Abstract:
An idling stop signal display apparatus is connected to traffic relating equipment for prompting a running automobile to stop. The idling stop signal display apparatus comprises display means for prompting an automobile driver to stop an engine and to restart the stopped engine, and control means, including said display apparatus, which prompts engine stop by determining a preferable period of time based on an input signal from the traffic relating equipment and functions to prompt the stopped engine to restart by determining a preferable timing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 09/635,126, filed on Aug. 8, 2000, and now U.S. Pat. No. 6,463,900. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an automobile engine idling stop signal display at an intersection or the like. 
     More specifically, this invention relates to an automobile engine idling stop signal display apparatus at an intersection or the like to wait for a traffic signal lamp to change. 
     2. Description of the Related Art 
     When automobiles wait for a traffic signal to change to red for a predetermined period of time, ordinarily, the drivers wait for the change of the traffic signal while keeping engines in an idling state in most cases. By continuing the engine idling, not only the fuel supplied thereto during the idling time is wastefully consumed but also global warming substances such as carbon dioxide (CO 2 ) and the like and gases such as nitrogen oxide (NOx) and the like which are harmful to human bodies are discharged. To cope with this problem, an “idling stop campaign” is being conducted in some districts to promote the idling stop of automobile engines when automobiles are at rest. 
     Apparatus for controlling the stop of automobile engines have been proposed. The engine stop control apparatus are arranged for temporary stop of the automobile engines when the automobile stops at a red signal or meets a traffic jam. These apparatuses are proposed in the technologies disclosed in, for example, Japanese Unexamined Patent Publication No. 11-62650. 
     According to the technology disclosed in Japanese Unexamined Patent Publication No. 11-62650, any one of a normal cruising mode or an idling stop/energy saving cruising mode is previously selected by a mode selection switch. In the case that the idling stop/energy saving cruising mode is selected, it is possible to stop an engine at temporary stoppage of an automobile and then to restart the engine, by the ordinary driving operation such as the depression of a brake pedal and the shift operation of a shift lever. By this operation, an idling-stop-controlled automobile can be realized, whereby fuel consumption is saved and atmospheric pollution is prevented in a global scale. 
     When a driver waits for signal change from red to green or a driver waits for train passing at a lowered gate of a railroad crossing, the driver usually keeps the engine in an idling state without stopping. The reason is to promptly start an automobile just after the red signal is changed to green or gate arm is lifted after train passing. However, gasoline is wastefully consumed by keeping the engine in the idling state during the automobile stoppage. 
     In addition to the above, the engine discharges global warming substances such as carbon dioxide (CO 2 ) and the like and gases such as nitrogen oxide (NOx) and the like which are harmful to human bodies. Therefore, an “idling stop campaign” is being conducted in some districts to promote the idling stop when an automobile is at rest as described above. However, a major reason why the “idling stop campaign” does not become widespread resides in the nuisance of stopping an engine. 
     FIG. 13 shows a discharge characteristic of an amount of nitride oxide (NOx) before and after stopping an engine idling. In the figure, “i” shows a NOx discharge level in idling state. Numeral t 1  denotes a time at which idling is stopped and numeral t 2  denotes a time at which an engine is restarted. A slanting-lined region M 1  shows an amount of exhaust gas that is reduced by an idling stop. A slanting-lined region M 2  shows an excess amount of exhaust gas that is increased by highly concentrated exhaust gas at engine restart, in comparison with the continuous idling. 
     Thus, no NOx gas is discharged for a period of time t by stopping the idling, and the amount of exhaust gas reaches a peak value that exceeds the level of the idling start by restart of the engine. It is then lowered to the level of the idling state as a time passes. In the case that the region M 2  is smaller than the region M 1 , the idling stop is effective to reduce the exhaust gas. Note that curves showing variations of the exhaust gases, which are similar to that of NOx, are also drawn similarly as to CO 2 , CO and THC. 
     However, there are cases in which it is not always preferable to stop idling when an automobile is stopped at a stop signal (red signal) and the like, for example, as shown below. 
     When an engine is restarted, the amount of fuel required in a cranking process (a process for restarting the engine by rotating a starter motor) is more than the amount of fuel needed in continuous idling. In this case, fuel is much consumed by the idling stop. 
     When an engine is restarted, harmful exhaust gas are discharged more than that of the exhaust gases discharged in continuous idling. In this case, the harmful exhaust gas is discharged more than that in the idling stop. 
     A battery load is excessively increased when the headlamps are turned on at night or air conditioning is carried out. In this case, there may be a possibility that the battery goes dead and an engine cannot be restarted. 
     In the above cases, harmful effects are caused by the stop of idling. 
     As a reason why “the idling stop” is not widely popularized even though a driver recognizes the effect of it, there is the conventional custom that the driver can not instantaneously recall the idling stop and misses a timing for the action, in addition to the driver&#39;s bothersome feeling of the idling stop action. 
     Further, still another reason is that the driver may find it unpleasant to have to promptly run an automobile by restarting the engine idling just before signal changes from red to green or just before a crossing gate is lifted. 
     SUMMARY OF THE INVENTION 
     To solve the above problems, an object of the invention is to provide an idling stop signal display apparatus as an apparatus effective to make an “idling stop” campaign become widespread, the apparatus being arranged such that it prompts a driver to stop an engine at a proper timing while a traffic signal device displays a red signal or while the gate arm of a crossing gate is lowered and then notifies the driver of a time at which the engine is to be restarted. 
     In a particular embodiment of the invention, there is provided an idling stop signal display apparatus connected to traffic relating equipment for prompting a walker or a traveling automobile to stop, comprising display means capable of making a display for prompting an automobile at rest at least to stop an engine and to restart the stopped engine; and control means having a function for determining a time zone during which it is preferable to stop the engine based on the signal input from the traffic relating equipment and causing the display means to make a display for prompting the engine to stop as well as a function for determining a time zone during which it is preferable to restart the stopped engine and causing the display means to make a display for prompting the engine to restart. 
     The traffic relating equipment may be a traffic signal device installed at an intersection or the like and connected thereto, and the control means divides the time zone during which a red signal is turned on for a predetermined period of time at predetermined intervals in a time series direction based on input red signal display information, and has a function for causing the display means to make a display for prompting the engine to stop in the first divided section of a plurality of divided sections and a function for causing the display means to make a display for prompting the engine to restart in the final section of the plurality of divided sections. 
     Specifically, in the case that the length of an preceding red signal exceeds a predetermined period of time, the control means may control the display means such that the display means sequentially makes a first display for prompting the engine to stop, a second display for prompting the engine to leave as it is which follows the first display and a third display for prompting to restart the engine, which follows the second display, whereas when the length of the information of the immediately preceding red signal does not exceed the predetermined period of time, the control means may control the display means such that the display means makes only the second display. 
     Further, the traffic relating equipment may be a crossing gate of a railroad and connected thereto, and the control means may cause the display means to make a display for prompting the engine to stop of the automobile based on a signal input to the apparatus that indicates that a train has approached or a crossing arm has been lowered and to make a display for prompting the engine to restart based on an input signal to the apparatus which indicates that the train has passed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view showing the schematic arrangement of an automobile engine idling stop system according to an embodiment of the present invention. 
     FIG. 2 is a view showing an example of the automobile engine idling stop system according to the embodiment of the present invention. 
     FIG. 3 is a view explaining an example of a signal transmitted by a transmitter. 
     FIG. 4 is a view showing a timing at which an automobile engine is restarted after the idling thereof is stopped. 
     FIG. 5 is a graph explaining conditions under which an idling stop effect can be obtained in the consumption of fuel. 
     FIG. 6 is a graph explaining conditions under which an idling stop effect can be obtained in exhaust gases (NOx). 
     FIG. 7 is an example of flowchart showing the processing steps performed by the automobile engine idling stop system according to the embodiment of the present invention. 
     FIG. 8 is a view explaining the relationship between a traffic signal device and an automobile at an intersection in the automobile engine idling stop system according to the embodiment of the present invention. 
     FIG. 9 is a schematic view showing timings at which the turning-on of the traffic signal lamps of the traffic signal device correspond to idling at the intersection and the like. 
     FIG. 10 is a block diagram showing the arrangements of a receiver and a transmitter. 
     FIG. 11 is a system diagram showing the functions of the respective sections of an embodiment of a signal display apparatus for displaying information relating to the idling stop of the automobile engine according to the present invention. 
     FIG. 12 is a view explaining an example showing how the signal display apparatus of FIG. 11 is installed. 
     FIG. 13 is a graph showing the change of an amount of nitride oxide (NOx) discharged before and after the idling of the automobile engine is stopped. 
     FIG. 14 is a view explaining the relationship between the contents of display for prompting the stop of the engine and the contents of display of traffic signal lamps. 
     FIG. 15 is a view explaining a reference for determining whether an idling display is necessary or not. 
     FIG. 16 is a front elevational view showing an example of a display surface corresponding to the display unit of FIG.  11 . 
     FIG. 17 is a front elevational view showing an example of another display surface corresponding to the display unit of FIG.  11 . 
     FIG. 18 is a front elevational view showing an example of still another display surface corresponding to the display unit of FIG.  11 . 
     FIG. 19 is a front elevational view showing another display example of the display unit of FIG.  18 . 
     FIG. 20 is a system diagram explaining the functions of the respective units of a modification of the apparatus shown in FIG.  11 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First, an example of an embodiment of an apparatus and a system of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiment is arranged such that the idling of an automobile engine is stopped and the automobile engine is restarted in response to a command transmitted from a traffic signal device. 
     FIG. 1 is a view showing the schematic arrangement of an automobile engine idling stop system  10  according to the present invention. As shown in the figure, the automobile engine idling stop system  10  is arranged such that the command transmitted from a transmitter  14  disposed to a traffic signal device  12  (refer to FIG. 2) is received by a receiver  18  provided with an automobile  16  and the received command is supplied to a controller  20  which stops the idling of an automobile engine and restarts the engine. In order to detect the state of the automobile  16 , the controller  20  is connected to a light switch  22 , an air conditioner  24 , a parking brake switch  26 , a foot brake switch  30 , an automobile speed sensor  28 , a neutral position detecting switch  32  and an engine control unit  34 , determines the state of the automobile based on the signals supplied from the respective units and controls the engine control unit  34 , thereby stopping the idling of the automobile engine and restarting the engine. 
     The light switch  22  connected to the controller  20  turns on not shown head lamps and rear combination lamps as well as supplies a signal indicating that the head lamps and the rear combination lamps have been turned on, that is, the switched state (ON/OFF state) thereof, to the controller  20 . 
     The air conditioner  24  regulates room temperature of the automobile  16  as well as supplies a signal indicating the operating condition (ON/OFF state) of the air conditioner  24  to the controller  20 . 
     The parking brake switch  26  is mounted on a parking brake lever, detects the operating condition of the parking brake, and supplies the detected signal to a meter panel so as to notify a driver of the present condition of the parking brake and supplies the signal to the controller. 
     The foot brake switch  30  is mounted on a foot brake  36  and turned ON when the foot brake  36  is actuated, turns on the rear combination lamps to thereby notify how the foot brake is used to a following automobile, and supplies a signal indicating the operating condition of the foot brake to the controller  20 . 
     The automobile speed sensor  28  is mounted on a transmission  38  of the drive system of the automobile  16  and detects an automobile speed from the rotational speed of the rotational shaft of the transmission  38 . Then, the automobile speed sensor  28  supplies the detected automobile speed to the meter panel (speed meter) as a signal so that a traveling speed is notified to the driver and supplies the detected automobile speed to the controller  20 . 
     The neutral position detecting switch  32  is disposed in the vicinity of a shift lever for shifting the transmission  38 , detects a neutral position and supplies a signal representing the result of detection to the controller  20 . 
     The controller  20  detects the state of the automobile (traveling and stopping state, a load imposed on a battery  48 , and the like) based on the signals output from the light switch  22 , the air conditioner  24 , the parking brake switch  26 , the foot brake switch  30 , the automobile speed sensor  28  and the neutral position detecting switch  32 , respectively. 
     Further, a starter motor  40  for starting an engine  42 , an ignition switch  44  for starting the engine by rotating the starter motor  40 , an igniter for igniting the engine and a distributor  46  as well as the controller  20  are connected to the engine control unit  34 . The engine control unit  34  starts and stops the engine  42  under the control of the controller  20 . Ordinarily, the driver starts and stops the engine  42  by actuating the ignition switch  44 . 
     Further, electric power to the electrical components mounted on the automobile  16  is supplied from the battery  48  mounted on an engine room. The power is supplied in such a manner that the negative terminal of the battery  48  is grounded to an automobile body and the positive terminal thereof is connected to the respective electrical components which are grounded to the automobile body. 
     Next, the signal transmitted from the transmitter  14  disposed to the traffic signal device  12  will be described. 
     The traffic signal lamp driven by the traffic signal device  12  is sequentially changed to red, green and yellow in an optional period of time set respectively. Further, the period of time may be fixed or may be changed externally according to the state of traffic jam or the like. 
     The transmitter  14  of the traffic signal device  12  transmits a frequency-modulated signal from the time when the traffic signal changes to red to the time when it changes to green. The signal frequency is modulated such that a signal of the predetermined frequency is f 1  when the traffic signal lamp changes to red and then the signal frequency is modulated to a higher frequency as a time passes so that it reaches a predetermined frequency f 2  at a time t A  when the traffic signal changes to green as shown in FIG.  3 . That is, the time-frequency characteristic of the output signal is represented by a straight line. Note that when the period of time for changing the traffic signal lamp of the traffic signal device  12  is changed, the inclination of the straight line of the time-frequency characteristic is changed so that the predetermined frequency f 2  is obtained at a time t A ′ when the traffic signal lamp is changed to green. As a result, a signal, which is modulated to satisfy the dot-dash-line shown in FIG. 3, is obtained. Further, in the above description, when the traffic signal lamp of the traffic signal device  12  is changed to red, the frequency of the signal is modulated to a higher frequency as a time passes. However, the frequency thereof may be modulated to a lower frequency as a time passes. 
     Next, it will be described how the controller  20  stops the idling of the automobile engine and the restarts it based on the signal transmitted from the transmitter  14 . 
     In general, automobile engines have different engine characteristics (characteristics of fuel consumption, exhaust gases or the like) depending upon the types and specifications of the engines. That is, a period of time (idling stop effective period of time), which is required to obtain the idling stop effect (reduction in wasteful fuel consumption and harmful exhaust gases), is not constant depending upon the respective engines. Therefore, the controller  20  determines whether idling is to be stopped or not depending upon the idling stop effective period of time of each engine, and controls the idling stop and the engine restart. 
     When the period of time t s  until restart of the engine satisfies the condition to be described below, the controller  20  judges the idling stop effective and stops idling of the automobile engine. 
     When the engine is restarted, an amount of fuel consumption is increased by M R (g) as shown in FIG.  5 . In contrast, an amount of fuel which can be saved by stopping idling during the period of time t S  can be represented by m f ×t S (g), where an amount of fuel consumed in continuous idling during t S  is represented by m f (g/s). Accordingly, the idling stop effect can be obtained when the condition m f ×t S &gt;M R  is satisfied, i.e., the condition t S &gt;M R /m f  is satisfied. 
     Further, when the engine  42  is restarted, an amount of nitride oxide (NOx) discharged from the engine  42  is also increased by M NOx  (g) as shown in FIG.  6 . An amount of discharged NOx which can be reduced by stop idling during the period of time t S  is represented by m NOx ×t S , where an amount of NOx discharged in continuous idling during t S  is represented by m NOx  (g/s). Accordingly, the idling stop effect can be obtained when the condition m NOx ×t S &gt;M NOx  is satisfied, that is, the condition t S &gt;M NOx /m NOx is satisfied. 
     Further, the hydrocarbons (HC) discharged from the engine  42  is also increased by the restart of the engine  42  likewise the NOx, and the idling stop effect can be obtained when the condition t S &gt;M HC /m HC  is obtained, where an amount of HC discharged is represented by m HC  (g/s) and an amount HC increased when the engine  42  is restarted is represented by M HC  (g). 
     Next, an algorithm for calculating the period of time t S  will be described with reference to FIG. 3, the period of time t S  being from the time at which the automobile  16  reaches a particular region such as an intersection or the like and stops there to the time at which the engine  42  is to be restarted as shown in FIG.  4 . The period of time t S  is important as a base of the criteria time T for judgment. 
     The controller  20  obtains the signal transmitted from the transmitter  14  of the traffic signal device  12  through the receiver  18 , and calculates the period of time until the traffic signal of the traffic signal device  12  changes to green as described later. 
     When the time at which the signal transmitted from the transmitter  14  is represented by a time t X , and the frequency of the signal at the time is represented by f X  and an amount of change of the frequency after a period of time Δt passes from the time t X  is represented by Δf, the inclination of the straight line of the time-frequency characteristic of the signal transmitted from the transmitter  14  is made to Δf/Δt. Therefore, the straight line can be represented by the following formula. 
     
       
           f=Δf/Δt×t+f   1   (1) 
       
     
     f 1  is represented by the time t X  at which the signal transmitted from the transmitter  14  is received and a frequency f X  at the time, therefore, the formula (1) can be represented by the following formula. 
     
       
           f=Δf/Δt×t+f   X   −Δf/Δt×t   X   (2) 
       
     
     The period of time t S  until the traffic signal changes to green is a value obtained by subtracting the time t X  at which the signal is received and a time Δt+α (α: coefficient of calculation time) necessary to the calculation from the time t A  at which the traffic signal lamp is changed to green. 
     
       
           t   S   =t   A −( t   X   +Δt +α)  (3) 
       
     
     When t A  is represented by the time t X  at which the signal transmitted from the transmitter  14  is received and the frequency f X  at the time, the formula (3) can be represented by the following formula. 
     
       
           t   s =( f   2   −f   x )×Δ t/Δf   A −(Δ t +α)  (4) 
       
     
     Note that the time Δt+α necessary to the calculation can be ignored because it is a minute period of time. 
     Therefore, if the frequency f 2  of the modulated signal at which the traffic signal changes to green is settled in advance, the period of time t S  until the traffic signal change can be calculated from relation between the frequency f X  of the received signal and the frequency deviation Δf during the time deviation Δt of the received signal. 
     And, by determining in advance the frequency f 2  at which the traffic signal changes to green, the time period of time t S  until the traffic signal is changed can be calculated even if the period of time until the traffic signal changes to green is variable (the time t A  at which the traffic signal is changed to green is not constant). Note that f 1  may be or may not be predetermined. 
     After the period of time t S  until the traffic signal lamp is changed is calculated, the controller  20  judges whether the idling is to be stopped or not based on the above condition. Note that the time t S  is not the time when the traffic signal changes actually to green as shown in FIG.  4 . It is preferable that the engine is restarted prior to the change of the traffic signal by providing the psychological idling preceding period of time. The psychological idling preceding period of time permits the engine  42  to be smoothly restarted without giving any anxiety to the driver. 
     Subsequently, the operation of the embodiment will be described below with reference to the flowchart of FIG.  7 . 
     First, it is judged whether the automobile  16  is in the state that the idling of the engine  42  can be stopped or not. In the embodiment, the controller  20  judges whether the lamps are turned on or not based on the signal supplied from the light switch  22  at step  100 . When the judgment is YES, that is, the automobile is not in the state that the idling can be stopped, the idling is continued and the process is finished. Whereas, when the judgment is NO, the controller  20  determines whether the air conditioner  24  is used or not based on the signal supplied from the air conditioner  24  at subsequent step  102 . When the determination is YES, that is, the automobile is not in the state to enable to stop the engine idling likewise the step  100 , the idling is continued and the process is finished. Whereas, when the determination is NO, the process goes to subsequent step  104 . 
     At step  104 , it is determined whether the receiver  18  has received the modulated signal transmitted from the traffic signal device  12  as described above or not. When the determination is NO, step  104  is repeated until the signal transmitted from the traffic signal device  12  is received. 
     And, when the judgment at step  104  is YES, the process goes to subsequent step  106 , and the period of time t S  is calculated as described above based on the signal received from the traffic signal device  12 . 
     At step  108 , it is judged whether the automobile  16  is at rest or not. The judgment is carried out by checking whether the signal output from the automobile speed sensor  28  indicates 0 Km/h, whether the foot brake switch  30  is turned ON, whether the parking brake switch  26  is turned ON, and whether the neutral position detecting switch  32  is turned ON (at the neutral position). In the case that all the above judgments are affirmed, automobile is judged as at rest. Note that the judgment at step  108  is not limited to the above method, for example, any sole one or plural combination of the above checking items, i.e., the automobile speed sensor  28 , the foot brake switch  30 , the parking brake switch  26 , and the neutral detecting switch may be used to judge a resting state of the automobile. 
     In the case that any one of the above items at step  108  is denied, steps  100  to  108  are repeated until the automobile is detected as in a rest state. In the case that the judgment at step  108  is affirmed YES, the process goes to subsequent step  110  and the period of time T (idling stop time) is calculated by subtracting the period of time until the automobile stops actually after receiving the signal and the psychological idling preceding time of period from t S  which is calculated at step  106 . 
     At step  112 , the controller  20  determines whether the idling stop period of time T is effective or not from a viewpoint of fuel consumption. If the judgment is NO, that is, it is judged that fuel is much consumed by stop/restart of the engine, the idling is continued and the process is finished. On the contrary, if the judgment is YES, the process goes to subsequent step  114 . 
     At step  114 , the controller  20  judges whether the idling stop period of time T is effective or not from a viewpoint of an amount of exhausted NOx. If the judgment is NO, it is judged that NOx is much discharged by stop/restart of the engine. The idling is continued, and the process is finished. On the contrary, if the judgment is YES, the process goes to subsequent step  116 . 
     At step  116 , the controller  20  judges whether the idling stop period of time T is effective or not from a viewpoint of exhausted HC which is increased when the idling is stopped and the engine is restarted. If the judgment is NO, that is, it is judged that HC is much exhausted by stop/restart of the engine being restarted, then idling is continued to steps  112  and  114 , and the process is finished. On the contrary, if the judgment is YES, the process goes to subsequent step  118 . 
     At step  118 , the controller  20  controls ignition by the engine distributor  46  through the engine control unit  34 , and stops the engine. 
     At step  120 , the controller  20  judges whether the idling stop period of time T has passed or not after the idling is stopped. If the judgment is NO, the process goes to step  124  and it is judged whether the engine is to be restarted or not. Note that the judgment at step  124  is carried out based on whether the driver has actuated the ignition switch  44  (operation for starting the starter motor  40 ) or not. If the judgment at step  124  is NO, steps  120  and  124  are repeated until the determination at step  120  or  124  becomes YES. 
     If the judgment at step  124  is YES, it is judged that the engine has been restarted by the intention of the driver and the process goes to step  126  at which the starter motor  40  is started by the ignition switch  44  and the engine  42  is restarted, whereby a series of the processing steps are finished. 
     If the judgment at step  120  is YES, the process goes to step  122  at which the controller  20  rotates the starter motor  40  through the engine control unit  34  so as to restart the engine, whereby the series of the processing steps are finished. 
     Thus, the period of time t S  until the traffic signal changes to green is calculated based on the signal from the traffic signal device  12  (steps  104  and  106 ) and it is judged whether the idling is to be stopped or not based on the calculated period of time t S  until the traffic signal changes to green and the period of time until the idling stop effect is obtained (steps  110 - 118 ). Accordingly, the wasteful consumption of fuel and the discharge of harmful exhaust gases can be reduced by stopping the idling and restarting the engine  42  without any detrimental effects caused by the idling stop. 
     Further, since the engine is restarted before the idling stop period of time T passes, that is, before the traffic signal is changed to green (preceding by the idling preceding period of time), the engine can be restarted without giving any anxiety to the driver. 
     While the idling is stopped based on the signal transmitted from the traffic signal device  12  in the above embodiment, the present invention is not limited thereto. For example, the transmitter  14  of the embodiment may be mounted on a beacon for detecting traffic jam, or the like. This arrangement is effective when the automobile is compelled to wait for the traffic signal to change at a place apart therefrom due to a large traffic jam. And, when the automobile  16  is stopped not due to the traffic signal change to red but due to a traffic jam, a stop period of time of the automobile is calculated. And, by judging whether the calculated stop period of time is effective or not for the idling stop, the wasteful consumption of fuel and the discharge of harmful exhaust gases can be reduced without giving any anxiety to the driver. 
     In the above embodiment, when the lamps are turned on or when the air conditioner is used, it is judged that the automobile is not in the state to enable to stop idling, and the idling is continued. However, it may be possible to stop the idling after the present state of the automobile is stored and the lamps and the air conditioner are turned OFF and then to restore them to the original states when the engine  42  is restarted. 
     In the above embodiment, the control method of the idling stop (and restart) during the traffic signal changes from red to green has been explained. In the case that an arrow signal to indicate a go straight or turn left/right is used, the wasteful consumption of fuel and discharge of the harmful exhaust gas can be reduced without any anxiety of the driver, by using another frequency signal in the other frequency band and by detecting the state of the direction indicator, as similarly to the embodiment. 
     The hardware of an apparatus according to the present invention and the timing chart thereof will be described with reference to FIGS. 8 to  10  as another embodiment which substitutes for the embodiment described with reference to FIGS. 3 to  7 . 
     FIG. 8 shows an example view to explain the relationship between a traffic signal indicator and an automobile  16  at an intersection according to the embodiment of the present invention for stopping the idling of an automobile engine at the intersection. The traffic signal indicator  12 , idling stop (IS) signal lamp unit (signal display)  12 ′ and a control signal transmitter  14  are installed at the intersection. 
     The signal from the control signal transmitter  14  is transmitted to the receiver  18  of the automobile  16  which is shown in FIG. 10, by using infrared rays. The traffic signal indicator  12 , the idling stop lamp unit  12 ′ and the control signal transmitter  14  are connected to a traffic signal controller  50 . 
     FIG. 9 is a schematic view to show the relation between the traffic signal indication and idling. FIG. 9 shows a sequential cycle of signal colors, green (G), yellow (Y), red (R), and green (G) along a time axis. The period of time of red (R) is further divided into periods of time of A, B and C in the upper view, and times t 9 , t 8 . . . t 1  are shown in the lower view in relation to the turned-on period of time of the red (R). The period of time A shows a preferable time region of stop idling of the automobile which stops movement at a particular area such as the intersection. During the period of time B (t 4 -t 1  in the example case of FIG. 9) the automobile keeps idling without interruption even though it stops movement, that is, the automobile  16  keeps an idling state as it is during the period of time B. Note that since the above periods of time vary depending upon the characteristics, type and the like of an automobile engine, these are set up to optimum values of the engine at the automobile side (on board apparatus of the automobile). FIG. 9 shows an example of an automobile which is set up B (t 4 -t 1 ) as an optimum period of time of the engine. The period of time C is a psychological idling preceding period of time, and at time prior to green signal indication, the engine starts idling. 
     FIG. 10 is a block diagram showing the system configuration of a transmitter device  14  installed at a pedestrian crossing, an intersection or the like and a receiver device  18  mounted on an automobile. The transmitter device  14  as a signal transmitting section for transmitting a signal for stopping idling includes a timing generation unit  14 A, an IS (idling stop) signal generation unit  14 B and an IS signal modulation and transmission unit  14 C. 
     The traffic signal controller  50  installed at the intersection or the like turns on the traffic signal lamps of the idling stop lamp unit  12 ′ and generates a timing signal including t 1 , t 2 , to t 9 . An IS signal display and drive unit  14 D drives the idling stop lamp unit  12 ′ by receiving the timing signal. The signal for indicating the idling stop of the engine is modulated by the IS signal modulation and transmission unit  14 C and transmitted as an infrared signal or a radio wireless signal. 
     The receiver device  18  mounted on the automobile includes a receiver unit  18 A, an IS signal encoding unit  18 B, an IS timing unit  18 C, a condition determination unit  18 D and an idling stop controller  18 E. An automobile state discrimination unit  20  discriminates various kinds of information as to the automobile and the like and sends the signal to the condition determination unit  18 D. The engine mounted on the automobile  16  is controlled by the signal from the idling stop controller  18 E. 
     Next, an embodiment of a signal display apparatus of this invention that gives the idling stop information to the driver will be explained hereunder in detail with reference to the drawings. 
     FIG. 11 shows a block diagram explaining the functions of the respective components of the idling stop signal display apparatus. 
     FIG. 12 shows an example in which the apparatus of FIG. 11 is additionally mounted on a traffic signal device installed at an intersection. 
     In FIGS. 11 and 12, numeral  101  denotes the traffic signal of the traffic signal device and numeral  102  denotes a traffic signal controller for controlling the operation of the traffic signal  101 . Numeral  115  denotes a display unit (hereinafter, called the signal display unit) for displaying indication whether the engine idling should be stopped or should be kept as it is when the automobile stops by the red signal at the intersection, and for displaying indication to inform restart timing of the engine to the automobile in idling stoppage. Numeral  110  denotes a controller (hereinafter, called an idling signal controller) for controlling the operation of the signal display unit  115 . 
     The idling signal controller  110  is composed of a power supply unit  111 , an interface circuit  112 , a display controller  113  and a display drive unit  114 . The power supply unit  111  and the interface circuit  112  are connected to the traffic signal controller  102  through a cable  109 . The power supply unit  111  supplies electric power to the display controller  113  and the display drive unit  114  and supplies the electric power to the signal display unit  115  through the display drive unit  114  too. 
     The display controller  113  receives red signal information from the traffic signal controller  102  through the interface circuit  112 , controls the display drive unit  114  based on the information and changes the indication displayed on the signal display unit  115 . 
     FIG. 14 shows relation between display to prompt the driver to stop idling and a traffic signal display. 
     In FIG. 14, G, Y and R in the display L 1  show time zones of green, yellow and red signal respectively. 
     A, B and C of an idling signal display L 2  show time zones of indication of “stop engine”, “leave engine as it is” and “restart engine” respectively. 
     In FIG. 15, S shows a reference period of time in which the area M 1  is equal to the area M 2  in FIG.  13 . Therefore, the period of time for indicating “stop engine” is equal to (R−S). 
     P is the psychological idling preceding period of time by which the driver can keeps his mind calm at starting the automobile. Therefore, the period of time to indicate “leave engine as it is”, is set up to (S−P) which is obtained by subtracting the preset idling preceding period of time from the reference period of time S. 
     The display controller  113  judges whether the idling stop signal is to be displayed or not based on the input information of the preceding red signal and displays indication of “stop engine”, “leave engine as it is” or “start engine” sequentially during the red signal based on the judgment. 
     FIG. 15 shows the traffic signal sequences to explain judgment criteria whether idling display operates or not. In case of L 11 , since the period of time of a red signal R 1  is longer than the reference period of time S, the idling signal is displayed. And in case of L 12 , since the period of time of a red signal R 2  is shorter than the reference period of time S, the idling signal may display “leave engine as it is” continuously during the period of the red signal or any idling display may not be performed. 
     FIG. 16 is an example of a front view showing the display of a signal display unit  116  that corresponds to the signal display unit  115  of FIG.  11  and FIG.  12 . The signal display unit  116  displays sequentially “stop engine”  116   a , “leave engine as it is”  116   b  and “restart engine”  116   c . In this example, however, the term “engine” which is commonly used in the above three indications, is always displayed on the display and the terms “stop”, “leave as it is” and “restart” are selectively illuminated at each time required. 
     FIG. 17 is a second example of front view showing the display of a signal display unit  117  that corresponds to the signal display unit  115  of FIG.  11  and FIG.  12 . In this example, a plurality of windows  117   a ,  117   b ,  117   c  and  117   d  are formed on a display surface and the characters of “stop engine”, “leave engine as it is” and “start engine” are repeatedly displayed in the windows by being scrolled one character by one character from right to left. 
     FIG. 18 is a third example of front view showing the display of a signal display unit  118  that corresponds to the signal display unit  15  of FIG.  11  and FIG.  12 . In this example, “stop engine”, “leave engine as it is” and “restart engine” are sequentially displayed by two groups of lamps, which are composed of red LEDs and green LEDs. 
     For example, numeral  118   a  in FIG. 18 shows “stop engine” by the emission of the red light, numeral  118   b  shows “leave engine as it is” by violet color obtained by mixing the red light and green light, and numeral  118   c  shows “restart engine” by the green light. 
     In addition to the above, various kinds of the display methods are available. FIG. 19, for example, shows another display example of the display unit  118  of FIG. 18, wherein numeral  119   a  shows “stop engine”, numeral  119   b  shows “leave engine as it is” and numeral  119   c  shows “restart engine”. 
     FIG. 20 shows an example of a modified block diagram of the idling stop signal display apparatus shown in FIG.  11  and FIG.  12 . The apparatus shown in FIG. 20 is used by connecting to a crossing gate controller installed at a railroad crossing and composed of an idling signal controller  120  and a signal display unit  125 . The idling signal controller  120  is a controller for controlling operation of the signal display unit  125 . 
     The idling signal controller  120  is composed of a power supply unit  121 , an interface circuit  122 , a display controller  123  and a display drive unit  124 . The power supply unit  121  and the interface circuit  122  are connected to a railroad crossing gate control circuit box  103  by a cable  129 . 
     The power supply unit  121  receives the electric power from the power supply unit  133  of the railroad crossing gate control circuit box  103  and supplies it to the display controller  123  and the display drive unit  124  and also supplies it to the signal display unit  125  through the display drive unit  124 . 
     The interface circuit  122  receives information about the state of a railroad crossing gate arm and a train passing signal from the interface circuit  132  of the crossing gate control circuit box  103 . Information about the state of the railroad crossing gate arm from a gate arm drive mechanism  130  and a train passing signal from a crossing gate control circuit  131  are sent to the display controller  123  through the interface circuits  122  and  132 . The display controller  123  controls the display drive unit  124  based on the above input information and signal and changes the display contents of the signal display unit  125 . That is, when the display controller  123  receives a gate arm lowering completion signal as the gate arm state information, it causes the signal display unit  125  to make a display for prompting “stop engine”, and when the display controller  123  receives the train passing signal, the signal display unit  125  display “restart engine”. 
     In the above case, the train is given priority of passing the length of the period of the railway crossroad and also the time length of being blocked by the gate arm cannot be presumed. Accordingly, the indications on the signal display unit  125  are limited to “stop engine” or “restart engine”. Indication of “leave engine as it is” is not displayed. The specific structure of the display may be arranged similarly to those of FIG.  16 -FIG.  19 . 
     The structure and the form of the signal display unit of the idling stop signal display apparatus connected to the traffic signal device or to the crossing gate are able to be variously realized in addition to those shown in FIG.  16 -FIG.  19 . However, any of them is included in the scope of this invention as long as it satisfies the gist of this invention. 
     As described above, this invention is to prompt engine stop to the automobile in stoppage and to give information of engine restart timing to the automobile in stoppage. 
     And also this invention rouses the driver&#39;s effort to contribute the environment protection, and is useful to reduce the exhaust gas.