-power terminal of each comparator 13, 14, and a divided voltage of the output voltage is inputted to each terminal as each reference value V*, Vs. Each of these reference values Vt. Vs can be varied by changing the position of the mover. Further, the voltage of the power supply is supplied to the other input terminal and the input terminal of each comparator 13 and +4, respectively. Each output of each of the comparators 13 and 14 is inputted to an OR circuit 15, and the output of this OR circuit 15 is led to a mono-multivibrator 16. When the OR circuit 15 outputs the H signal, the mono multivibrator 16 outputs the H signal as an abnormal signal to the automatic power control circuit 2 for a predetermined period of time.

In the above configuration, the video signal is processed by the video signal processing circuit l.
, the video signal processing circuit 1, the automatic power control circuit 2, and the laser diode 3 are operated, and the laser diode 3 outputs a laser beam of a predetermined output as in the above-mentioned Embodiment 1.

During this operation, if the voltage of the power supply is within the appropriate range (between V and ■3), each converter 13. +4 outputs are both in the L state, so the mono multivibrator l6
No abnormal signal is output from the automatic power control circuit 2, and the automatic power control circuit 2 performs control based on the control signal.

Now, the voltage of the power supply fluctuates and the voltage is less than the reference value V,
or the reference value V, or above, the output of one comparator l3 or the other comparator l4 becomes H state, and the mono multi-by-layer 16 outputs an abnormal signal to the automatic power control circuit 2, and the automatic power control circuit 2 The same operation as in the first embodiment is performed to reduce or stop the laser output.

It is thought that the laser output will decrease if the power supply voltage is below the reference value V, but this is not necessarily the case and the laser output may become unstable and cause excessive light emission. It is assumed that an abnormality is also determined when the value is less than or equal to the value V.

Further, in the case of the first embodiment, an abnormality is detected after the laser diode 3 emits excessive light, whereas in the case of the second embodiment, an abnormality can be detected before the laser diode 3 emits excessive light. However, since the causes of abnormalities that can be detected are different, it is recommended to use both together when using an unstable power supply.
An example of this is shown in the following third embodiment.

FIG. 5 shows a third embodiment to which the third invention is applied. FIG. 5 shows a circuit block diagram of a laser drawing device, and since this third embodiment has a configuration that is almost a combination of the first and second embodiments, the same components are The same reference numerals are given to the drawings, and the explanation thereof will be omitted.

That is, a power supply whose stability is not guaranteed is used, and the output of the power supply stabilizing circuit l2 of the power supply voltage detection circuit 11 is configured as a driving power supply for the laser level detection circuit 7, so that the laser level detection circuit 7 does not malfunction. There is. The abnormality signal of the power supply voltage detection circuit I1 and the abnormality signal of the laser level detection circuit 7 are respectively input to an OR circuit 17, and the output of this OR circuit 17 is led to the automatic power control circuit 2. Therefore, the foot detector 6, the laser level detection circuit 7, the power supply voltage detection circuit II, the power supply circuit 17, and the automatic power control circuit 2 constitute a laser output guarantee device.

The laser level detection circuit 7 detects that the detection output of the photodetector 6 is outside the permissible range, or the power supply voltage detection circuit 1 detects that the power supply voltage is outside the appropriate range.
1 is detected, an abnormal signal is output from the OR circuit 17, and the automatic power control circuit 2 stops the control by the control signal and forcibly controls the drive signal to reduce or stop the laser output.

In the first to third embodiments, the laser output is only reduced or stopped when an abnormality occurs, but by adding means such as alarms and warning displays, abnormalities can be quickly recognized. preferred.

〔Effect of the invention〕

As described above, the present invention has the following effects.

According to the first invention, a photodetector is provided to detect the laser output of the laser emitting element, and a laser level detection circuit is provided to detect whether the detection output of the photodetector is outside the allowable range. When it was detected that the automatic power control circuit of the laser emitting element was in a state of failure, the automatic power control circuit of the laser emitting element controlled the driving signal to reduce or stop the laser output with priority over the control signal. This prevents excessive light emission, thereby preventing danger to the human body and damage to the drawing surface due to excessive light emission.

According to the second invention, there is provided a power supply voltage detection circuit that detects whether the power supply voltage that drives the automatic power control circuit is outside the proper range, and when the power supply voltage detection circuit detects that the power supply voltage is outside the proper range, the automatic power control circuit Since the power control circuit controls the drive signal to reduce or stop the laser output with priority over the control signal, it prevents the laser emitting element from emitting excessive light due to instability of the power supply voltage, thereby preventing danger to the human body.
This is to prevent damage to the drawing surface.

The third invention includes a photodetector that detects the laser output of the laser emitting element, a laser level detection circuit that detects whether the detection output of the photodetector is outside the allowable range, and a power supply voltage that drives the automatic power control circuit. A power supply voltage detection circuit is provided to detect whether the laser level is outside the permissible range, and when the laser level detection circuit detects that the laser level is outside the permissible range, or when the power supply voltage detection circuit detects that it is outside the permissible range, the automatic Since the power control circuit controlled the drive signal to reduce or stop the laser output with priority over the control signal, excessive light emission of the laser emitting element due to failure of the automatic power control circuit or instability of the power supply voltage can be prevented. This is to prevent danger to the human body, damage to the display screen, etc.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention, FIG. The figure shows a second embodiment of the present invention, FIG. 3 is a circuit block diagram of a laser drawing device, FIG. 4 is a circuit diagram of a power supply voltage detection circuit, and FIG. 5 is a laser drawing device showing a third embodiment. FIG. 3 is a circuit block diagram of the device. 2... Automatic power control circuit, 3... Laser diode (laser light emitting element), 6... Photodetector, 7... Laser level detection circuit, l1... Power supply voltage detection circuit.

Claims (3)

[Claims] (1) In a laser drawing device in which a control signal corresponding to the level of a video signal is supplied to an automatic power control circuit, and the automatic power control circuit outputs a drive signal based on the control signal to a laser emitting element, A photodetector for detecting laser output is provided, and a laser level detection circuit is provided for detecting whether the detection output of the photodetector is outside an allowable range,
A laser drawing device characterized in that when the laser level detection circuit detects that the laser level is outside the permissible range, the automatic power control circuit controls the drive signal to reduce or stop the laser output in priority to the control signal. Laser output guarantee device. (2) A laser drawing device in which a control signal corresponding to the level of a video signal is supplied to an automatic power control circuit, and this automatic power control circuit outputs a drive signal based on the control signal to a laser emitting element, the automatic power control circuit A power supply voltage detection circuit is provided to detect whether the power supply voltage driving the is outside the appropriate range.
A laser drawing apparatus characterized in that when the power supply voltage detection circuit detects that the power supply voltage is outside the appropriate range, the automatic power control circuit controls the drive signal to reduce or stop the laser output with priority over the control signal. Laser output guarantee device. (3) A laser drawing device in which a control signal corresponding to the level of a video signal is supplied to an automatic power control circuit, and this automatic power control circuit outputs a drive signal based on the control signal to a laser light emitting element, wherein the laser light emitting element is A photodetector for detecting laser output is provided, and a laser level detection circuit is provided for detecting whether the detection output of the photodetector is outside a permissible range, and detects whether a power supply voltage for driving the automatic power control circuit is outside an appropriate range. A power supply voltage detection circuit is provided, and when the laser level detection circuit detects that the laser level is outside the permissible range, or when the power supply voltage detection circuit detects that the power supply voltage is outside the proper range, the automatic power control circuit controls the control. A laser output guarantee device for a laser drawing apparatus, characterized in that the drive signal is controlled to reduce or stop the laser output in priority to the signal.