JP2002006809A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the exchange of a defective lamp by detecting that the lamp among plural lamps for a back light is broken in a liquid crystal display or the like which is provided for a display device where an input operation is possible from a display panel. SOLUTION: Resistance R3, R4 in the inverter circuit 51b of a back light device 5 detect currents flowing respectively through lamps 52, 53 as voltages and filter circuits 54, 55 convert respectively these voltages into logic levels in accordance with the presence or absence of the current. When a current flowing through the lamp 52 or 53 is cut off, either the filter circuit 54 or the filter circuit 55 outputs the signal of a low level. When a CPU 11 receives the signal, its displays that a lamp current is cut off on the display surface of a display 14. Moreover, when both lamps current are cut off, the CPU prevents an erroneous operation by not making the device accept an input operation by a touch panel 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device having a backlight lamp such as a liquid crystal display, and more particularly to a programmable display device having a function of determining whether to stop turning on a lamp for replacing the lamp. The present invention relates to a display device capable of performing various input operations.

[0002]

2. Description of the Related Art In the field of factory automation (FA),
In recent years, programmable displays have become widespread as displays such as programmable logic controllers (PLCs). The programmable display is an operation display including a dot display screen, an operation input switch, an interface with a host controller (PLC), a program memory for performing control such as operation input on the screen, and the like. Generally, a programmable display is originally a PLC.
Has been developed as a substitute for an operation panel for issuing control instructions to the control panel and an indicator light indicating the operation status of the PLC. The graphic display provides functions such as an operation panel, switches, and indicator lights. Target device (device)
It has a function as a terminal for inputting setting values for various monitors and devices for management, such as the operating status of the device and work instructions. Due to such a function, the field of the programmable display is not limited to the field of FA, but the field used as a display capable of performing input operation is expanding.

In general, such a display device needs to be small in size so that it can be incorporated in a control panel or the like. Therefore, a flat display is provided as a display device. Further, as a flat panel display, an LCD (liquid crystal display) capable of easily realizing multi-color display is often used. Transmissive LCDs are usually provided with a backlight to ensure the brightness of the display surface.

Generally, a fluorescent lamp is used as a light source for a backlight. The main backlight method is, for example, a direct type in which the light of the lamp is directly illuminated from the back of the display surface, or a side light in which the light of the lamp arranged laterally using a light guide plate is spread over the entire display surface. Type.

[0005] Conventional LCDs have low luminance and are inferior in visibility to CRTs. Therefore, in such a display device, two or more lamps are often provided as backlights in order to ensure high luminance on the display surface.

[0006]

When a plurality of lamps are provided as described above, when one lamp is cut off in a state of relatively high luminous intensity, the brightness of the display surface is greatly reduced. The cut can be recognized. However, if the luminous intensity gradually decreases due to deterioration of the fluorescent substance in the lamp or a decrease in the amount of mercury due to long use, the brightness of the display surface gradually decreases, and the operator notices the decrease in brightness. Hateful. Therefore, even if the lamp in such a state goes out, the operator may not recognize that the lamp has gone out. In addition, since the lifespans of the lamps vary, a plurality of lamps hardly burn out at the same time.

Further, in the inverter circuit of the backlight lamp, since the total amount of current supplied to a plurality of lamps is determined, when one of the lamps is cut off, a large current flows excessively to the lit lamp. The total current flowing through the lamp is detected to suppress the total current.
However, since the brightness of the display surface can be adjusted in the display device, when the brightness is adjusted to decrease, the average current flowing through the lamp decreases. For this reason, it is difficult to determine whether the brightness is reduced when all the lamps are turned on or the brightness has been reduced due to one burnout of the lamp.

As described above, when one lamp is cut off, it is not easy to determine whether the lamp is cut off based on the luminance of the display surface.

The present invention has been made in view of the above circumstances, and provides an indicator capable of detecting that one backlight lamp has burned out and facilitating replacement of the lamp. It is intended to be.

[0010]

A display device according to the present invention comprises a plurality of input means for enabling an input operation from a display surface, and a plurality of backlight lamps for irradiating the display surface with light from the back. In the display device, in order to solve the above-described problem, current detection means for detecting a current flowing through each lamp;
It is characterized in that it is provided with lighting-impossibility determining means for determining that lighting of each lamp is not possible based on the detected current, and notifying means for notifying that the lighting of one lamp is determined to be impossible. .

In the above configuration, the current flowing through each lamp is detected by the current detecting means. If one of the plurality of lamps cannot be turned on, no current flows through the lamp. It is determined by the means that the lamp cannot be turned on. Then, this is reported by the reporting means.

As described above, the operator can easily recognize that one lamp cannot be turned on by judging and notifying that the lamp cannot be turned on based on the current flowing for each lamp. Since the life of the lamp usually varies, almost no lamp burnout occurs almost at the same time. Therefore, if even one lamp becomes unlit before all the lamps become unlit, the lamp can be quickly replaced.

In the above-mentioned display device, it is preferable that the notifying means notifies that one lamp cannot be turned on by displaying on the display surface. Even if one lamp cannot be turned on, the brightness of the display surface is ensured to some extent by turning on the other lamps, so that the visibility of the image displayed on the display surface is ensured. Therefore, with the above configuration, the operator can easily recognize on the display surface that the lamp cannot be turned on. In addition, it is not necessary to separately provide a display for notification or the like, and the content of the notification can be described in detail in the form of a message or the like.

Further, as described above, when the notification is made on the display surface, it is preferable to notify which lamp cannot be turned on. Such notification allows the operator to easily recognize which lamp is to be replaced. When replacing the lamp, the operation is performed while the operation of the display device is stopped, so that the operator cannot know which lamp has been cut. Therefore, the lamp replacement operation is facilitated by knowing which lamp is cut before the replacement operation.

In any of the above configurations, if the lighting-impossible determining means determines that all the lamps cannot be lighted,
It is preferable to include an input operation prohibiting unit that prohibits the input operation by the input unit. Because one lamp was not replaced after one lamp became unlit,
Further, if other lamps cannot be turned on and as a result all lamps cannot be turned on, the display surface cannot be irradiated with light and the display surface becomes dark. If the operator attempts to perform an input operation using the input means in such a state, an erroneous operation is likely to occur. However, in such a state, the input operation by the input unit is prohibited by the input operation prohibition unit, so that an erroneous operation can be prevented.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, a programmable display 1 as a display device includes a CPU 11, a memory unit 12,
RAM 13, display 14, graphic controller 15, touch panel 16, touch panel controller 17, maintenance port 18, communication controller 1
9, an alarm lamp 20 and an inverter unit 5 are provided.

The memory unit 12 includes a DRAM 12a, an FEP
ROM (Flash Erasable and Programmable ROM) 12b
Including memory. The DRAM 12a mainly includes
In addition to being used for operations during arithmetic processing such as display control,
Used for temporary storage of data exchanged with the LC2. The FEPROM 12b is a rewritable read-only flash memory and plays a role of a hard disk drive in a general personal computer. The flash memory has no moving parts and is resistant to impact, so that it operates stably even in a poor surrounding environment.

The above-mentioned FEPROM 12b is similar to the one shown in FIG.
As shown in (1), the display control system program has a storage area for storing a display control system program, a communication protocol, and screen data. The display control system program is a program for realizing a basic function for performing image display control. The communication protocol is a protocol used in a communication process with the PLC 2, and a model (manufacturer) of the PLC 2
It is uniquely determined according to. The screen data is created by a drawing editor 32b described later, and
Downloaded to M12b. The screen data includes a base screen to be displayed on the display 14, data of a mark as an image block, a processing instruction word W (see FIG. 3) given to each mark, and the like, and constitutes a display content program. are doing.

The above-mentioned marks are prepared in advance as imaged basic parts such as touch switches, lamps, various displays, and the like. In addition, as a mark, a rectangular area set at a desired position in order to express a dynamic change of a switch or a numerical display at an arbitrary position on a screen or to display a character string, a numerical value, or the like. Also, a display function unit called a tag set in is included.

As shown in FIG. 3A, the processing instruction word W included in the screen data is created for each event to be executed on the base screen. The processing instruction word W basically includes a file number F of a base screen on which a display control operation is to be executed, an event name T for specifying an operation content to be executed on the base screen, And reference information I including one or a plurality of pieces of data referred to as a set.

Further, as shown in FIG. 3 (b), in the base screen of the file number F _1, below the touch panel 1
6, a processing instruction word WT that defines an input operation includes input coordinate ranges X ₁ and Y ₁ on the touch panel 16 and a write bit position A that is turned on in conjunction with the designation of the input coordinate range.
₁ is provided as reference information I.

In addition, as shown in FIG. 3C, the output value of _one of the filter circuits 54 and 55 is set to a high level (for a detection device name D1 that specifies the filter circuit 54 or 55 described later). processing instruction words W ₁ to turn on a given write bit position a ₂ are prepared when it becomes an event name n _2). In the process shown in FIG. 3D, the instruction word W ₂ is used to display a message indicating that the lamp has run out (event name n ₃ ), so that the display coordinate range X ₂ , Y ₂ on the display surface of the programmable display 1 is displayed. When, a reference bit position a ₃ is turned on in conjunction with the specified the display coordinate range as a reference information I.

[0024] Additionally, as shown in FIG. 3 (e), with respect to the detection device name D ₂ that specifies a filter circuit 54, 55 to be described later, the output value of the high level of both of the filter circuit 54, 55 (event processing instruction words W ₃ for turning on a predetermined write bit position a ₄ are prepared when a name n _4). Further, with respect to FIG. 3 (f), the in conjunction with the predetermined reference bit positions A ₅ is turned on, the display device name D ₃ that specifies the indicator lamp 20 will be described later,
To turn on the notification lamp 20 (event name n ₅ ),
Processing instruction word W ₄ needed to control hardware is available.

The CPU 11 is connected to the FEPROM 12b
The operation of each unit of the programmable display 1 is controlled in accordance with the display control system program stored in.
The CPU 11 also includes a maintenance port 18 described later.
And has a function of controlling communication with a computer device 3 to be described later through the FAX. When receiving screen data from the drawing editor 32b, the screen data is stored in the FEPROM 12b,
When a ladder program is received from the ladder editor 32a, the ladder program is transferred to the PLC 2.

In accordance with another program, the CPU 11 outputs an output from a filter circuit 54 or 55, which will be described later, to one of the lamps 52 and 53 so that the lamp cannot be turned on (lamp has run out).
Is reached, a message or the like is displayed on the display 14 in order to notify the operator of this. Further, when the output from the filter circuits 54 and 55 reaches a level at which it is determined that the lamps 52 and 53 cannot be turned on, the CPU 11 controls the touch panel controller 1 so as to prohibit an input operation from the touch panel 14 described later.
7 has a function as an input operation prohibiting means because required processing is not performed on the output data from.

The VRAM 13 is a memory for temporarily storing a screen image displayed on the display 14, and stores the image of the screen data from the FEPROM 12b as dot data in the order displayed in the horizontal direction.

The display 14 is constituted by a flat display element such as a transmissive liquid crystal panel, and incorporates a backlight device 20 described later. The graphic controller 15 is driver software for drawing an image of a screen developed in the VRAM 13 on the display 14. Touch panel 16 as input means
Is provided for performing input on the display screen of the display 14, and an analog resistive touch panel or the like is preferable. The touch panel controller 17 converts the output voltage of the touch panel 16 into input position information and
11 is output.

The maintenance port 18 is a communication port for performing communication with the computer device 3 such as a personal computer. On the other hand, the communication controller 1
An interface 9 controls transfer of data related to control and monitoring of the input / output devices 4 to / from the PLC 2 via a communication cable (for example, RS-232C) and capture of output data of the PLC 2.

The notification lamp 20 is a lamp that lights when all the lamps 52 and 53 of the backlight device 5 described later are cut off and notifies the operator of the fact.
The lighting is controlled by. As shown in FIG. 4, the notification lamp 20 is provided in a part of the housing 1 a of the programmable display 1, for example, in a frame around the display surface 1 b of the programmable display 1.

The backlight unit 5 includes an inverter unit 5
1, lamps 52 and 53 and filter circuits 54 and 55 are provided to irradiate the display surface of the display 14 with light. The backlight device 5 includes a light guide plate (not shown) that guides light emitted from the lamps 52 and 53 over the entire display surface, a reflection plate provided on the back surface of the light guide plate, a diffusion layer that diffuses light over the entire surface of the light guide plate, and the like. Is further provided.

The inverter section 51 has a DC / DC converter 51a and an inverter circuit 51b.

The DC / DC converter 51a is a variable output power supply for changing the input voltage Vin to the inverter circuit 51b for adjusting the luminance. The DC / DC converter 51a is connected to a power supply circuit (not shown) that converts a commercial AC voltage into a DC input voltage Vin.

The inverter circuit 51b has a DC / DC converter
Converts the DC output voltage of the converter 51a into a high AC voltage
A coil L and a resistor R₁~ R_Four, Transis
TA Q ₁・ Q_Two, Capacitor C₁~ C_Three, Transformer T and
And diode D₁~ D_Fourhave.

The coil L has one end connected to the output end of the DC / DC converter 51a, and the other end connected to the transistor Q via the tap of the transformer T and the resistors R ₁ and R _2.
It is connected to the base of the ₁ · Q _2. Transistor Q ₁
And the emitter of Q ₂ are both DC / DC converter 51a
Is connected to the other output terminal of The collector of the transistor Q ₁ is connected to one end of the primary side main winding N ₁ of the transformer T,
It is connected to one end of the capacitor C _1. The collector of the transistor Q ₂ is, the other end of the primary main winding N _1, are connected to the other end of the capacitor C _1. The other end of the resistor R ₁ is connected to the primary end of the auxiliary winding N ₂ of the transformer T, resistor R ₂
The other end is connected to the other end of the primary auxiliary winding N _2.

One end of a secondary winding N ₃ of the transformer T is connected to one end of a lamp 52 via a capacitor C _{2 and} to one end of a lamp 53 via a capacitor C ₃ . The other end of the secondary winding N ₃ of the transformer T is grounded. The other end of the lamp 52 is grounded via a resistor R _3, the other end of lamp 53 is grounded via a resistor R _4.

The diode at one end of the ground side of the resistor R ₃ D
₁ of anode connected, the lamp 52 side of the other end of the resistor R ₃ is connected to the cathode of the diode D _1. The cathode of the diode D ₁ the anode of the diode D ₂ is connected, the cathode of the diode D ₂ is connected to the input terminal of the filter circuit 54. On the other hand, the ground side end of the resistor R ₄ is connected to the anode of the diode D _3, the lamp 53 side of the other end of the resistor R ₄ is connected to the cathode of the diode D _3. The cathode of the diode D ₃ is connected the anode of a diode D _4, diode D ₄
Is connected to the input terminal of the filter circuit 55.

The inverter circuit 5 configured as described above
1a, the primary auxiliary winding N of the transformer T_TwoInduced by
Transistor Q alternately with voltage₁・ Q_TwoON / OFF
The commutation capacitor C₁Charge and discharge
The AC voltage is returned. The frequency of this AC voltage
Is the capacitor C₁~ C_ThreeAnd transformer T
It is determined by the free vibration of the tank circuit formed. Tank circuit
In order to vibrate freely, the inverter viewed from the tank circuit
It is necessary to increase the impedance on the input side of the circuit 51b.
However, the coil L is provided for that purpose. Ma
The capacitor C _Two・ C_ThreeIs the current limiting function
have.

The resistor R ₃ detects the current flowing through the lamp 52 as a voltage, and the resistor R ₄ detects the current flowing through the lamp 53 as a voltage. Although this voltage is not shown,
This is fed back to the C / DC converter 51a. The DC / DC converter 51a adjusts the output voltage so that the supply current to the lamp side is suppressed to a predetermined value when the detection current decreases due to the lamp running out and the above-mentioned voltage decreases. The diodes D ₁ and D ₂ perform full-wave rectification of the AC voltage appearing across the resistor R ₃ , and the diodes D ₃ and D ₄
Is an AC voltage appearing across the resistor R ₃ for full-wave rectification.

The filter circuit 54 includes a diode D ₁ · D
_The filter circuit 55 is a circuit that smoothes the rectified voltage from the diode ₂ and converts it into a DC voltage, and the filter circuit 55 is a circuit that smoothes the rectified voltage from the diodes D ₃ and D ₄ and converts it into a DC voltage.
Filter circuits 54 and 55 include lamps 52 and 53, respectively.
A logic level is output which can distinguish between a state in which the current stops flowing and the lamps 52 and 53 no longer flow and a state in which the luminous intensity is reduced but the current flows in the lamps 52 and 53. As described above, since the filter circuits 54 and 55 determine that at least one of the lamps 52 and 53 cannot be turned on based on the detected current, the filter circuits 54 and 55 have a function as a lighting disabled determination unit.

The lamps 52 and 53 are fluorescent lamps such as cold-cathode tubes. In the sidelight type backlight device 5, while the lamp 52 is arranged on the left side, the lamp 5
3 is arranged on the right side.

The PLC 2 as a control device has a built-in C
The operation of the input / output devices 4 is controlled by the PU unit according to the control function program and in the procedure determined by the ladder program. The memory in the PLC 2 is set so that the word device and the bit device can specify the storage location by specifying an address. In the word device, input / output data is set for word data such as a numerical value, and for the bit device, bit data such as an on / off state is set. With such a setting, the input / output devices 4 can be accessed simply by accessing an arbitrary word device or bit device in the PLC 2.
, Or individually retrieve information about its operating state.

The programmable display 1 includes, among the status information indicated by the bit device or the word device,
While the necessary information is read into the memory unit 12 in a timely manner, the processing instruction word W is repeatedly read and the operation of the content specified by the event name T of each processing instruction word W is executed while referring to the state information on the PLC 2 side. I do. Thus, a display operation that changes according to a change in the state of the bit device or the word device is performed.

Next, the operation according to the lighting state of the lamps 52 and 53 of the programmable display 1 configured as described above will be described.

In a state where both the lamps 52 and 53 are normally lit, a normal current flows through the lamps 52 and 53, and the current is detected by the resistors R ₃ and R ₄ and the respective filter circuits 54 -Input to 55. The filter circuits 54 and 55 output a high-level signal with the input voltage as a logic level indicating that the lamps 52 and 53 are lit. When the CPU 11 receives the signal,
Since it recognizes that the lamps 52 and 53 are lit,
Maintain the normal control state.

For example, when the lamp 52 becomes unlit,
Since the current stops flowing through the lamp 52, it is determined by the resistance R ₃
And is input to the filter circuit 54. The filter circuit 54 outputs a low-level signal with the input voltage as a logic level indicating that the lamp 52 is not lit. When the CPU 11 receives the signal, the lamp 5
Since it is recognized that only 2 is not lit, a message for notifying the operator of the fact is displayed on the display 14. The display 14 displays the message at an arbitrary position on the screen displayed on the display surface. This message indicates that the lamp 52 is off, for example, "The left lamp is off. Please replace it." The message is prepared as a tag for text display. Thus, the operator can easily recognize that the lamp 52 has been burned out, so that the lamp 52 can be quickly replaced.

At this time, even if the lamp 52 is cut off, since the lamp 53 is lit, the luminance of the display surface is greatly reduced, but the displayed screen can be visually recognized. Input operation from 16 is also possible. Therefore, there is no need to immediately interrupt the input operation from the touch panel 16. Also, the above operation
The same operation is performed when only the lamp 53 is cut off.

[0048] Further, when even the ramp 53 without replacing the lamp 52 has expired becomes impossible lighting, since no current flows through the lamp 53, it is detected by the resistor R _4,
The signal is input to the filter circuit 55. The filter circuit 55
A low level signal is output as the input voltage as a logic level indicating that the lamp 53 is not lit. CPU
When the signal 11 receives the signal, it recognizes that both the lamps 52 and 53 are not lit, and thus invalidates the output data from the touch panel controller 17. As a result, even if the operator performs an input operation using the touch panel 16, the input operation is not accepted, thereby preventing an erroneous operation caused by the operator performing an input operation relying on intuition when the display surface is dark and the screen cannot be visually recognized. it can. Therefore, it is possible to avoid a malfunction of the input / output device 4 due to a malfunction.

Here, the processing procedure of the above operation by the CPU 11 will be described with reference to the flowchart of FIG.

First, initialization is performed after the power of the programmable display 1 is turned on (S1). At this time, processing such as resetting the bit in each processing instruction word W is performed. In addition, a write bit position A ₂ that is turned on by one of the filter circuit output processing instruction words W ₁ is referred to in advance as a reference bit position A ₃ (FIG. 3D) for displaying a lamp-off message. (FIG. 3C) is designated.
As a reference bit position A ₅ (FIG. 3 (f)) referred to for turning on the notification lamp 20, a write bit position A ₄ (FIG. 3) that is turned on by the processing instruction word W ₄ for both filter circuit outputs. (E)) is specified.

Next, it is determined whether one of the lamps 52 and 53 has been cut off based on the outputs of the filter circuits 54 and 55 (S2). Here, if it is not determined that the lamp has run out, the process returns to S2, while if it is determined that the lamp has run out, a message is displayed on the display 14 (S3).

In a state where one of the lamps 52 and 53 is cut off, the other is cut off.
It is determined whether both the lamps 52 and 53 have been cut (S
4). Here, if it is not determined that the lamp has run out, the process returns to S4, while if it is determined that the lamp has run out, the notification lamp 20 is turned on (S5).

Further, it is determined whether or not an input operation has been performed on the touch panel 16 (S6). Here, if there is no input operation, the process returns to S6, while if there is an input operation, the input operation of the touch panel 16 is invalidated by not performing the process based on the output data from the touch panel 16 (S7). , End the process.

As described above, the programmable display device 1 according to the present embodiment displays the fact on the display surface of the display 14 when one of the two lamps 52 and 53 is cut off. It is configured as follows. As a result, even if the brightness of the display surface is significantly reduced, the brightness of the display surface is secured to a certain extent by turning on the other lamp. Can be visually recognized, and an input operation using the touch panel 16 is also possible. Therefore, since the programmable display 1 can be used without immediately replacing the lamp, there is no need to stop the operating system for replacing the lamp. In addition, it is not necessary to separately provide a display for notification or the like, and it is also possible to explain the information about the lamp out in more detail in the form of a message or the like. Therefore, it is possible to more reliably prompt the operator to replace the lamp.

Also, by notifying which of the lamps 52 and 53 is cut off, Such notification allows the operator to easily recognize which lamp is to be replaced. In the lamp replacement, since the operation is performed while the operation of the programmable display 1 is stopped, the operator cannot know which lamp has been cut. Therefore, it is possible to efficiently perform the lamp replacement operation by knowing which lamp is cut before the replacement operation.

Further, the programmable display 1 is configured not to accept an input operation from the touch panel 16 when all the lamps 52 and 53 are turned off. Thus, even if the operator attempts to perform an input operation on the touch panel 16 in a state where the display surface is dark, the input operation is not accepted, so that an erroneous operation can be prevented as described above. Therefore, the reliability of the programmable display 1 can be further improved. In addition, the fact that all the lamps 52 and 53 have been cut off is notified by turning on the notification lamp 20, so that the operator can easily recognize the reason why the input operation of the touch panel 16 is impossible, and confusion is caused. Can be avoided.

In this embodiment, the two lamps 5
Although the configuration having 2.53 has been described, the number of lamps is not limited to two, and may be three or more. Further, the message may be output not only by display but also by other means such as voice. Furthermore, in the present embodiment, an example in which an LCD is used as the display 14 has been described.
However, the invention is not limited thereto, and a display device that requires the backlight device 5 may be used.

[0058]

As described above, the display device of the present invention comprises: an input means for enabling an input operation from a display surface; a plurality of backlight lamps for irradiating the display surface with light from the back; Current detection means for detecting a current flowing through each lamp;
It is configured to include a lighting disable determination means for determining that each lamp cannot be turned on based on the detected current, and a notification means for notifying that the lighting of one lamp is determined to be impossible.

As a result, since it is determined that the lighting is impossible based on the current flowing for each lamp and the notification is made, the operator can easily recognize that one lamp is not lighting. Therefore, if even one lamp becomes unlit before all the lamps become unlit, the lamp can be quickly replaced. By easily recognizing the lamp replacement time, it is possible to easily avoid a situation where all the lamps cannot be turned on and the display device cannot be used, thereby improving the reliability of the display device. It works.

In the above display device, the notifying means notifies the operator that one lamp cannot be turned on by displaying on the display surface, so that the operator can easily indicate on the display surface that the lamp cannot be turned on. Can be recognized. In addition, it is not necessary to separately provide a display for notification or the like, and the content of the notification can be described in detail in the form of a message or the like. Therefore, there is an effect that the operator can be more reliably prompted to replace the lamp.

Further, as described above, when the notification is made on the display surface, by notifying which lamp cannot be turned on, the operator can easily recognize which lamp is to be replaced. can do. Therefore, it is possible to efficiently perform the lamp replacement operation by knowing which lamp is cut off before the replacement operation.

In any of the above configurations, if the lighting-impossible determining means determines that all the lamps cannot be lighted,
By providing the input operation prohibiting unit for prohibiting the input operation by the input unit, the operator performs the input operation by the input unit in a state where the display surface is dark because all the lamps cannot be turned on. However, since the input operation by the input unit is prohibited, erroneous operation can be prevented. Therefore, there is an effect that the reliability of the display device can be further improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a programmable display device according to an embodiment of the present invention and a connection relationship with another device.

FIG. 2 is an explanatory diagram showing a program stored in a FEPROM of the programmable display.

FIGS. 3A to 3F are explanatory diagrams showing a basic format of an instruction processing word included in data of a screen displayed on the programmable display device.

FIG. 4 is a perspective view showing an appearance of the programmable display.

FIG. 5 is a flowchart illustrating a procedure of a process for lamp burnout in the programmable display.

[Explanation of symbols]

Reference Signs List 1 Programmable display (display device) 1a Display surface 5 Backlight device 11 CPU (notification means, input operation prohibition means) 14 Display 16 Touch panel (input means) 20 Notification lamp 51b Inverter circuit 52/53 Lamp 54/54 Filter circuit ( lighting impossible judging means) R ₃ · R ₄ resistor (current detecting means)

Claims (4)

[Claims] 1. A display device comprising a plurality of input means for enabling an input operation from a display surface and a backlight lamp for irradiating the display surface with light from a back surface, wherein a current flowing through each lamp is detected. Current detecting means for determining whether or not each lamp is illuminated based on the detected current, and notifying means for notifying when one of the lamps is determined not to be illuminated. A display device. 2. The display device according to claim 1, wherein said notifying means notifies that one lamp cannot be turned on by displaying on said display surface. 3. The display device according to claim 2, wherein said notifying means notifies which lamp is not lit. 4. An apparatus according to claim 1, further comprising an input operation prohibiting means for prohibiting an input operation by said input means when said lighting impossible determining means determines that all the lamps cannot be lighted. 2. The display device according to claim 1.